Irongrave

92 XJ 4.0

I'm having issues with my fuel pump replay. Its not energizing to pull its closed to click the fuel pump on. I've swapped a few relays around and same issue. I can manually engage with the keep off and the fuel pump turns on. Also I can put a business card to hold it closed and can start the motor. Once running it stays closed no issues there. Battery has a good 13.6 volts in it. I just replaced the terminals on the battery. After that I'm at a loss on what it could be or how to fix it.

Drew

Niac

My 01 has an auto shutdown relay. It only lets the pump run for a short time if the engine doesn't start. I am not sure but I believe it;s controlled by the Engine control unit. But it's located in the fuse and relay box under the hood.

Irongrave

I've tried swapping that relay out as well same issue. I hope its not a ECU type issue. if so any one got a bypass (not my DD)

redmuck

are you using the same old relays that came from the factory? if so, they are probably all bad after 18 years or so. are talking about the relay under the hood? im pretty sure there is one there,i changed like 3 or 4 different relays on mine. a couple of them read wrong on the meter.

Irongrave

might try and mess around with it some more tomorrow when i come home from work if its not raining. Once its running 0 issues with it, nice and smooth at idle and plenty of power. Going to hope my local auto parts store has the relays. if its not that time to look at all the connections

jeans

Got a multimetre? Id check for power. There will be two pins with power (one with close to 12v and one with somewhere between 5 and 12v. The 12v will be the power that goes to pump, the other will be the signal wire that comes from the ignition switch). If you have both power's, id look at the ground at the relay. There has to be a ground for the signal circuit. If the signal ground is bad, its going to have a hard time staying engaged.

Irongrave

the pins in my multi meter didn't fit going to have to grab my better one from work tomorrow and look into that.

As far as how it works.

ASD relay energized = fuel pump relay energized if the jeep doesn't start ADS down fuel pump down. or am I way off on that?

Niac

That's the way it works on mine. The pump only runs for 2sec.s before the asd shuts down.

Irongrave

ok so seems like i have an ASD issue power not getthing threw that to the fuel pump.

any way to bypass it like the have in say a nascar race car, have a fuel pump switch on the dash and do it that way.