67 GMC

Fuel pressure should be about 31 PSI and rise to about 39 when you pull the vacuum line of the fuel pressure regulator at the end of the rail.

You already changed the fuel filter so that's good. If you have fuel pressure, in the above range, that would be good and you could move on to other issues. I simple check is to turn the key to RUN to hear the fuel pump prime the rail, turn it back to off and then to RUN again and then START. If it starts quicker after doing that, you have a problem with the fuel leaking (either at injectors or somewhere else).

These Jeeps are bad for grounding issues. Check all ground wires by removing them from the block, firewall and cleaning the surface to bare metal before re-attaching.

Does it take a long period of cranking until it starts?

rusty_bucket

The fuel filter had not been changed in a very long time. I will update the information and write everything that I know soon.

rusty_bucket

Thanks, it usually does take a little while of cranking to get it started, first start about 10 seconds of cranking, once it dies it can take up to a minute of cranking.

I cant check the rails right now though so...

jpmarine6786

ok. Hand over $20,000.

67 GMC

Try the key ON, OFF, ON a few times and see if cranking time gets less.


Also, a plugged catalytic converter wouldn't usually stop it from running, it would just keep you from getting power. I had an old Buick with a plugged converter. It always started fine but had no power to go up a hill or pass anyone. A few mechanics couldn't figure out the problem. I pulled into a Midas Muffler shop and the guy there knew right away what the problem was. Best $200 I ever spent on a car. Squealed the tires on the way out of the garage. That much of a difference.

rusty_bucket

That's is kind of like what is happening, it always sounds like it is going to die. Sometimes it will rev back up, or it will just die. Usually it stalls on the way up a very slightly sloped hill after about 300 yards. When you step on the gas sometimes there is a delayed reaction, it takes a second to rev up after the you step on it. Also I noticed that when the jeep is idling and I step on the gas, it revs up as it should but if I keep my foot on the gas, it will eventually loose RPMs or die, even if you keep gassing it.

I'm just trying to give you more info, I may be able to upload a video tomorrow of the symptoms. I also will try to get my hands on the pressure gauge.

Thanks for the help everyone!

rusty_bucket

added some more details, will add more soon.

jhamXJ

The cat wouldn't cause that(to my knowledge) it sounds like its fuel related.

jhamXJ

I could see that. I guess there's just one real way to find out. Replace one then try the next. I have seen fuel pumps cause the vehicle to stall, even with the foot feed to the floor. You never know

toasterknight

that behavior almost sounds like a dead tps.

93_xjcherokee

Wrong thread. Sorry

quneur

Very similar to my situation. I bought a 91 Laredo 214K miles for $500 at a towing auction and it sat for awhile - moss growing all over it. It looked like it was partially rolled as the A pillar is somewhat messed up but it also came with a 3" procomp lift; the same lift a member said he feels it every time he drives over a pencil.

For your problem, I would first ask what did you replace stuff with? Brand? Although the 4.0L is fairly bulletproof, it still doesn't like certain type items. Spark plugs? Wires? Oil viscosity?

I would first look for vacuum leaks. Look for any unconnected or burned hoses. Go underneath the vehicle and look at the exhaust manifold for cracks at the 'Y'. Downstream O2 sensor is on the pipe pre-cat so a faulty sensor or exhaust leak can cause engine to do funny things.

Check to see if CCV (PCV) hose isn't filled with crud.

Check sensors connections have power.

Check fuel relay. You can take it to a parts store or use a 12v drill battery. While you're there you may want to pick up coolant combustion test kit to see if cylinder head and gasket is okay.

Adjust throttle valve cable.

Sludge can cause problems and if your car sat for 3 years its likely has sludge in the oil pan.

rusty_bucket

The spark plugs were autolite platinums, the wires were a vehicle specific Bosch set, the oil was Quaker state 5w-30.

I have noticed one hose that was not even on when I bought it coming off of the head cover (fresh air inlet?). The sky has decided to pour water right now so I cant check for any other leaks but as soon as it stops I will look.

rusty_bucket

Apparently when you open one can of worms, you have to open two. When I was checking the fuel pressure at the rail, I noticed that the serpentine belt had slipped off. So, I put it back on. The next time we started it up, it slipped off. I put the belt back on 4 times today until I realized something. It appears that the pulley for the crank has either unbolted or unscrewed. I do not know how to fix this problem, however I am pretty sure that I got an accurate reading on the fuel pressure, and it's not good:

I measured around 13 PSI.

So it appears that this is the problem, where do I go from here?

Turbo X_J

Replace the fuel pump & harmonic balancer.