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View Full Version : 93 Mm v6 4x4 has just given up on life



Chyrio
02-27-2016, 09:55 PM
So I know there are plenty of these "truck won't start" threads but most of the ones I can find pertain to the 4 cylinders. Also I can't find any specific guides or lists on steps to fix issues so any help would be appreciated. First of all got a 93 Mm from a friend for free and I have checked for fuel: got it. Checked for air: obviously got it. Checked for spark: got it. Swapped whole distributor, cap, and rotor with the ignitor from a working 6G72 still same issue. Don't have the tool to check for fuel pressure but when I pulled the fuel pressure line off there was pressure in the line. I also took the fuel pressure regulator out and cleaned it. Nothing. Fuel pressure relay does click when turning ignition on and I took the ECU out and verified that there are no busted caps, bad connections, or leaking fluids the inside of the thing looks brand new. My next step is looking at timing. But is there something I'm missing? Something obvious to check? I will owe you several beers just for opinions... O and the truck has just shy of 80k on it.

geezer101
02-28-2016, 12:45 AM
Hi Chrio, welcome to mightyram. First up - get someone to do an error code check on it. Just because the innards of the ECU 'look' ok, doesn't make it so. And it will nail down the fault 95% of the time. 80k is past it's timing belt service interval - any stickers showing it has been replaced around the 60k mark?

GoodApollo
02-28-2016, 03:21 AM
Also post up some picks of your Alaskan 4x4!

Chargerx3
02-28-2016, 07:16 AM
Sounds like you came across a lucky low mileage truck. As mentioned I would verify your ecu is working properly. You could also swap in a 91-93 3000gt/stealth sohc ecu to verify it's running properly. On a side note my MM was having a hard time starting. Would have to crank, stop, crank for days then hopefully start. Crawled under the truck and noticed someone had attempted to do some electrical work to my fuel tank. Needless to say that work extended into the tank too. I have finally fixed it and it performs like a pro.

Chyrio
02-28-2016, 11:33 AM
Hi Chrio, welcome to mightyram. First up - get someone to do an error code check on it. Just because the innards of the ECU 'look' ok, doesn't make it so. And it will nail down the fault 95% of the time. 80k is past it's timing belt service interval - any stickers showing it has been replaced around the 60k mark?

I tried to check it for codes but all I had was a digital multimeter that only went down to 200 ohms... But the check engine light doesn't stay on if you leave the key in it. I tried using the multimeter on volts so I could actually get a reading and it goes like 2v, 1v, 4v, 1v, 11v, 3v, 2v, 10.5v and repeat.

Chyrio
02-28-2016, 11:35 AM
Sounds like you came across a lucky low mileage truck. As mentioned I would verify your ecu is working properly. You could also swap in a 91-93 3000gt/stealth sohc ecu to verify it's running properly. On a side note my MM was having a hard time starting. Would have to crank, stop, crank for days then hopefully start. Crawled under the truck and noticed someone had attempted to do some electrical work to my fuel tank. Needless to say that work extended into the tank too. I have finally fixed it and it performs like a pro.

I tried using a ECU from a auto 94 montero that ran when it was left sitting thereand got a check engine light and the truck still wouldn't start. I didn't know about the ECU from the stealth/3000gt though thank you!

Chargerx3
02-28-2016, 11:46 AM
I don't know about the 94 monteros. I think there was an ecu generation change in 94 if they are anything like the 3000gt's. I currently am running a 92 sohc stealth ecu for a while now. Runs great.

Chyrio
02-28-2016, 11:47 AM
Also post up some picks of your Alaskan 4x4!

Only good picture i have at the moment! will post more when i can get the thing moving!
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Chyrio
02-28-2016, 11:51 AM
I don't know about the 94 monteros. I think there was an ecu generation change in 94 if they are anything like the 3000gt's. I currently am running a 92 sohc stealth ecu for a while now. Runs great.

Now i just have to find a stealth or 3000gt ha ha they are not very common up here in Alaska :shrug:

Chyrio
02-28-2016, 11:53 AM
I don't know about the 94 monteros. I think there was an ecu generation change in 94 if they are anything like the 3000gt's. I currently am running a 92 sohc stealth ecu for a while now. Runs great.

