Fuel pump

[swervin]

Im not getting power to my fuel pump, and after a couple tests i think its my relay. Can i just delete the relay and use a switch? (Probably cheaper considering i have a few switches already) If so what size wire should i run, how many amps should the switch (and probably fuse) be rated for, and would it be a potential safety hazard? if so what precautions would be necessary to try and aviod issues? Its for my 88 k2500 with the 5.7 btw

 

[Urambo Tauro]

Are you sure it's the relay? If so, they're really not that expensive. But I guess if you really wanted a manual switch, you could do it that way.

Where are you losing power? Have you checked the ground wire?

 

[someotherguy]

Yeah I don't understand the desire to hack around the least likely suspect in the TBI fuel system. The relay rarely goes bad. If it is bad, replace it, and rock on for the next hundred thousand miles or so...

Richard

 

[c1500deathtrap]

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On the first pic to test the pump, jump from Batt+ to the pump. If it runs pump is a ok. Next check for power with ignition switch in run on the hot on key terminals. one will go hot i cant remember which. If they don't go hot, no signal to run pump is being received. If the hot on key terminal lights up , and the relay isn't clicking and we know the pump works, then the relay is bad.

 

[swervin]

1 terminal is hot. I just watched something on youtube about the clicking befor i saw this, so im going to test that now. And while im there ill also try jumping bat+ pump. Thanks for the advice, saves alot of time and money which is deffinatly needed lately!

 

[swervin]

Are you sure it's the relay? If so, they're really not that expensive. But I guess if you really wanted a manual switch, you could do it that way.

Where are you losing power? Have you checked the ground wire?

Not sure about too much when it comes to mechanics tbh. I just dont want to bus or something like that to go pay for a relay when i have switches laying around here. I would say the switch is temporary but if something works it usually stays or is no longer a priority on the to do lists..

 

[swervin]

Yeah I don't understand the desire to hack around the least likely suspect in the TBI fuel system. The relay rarely goes bad. If it is bad, replace it, and rock on for the next hundred thousand miles or so...

Richard

Not trying to sound like a dick.. im just curious, why did you specify tbi? is there common fuel problems with tbi vs mpfi or..?

 

[c1500deathtrap]

Just try the trouble shooting and see what happens, no need to speculate.

 

[someotherguy]

Not trying to sound like a dick.. im just curious, why did you specify tbi? is there common fuel problems with tbi vs mpfi or..?

No worries...the Vortec trucks have a pretty well-demonstrated history of burning up the fuel pump relay and melting the socket in the electrical convenience center. TBI's on the other hand generally just lose a pump every now and then, and the relay often lasts the life of the truck. Vortec pump is considerably higher pressure so presumably a higher current draw; I personally think the relay and circuit are marginally spec'd.

Richard

 

[someotherguy]

If your concern is not having transportation to go pick up parts and randomly throw them in to troubleshoot...you can test the pump on its own outside of the relay circuit. If you follow the harness bundle under your brake booster down towards the floorboard (inside the engine compartment), you will see a 2 pin connector on its own. I forget the wire colors as it's been a few years but the TBI trucks have this connector to the fuel pump power. You can temporarily jump this to the battery using some scrap wire and alligator clips, just to see if the pump runs. Polarity matters so if it doesn't run one way, swap the wires and try again. Don't drive it like this, just do it momentarily so you can see if your pump is good or not.

Also don't overlook the pump ground to the frame near the tank/sender. This sometimes gets damaged due to corrosion, age, debris getting caught up in it, etc.

Richard