1994 Mighty Max Help Needed

[jameyw]

Hello everyone. New to the forum here.

I have a 1994 Mighty Max with the 3.0L V-6. The truck belonged to my dad but has been sitting and not driven or started since 2006. The truck is in good shape and my son wanted to drive it so we have been working on getting it going. We changed all the belts (including the timing) and hoses, changed the oil, replaced the fuel tank and fuel pump, replaced all the filters, and installed new valve cover gaskets.

Today, after replacing the fuel pump we were finally able to start it. It was a little reluctant to start (which I expected) but it finally did. This is where I noticed the first problem.

When the accelerator pedal is pressed the engine is very slow to respond and increase RPM. After running for a few minutes it gets better but when the engine is shut off and then started again the problem returns.

The next problem I noticed was that the engine won't idle. My son has to keep his foot on gas pedal just a little bit for the engine to run. I see a screw that looks like it is an idle adjustment screw but not sure. This is a fuel-injected engine.

The last problem is harder to explain. When the RPMs are raised occasionally a thump can be heard. I have about come to the conclusion that it is back-firing or maybe back-firing into the intake. It isn't constant but it is pretty consistent one the RPMs are around 2000 or so (no RPM gauge so I have to approximate). Could this just be from a sticky valve because of not running in 8 years?

Thanks

Jamey

[Fordubishi]

Sounds like you didn't get the timing belt set up right and could be off a tooth on either cam. I did the same thing on a 3.0L and what had happened was when I released the tentioner the belt on the passengers side skipped a tooth. Reset everything and carefully released everything and it ran like a champ after that.

[BradMph]

Welcome to the forum :)

[jameyw]

That thought had crossed my mind but I was really hoping that wasn't the problem. I was super careful when I re-installed the belt but I guess I'll pull the covers and double-check.

Jamey


Sounds like you didn't get the timing belt set up right and could be off a tooth on either cam. I did the same thing on a 3.0L and what had happened was when I released the tentioner the belt on the passengers side skipped a tooth. Reset everything and carefully released everything and it ran like a champ after that.

[lush90]

It is not uncommon for fuel injectors to be clogged in vehicles that have sat for a long time. The backfiring sounds like timing, though. Good luck, these 4x4's are great trucks!

[BradMph]

Fuel sucks nowadays, ethanol should not be left in the tank for more then 30 days according to imformation found on internet. Collects moisture and starts breaking down rubber stuff and what not.

[jameyw]

When the rain quits and it warms up later in the week I'll pull the covers and check the timing belt and marks on the gears. You should have seen inside the old gas tank and the fuel pump assembly. The old tank looked like it had be shot with a shotgun it had so many rust holes in it.

[sleeps]

Sounds alot like timing is off.

[lush90]

Not to argue about gas quality but last year I picked up a van that had been sitting in a field for 2 1/2 years with ethanol gas in it and it started almost immediately with a jump. I drove it about 10 miles home without a problem, filled it up and have been driving ever since, aside from an intermittent electrical problem.

[jameyw]

I finally got to work on the truck today and am thoroughly confused and working on being frustrated now.

I have determined that the timing is most definitely off. How far? I'm not sure. I decided that the best ting to do was to start over. I decided to put Cylinder #1 at TDC and then check all of the timing marks and see where things were. For good measure I consulted the manual and the description of the location of #1 Cylinder is confusing. So, that brings up the first question: Is cylinder #1 the first cylinder on the left when standing in front looking at the engine? If so, great. When I rotate the engine to try and get that particular cylinder at TDC nothing seems to line up right. First, I am having trouble feeling when the cylinder is at TDC. Second, the distributor rotor never is at the #1 mark when the mark on the harmonic balancer pulley is aligned with the timing mark. It is always aligned with #5. This is odd since the distributor hasn't been removed since we rebuilt the engine 15 yrs ago. Since I am trouble finding TDC it makes this questionable. When the timing mark is aligned with the mark on the cover and #1 is where I think TDC is, the timing marks on the camshaft pulley and off.

Been a long time since I had to get this deep into timing and I am out of practice. Sadly, my mentor and teacher, my Dad, is no longer able to help or provide guidance.

Thanks

Jamey

[BradMph]

You have a v6 right Jamey? I almost answered your question thinking you have a 4 cylinder, DOH!

http://www.3sx.com/faq/manuals/Service-Manual-Mitsubishi-Engines-6G72.pdf


Not to argue about gas quality but last year I picked up a van that had been sitting in a field for 2 1/2 years with ethanol gas in it and it started almost immediately with a jump. I drove it about 10 miles home without a problem, filled it up and have been driving ever since, aside from an intermittent electrical problem.

Could it possibly be fuel without ethanol. :) 2 1/2 years ago I think ethanol really wasn't being shoved down our throats like the gas companies are doing to us all now. Probably with us in Washington the air doesn't have a large amount of moisture to be trapped and condensed either. I have left fuel in my boat over winter time and it wasn't to bad when I ran boat the next spring and summer. The rubber and non metal parts is what I think gets the bad treatment in time also.

[jameyw]

Yes, it is a V-6

[jameyw]

After tearing it back down and verifying the timing was off and then re-adjusting it, and then re-assembling everything, t he truck started right up and runs great. The look on my son's face was priceless. After letting it run a few minutes and checking everything, we drove it a mile down the road to the store and aired t he tires up to the correct pressure and put some gas in it.

Thanks everyone for the input.

Now to see if we can adjust the clutch a little.

jamey