Are there any other Mitsubishi's i could borrow a ecu from to test?

Chargerx3
02-28-2016, 12:20 PM
I think 90-93 montero and raider v6 too.

Chyrio
02-28-2016, 12:56 PM
I think 90-93 montero and raider v6 too.

I'll see if i can find any donors. what codes are common for it to throw when the ecu is bad?

Chargerx3
02-28-2016, 03:50 PM
Depends on what circuit the electrolyte flows to. You likely won't ever get a cel.

Chyrio
03-01-2016, 11:27 PM
Alright I got the ECU out and apart and i cant see anything to drastic. here are some pics though. what do you guys think?159091591015911

Chargerx3
03-02-2016, 06:47 AM
Can't see anything but check closely to the bottom of those 3 large capacitors. Anything wet is a bad sign.

Chyrio
03-03-2016, 12:21 AM
Can't see anything but check closely to the bottom of those 3 large capacitors. Anything wet is a bad sign.

Ok got the capacitors off and one of them had a drop of something on the board (circled blue). and is the stuff circled in red in the pictures just sealant??
15940159411594215943

geezer101
03-03-2016, 12:30 AM
if the caps have left stains on the PCB - they're toast. As for the mystery substance in your red ringed image, I got nada on that.

Jeff V.
03-03-2016, 08:09 AM
I think the stuff in the red circle is just where some of the anti-condensation coating pooled up. It's nothing to worry about.

Chargerx3
03-03-2016, 08:49 AM
Looks good. The film layer you are seeing is the conformal coating. Its there to protect your electronics from oxidation. Are you installing your own capacitors? If so, I hope you noted which way they were oriented. Don't install them backwards.

Chyrio
03-05-2016, 12:14 AM
Looks good. The film layer you are seeing is the conformal coating. Its there to protect your electronics from oxidation. Are you installing your own capacitors? If so, I hope you noted which way they were oriented. Don't install them backwards.

Ok new capacitors soldered on. not the same size but the same ratings on all of them and they are not crappy rubycons. also stripped the old peeling coating and got some epoxy to paint on to coat it. why do you need to coat the PCB? why couldn't you just seal the metal case the board comes in?
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geezer101
03-05-2016, 01:04 AM
Maybe coat it with clear nail polish? If a track on a PCB oxidises there's a good chance it will burn off the board.

pennyman1
03-05-2016, 11:19 AM
It is also to insulate the traces on the board

BUGS4G
03-07-2016, 11:37 AM
I tried to check it for codes but all I had was a digital multimeter that only went down to 200 ohms... But the check engine light doesn't stay on if you leave the key in it. I tried using the multimeter on volts so I could actually get a reading and it goes like 2v, 1v, 4v, 1v, 11v, 3v, 2v, 10.5v and repeat.
you nee to use old style analog meter, not digital. voltage changes to quickly to read on digital. on analog meter you can count as the needle swings back and forth, long and sort pulses. it will repeat the codes continually one after another as many as are in the system. and In order. such a 1 long 3-short, 2 long 4-short and if nothing else it will repeat the same thing.

Chyrio
03-07-2016, 12:58 PM
Alright put the ecu with the brand new capacitors in and tried it and nothing. Same issue.... Another note i moved it into the garage so now it's warm and i also charged up the battery. Still no check engine lights but i am going to go buy a analog meter like BUGS4G suggested soon and double check. What's the next thing to check? I'm thinking injectors. And start tearing the engine down looking for issues. And other ideas gentleman?

Jeff V.
03-07-2016, 01:37 PM
Most of the diagnostic tests don't run until the engine has been running for a little bit. You generally won't find any fault codes that'll help with a no-start condition, especially on older cars and trucks.

I'm chasing a similar issue on a friend's 94 Stealth TT. It's got fuel and spark, it cranks strong, the electronics all check out, the computer works in my Stealth....but his car just won't run. I'm absolutely dumbfounded.

About the only thing I can suggest is to check your timing marks and do a compression test. I'm interested to see what you find out. Maybe it'll help me with my friend's car.

