Stumped. It's gotta be something simple.

[87junker]

I've had this truck about two weeks now. PO threw a bunch of parts at it to try and make it run. What I found was he scrapped the old carb for a Weber swap replaced coil resistor icm cap rotor. And still couldn't get it to run right. Since I've had it I've removed the factory pump and replaced with an electronic pump And got the timing and plug wires lined out (it was 180 out and plug wires out of order). But still only get 15 mins of run time before it dies. Any help would be appreciated.

[tortron]

Hi, i would check your carb float is set correctly and that the fuel bowl is filling. I would also check if the pump is continuing to operate or is it getting hot and turning off, or is something else turning it off?
Good time to check fuel filters and the lines are run correctly
If theres good fuel supply i would then suspect the coil is over heating

Its never the coil, except when it is

[Giovanni89]

My truck was sitting for a week while on a trip for work to Japan this summer. When I got back it had what felt to be a strange ignition problem that ended up being the float. During normal driving it was totally fine. Extended idling, or sitting with the engine off but hot more than five minutes and it would start flooding. But if it sat for a few hours it would clear out and start normally which is why I was thinking heat related ignition issue. Take off the air filter when it is idling or after you have shut it off and see if you can see any fuel dripping out of the little venturi for the main jet. At idle all of your fuel should be coming out below the throttle plate from the transition holes.
Giovanni

[geezer101]

I've had this truck about two weeks now. PO threw a bunch of parts at it to try and make it run. What I found was he scrapped the old carb for a Weber swap replaced coil resistor icm cap rotor. And still couldn't get it to run right. Since I've had it I've removed the factory pump and replaced with an electronic pump And got the timing and plug wires lined out (it was 180 out and plug wires out of order). But still only get 15 mins of run time before it dies. Any help would be appreciated.

And he/she got a 'genuine' Weber? If they didn't do their research there's an unfortunate chance they got burned. There's a bunch of fake carbs (read as 'licensed copies') on the market and they are GARBAGE. When it's running does it run OK? Check the coil polarity (this gets a few victims when they swap the coil over). And what are you using for a fuel pump? Webers require fuel flow and not pressure for them to do their funky thing.

[87junker]

Here is a long one. I ordered a basic rebuild kit. Once I got into it I found the float was way out. The needle valve had some wear but not terrible. Both diaphragms were worn out and the air corrector valves were 170 on the primary and 160 on the secondary. Got it all back together mow just to fire it up and see what happens.

[87junker]

Still no luck. It ran for 10 mins and died. As soon as it died checked the plugs and still had spark. Pump still had power. The primary side seem to stay wet and it tried to back fire thru the primary side. I'm gonna order a jet kit next.

[pennyman1]

did you replace the power valve? And did you soak this carb in carb cleaner before reassembly and blow out the passages? Jets are not the problem unless they are plugged. Did you check the float to be sure it isn't bad and filling up with fuel?

[geezer101]

OOC what fuel pump are you using? (it might be in another one of your posts but I'm lazy lol). If the pump is overpowering the fuel float needle it'll drown the carby in fuel.

[87junker]

I replaced the power valve it was for sure bad. Took out the main jets and air correctors. I couldn't get the venturi tubes out. Didn't take the idle jets out either. I set the float to parallel and it seemed solid. No fuel in it and it didn't seem saturated.

[87junker]

The pump is an Amazon special. It was 2-5 psi 34lph I got a regulator and set it to 3psi. If u let it just set and idles it dies faster but if u run the rpm up around 1500 it will last longer.

[87junker]

This morning it started and ran for 15 mins so I shut it off it tried to keep running and puffed smoke thru the carb. It got me getting too much fuel.

[Giovanni89]

Look down the carb throat and see if it is dripping gas after you shut it off. It would be dripping from the secondary venturi down onto the throttle plates.

[87junker]

Look down the carb throat and see if it is dripping gas after you shut it off. It would be dripping from the secondary venturi down onto the throttle plates.
Would that indicate float level is still off?

