C2500 w/ fuel coming out of the exhaust

[dkennedy]

I just bought a 1998 C2500 w/ V8 - 5.7L (vin R) 350ci engine. When I got the truck I could smell the raw fuel coming out of the exhaust pipe so I decided to start with a tune up. So far I've replaced the spark plugs (gapped @ 60), plug wires, distributor cap and rotor - ran a can of Sea Foam through the injection system and tested the fuel pressure (it's 58/60 psi). Although it does run a little better, I still have the fuel running out of the tail pipe, rough idle, and smoke coming out of the exhaust. I'm leaning toward injectors being the main thrust of my issues, but I'm not one to start throwing parts at a problem, so I thought I'd sign up here to get a few tips and bounce some ideas around. I am a bit above average as far as mechanical ability, but have zero experience with the Vortec engines.

BTW - I've read a ton of information online, but most of the forum threads were dead ends because the OPs had not posted the end results of their efforts. I also tried the search feature on this forum, but trying to search for my problem using 2 key words (gas + exhaust) posed a problem.

Thanks in advance,
Donnie from Arkansas

 

[Horns]

You say the engine runs rough, is it missing?

 

[dkennedy]

yes... pretty badly.

 

[ChrisAU]

Leaky injectors. I see you posted in my thread about replacing the spider, look in the TB to see if you can see fuel in the upper plenum.

 

[Horns]

Leaky injectors. I see you posted in my thread about replacing the spider, look in the TB to see if you can see fuel in the upper plenum.

The fact that he has a bad miss I'm going to go ahead and say one of the cylinders isn't firing.

This is probably the 20th (literally) time I've said this this week, but check compression! start pulling plug boots until you find out which cylinder is missing and check the compression in that cylinder.

When my 94 had a bad miss and a lot of fuel in the exhaust because of a burnt valve it had 0 compression.

 

[dkennedy]

Leaky injectors. I see you posted in my thread about replacing the spider, look in the TB to see if you can see fuel in the upper plenum.

Got out to the shop this afternoon and turned the key over a few times to build up the fuel pressure in the lines and I did find gas pooling in the bottom of the intake. I also noticed that the fuel pressure bled off about as quickly as the fuel pump quit pumping so at least now I do know there are some injector issues.

I also cranked it up and started snatching plug wires off and determined that the #5 and #7 are not firing well... it was kind of hard to tell how bad they are due to the engine already running so bad. A buddy and I are going to run compression tests on all cylinders in the morning to try and see what kind of shape the rings, valves, and gaskets are in.

 

[dkennedy]

I completed the compression test a few minutes ago with the following results:

#1 = 185/185
#3 = 182/182
#5 = 186/182
#7 = 186/184
#2 = 184/184
#4 = 184/184
#6 = 182/182
#8 = 186/186

These numbers are pretty high, but I attribute that to the excess fuel carbon/gunk that is probably built up on the tops of the pistons due to this vehicle being driven in such poor condition. There also wasn't any issues with bleed down so I'm felling more comfortable with the condition of the rings and valves.

One interesting thing I ran across was just how much fuel was getting past the injectors, especially in the #s 5 & 7 cylinders and from #8 to a much lesser extent... see pic below.

You must be registered for see images attach

This thing probably shot a 1/2 pint of gas out of the spark plug ports after about 8 or 10 revolutions of the engine, so I pulled the fuel pump relay to do the compression test.

While I'm testing, what other components should I tackle before I start making my parts list?

 

[ChrisAU]

Hey, coming over from the Seafoam thread, I had been keeping up with this one too. With the consistent compression numbers and that much fuel coming out, I'd say that you def have leaking injectors and/or a bad FPR.

 

[dkennedy]

I'm working out a list of fuel and ignition components to test now... and all of the how to test them. Just discovered my multi-tester is toast so I'm going to head into town in a little while to snatch one up.

While I'm at it, can anyone tell me what this little doer is?

You must be registered for see images attach

The book I have doesn't have many good images of all those little electrified bits on top of the engine.

 

[bluex]

At this point I would not waste time with anymore fuel tests. From what you describe your spider/fpr are shot. Get the upgraded spider an replace it, along with plugs at least. I would do wires also cause those look like some cheapys.