BradMph
03-07-2016, 03:16 PM
Fuel, electrical, mechanical, if things get to be causing headaches you can always revert back to basics. If you had another computer you could try could be helpful. Repairing those boards is so touchy and what you see with eyes that may need repairing is all good and stuff, but what made it fail could be something entirely different.
Careful not to chase the problem with money either. This has happen before and I have done it, but when you find the problem you will probably kick yourself about it for not noticing it before the work began.


We have coated boards with a harder wax as well. Just like candle wax but not as soft as what a candle is made of. Kept moisture out and was a basic easy fix and you can remove it to make additional repairs.


Hey Jeff,
I was having issues like you may of been having. In my case I was using the stock in tank fuel pump when trying to keep a modded motor running. I finally located the problem which was the car thinking it was not firing up an engine from the false signals the computer was getting. So, computer would send a signal to the in tank fuel pump cutting power and shutting it off and the car died after it finished the fuel off in the lines. In tank pump is removed and 2nd return line also since it was not required on the build and bypass computer on new exterior fuel pump.

Chargerx3
03-07-2016, 03:16 PM
I would go back through and double check everything. Make sure your fuel quality is good and that your tank is filled up enough. Also make sure timing marks are on, spark plugs are in good condition, adequate spark from the distributor, etc.

Chyrio
03-07-2016, 04:28 PM
I went over the board with a magnifying glass and then sealed it with rustoleum leak-seal which seemed to do the job. Also could it be that the previous owner put copper plugs in it? I know the manual calls for nickel? Tonight i will check the timing and injectors and the pump if i can. I'll take pictures if i can!

Chyrio
03-07-2016, 04:30 PM
I also i know it sat for a while because the battery was completely dead but i don't think it sat long enough for the fuel to go bad.

Chyrio
03-07-2016, 08:36 PM
PROGRESS!!! Alright so i checked again to make sure the pump was working so i took a bucket and manually pumped some fuel out with the bypass and noticed the fuel looked like this
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So i drained most of it out and went down and filled up my 5 gallon fuel can with 90 octane and put some of that in there and bam! it stumbled and stumbled and tried to start then died. then i tried again and it stumbled and stumbled and then misfired and died. so onto a new issue but atleast i know that it will start sort of! sounds like timing to me what do you guys think?

tink
03-07-2016, 09:15 PM
You don't necessarily have to get it to run to read codes sent out by the ECU/ECM, just putting the key in the 'on' position can (not promising 'will') do the trick. For using the paperclip method the engine is to be left OFF. I had went thru this on a '93 3000gt & was able to figure it out by reading the long & short bursts on the analog meter. See: http://web.archive.org/web/20121201144325/http://www.stealth316.com/2-diagcodes91-93.htm for basic idea instructions BUT you will need to find the pins & fault codes that match up w/the ECU you are working with. Highly suggest letting it tell you whats wrong if it will rather than chasing a likely combination of issues. Good luck :)

Chyrio
03-07-2016, 10:01 PM
You don't necessarily have to get it to run to read codes sent out by the ECU/ECM, just putting the key in the 'on' position can (not promising 'will') do the trick. For using the paperclip method the engine is to be left OFF. I had went thru this on a '93 3000gt & was able to figure it out by reading the long & short bursts on the analog meter. See: http://web.archive.org/web/20121201144325/http://www.stealth316.com/2-diagcodes91-93.htm for basic idea instructions BUT you will need to find the pins & fault codes that match up w/the ECU you are working with. Highly suggest letting it tell you whats wrong if it will rather than chasing a likely combination of issues. Good luck :)

Thank you sir! this is awesome i was looking so hard for a chart that shows just this a couple days ago!! Now i just need to go buy a analog multi-meter. But i just ripped the front of the engine apart and checked the timing and it looks like everything is on point and the belt doesnt look to bad i suppose it has been done in the past 20k or so.
160091601016011

Chargerx3
03-08-2016, 06:15 AM
Great start. This has me wondering now that your fuel system is the culprit. I just got done with a similar not WA ting to start issue. Turned out that the last guy installed the new fuel pump wrong. I'm wondering if your fuel pump is on its way out. Also have you changed your fuel filter?

Jeff V.
03-08-2016, 07:15 AM
You don't necessarily have to get it to run to read codes sent out by the ECU/ECM, just putting the key in the 'on' position can (not promising 'will') do the trick.