[geezer101]

The dripping fuel may be from high idle speed (it's trying to continuously draw fuel, creating enough vac to 'diesel'). Also check your engine tune. The timing sounds like it might be advanced a little as well. The fuel pump sounds a little 'iffy' too for this application. The Weber thrives on high flow/low fuel pressure to run. You haven't been able to get it on the road and fully test it but if it loses power under throttle for a while or runs lean, your fuel flow might not be up to it. If you have doubts about your pump and need an alternative I've got the pump for you -

https://www.ebay.com/itm/New-42S-Electric-Fuel-Pump-Carbureted-42-GPH-2-3-5-PSI-Fuel-Transfer-Pump-12V-/122439509134?hash=item1c81f6a48e:g:kokAAOSwE0JY~tH 5&vxp=mtr

[Giovanni89]

If it is dripping with the engine off it would indicate a a bad float or needle and seat. Let your electric fuel pump run for a minute or two with the engine off and look down the throat. I had a genuine Weber float that got porous, would start cold and then start bucking and snorting when idling hot. If I was driving down the road Then the demand would overcome the extra fuel
If it’s dripping while running then yes, a high idle speed screw adjustment will cause it too. That’s why you should look while it’s not running

[87junker]

Got the timing set at 7*btdc readjusted the float level. I made it a mile down the road before it died. Only made it to 40 (speed limit) but pulling a little hill was rough third gear heavy in the throttle. Let it cool down for about 20 mins it started right back up the hill back the other way was still rough but it made it back home and didn't try to over run and back fire when I shut it off.

[87junker]

Here is the pump I'm using.

[geezer101]

Dude, I'm seeing bench tests on those pumps and they aren't exactly stellar... hardly any fuel flow (seem to be relegated to fixing ride on lawn motors and small carbs). Is the chassis of the pump grounded properly/good voltage/close to the tank etc? I still suspect it's a combo of tune and fuel flow.

[bbrewer2005]

Im running that same pump geezer linked. It has done great for me and I dont run a regulator with it due to it having the correct pressure.
The only issue I had was on a top speed run. It did starve for fuel for a second on 2 occasions but that was only after being wide open throttle for well over a full minute. Lets be real though, most people that have one of these trucks arent doing that. Could be hose routing. Its a great pump for the price and works well.

[87junker]

Sounds like I'll be junking that pump. But I did notice today when I went to put some seafoam in the fuel the fuel tank had all kinds of pressure in it.

[bbrewer2005]

I wanted to add something to my last post, but cannot figure out how to edit posts.

That exact pump (Same part number stamped in plastic) is sold under mr gasket brand at autozone, which is where I got mine. Pretty much every autozone in the nation have these on the shelves in the "performance isle".
20319

[bbrewer2005]

If youre not reading more than 3-3 1/2 psi after the regulator, the pressure in the tank shouldnt have much of an effect.

As for the pressure itself. Check the hose/pipe routing to and from the charcoal canister. One of them goes to the factory mikuni carb. Make sure the previous owner didnt stick a bolt in the hose, or clamp any of them off.

[geezer101]

^ +1 on that. Check that the breather line is able to vent. It will mess with fuel delivery if the tank develops a vacuum in cold weather or pressurises in hot weather. It develops vapour lock and the pump won't be able to overcome it.

[geezer101]

Im running that same pump geezer linked. It has done great for me and I dont run a regulator with it due to it having the correct pressure.
The only issue I had was on a top speed run. It did starve for fuel for a second on 2 occasions but that was only after being wide open throttle for well over a full minute. Lets be real though, most people that have one of these trucks arent doing that. Could be hose routing. Its a great pump for the price and works well.

Sooo... in your not-on-public-road, under strict controlled conditions top speed run, what did your truck reach?

[87junker]

https://youtu.be/BFwzRMnja2k
Here is a video if u skip to about 2 mins left u can see and hear what it's doing.

[87junker]

https://youtu.be/4Md2wYVznB8
Here is a second video after it shuts off down into the top. First part is with pump off second half is with pump on. Nothing is coming out after it died.

