wont run

got a buddy with 91 XJ who recently rebuilt his 4.0. We got it all put back together and it'll start but dies almost instantly. We have replaced battery, coil, plugs/wires, it seems to be getting fuel. Don't really know where to go from here. Any tips/help would be appreciated.

jamijay said:

got a buddy with 91 XJ who recently rebuilt his 4.0. We got it all put back together and it'll start but dies almost instantly. We have replaced battery, coil, plugs/wires, it seems to be getting fuel. Don't really know where to go from here. Any tips/help would be appreciated.

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running lean? Check everything intake and exhaust related. Once I had a small tear in the intake boot of an engine and it would start, run for a sec, then die.

also, try holding the gas pedal like half-to three quarters of the way down and starting it like that; have somebody watch and if it backfires out the intake you can be sure you have a leak somewhere.

FIRST I WOULD CHECK TO MAKE SURE THAT THE FIRING ORDER IS RIGHT! AND MAKE SURE THAT YOUR DISRIBUTOR IS IN THE RIGHT SPOT! BUMP ENGINE OVER TO TOP DEAD CENTER MAKE SURE THE CRANK PULLEY MARK IS AT O DEGREES TDC. THEN PULL OF THE DIST CAP AND MAKE SURE THE ROTOR IS POINTING AT THE #1 CYL ON THE CAP, IF BOTH THE FIRING ORDER AND DIST ARE IN RIGHT I WOULD TRY UNPLUGGING THE CRANK SENSOR CONNECTOR TIGHTEN THE PINS AND PLUG IT BACK IN SEE IF SHE FIRES.ALSO MAKE SURE YOU HAVE GOOD VACUME GOING TO THE MAP SENSOR ON FIRE WALL. IF NONE OF THIS WORKS YOU WILL HAVE TO TAKE IT TO SOME ONE WITH A SCANNER WHO CAN CHECK THE DATA STREAM FOR SOMETHING WRONG MIGHT HAVE BAD MAP SENSOR! ALSO TRY TAKING OUT THE IDLE AIR CONTROL MOTOR

thanks for the help! we'll give it a try!!

I think I'd check my ballast resistor, either disconnected or not working. Sounds like it COULD be the problem. Go there first.