The ECU will show stored codes without the engine running, but it doesn't actually run the tests that set the codes, until the engine has been running for a period of time. Since he's unplugged the ECU, there won't be any codes stored from the previous run cycles.

It doesn't hurt to check, but I wouldn't get my hopes up that there will be any results.

Chyrio
03-08-2016, 12:13 PM
Great start. This has me wondering now that your fuel system is the culprit. I just got done with a similar not WA ting to start issue. Turned out that the last guy installed the new fuel pump wrong. I'm wondering if your fuel pump is on its way out. Also have you changed your fuel filter?

well the fuel pump is running strong. i mean it pumped out that whole tub of bad fuel in like 3-4 minutes. the filter looks like it has been tampered with recently but it hasnt been on there long, its not even close to as dirty as the bottom of the truck. plus if it was not getting enough fuel why would it be misfiring? maybe they put the filter on wrong. my thoughts right now are 1. wrong spark plugs + possibly fouled spark plugs from me trying to start it so many times with the bad fuel. 2. distributor is on the wrong way and its firing on the exhaust stroke (had a toyota do the same thing when the distributor was reversed) possibly happened during troubleshooting on accident? 3. ecu could still be bad. but like everyone has been saying because i unplugged it to check i lost any codes. i am going to go pick up a analog multi-meter soon to double check.

Chargerx3
03-08-2016, 12:37 PM
I like your new order of operations. Do that.

Chyrio
03-08-2016, 05:26 PM
I cant seem to find nickel spark plugs (what the manual calls for) anywhere in town? what kind do you guys run?

pennyman1
03-08-2016, 05:36 PM
NGK plugs - autozone has them - use platinum plugs, they will run smoother and last longer than nickel plugs

Chyrio
03-08-2016, 07:40 PM
NGK plugs - autozone has them - use platinum plugs, they will run smoother and last longer than nickel plugs

I have actually never heard of nickel plugs, combined with the fact that no one seems to carry them I'm assuming they are not very popular. Looks like buying new plugs might solve my issue ha ha.

16015

Chargerx3
03-08-2016, 07:52 PM
Yea those aren't the best looking. Platinum will do just fine.

Chyrio
03-08-2016, 07:56 PM
plus whoever changed them only changed 4 of them??? so there where 2 NGK nickel OEM plugs and 4 Champion Copper plugs???

Chyrio
03-08-2016, 11:09 PM
Ok, so changed the spark plugs and that didn't make any difference, climbed under the truck and noticed the fuel filter was in the wrong direction.... stupid people man... so i took it out and did my best to clean it out with some brake cleaner and blew some air threw it and it doesn't seem clogged. Put it back in in the correct orientation and with high hopes tried to start it and.... nope same issue. so far here is what i have checked:
Timing
Fuel
Fuel Pump
Fuel Filter
Spark Plugs
Camshaft Position Sensor
Replaced Capacitors on ECU
Cap and Rotor
Ignition Coil
Distributor is in the correct direction at TDC

What happens when i try to start it:
Press Clutch
Turn key
Immediately hear a relay click on the passenger side
Turn key to the Start position
Immediately hear the relay click again
Truck turns over several times
Stumbles
Stumbles
Dies

Only things i can think of that i have not checked:
Compression
Swapping ECU for a good one

Any other advice/ideas???

mightymax37110
03-09-2016, 09:16 AM
Mine was doing the stumbling thing until I changed the MAF

Chyrio
03-09-2016, 12:17 PM
Mine was doing the stumbling thing until I changed the MAF

but wouldn't, in that situation, unplugging the maf make it run right? because i tried that too...

Chyrio
03-09-2016, 12:26 PM
Another note worth mentioning. If you try and try and try to start it, eventually (4 or 5) tried it will start to smell like bad exhaust. like not burning antifreeze or oil smell just like old musty engine exhaust smell. Also if you try it 4 or 5 times. around the 5th time, you will hear a POP noise from the engine bay, not from the exhaust.

