IQuick intro- working on my buddy's 92 Cherokee 4.0 l 4x4 automatic( 6"long travel,35"km2,snorkel). So we went wheeling month ago and went in deep water bog over the hood, wheeled the rest of the day, parked it in garage over a month and now won't start..

I covered the basics, battery is good, ground wires good, has gas in tank, pump turns on, has fuel pressure at rail on my gauge35-40psi primed, checked all fuses and relays... Just replaced the CPS and TPS sensors, MAP..tryed different relays for ASD,pump.. jumped fuel pump ballast wires!

It has spark, it will turn on for two sec. Than shuts off...... I can keep it running with starter fluid, so telling me it has spark but not getting fuel.....

What controls the injectors or pump? I've done a bit of research, could it be a bad PCM? We're tring go wheeling this weekend, please help!!

 

ASD relay.

 

Good guess but did not fix it, I played musical relays, none fixed it, .....what does pcm controll?

 

So the fuel pressure goes to 0 after 2 seconds? Does the fuel pump circuit use a ballast resistor?

ETA:
With the water soak 1 month ago thats more than long enough for corrosion of electrical connectors to set in, could be almost anything with high resistance.

 

Fuel gauge primes to about 40psi, I crank it over and runs for about 2 sec. ( the fuel drops to about 35psi and when engine stops, pressure goes back to 40psi....where would the ballast be or look like?

Ya I know anything could have corrosion.. It's going be a pain going threw everything, but seems like all the plugs are sealed with rubber gasket of some sort from factory

 

Try bypassing the ballast resistor for the fuel pump. Just connect the wires at each end together, see what happens.

 

Assuming its the white piece on driver side inner fender on top by the hood with two wires on each end? I will check tomorrow after work, that sounds like a good possibility if it controls fuel or pump, thanks

 

Should be on the drivers side firewall, white, with 1 wire @ each end.

 

Power to the fuel pump passes through it, except when the key is in "Start" which bypasses it. When it fails the fuel pump runs while you're cranking, but stops once the engine starts. It's only there to reduce fuel pump noise, it can safely be bypassed and removed if you like.

 

Thats what it is exactly doing, fuel pump is on and working until engine turns on for few sec. then motor starves for fuel and shuts off.., so I figured something that controls injextors or fuel pump... I can't wait to test it tomorrow after work... Will keep it posted.. Thanks guys

 

Well just got home from work, bypassed the two green wires of the fuel pump ballast that is located on driver inner fender by the firewall.....still wont keep running....same symptoms....any other suggestions? Also bought new map sensor and put on, still won't run...

What does the pcm controll? Is there a cam sensor in the distrib. Someone told me

 

Fixed!!!!!! Bought a pcm off of craigslist and plugged it in.... So thanks for the people responded and keep thread in archive for people with same issue....Now I have to try return $200 worth sensors I bought lol

 

Man I have the same problem i put a new fuel pump relays cps sensor and i have strong fuel pressure and strong spark there for a bit it would run off starting fluid now i can pour gas in tb or do whatever no start to run it pops off a little but nothing so next try is CPU tmrw i will reply with results to confirm similar issue thanks matt