2000 Jimmy Yet Another Fuel !ssue....

[mad419iou1]

My wife's 2000 Jimmy 4 door 4.3 died on her on the highway. I have nothing on the fuel gauge and low fuel light is on. There is definetly fuel in the tank. I also have no sound at all from the fuel pump at all. Truck cranks fine. I had this exact same problem one time before about 8 months ago and it turned out to be a fuse. Checked the relays in the fuse box under the hood and everything is good. Any ideas???

Mike

[old_master]

Does the fuel pump relay click when the key is turned to the RUN position? It should click again after approximately 2 to 3 seconds.

[mad419iou1]

don't remember hearing it click.

[old_master]

There should be a label on the underside of the underhood fuse panel lid that shows where the relay is located. There are four terminals in the underhood fuse panel that the fuel pump relay plugs in to. Remove the relay and check the circuits. One terminal comes from the ECM B 20 amp fuse. It should have battery voltage at all times. One terminal comes from the ECM and should have battery voltage for 2 to 3 seconds after the key is turned to the RUN position, and then drop to zero volts. It should also have battery voltage any time the ignition switch is in the START position. One terminal goes to ground and must be less than 5 ohms resistance to ground. The fourth terminal goes to directly to the fuel pump. If the circuits check out OK, there are several identical relays in the fuse panel, try swapping with one of them. If the pump works, you need a new relay. If not, continue on…

Next to the fuel pump relay there is a single unused, recessed terminal. This terminal goes directly to the fuel pump. Connecting a 20 amp fused jumper wire from battery positive to this terminal should result in the fuel pump running continuously, regardless of ignition switch position. If the pump does not run, voltage and ground need to be checked at the fuel pump, (tank must be dropped to access the connector). Hope this helps.

[mad419iou1]

I swapped around the relays this morning and got nothing. I'm gonna go out now and check the circuits now. i'm running out of daylight and working on the street so I don't know how much more i'm going to be able to do today.
Thanks for the help.

[mad419iou1]

OK when I rin the jumper wire to the single terminal that goes to the pump the pump runs. Ground at the fuse panel is around 3 ohms. One terminal has power with ignition off and with the key to run. The other 2 only have power when the key is in the start position.

[old_master]

Are you checking with the relay removed? If so, one of the terminals, the one that goes to the pump, should not have voltage at all during the test.

Your ground at the relay is good. The pump running when jumped means the pump is getting voltage and ground. Your feed from ECM B to the relay is good. There should only be one terminal that the voltage ever changes on, and that's the triger from the ECM. It should be hot in RUN for 2 to 3 seconds, then drop to zero. It should be hot in START continously. Check it again to be sure.

You can check if the relay is switching by checking for voltage in the unused terminal. With the relay plugged in, it should show battery voltage for 2 to 3 seconds after the ignition is turned to the RUN position, then drop to zero. It should also show battery voltage continously when the ignition switch is in the START position.

[mad419iou1]

Yeah I was checking with the relay removed. let me go check it again with it in quick before I run out of light.

[mad419iou1]

just checked again and everything tests the same with the relay in.

[old_master]

If the results in the third paragraph of post 7 are ok, it's time to check the fuel pressure.

[mad419iou1]

The truck doesn't seem to be getting spark either. I just sprayed a bunch of starting fluid down the throttle body and it didn't even sound like it wanted to start. I can't verify for sure on the spark until tomarrow after I do the brakes on my Mazda. Am I still looking at a fuel issue or can this be a PCM/ECM issue??

[old_master]

Try not to guess, it gets real expensive real quick See if you have a blue, not orange, spark at more than one spark plug.

[mad419iou1]

Yeah i hear you on the guessing. LOL This whole truck gets real expensive real fast . I've got the battery out and charging. As soon as I get my brakes taken care of I'll check the spark and let you know how I make out.

[mad419iou1]

O.K. I definetly have NO spark. Absolutely nothing at all.

[rockwood84]

no spark at plugs. do you have a spark at the coil wire ?