Chyrio
03-09-2016, 12:38 PM
I was thinking, when your looking at the distributor while the engine is at TDC. should the rotor be on its way past #1 or like it just started the spark? I made a picture showing what I'm saying, Red is where its currently touching the cap at TDC:

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Chargerx3
03-09-2016, 12:46 PM
Which way is the distributors direction? It's either advanced or full retard. Pun intended.

Chyrio
03-09-2016, 01:00 PM
Which way is the distributors direction? It's either advanced or full retard. Pun intended.

Well if your referring to the direction of the adjustment bolt for the distributor, i have it set smack dab in the middle right now.

tink
03-09-2016, 01:02 PM
basics are fuel spark air. if you've already covered the fuel (tank to combustion chamber) and spark (battery to spark plug tip) , then air is left ... other than computer controls / wiring / and moving metal bits. advice to stick to the basic that remains: air. if the air flow in/out is decent enough, double check the fuel flow since it could be getting a good enough amount of air in AND out, but the air /fuel mixture is so far off balance that you're smelling smells to indicate that even if/when it runs for a few minutes it's set to be running way too rich. the pops could be air pressure build up escaping or could be mini explosions of doom ...

hard to guess so thinking best to stick to the basic air flow that should be happening, from intake to exhaust. vacuum tube got blockage or pinched off, banana in the tail pipe or what? i hate guessing. but if the exhaust smell isn't making OUT the tailpipe, where is it getting hung up or where is the air blockage that's making the smell so strong?

the last time I heard pops from the engine bay was after I ran the truck out of gas, and so all the sludge that was at the bottom of the tank got pulled into the line right before the fuel filter, gummed up the filter, hesitations and no power and stuttering and ... POP. 3x it popped limping on the way home. changed the filter, and filled up the tank & been keeping it over 1/4 full since then, lol.

when you pumped out all that fuel you didn't happen to empty the tank did you? just a thought. if your filter is semi-see through, i'd shine a flashlight behind it & look in & double check it for gunk if your tank got down to E in the process of checking the fuel pump.

tldr; either way: pop can = air /fuel mixture way off.

hope my random thoughts from limited experience helps in some way. I totally feel your frustration & surely you'll figure it out anyway :)

Chyrio
03-09-2016, 03:43 PM
hard to guess so thinking best to stick to the basic air flow that should be happening, from intake to exhaust. vacuum tube got blockage or pinched off, banana in the tail pipe or what? i hate guessing. but if the exhaust smell isn't making OUT the tailpipe, where is it getting hung up or where is the air blockage that's making the smell so strong?

the last time I heard pops from the engine bay was after I ran the truck out of gas, and so all the sludge that was at the bottom of the tank got pulled into the line right before the fuel filter, gummed up the filter, hesitations and no power and stuttering and ... POP. 3x it popped limping on the way home. changed the filter, and filled up the tank & been keeping it over 1/4 full since then, lol.

when you pumped out all that fuel you didn't happen to empty the tank did you? just a thought. if your filter is semi-see through, i'd shine a flashlight behind it & look in & double check it for gunk if your tank got down to E in the process of checking the fuel pump.

tldr; either way: pop can = air /fuel mixture way off.

hope my random thoughts from limited experience helps in some way. I totally feel your frustration & surely you'll figure it out anyway :)

Ok so to answer some of your questions:
Yes i drained the tank to below E but fuel was flowing properly, their was a steady stream of fuel coming out of the pressure line.

Checked the fuel filter and there was gunk that came out of it especially since it was installed in the wrong direction. But i tried to clean it out with brake cleaner and blew air through it and it does not seem clogged.

And i have checked every vacuum line i could find as well as you're apart the intake and there was no noticeable blockage or damage. I have tried with the MAD plugged in and Unplugged. However i have not checked the TPS or throttle body for issues which i shall try tonight.

Thank you for your thoughts! Any advice is appreciated!

Chyrio
03-09-2016, 03:45 PM
I mean tore apart intake and MAF not MAD stupid autocorrect

tink
03-09-2016, 05:31 PM
My head is pretty much spinning right now going between what I'm thinking is your truck & what I know my car is, and trying to remember past issues (~275k miles on it takes a bit to remember problems of the past, lol) but maybe something here will help you: http://www.3swiki.org/Engine:_Adjust_Throttle_Position_Sensor_%28TPS%29 there are things you can do w/the engine OFF but the key in the ON position --- but I do NOT know exactly what you're working on so hoping I'm not sending you to a wrong direction. Hoping even if that's not 'exactly' what you've got under the hood the concepts should be close enough to the same to point you in a good direction to diagnose any TPS issue instead of guess.

