i am working on a 1990 xj and have replaced almost all the electronics on the motor idles fine as soon as you touch the throttle it comes apart backfiring and ******* down gonna replace fuel pump tomorrow. any other suggestions ? i have to get this running only vehicle i have and i have a baby due any day now

 

got the new fuel pump in it will start and adle about 1000 rpm rough then it will start to smooth out and then die and if you touch the throttle it backfires and comes apart PLEASE HELP

 

sound like either tps or map sensor

 

I'd start by testing AND adjusting your throttle position sensor. The TPS on the RENIX vintage is adjustable and adjustment is important.

Did you replace the fuel pressure regulator when you replaced the pump? They work together, along with the TPS to deliver the right amount of fuel.

Test to a solution. With a fuel pressure gauge on the schrader valve on the fuel rail,
you should have approx. 31 psi. Now disconnect the vacuum line leading to the fuel pressure regulator. Your fuel pressure should jump to approx. 39 psi. If it doesn't, check that line for damage, blockage, etc and be sure it is pulling good vacuum.

And of course, be sure that all tuneup hardware is fresh including plugs, plug wires, distributor cap and rotor.