fuel pump relay?

Test the coolant temperature sensor if okay check the fuel pressure to rule out a failing fuel pump or a pressure regulator not maintaining the fuel pressure.

I thought my fuel pump was bad when i tried to start it and it would just crank, and no fuel was getting to the injectors. so i changed the pump and filter and still no fuel is getting to the injectors, and i cant hear any noise from the pump...also i noticed that the fuel guage was working with the old "broken" pump but now reads empty with the new one (has about 3/4 a tank of gas in it) dont know if its the fuel relay or an electrical problem, i checked all the inside fuses but their fine.

Hello, did you check wiring at the fuel pump relay, orange wire is hot all the time? The gray wire carries voltage for the pump. If you use a jumper between those two terminals, the pump should run, use an inline fuse. Any fuse you check, also check that the fuse circuit is hot.

Make sure power is going to your engine

truck is not getting power to fuel pump i have power to the red wire in middle of conector and power to purple wire that goes in the tank to the float or gas gage but no power to fuel pump. it has good ground i even ran two ground wires of the ground to see if that helped it did not. I have put a new fuel pump relay fuel filter and a tps. still nothing im lost please help

The fuel pump will only power up for 2 secs due to the fuel pump relay de-energizing. The computer energizes the relay thru its fuel pump control

Have you tried direct power to the fuel pump? If it comes on when direct power is use and the relay has been replaced. Test the wirng-wiring okay, Test computer fuel pump control and fuel pump and oil pressure sending unit.

I am attempting to trace why I am only getting 8.4 volts to my dual tank switch on my 87 R30. I have ohmed all the fuses, checked every ground I can find, have jumpered 12 volts directly through the switch, switch connection, and both relay's and got 12 volt's to the fuel pumps, which work fine. I am currently trying to locate a fuseable link that I read about behind the gauges. Have yet to find this mystic wire. Any suggestions??

most fusible links on that year are attached to the starter under the manifold. if you rlinks were bad it could cause this but it almost sounds like a wire is grounding out partially. the pink wire leads to the fuse box off of the ign switch. see diagrams

Thank-you for the response. If I find the problem based on your advice I assure you that I will make a donation to this web site. You are the only one out of ten responses from other sites that have made any sense. I will be sure to let you know the results.

Dan

I changed my fuel pump a year ago and it went bad again about a month ago. I have since had intermittent problems with it. Now it won't work at all. I have checked my relay and it is getting voltage. My fuel gauge jumps all the way to the right and then back to the left when I turn the key on. It then settles down. When I installed the new pump it had different colored wires than the other one and I think I have it wired right but is it possible that I have connected a ground incorrectly? Thank you very much.
This is a 1998 Chevrolet silverado 5.0 L 2wd

The fuel pump gets its power from the gray wire the black is ground. The fuel pump relay only works for 2 secs. and its energize by the computer below is the fuel circuitry

www.eautorepair.net

I need help. Fuel pump not working, replaced filter, fuel pump, relay and still will not pump. Can some one help?

check fuse for fuel pump circuit, is voltage getting to the relay?

Fuse was burnt and replaced but no power. Does the switching valve have anything to do with the pump getting voltage? Tank switch RH LH was burnt as well. Could the ECM gone bad? Wired the pump directly to the battery and pump worked truck turned on. What else can i trouble shoot.

1. Could it be the ECM.
2. Voltage at switch valve fluctuates between 2 an 8 volts.


HELP? TRUCK is CLassic

must be getting too much voltage on system then to have popped the fuse and the switch. yes it could be caused by a failing ECM. may also be the oil pressure switch, the fuel pump circuit runs through the oil switch as safety measures. does the oil pressure gauge work ?

Electrical problem
1987 Chevy Silverado V8 Two Wheel Drive Automatic

the fuel pump relay has been changed and the switchvalve under has been changed could it be the switch in the cab . I got it started and it run for about 10 minutes then cut off and wouldn,t start backup.

Have you run battery power and ground directly to the fuel pump to determine if the pump is good?

the pumps are good 0ne is new,when it ran ran for 10 minutes it ran at a high idle but both pumps worked and then cut off and wouldn,t start back up ,like no power was getting to the pumps.

I'll ask you again. Since your problem re-occurred, have you tested the pump by powering it manually?

If not, you need to do that before going any further. Also see if it will run when you do that.

I haveen,t are you saying run a wire from the battery to the fuel pump connector.

i just replaced fuel pump cause had no power lucky i did cause strainer was bad but still no power to it but when i run jumper from fuel relay to 12 volts the pump works it does have dual tanks but the passenger side doesnt work there is not any fuse links on power wire by battery only by alternator and down by starter both are good check fuel relay and its good. did separate the fuse box from outer but dont see any fuse links there either...have any idea on where else i can check?

Not really sure if I check it and I dont have voltage there where do I go from there as I already tried changing ecm and no difference

Yes, before we waste a bunch of time looking elsewhere, we need to know the pump isn't part of the problem and that fuel supply is the only problem.

At the ECM, check terminal A1 for battery voltage with ignition turned on. This would only last a couple of seconds as the fuel pump primes. Crank the engine and if battery voltage is available, you have a broken connection between the ECM and the relay. There are 5 terminals for the fuel pump relay, do you have battery voltage at the Tan/White wire? If no, check the oil pressure switch.

Here is a guide to help you test the relay

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Please let us know what you find.

Cheers

alright i,ll check and get back with you tuesday as it isn,t at my house.

do u have the wiring diagram for the fuel system in my truck that u can post for me

While your in the area, make sure the tension on the contacts of the harness plug are sufficient to make good solid contact. They have a known problem with them. You can use a pick to bend them a little to make them tighter.

Here you are. They are too small so I split them up. See if you can print them out and join together for a clearer picture.

will do.

ok on my truck on same bracket as fuel relay theres another relay there with different number but nothing plugged into it do u have any idea on what its there for

i read on another website that some trucks cam out with a 20 second relay for harder starting trucks not sure if thats what it is or not

These are what I have for the relay.

Sorry I do not know anything about the 20 seconds relay.

Thanks! I will get the number off the relay thats next to fuel relay. gonna go out in little while to see if i can trace down my loss voltage will keep u updated

Hot fuel is actually a small pcb inside a black plastic box located on the steering column most likely the right side just above the brake, it is usually found on pickups with the 7.4 and is used to prevent vapor lock,it runs i thought 15 sec. I have had them both stop the fuel pump as well as allow the vehicle to run with the key off because one shorted.I have found newer trucks to have them also behind the glove box. In case you are looking in a wrecking yard, i believe dealer price is around 80.00. good luck.

Great addition to this thread! Please feel free to help out whenever you are on the site :)

Cheers, Ken