Topic: My jeep keeps falling on its face

[93yjFirstJeep]

So my 93 yj is having a problem. It runs fine when i first start it up, and runs fine as long as i keep my foot out of the throttle, but if i get on it, it has way less power than normal, and when i pull out even remotely quickly, it just falls on its face and acts like it wants to stall, but if i let my foot back out of it, it goes back to normal. Also,  I recently changed the fuel pump and filter and im not throwing a cel. What could be causing this? I'm thinking maybe a leaky injector considering i bought some used 19 pounders off ebay last year, but any other suggestions? Also, if i turn the car off and let it sit for a few minutes, it'll run fine again for a while, then the problem pops back up.

[sharpxmen]

So my 93 yj is having a problem. It runs fine when i first start it up, and runs fine as long as i keep my foot out of the throttle, but if i get on it, it has way less power than normal, and when i pull out even remotely quickly, it just falls on its face and acts like it wants to stall, but if i let my foot back out of it, it goes back to normal. Also,  I recently changed the fuel pump and filter and im not throwing a cel. What could be causing this? I'm thinking maybe a leaky injector considering i bought some used 19 pounders off ebay last year, but any other suggestions? Also, if i turn the car off and let it sit for a few minutes, it'll run fine again for a while, then the problem pops back up.

1. catalytic converter

2. fuel pump but since you changed it i would think maybe FPR or plugged lines (long shot on both)

most likely #1

not likely to be a fuel injector, would idle rough or idle in 3 cyl if it was plugged but maybe worth a shot to replace them with your stockers for a test in case the cat turns out to be ok.

[93yjFirstJeep]

I just replaced the cat about a year ago, and wouldnt a cat cause this to happen all the time?

[sharpxmen]

I just replaced the cat about a year ago, and wouldnt a cat cause this to happen all the time?

it usually gets worse once the cat gets hotter - but since you replaced it i don't know in that case. maybe ignition coil, that can get worse when heating up too but i would think you'd rather have misfires and hiccups (would be more obvious).

might be fuel related, but then again you replaced the fuel pump, but it might be something with that if you have it at wot (pedal to the floor) - like i said, maybe the FPR or plugged lines.

[jfrabat]

I agree with the ignition part and the fuel pump part...  Also, check the air filter.  Fast accellaration requires more power, which means more air and more fuel (and a spark strong enough to ignite it).  Any of those fails, and you have your condition.  Since the exhaust (cat) part of the issue has less doubt (because you recently replaed it), I would check the above.

[Torch_Ind]

I agree with the ignition part and the fuel pump part...  Also, check the air filter.  Fast accellaration requires more power, which means more air and more fuel (and a spark strong enough to ignite it).  Any of those fails, and you have your condition.  Since the exhaust (cat) part of the issue has less doubt (because you recently replaed it), I would check the above.

this may not be the case check over the other stuff first but new parts fail to!!  doesn't hurt to check them

[93yjFirstJeep]

My cat is fine, and i just did new plugs, wires, cap, and rotor about 3 days ago. That did make it run better, but didnt help my problem when i get on it. I'm going to put in my stock injectors and throttle body next to see if that works 

[mbolan]

Really sounds like a fuel pressure problem. I have taped a fuel pressure gauge to my windshield before so that I could drive down the road and see the feul pressure while the problem occurs. I have also had brand new fuel pumps go bad after only a week. Being able to monitor the guage while the problem is occuring will tell for sure.

[93yjFirstJeep]

Well i checked my fuel pressure, and its at 30 pounds idling, which i'm pretty sure is about 10 pounds low. I'm gonna try and change the regulator before the pump

[Jeffy]

Well i checked my fuel pressure, and its at 30 pounds idling, which i'm pretty sure is about 10 pounds low. I'm gonna try and change the regulator before the pump

31psi at idle is normal.  If you remove the vacuum line then it should jump to 39psi.

[sharpxmen]

31psi at idle is normal.  If you remove the vacuum line then it should jump to 39psi.

but you also need to look at it when it has the nose down occurrence

[mbolan]

definatly try to monitor the pressure when the power is cutting off. Go to an autozone or any of the other parts big chains and rent for 'free' thier fuel pressure system test kit. The ones by me have a guage with a long enough hose to reach outside the hood and tape it to your windshield. Drive around and watch the pressure when it nose dives. The kit also has a bunch of fittings so you can "T" into the fuel line before the regulator or filter. That way you can ttell if its a pump, filter, or regulator problem. Its a no cost test that will save you from the shot gun approach of wasting money. I just had to change a pump in my kids Daytona that was doimg teh same thing. New pump, ran fine until it warmed up.

[93yjFirstJeep]

Well i ended up replacing the pressure regulator, and that seemed to be my problem. Shes runnin like a top now, so i guess that must have been it. thanks for the help guys 

[93yjFirstJeep]

Ok, so the regulator helped, but on my way home from college today, about 50 miles down the interstate, the Jeep started the viscious cycle again. It would drive fine, then slowly lose power, then fall on its face. Then i would stop, let her "cool off" for about 5 minutes, then start the whole process over again. Im honestly stumped as to what  this could be 

[jfrabat]

Ok, so the regulator helped, but on my way home from college today, about 50 miles down the interstate, the Jeep started the viscious cycle again. It would drive fine, then slowly lose power, then fall on its face. Then i would stop, let her "cool off" for about 5 minutes, then start the whole process over again. Im honestly stumped as to what  this could be 

When I bought my Jeep, it started doing something similar; it would start fine, but when it would get hot, it would start stumbling.  The problem just kept getting worse, to the point where it would just stall if I put any load on the engine (like popping it in 1st and traying to get the Jeep moving).  It turned out to be a bad fuel pump.  If I were you, I would check this as well...  By the way, when was the last time you changed the fuel filter?