highmiles

got an 88' cherokee with the 4.0.. it turns over but won't start, i have fuel and spark. it was running fine, i came back from the store, started it and drove about 50' and there i sat.

i replaced the crank sensor. i'm curious if maybe the spark is low or if maybe it jumped time.

i was gonna have someone turn the motor over and try turning the distributor to see if it will start..

is this in the right direction or is there a better approach?

scoob

do you have injector pulse or just fuel pressure?
if the crank sensor was bad you would have no spark at all
if you have no injector pulse i've seen the hall sensor go bad in the distributer
if your coolant temp sensor went i've seen them not dump enough fuel to run(sensor tells the computer its running at like 300 degrees so hardly any fuel)

highmiles

the only fuel pressure i checked was in the fuel rail.. to check pulse do you unplug an injector?

dotyjeep

fuel pump

highmiles

fuel pump is turning on

dotyjeep

take catalytic converter off & start

dotyjeep

you can take to A muffler shop and do A precat intrusion test

cruiser54

Check the fuel pressure with a gauge. The presence of fuel means nothing if it doesn't have the right pressure.

DFlintstone

The cat won't keep it from starting. Distributor shouldn't move and doesn't do timing. The injectors will fire with the wires on the dizy unplugged. Basics, plugs cap rotor wires, been checked?

And always listen to Cuiser!

tjwalker

Good advice. Gotta use a gauge. Many big box parts stores will rent you a gauge if you don't have access to one. You need approximately 31 psi for your engine to fire.

highmiles

thanks fellas, plugs, cap and rotor look so i'll check the fuel pressure

cruiser54

Huh?

driv1923

Had the same problem a while back on my 88. Turned out to be the fuel pump relay. It would energize the pump momentarily enough to pressurize the fuel rail but would kick out before the eng could start.