Mechanics

NO POWER TO FUEL PUMP

1998 Isuzu Hombre • 4 cylinder 2WD Manual • 268,000 miles

1998 Isuzu Hombre 4cy 2wheel dr. No power to the fuel Pump. Changed relay, checked ignition moduel, changed fuse. There is power to the fuse and power to the relay. What could be the problem?
Rich
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Rrsutton97
November 21, 2010.



If you jump the relay, does the pump run?

I am not sure how to jump relay. It is a new pump. I replaced it when it lost presure when driving down road. After siting over night it started but only ran for 2-3 min then presure went to zero.

Tiny
Rrsutton97
Nov 21, 2010.
You either have a bad relay or a broken wire. Rather than jumping the relay, switch the relay with one that has the same part number to see if the fuel pump runs.

Let me know what you find.

Joe

I had already put a new relay in it. No change

Tiny
Rrsutton97
Nov 21, 2010.
Okay, then we need to check for power to the relay slot. Using a test light, touch one wire at a time to see if there is power to any of them.

With ignition on I checked power where relay plugs in.
87 from control moduel. Yes, has power.
85 no power.
86 no power.
30 no power.
ECM B fuse has power both sides.

All the wiring comes in under the fuse/relay block. I'm not sure how to access it.

Tiny
Rrsutton97
Nov 22, 2010.
You have it where it is needed. If the relay is good (you replaced it), then there has to be a broken wire between the relay and the fuel pump. Not a fun job, but you have to check for continunity to see if there is a break (open circuit).

Thanks, I started checking all the wiring possibilities. I found that when I grounded to the frame at the pump, it worked. The ground coming through the wiring bundle must be faulty. I bolted a ground wire to the frame at the pump. This will not cause any problems, will it?

Tiny
Rrsutton97
Nov 22, 2010.
No, it will work fine. Just make sure it is protected so nothing can happen to it. Also, make sure where you placed the two ground wires together is tight and won't come apart or be able to tough any of the power leads.

Let me know if you have other questions, and congratulaions, you just saved yourself about 200 dollars in diagnosis time from a shop.

Take care, and thanks for using 2carpros. Com.

Joe