Fuel in cylinders

Messages
9
Location
West Columbia, TX
Thread starter
I was having issues with my 98 GMC k1500 z71 with 5,7 vortec sputtering and running weaker than it had been. So I bought new plugs and wires and came home and changed the plugs that night. Auto Zone have me the wrong wires. The next day it's running worse. So I decide to do a complete tune-up on it... Plugs, wires, coil, distributer cap and rotor. Only to see that the outer edge of the plenum on my intake manifold is cracked... Bad. So I go to the junkyard and by another. Mind you, I've never been into an engine solo this far before, but I go for it. With the you tube videos I manage to get it apart and I decide that the bottom of the intake looks ok and to just change out the plenum, and the injectors. I put in the injectors that came in the intake from the junkyard and put it all back together to find that my battery is bad... Left the key turned forward after checking compression on motor before pulling intake accidently. Put my battery charger on it and pulled the key and let it charge for a couple of hours. Went back out and it started right up. Sputtered and died. Wouldn't re-start. Chalked it up to dead battery. Bought new battery and installed it. Tried to crank and only heard a locked up jarring sound that sounded as a locked up motor. I smelled gas and decided to pull plugs. Number 8 cylinder full of fuel. Today I pulled all of the plugs and changed the oil. All but 3 cylinders had fuel either holding in the cylinder or the plugs were wet with fuel. I left plugs out for a few hours and I squirt some oil in the plug holes, and put the plugs back in. I take out the fuel pump relay and turn the key, still the same sound. Any advice
 
Messages
2,700
Location
USA
Engine should spin freely with the plugs out (disconnect the fuel pump and the ignition coil when you do that). Once you have the cylinders clear, put the plugs back in, do not add oil. Injectors can leak. Swap back to original injectors.
 
Messages
23,741
Location
MA, Mittelfranken.de
This was your mistake..
Quote
just change out the plenum, and the injectors.
Never use junkyard are even used injectors without cleaning and leak testing them first.
 

4WD

Messages
13,137
Location
Texas
Originally Posted by Trav
This was your mistake..
Quote
just change out the plenum, and the injectors.
Never use junkyard are even used injectors without cleaning and leak testing them first.
^^^There he is, I found him^^^ 👀
 
Messages
4,165
Location
WA
Could it have hydrolocked? If so, does taking the plugs out and cranking it clear it?.. and yeah, gotta wonder about the state of the rods on those 3cyls.
 
Messages
1,010
Location
dayton oh
this has the spider type injector module? its more likely the fuel pressure regulator is leaking. i have seen those bad enough to hydrolock the engine.
 
Messages
1,385
Location
RI
What year Truck did you dig that plenum out of? You just might have some stuck poppets.
 
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Messages
9
Location
West Columbia, TX
Thread starter
They Said it was another 98. They looked great compared to mine. I'm going to take the plugs out and try to turn her over by hand when I get home.
 
Messages
23,741
Location
MA, Mittelfranken.de
Originally Posted by Smittyzzz
They Said it was another 98. They looked great compared to mine. I'm going to take the plugs out and try to turn her over by hand when I get home.
Disable the ignition by removing a fuse, connector, etc then turn the key on with the plugs out, do not crank the engine you just want fuel pressure. if fuel comes out of the plug hole the injector is stuck open. Looks mean nothing at all, I have seen some horrible looking injectors that run and test out perfect while some that look new but have dried out flow poorly, stick open or closed and have other problems.
 
Messages
4,165
Location
WA
Originally Posted by Trav
Originally Posted by Smittyzzz
They Said it was another 98. They looked great compared to mine. I'm going to take the plugs out and try to turn her over by hand when I get home.
Disable the ignition by removing a fuse, connector, etc then turn the key on with the plugs out, do not crank the engine you just want fuel pressure. if fuel comes out of the plug hole the injector is stuck open. Looks mean nothing at all, I have seen some horrible looking injectors that run and test out perfect while some that look new but have dried out flow poorly, stick open or closed and have other problems.
Gonna have to remember that one.👍
 
Messages
9
Location
West Columbia, TX
Thread starter
Well I got home and pulled the plugs and grabbed the flywheel... To my total disbelief and and relief, the motor turned. So I then unhooked the coil and got the ignition, there was still some fuel in 3 of the cylinders so I left the all of the plugs out and I'll pull the plenum and the devil injectors tomorrow and get some NEW ones ordered. I'm also going to order a new PCM. Any advice on that would be appreciated. I am disabled so money is very limited. I need reliability. That's the reason I used the junkyard parts... That and ignorance. I feel lucky and blessed I'm not buying a new motor.
 
Messages
4,616
Location
Fort Worth, Texas
Why do you need a new PCM? Either take your 2 Spider assemblies to a good mechanic the that can clean & flow them or buy a Updated MPI conversion Spider! DO NOT bother with changing individual Injector/Poppet assemblies.....GM tried having us do that when these first came out, Didn't work well then & it doesn't work any better 24 years later! Don't overlook the possibility of the Fuel Pressure Regulator leaking badly!!! You can remove the upper plenum, Hook back up the fuel lines, Pressurize the system & check the FPR.
 
Messages
23,741
Location
MA, Mittelfranken.de
The MPI conversion is what I recommend also when people want to send them in for cleaning, those and most TBI injectors are not worth doing. I see new USA made TBI injectors for under $20 ea why spend almost that to clean the old ones, makes no sense. OP Here is a ACDelco conversion kit that inc the bracket, its a plug and play and much more reliable that what is on the truck now. Well worth spending the money on IMO. https://www.summitracing.com/parts/...qre725QIVhZ-zCh1R0gX2EAQYAiABEgJ9PPD_BwE
 
Messages
9,986
Location
Waco, TX
Originally Posted by Smittyzzz
. I'm also going to order a new PCM. .
SERIOUSLY? Load up the ol' "Parts Shotgun" and start blasting away!!!
 
Messages
2,700
Location
USA
Wow. Put it back together with the original injectors. If it still doesn't run right with the new plugs, wires, cap and rotor, get in there and troubleshoot for the original problem. Also if it runs really badly, the plug wires may be out of order. The distributor cap with four wires coming out of each side does not mean you run the wires to the cylinders in that order. Yes the four wires on each side go to the four plugs on that side of the engine. No they do not go in exactly front to back order. There are little numbers on the cap. Goes without saying that the PCM almost never needs to be replaced.
 
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