jeepguy18

i got a 91 jeep cherokee im just getten started in to jeeps from being a ford guy. well i got my jeep its 4x4 lifted tires all that im haven problems with it tho it will start and idle every now and then and rev up But it wont stay running it just dies ive put a fuel filter spark plugs the little ceramic ballsister thang and none of that helped could the fuel pump be going out if so why will it rev up and idle every now and then. ne suggestions i kno nothen about em its a 4.0 motor. thanks in advance

tiwvr1

Because at idle, in park or neutral, requires very little fuel, only when there is a load on the engine will it demand more. We often check for bad fuel pumps at work by spraying carb cleaner down the intake, when it starts it will sound like it is running great, u can rev it and everything, but the second you put it in gear it just dies.

landon71

if you can get a hold of a fuel pressure gauge you can hook it up to the port on the fuel rail and see what your pump is doing while its running.. should idle at 31 psi... pull the vacuum hose on the pressure regulator and it should jump up to 39+-.

jomps

or could let jeep sit for a a few hours and press valve on the check pressure with engine off...should be good spray of fuel...if you get air hissing then regulator is failing

jomps

just be sure to clean up afterwards

jeepguy18

thanks it endend up being the ballaster resistor it runs to the fuel pump to break the volts down