[Giovanni89]

I’m going to agree with all you guys that it’s probably the pump. I thought it was dieing idling, not under a load. I have been running a carter electric pump and Holley regulator mounted where the emissions control once was, above the drivers side front wheel well. Keeps the road salt off of it. A little pricey compared to some of the others, but made in the US and works great

[geezer101]

After watching a number of bench tests and looking at your set up, I think you should at least remove the pressure regulator. It's already getting hardly any fuel. Thing to note in vid #1 after revving the engine, it stumbles at the 1 minute mark. At the end of the vid, idle speed goes up to 1,000 rpm and it starts to run erratically like it's leaning out. The initial idle speed is not bad for an engine at operating temp. As vid #2 shows that it's not dumping fuel but only shows signs of some blowback into the carb (in the primary throat side? could only mean open throttle). A simple test to determine if it's fuel deprivation - start it and open the throttle up and observe. If it starts to stumble and tries to stall out, I'll put money on the main culprit being not enough fuel.

[87junker]

After watching a number of bench tests and looking at your set up, I think you should at least remove the pressure regulator. It's already getting hardly any fuel. Thing to note in vid #1 after revving the engine, it stumbles at the 1 minute mark. At the end of the vid, idle speed goes up to 1,000 rpm and it starts to run erratically like it's leaning out. The initial idle speed is not bad for an engine at operating temp. As vid #2 shows that it's not dumping fuel but only shows signs of some blowback into the carb (in the primary throat side? could only mean open throttle). A simple test to determine if it's fuel deprivation - start it and open the throttle up and observe. If it starts to stumble and tries to stall out, I'll put money on the main culprit being not enough fuel.

Once the timing was set correctly I had to adjust the idle back down to 800 but it was alot worse on the primary side before I cleaned it up. It could use some more tlc on the cleaning. But I was wondering about the idle slowly rising as it ran.

[87junker]

Well I removed the regulator and it made it worse than ever. Only made it about 5 mins. Had to keep playing with the throttle to keep it running. I tried to adjust the idle air screw it didn't matter either way it didn't change. I did realize the throttle screw is almost bottomed out. But when I finally shut it off it puffed a huge cloud of white smoke. Almost thought I was gonna need a fire extinguisher.

[BradMph]

If you have a regulator on an electrical pump for your weber, you should have a mini gauge installed on the regulator to assure it is pumping the correct amount of fuel to the carb. 3-4psi is good for the weber. They have little mini-gauges you can install which I have used for years. hey are simple, plastic, and do the job well for what you need.


I use one of these Spectre Performance Fuel Pressure Gauge 59013, from walmart. The face is like inch and a half and screws right into the gauge oulet of a regulator.
20327

[geezer101]

OK so this fuel delivery issue is starting to freak me out a little so I may have a plausible theory on it. Lets say the fuel pump you have installed has undersized fuel lines (the Weber should have something like 5/16"-3/8" for the fuel inlet) and is already pushing more pressure than the needle and float can handle. It runs for a while but eventually the fuel pressure overpowers the float and the engine drowns but when you go on throttle, the pump can't keep up with demand and it leans out and dies. Now this sort of fits with your initial video. At the end of it the rpm's increase by themselves (simulating open throttle slightly) as it's somehow getting extra fuel until it can't handle it anymore and floods. As I haven't seen what happens after the engine conks but the ignition is still on, it's hard to say if the electric pump is indeed flooding the carb. So in theory, if the pump was replaced to a low pressure/high volume unit and fuel lines upsized to the corrrect internal diameter, this should solve both the stall out under throttle and the flooding at idle. Anybody got a thought on my synopsis? :think:

[geezer101]

Oh an added observation on your pump install. The pump should be mounted as close to the tank as practical so it isn't struggling to pick up fuel. :thumbup:

[87junker]

I finally got to mess with it again. Put the regulator back on set carb to baseline settings got it running. Did find that to get it running smooth I'm almost 3-1/2 turns out on the idle mixture screw. It ran great idles @ 800rpm it lasted almost 30 mins like 25 ish. It's been the longest it's ran. I'll post a video here in a little bit down into the carb. It never had any fuel puddling up in the primary. So I'm still stumped. I feel the fuel side is better but something electrical is still giving me issues.