When my ptu went bad, omg, there was this beautiful sports car that sounded worse than a lawn mower - no exaggeration - funny now but then it was frustrating as heck. Glad to see you not just throwing parts at it (or just going mad cutting hoses hahaha, been there :) You'll get it :)

claych
03-09-2016, 06:56 PM
Sorry Chyrio... the cell just shat the bed in the middle of our 'talk'... I will ring You up later.

Chyrio
03-12-2016, 07:50 PM
So i think i found the issue... idk what some idiot dumped in the fuel tank but damn.... might need to take the injectors out and replace/clean them.
1605316054

geezer101
03-12-2016, 09:23 PM
That looks like water. And it has been there for a long time. Yep, that'll screw up how the engine is running - you can try adding methylated spirits to the fuel to force the water into solution. Afterwards add a good quality injector cleaner and fingers crossed it will sort it out.

Chyrio
03-13-2016, 11:11 AM
That looks like water. And it has been there for a long time. Yep, that'll screw up how the engine is running - you can try adding methylated spirits to the fuel to force the water into solution. Afterwards add a good quality injector cleaner and fingers crossed it will sort it out.

I just wonder how it got in there? The seals are good around the fuel level thing, and the fuel pump and as far as I can tell the tank hasn't been compromised, as well as the filler neck is in tact and not ripped. Maybe some idiot dumped some mixture of fuel and water in it a long time ago.

I'm gonna drop the tank and clean it out and take the injectors out and inspect. I have until Thursday when my new denso fuel pump gets here.

geezer101
03-13-2016, 02:32 PM
Condensation is one way. And country fuel supplies were notorious for having water in their storage tanks. Don't know if it as much an problem now but it happens...

royster
03-13-2016, 03:11 PM
My understanding is that one of the horrors of ethynol is it attracts moisture. That's one reason to use fuel additives that remove moisture, or seek out filling stations that serve real 100% gasoline.

Chyrio
03-13-2016, 03:20 PM
My understanding is that one of the horrors of ethynol is it attracts moisture. That's one reason to use fuel additives that remove moisture, or seek out filling stations that serve real 100% gasoline.

I use shell or chevron exclusively. Might settle for Conoco if I have to. Sad thing is I just put 5 gallons of 90 octane and some injector cleaner in that tank for trouble shooting. Debating about getting one of those fuel filter things that filter out water to conserve the fuel I dumped in there.

Chargerx3
03-13-2016, 07:19 PM
Pull the plug and let it all drain out.

Chyrio
03-13-2016, 09:23 PM
Pull the plug and let it all drain out.

I just dropped the tank and pressure washed the inside of it. And cleaned the outside it wasn't that hard to get out and since the old nasty stuff settled to the bottom I was able to pull out most of the good fuel with the old pump before I drained the tank. Letting the tank dry out in my garage right now. commencing removal of injectors now.

Chyrio
03-13-2016, 11:55 PM
alright this is just disgusting. it looks like my engine has a disease... I'm gonna take the heads off and clean them out, replace the head gaskets, valve stems, and seals while I'm at it. doesnt seem like that much of a challenge this engine is so freaking easy to work on. does anyone have a link to a guide that shows the deletion of emissions stuff? AK doesn't require it.
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Chyrio
03-14-2016, 12:15 PM
I only buy the good stuff! ha ha
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Chargerx3
03-14-2016, 04:28 PM
Might as well throw in a new pump and strainer while you are in there.

