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chrisjeep
September 27th, 2017, 18:07
I cleaned the TPS/TB/IAC and now I have a rough start , low idle and a slight miss.
I changed the fuel pump(bosch),was getting 25-30 psi before the change and the same after change. I installed a check valve near the tank, no change. changed plugs. I hate throwing part at issues, can someone tell me the order in which I should go about fixing this. it's a 1994, 4.0 .

4x4JeePmaNthINg
September 28th, 2017, 04:56
Injectors stock? They could be bleeding down pressure

cruiser54
September 28th, 2017, 05:39
That fuel pressure is loooow.

chrisjeep
September 28th, 2017, 19:27
stock injectors. fuel pressure on gauge goes right to zero when engine is turned off. would like to know what series of test I can do instead of throwing parts at it.



Injectors stock? They could be bleeding down pressure

cruiser54
September 29th, 2017, 05:19
What happens if you pinch the fuel return line with the pressure gauge on it?

Replacing those injectors with the Volvo 746s is never a bad idea. Under $100

https://www.cherokeeforum.com/f72/78...ectors-222140/

chrisjeep
September 30th, 2017, 06:44
going to do the injector swap, keep you guys posted. thanks for the help



What happens if you pinch the fuel return line with the pressure gauge on it?

Replacing those injectors with the Volvo 746s is never a bad idea. Under $100

https://www.cherokeeforum.com/f72/78...ectors-222140/

lawsoncl
October 1st, 2017, 17:02
stock injectors. fuel pressure on gauge goes right to zero when engine is turned off. would like to know what series of test I can do instead of throwing parts at it.


Bad fuel pressure regulator?

4x4JeePmaNthINg
October 1st, 2017, 18:49
try priming the injector first by turning the key to on a few times, but dont start it until the 4th or 5th time. if it stumbles starting the injectors may be leaking and the engine is clearing its self because its flooded.
however if it fires right up instead, the fuel pressure regulator isnt a bad bet, its starving/ hard starting until fuels getting pumped to the injectors.

old_man
October 4th, 2017, 19:06
Throttle position sensors do not respond well to cleaning and routinely fail afterwards.

Runnin'OnEmpty
October 4th, 2017, 20:37
stock injectors. fuel pressure on gauge goes right to zero when engine is turned off. would like to know what series of test I can do instead of throwing parts at it.
The fuel pressure shouldn't bleed down nearly that fast.
When you replaced the fuel pump, did you check the upper
section for cracks? The hose tends to crack near the clamp
and will release pressure back into the tank.

old_man
October 4th, 2017, 20:54
The fuel pressure shouldn't bleed down nearly that fast.
When you replaced the fuel pump, did you check the upper
section for cracks? The hose tends to crack near the clamp
and will release pressure back into the tank.
X2

trippled
October 4th, 2017, 21:22
The fuel pressure shouldn't bleed down nearly that fast.
When you replaced the fuel pump, did you check the upper
section for cracks? The hose tends to crack near the clamp
and will release pressure back into the tank.

X3, however usually new fuel pumps include that piece of hose as long as it was used. I would say you have a failing regulator. If it was an injector bleeding of 10psi running it would probably hydrolock the motor or have a lot of black smoke. Pinch the return line momentarily and see if the pressure comes up.