[87junker]

https://youtu.be/jsSDLsRVXdw
Here is the video right before it died. I missed it actually dying this time. Never had a hiccup until it started to die. Once it died it wouldn't hit a lick. Letting it cool down now.

[Giovanni89]

s

https://youtu.be/jsSDLsRVXdw
Here is the video right before it died. I missed it actually dying this time. Never had a hiccup until it started to die. Once it died it wouldn't hit a lick. Letting it cool down now.

Junker,
When it dies, how does it do so? It it sitting idling, or are you driving down the road?
Fuel starvation is going to cause bucking and bogging under a heavy load; going up a hill, heavy acceleration. Letting off the throttle will reduce demand enough that it should recover before stalling, or at the very least, it will restart after you have given the pump a few seconds to refill the bowl.
Flooding is usually going to have more of an effect at idle or light load. When you crack the throttle open, the extra air will usually take care of the extra fuel, enough so that the engine may be running rich, but stay running.
Another thing to consider is that this is not a fuel issue. While it sounds likely that it is, it could be ignition or mechanical. Put a vacuum gauge on the manifold and see if you start having fluctuations or a lower reading as the engine warms up. Check you timing again with the engine hot. A bad ICM (pickup in the distributor) can fail without totally failing. Before I replaced mine, when hot the timing would start jumping all over the place.
A possibility if it is fuel starvation that takes 15-30 minutes to show up is that the vent to your fuel tank could be plugged up, and as the tank builds vacuum the pump will not be able to overcome it. A quick way to test this is to remove the gas cap. This will release the vacuum building in the tank with a whoosh of air at the cap. If this is happening I would expect the fuel pressure to the carb is dropping as well. If you haven't installed a fuel pressure gauge yet, I would do so.
Giovanni

[87junker]

So far it's been all at idle. I've drove it around the block a few times and down the road once where it died until it cooled down and I was able to get it home. Today was the best and longest it ran. I have the vacuum line pulled off the tank but that doesn't mean it's not In the fitting. Now when it's running it doesn't smell like it's running rich like before. I'm gonna try to relocate pump down low next chance I get to work on it. But the PO gave me all the receipts for stuff he bought( cap, rotor , and icm) just to eliminate those as causes.

[geezer101]

How long after it conks out that you are able to restart it? If there's a gremlin in the coil/ballast resistor, they will overheat and consequentially die and won't run until they've cooled down (appears the ICM also has similar effect when it's faulty...). I am a bit concerned at the number of turns you have your idle mixture screw wound out (about 2 turns is normal give or take 1/4-1/2 a turn)

Not sure if this is for tuning legit carbs but might still be useful as a guide on how to set it up - http://www.carburetion.com/Weber/adjust.htm

[Giovanni89]

Another thing to consider, especially with electrical parts, is that just because it is new does not mean it is working correctly. The previous owner could have swapped some of the wires on the ballast resistor and been running 12 volts to the coil and 9 volts to the ICM and burned something up.

It can't hurt to verify that you are getting fuel to the carb when it dies. Pull the fuel line off and run it into a jug. If it's pumping fuel but won't restart until it has cooled off, I would start looking at the ignition. If the fuel flow is weaker than when it is cold, it's either going to be that the tank is building vacuum, or the pump/regulator are unhappy with the under hood heat.
Geezer's link for weber setup looks spot on :thumbup:

[87junker]

So I swapped some parts around this evening found the one of the icm's I have is for sure bad. Put the ballast resistor back inline. I got a new volt meter and checked the resistance of the coil and of the ballast. It ran for 15 mins before dying. Let it sit for 30 mins started right up no problem. I did pay attention to the pump and it did change tone and seemed to sound like it was cavitating so I'll be changing that for sure. I did have a few readings that weren't quite right. The farthest out was across the secondary coil. 2034120341

