91 Suburban

[91Suburban]

Just picked up this truck, has new 350 engine, new tranny, been sitting for awhile and sometimes it starts then doesnt, runs mint for awhile then falls on its face, fuel smells terrible in tank, put lucas in it, any ideas??? tune up was done.

 

[Molson02536]

Just picked up this truck, has new 350 engine, new tranny, been sitting for awhile and sometimes it starts then doesnt, runs mint for awhile then falls on its face, fuel smells terrible in tank, put lucas in it, any ideas??? tune up was done.

Start with the simple and replace your fuel filter. But that doesn't help, then inspect all your vacuum lines and have your ICM tested. Most case, the ICM will start to fail when it heats up and work fine again when the Engine has been shut down giving time for the ICM to cool down.

Its just a matter of time if the ICM is going bad, it will fail totally and your engine will not run.

Keep us posted
Molson02536

 

[91Suburban]

Start with the simple and replace your fuel filter. But that doesn't help, then inspect all your vacuum lines and have your ICM tested. Most case, the ICM will start to fail when it heats up and work fine again when the Engine has been shut down giving time for the ICM to cool down.

Its just a matter of time if the ICM is going bad, it will fail totally and your engine will not run.

Keep us posted
Molson02536

thanks, so tonight i checked all the vacuum lines and they seem fine, i pulled the plugs and they are fouled, gonna get new plugs, replaced the fuel filter, where is the ICM located?? and how do i test it??

 

[1988IndySierra]

ICM is located inside the distributor, there are 2 5.5mm (or 7/32) bolts (usually, sometimes there's phillips) holding it down and has two plugs going in.

I'd say your electric in-tank fuel pump is going bad.

Since it's been sitting, I'd recommend replacing it all, it's common for the ICMs to go bad as well as the fuel pump.

 

[91Suburban]

ICM is located inside the distributor, there are 2 5.5mm (or 7/32) bolts (usually, sometimes there's phillips) holding it down and has two plugs going in.

I'd say your electric in-tank fuel pump is going bad.

Since it's been sitting, I'd recommend replacing it all, it's common for the ICMs to go bad as well as the fuel pump.

its very weird it will run mint for a good hour, then all of a sudden, start stumbling, then picks itself back up, gas thats in there smells terrible, and also noticed my fuel gauge works then doesnt work, put fresh plugs and wires, they were fouled out bad

 

[91Suburban]

pulled the tank, fuel was black, pump and sender and tank are shot

 

[91Suburban]

got new tank and pump and sender in runs alot better, only issue is when its idling cold sounds like it has a miss or is running rich, once it warms up it runs amazing

 

[irishburb94]

ask

How long was the truck sitting? Im a professional mechanic and the first thing I would have said would have been to change the fuel if it smells bad. Now that you have run the nasty gas into your motor you mag have caused yourself more problems... your misfire could be a number of things, considering that you've already done your plugs I would recommend changing your fuel filter and then your pcv valve. A can of seafoam or a bottle of royal purple max clean would be my next suggestion to clean out any other carbon and crap from the bad fuel from the injectors. Pull the tbi and check the butterflys and injectors and clean or rebuild as necessary. Running bad gas is a nightmare for a motor and can lead to a world of extra work that needs to be done. Plus the misfire could be the typical 350 miss, every one ive ever owned(which is more than I would like to admit lol) has had a very slight miss until it warms up, nothing major just enough to make it puff when idling. If you have any other questions you can email me directly and ill be happy to help you out. Irishprince114@gmail.com