fuel pmp relays???

I am having a problem with getting no fuel pressure an di want to check the relays I have a 1991 cherokee xj auto 4.0 HO. my haynes manual schematics show there are 2 relays for the fuel pump....I found one under the hood with the other relays but I can't find the other one, any one know where it is located???

I wouldn't trust a haynes manual to wipe my butt with.

IIRC...there is only one, and I believe that it is located in the fuse box by the radiator overflow bottle.

bigredrangerxlt said:

I am having a problem with getting no fuel pressure an di want to check the relays I have a 1991 cherokee xj auto 4.0 HO. my haynes manual schematics show there are 2 relays for the fuel pump....I found one under the hood with the other relays but I can't find the other one, any one know where it is located???

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If you have two ones in the PDC and the others on the firewall above the heater/AC

Per my handy 1991 FSM...

There is a "Ballast Bypass Relay" located near the coolant recovery bottle and PDC, it's the one oubside the PDC by itself, which should only be engaged when the key is turned to START. In normal operation, the fuel pump is powered through a ballast resistor (for reasons of NVH - because peope complain that their Jeep is louder than their Lexus. Of course it is - the Jeep actually runs and makes useful power!)

The ballast resistor is located behind the windscreen washer tank on what looks like the driver's side fenderwell. It can be tested with an ohmmeter - disconnect one terminal before measuring, and you should find the rated resistance value stamped into one of the terminals on the reisistor proper. The ballast may either fail or become contaminated (and the resistance will increase significantly,) both of which will cause a loss of fuel pressure or a simple failure to operate.

Rated fuel pressure is 31psig with vacuum applied to the pressure regulator, and should it 8-10psig higher with vacuum NOT applied. A standard fuel pressure test gage with a Bosch/Schrader valve adapter should work.

Relay #2 in the PDC should be your fuel pump primary relay, this is the one that is energised during normal operation. From the looks of things, it should be a standard Bosch relay - which you should be able to get locally for less than $10 (and order in quantity from various suppliers for significantly less.)

What are your symptoms, and why do you suspect low fuel pressure? Have you cleaned your injectors recently? All claims of mileage benefits aside, I'll pour about four ounces of acetone into my fuel tank about every other month (it's used by the gasoline companies as a cleaner, and you'll just be increasing the concentration slightly) just to keep varnish, deposits, and general crap down. It tends to be cheaper than most commercial cleaners, and works well once you've got things clean to begin with (as a maintenance cleaner.)

If you haven't cleaned your injectors and fuel system in a while, you might want to buy a can of Berryman's B-12 (which I've used with good results,) or SeaFoam (which I hear about, but haven't used yet,) and follow the directions on the back of the can. You'd be surprised how many fuel system issues come back to contamination...

5-90

well i wa sout 4 wheleing and took a creek crossing that proved too deep for my stock cherokee and it stalled out the water ended up half way up my door, so needless to say i had a pond inside. after we pulled the jeep back out of the hole and let the started dry out and checked for wet plugs and water in the oil we found no water got in. an dafter the starter dried off it started up but i started reversing back out of the creek and it stalled and hasnt started since. the fuel pump doesnt engage and there is no spark i think i killed th ecoil and the fuel pump. there is power to every accessory but no fuel pump engagement and no spark from the coil. all the fuses are good, the relay female ends are powered, i changed a few relays around to see if anythign changed but nothing. checked shrader valve...no fuel pressure at all. everythign turns over fine but no start obviously. poured gas in intake but didn't start due to no spark. I am going to swap in my buddies coil to see if it is the coil and the fuel pump or just the pump. I just dont know why it started after we let the starter dry out and then died. lol thats what i get for trying to hang with the big boys lol.

Check your CPS, plug and unplug it several times. Give yourself some time to
allow the ECM to dry out, if the water was that high.

Sometimes the CPS will get forced out from it's mount by water pressure.
Top of bell housing just behind motor.

If you were creek crossing in a stocker and got over the front signal lamps, you may have a whole other problem because that's where the air intake is

bigredrangerxlt said:

well i wa sout 4 wheleing and took a creek crossing that proved too deep for my stock cherokee and it stalled out the water ended up half way up my door, so needless to say i had a pond inside. after we pulled the jeep back out of the hole and let the started dry out and checked for wet plugs and water in the oil we found no water got in. an dafter the starter dried off it started up but i started reversing back out of the creek and it stalled and hasnt started since. the fuel pump doesnt engage and there is no spark i think i killed th ecoil and the fuel pump. there is power to every accessory but no fuel pump engagement and no spark from the coil. all the fuses are good, the relay female ends are powered, i changed a few relays around to see if anythign changed but nothing. checked shrader valve...no fuel pressure at all. everythign turns over fine but no start obviously. poured gas in intake but didn't start due to no spark. I am going to swap in my buddies coil to see if it is the coil and the fuel pump or just the pump. I just dont know why it started after we let the starter dry out and then died. lol thats what i get for trying to hang with the big boys lol.

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What year? Did you get the computer wet?