[geezer101]

We'll see how you get it to run once you have the ignition debugged. Then getting the carb dialled in should be a cake walk :thumbup:

[87junker]

It ran for 30 mins this evening. Before I started it I tested the coil the ballast and had a reading on the imagine cold. I let it run till it died and jumped out and started testing everything while it was hot. All my readings were the same for the coil and ballast. BUT the icm was on fire hot and I couldn't get an ohm reading thru it. (NOTE) the whole distributor was hot to touch the little screws to undo the icm were hard to hold hot. I know it's right by the thermo housing but it was ridiculous hot. I'm gonna wait till it all cools down and retest.

[87junker]

Imagine=icm

[87junker]

So after it cooled down I put the icm back in and ran it till it got hot again. Once the distributor housing got to about 150* it started missing and cutting out. On average the intake side is about 150-190 degrees.its hard to see but the pic is the distributor body. 20343

[Giovanni89]

It ran for 30 mins this evening. Before I started it I tested the coil the ballast and had a reading on the imagine cold. I let it run till it died and jumped out and started testing everything while it was hot. All my readings were the same for the coil and ballast. BUT the icm was on fire hot and I couldn't get an ohm reading thru it. (NOTE) the whole distributor was hot to touch the little screws to undo the icm were hard to hold hot. I know it's right by the thermo housing but it was ridiculous hot. I'm gonna wait till it all cools down and retest.
Winner winner chicken dinner! Looks like you found your problem. I'm betting a new ICM and she'll idle til the tank is empty. :thumbup:

[87junker]

Winner winner chicken dinner! Looks like you found your problem. I'm betting a new ICM and she'll idle til the tank is empty. :thumbup:

All the icm I'm finding run 50-100 bucks. I have a gut feeling that it's getting hot due to bearings in the distributor. It looks to be the original distributor. But for 50-70 bucks more I'd be willing to replace the distributor.

[87junker]

** UPDATE ** I installed the new distributor got the timing set. Let it run for 20 mins. Then took it for a spin... an hour later it was still running. Set a new top speed of 60mph. Got home and double checked the timing it was at about 12* btdc set it back down to 7 run it for a lil longer shut it off. It didn't diesel when I shut it off and fired right back up.

[geezer101]

Nice. With a bit of tweaking you should be able to gain a little more on top speed and get it to feel more responsive. Big question will be - what was wrong with the old distributor?

[87junker]

Nice. With a bit of tweaking you should be able to gain a little more on top speed and get it to feel more responsive. Big question will be - what was wrong with the old distributor?

I believe the bearing in the body of the distributor was building heat. I had a thermal imaging camera and was getting temps 190+ where the icm sets. I'll keep driving it around when I can since it's not street legal yet and make sure it's a for sure fix.

[Giovanni89]

Sweet! I’m curious what the temp difference is from the old distributor to new.

[87junker]

I starts great runs great but it likes to diesel when I shut it off. Gonna double check the timing.

[87junker]

Seafoam didn't help so far.

[pennyman1]

what plugs are you running? your heat range may be off, causing the dieseling. You can also get an anti- dieseling solenoid for some Weber's - you use the same wire that goes to the electric choke - ignition off, fuel shuts off. Joetlc on eBay carries them.

[Giovanni89]

Also if your idle speed screw is too far in exposing a transition port from the idle circuit it will diesel frequently. The solenoid will shut off fuel to that as well. Allstate Carb out of New York has the solenoids, and good prices on all the weber jets.

[87junker]

Pennyman plugs are an ngk. I'm not sure on part # but that's my next purchase.
Giovanni I got my rebuild kit from all state. I need to get into mine and see what jet it has. My idle air screw is close to three turns out. I've been slowly adjusting it to get it running good. If getting it tuned right doesn't solve it I'll get a solenoid.

[87junker]

Added a muffler today so it's one step closer to being completely street legal. And it's up to 50 miles with no problems so far and with being said the gremlins should start popping anytime now.