Chyrio
03-15-2016, 12:09 AM
Might as well throw in a new pump and strainer while you are in there.

i ordered it last week since that's what i suspect is what is bad. it will be here Wednesday i think. but the rest of the parts wont be here til like the 25th so i have some time to kill. honestly besides the horrible nasty fuel buildup of whatever was in the tank this engine is in great shape. the head gaskets where not bad the timing belt and water pump where in pretty good shape accept some idiot decided to use red rtv all over everything. its the little things about this engine that make me think the previous owner took care of it but used the cheapest stuff he could when doing maintenance. does this engine have a front main seal that is easily replacable while I'm in there? the oil pump seal on the crank looks pretty good and is not leaking but if there is a front main back there i would consider replacing it since i have the time and its already all torn down.

some pics of the progress:
1607516076

Chyrio
03-19-2016, 08:00 PM
Parts are rolling in!! looks like its gonna be a while before my timing belt will get here though. sometimes i hate living in AK.

16102

speednsnake
03-20-2016, 02:19 AM
Well, your last post shows it pretty tore down, but I'll give you what I know anyway, since I happen to own a V6 truck and have done lots of troubleshooting myself.

Since you say that you have spark I'll assume that your ICM is fine, but you have to make double sure that your plug wires are in the correct order. Unlike almost every other engine (in my experience at least), the 6G72 cap has the rotor contacts in different locations than the wire terminals. If you look on the inside of the cap you'll notice that there are raised portions leading from the wire terminals to the rotor contacts. The cap should be wired 6-4-5-3-1-2, clockwise, starting from the terminal closest to the oil fill cap. Despite that, the firing order is actually 1-2-3-4-5-6 (as you probably know). When you put the distributor back in, the rotor should be pointing directly at the firewall at TDC #1.

If that isn't your issue (it was mine at one point, and the symptoms matched yours pretty well), you can eliminate the ECU as your problem by hooking up a noid light to an injector plug to make sure that they are in fact getting pulse. That's all I got. That bad fuel you found couldn't have been helping anything, and it never hurts to clean up an old motor. Hope you get it back on the road without much more trouble :).

BradMph
03-20-2016, 02:43 PM
Wow, sure have a build up of muck on those pistons. Makes me wonder how much more compression you get with that, lol.

With emission removal, your going to have some freaky stuff happening with the computer if you just start removing items.

On the 4 cylinder (which hardly compares to a v6) The weber helped remove several items and it gives a pretty good explanation in there installation guide. We have a free Weber manual here on forum also if needed at anytime. Then the header installation removed the other half of emission stuff. Your V6 will probably be a little intense and it might be a good idea to remove a little and try it, then repeat the process as you go along. Someone here must know a little more about this and I hope will probably chime in to give their thoughts.
Most the time when removing that crap is to be sure you cap off those removed items which isn't hard to remember, but with so much controlled by those computer boxes it is hard to give anything specific.

Chyrio
03-28-2016, 12:44 PM
Well, your last post shows it pretty tore down, but I'll give you what I know anyway, since I happen to own a V6 truck and have done lots of troubleshooting myself.

Since you say that you have spark I'll assume that your ICM is fine, but you have to make double sure that your plug wires are in the correct order. Unlike almost every other engine (in my experience at least), the 6G72 cap has the rotor contacts in different locations than the wire terminals. If you look on the inside of the cap you'll notice that there are raised portions leading from the wire terminals to the rotor contacts. The cap should be wired 6-4-5-3-1-2, clockwise, starting from the terminal closest to the oil fill cap. Despite that, the firing order is actually 1-2-3-4-5-6 (as you probably know). When you put the distributor back in, the rotor should be pointing directly at the firewall at TDC #1.

If that isn't your issue (it was mine at one point, and the symptoms matched yours pretty well), you can eliminate the ECU as your problem by hooking up a noid light to an injector plug to make sure that they are in fact getting pulse. That's all I got. That bad fuel you found couldn't have been helping anything, and it never hurts to clean up an old motor. Hope you get it back on the road without much more trouble :).

that was one of my thoughts but i triple checked my orientation before i tore it down. and at first i jacked it up just like you said then i fixed it and made sure all the plug wires go to the corrosponding cylinder. but after seeing the intake manifold i just decided screw it and tore everything apart. replacing everything i could and did the best i could with a plastic scraper to clean the carbon and muck of the cylinders. would have had it back together by now but rockauto lost my parts and shipped me a new set friday so i should have progress this weekend when the head gasket and the timing kit get here thursday. but i still need to get a valve spring compressor to take the heads apart then im going to steam clean them at my buddies shop. hopefully not to much longer