1992jeepxjdd

i need some help with my 1992 jeep Cherokee Laredo 4.0 with automatic transmission.

i did a motor swap i got everything together then went to start it well it starts for about 2 seconds at most then just shuts off and it will keep doing that, so i worked on it my self for about 2 months, i went through the wiring and checked all the wiring and everything is plugged in and wires look good.
ive changed the throttle position sensor, crank shaft position sensor, distributor, cap, wires, spark plugs, well it is still doing the same thing.

well everything ive done it hasnt worked so i took it to a shop and it was at the shop for 6 months they went through all the same stuff i did and they came up with nothing other then they thought it was the computer, so i got the jeep back and i bought the computer brand new and it didnt work. i checked spark and i got good spark so i checked the injectors and they all have good spray and there all working great.

WHAT DO I DO NEXT?

thank you for your help and thanks for reading....

salad

What swap did you do?

1992jeepxjdd

i kept the 4.0 in it i just put a better 4.0 in it

cruiser54

Have the distributor out? What year 4.0? which flywheel did you use?

1992jeepxjdd

i had a mechanic shop put a new distributer in cap and rotor, i used the 92 flywheel. the one flywheel that came out of it off the bad motor is the one i used

Turbo X_J

"starts for about 2 seconds at most then just shuts off"

What's missing fuel or spark?

1992jeepxjdd

ive got great spark and great fuel pressure

ZJMAX

timing? When it does start for the 2 seconds does the motor sound ok or is it running rough?

Max

Turbo X_J

It's got 30 psi fuel and white hot spark engine starts immediately then runs for 2 seconds followed by stall and fuel and spark are still present?

1992jeepxjdd

motor sounds great when its running, 31 lbs pressure great spark

cruiser54

Look here:

1992jeepxjdd

i tryed to jumper the ballast resistor and it does the same thing doesnt change anything and i tested the map sensor and the map sensor is good

BlueRidgeMark

Hmmm. Had a computer problem on my 94. No start when hot. Confirmed it was the 'puter by cooling just that component. Once I did, it started every time, no problem.

So, I ordered a new one from the guy on eBay who has great customer service. That computer did the same thing. Start, then die like it was shut off. He replaced it. Next computer from him did the same thing.

He refunded my money and sent back the old one at my request. His service was fantastic, and he was willing to go a third round, but I said no. I felt bad for the guy.

I never did get it running. It's in the process of being parted out.