Fuel pump

swervin · Nov 24, 2017

I grabbed the relay out of my other truck and poked the wires right at my fuel pump with my test light and i got power but still no fuel getting pumped (disconected the fuel filter incase it was clogged, even though i still cant here the pump) has anyone ever had their relay and fuel pump go at the same time? Seems a bit weird to me. Backstory to the night of the towing... i was running low on gas (close to completely empty which i know isnt the best for it) so i put $40 in drove for a bit (used about $5-$10 worth of gas if that) parked for about an hour then it wouldnt start.. tried hitting the tank and filter a bit with a hammer, still no start sprayed carb cleaner in the intake and it ran off that for maybe a second or 2 then just got a tow home because it was almost midnight and i had hardly any tools or anything i needed to do much

swervin · Nov 24, 2017

c1500deathtrap said:
Just try the trouble shooting and see what happens, no need to speculate.

Ended up doing the jumper between terminals in the relay tested if there was power to the pump but no fuel going through the line. Id say its safe to say the pump its self is shot then eh?

swervin · Nov 24, 2017

someotherguy said:
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

I just put a wire with male spade connectors on either end in the relay its self in the pos batt term and the fuel pump term... basically the same concept- hardwiring. Then put my test light on the ground screw of the pump and poked each wire feeding the pump and i lit up on all 3 so im getting ground and pos

swervin · Nov 25, 2017

someotherguy said:
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

That makes sense, good to know thanks!

swervin · Nov 25, 2017

Also should i get an oem replacement or after market pump? I have a couple quadrajets kickin around so i might end up carb swapping one of my trucks if not both, if i only end up just carbing 1 it would probably be my 1990 project truck (i want to keep it longer then the 1988 daily with the fuel issue) (the 1990 has a newer fuel pump in it around 3 or 4 years old) so im basically wondering if i should take the pump from the 90 dump it in the 88 then buy a higher pressure for the 90 later on if i decide to build it out (allow for possible fuel increase if i increase performance later)

Keepinitoldskool · Nov 25, 2017

No need to drop coin on a delco pump, but dont buy the cheapest. Whatever tou do stay away from airtex brand. The tbi pump only does between 10-14 psi so it doesnt need much. If you can find a delphi for a decent price then get it.

Sent from my SAMSUNG-SM-G890A using Tapatalk

swervin · Nov 25, 2017

Keepinitoldskool said:
No need to drop coin on a delco pump, but dont buy the cheapest. Whatever tou do stay away from airtex brand. The tbi pump only does between 10-14 psi so it doesnt need much. If you can find a delphi for a decent price then get it.
How much psi would you want from a pumpfor a carb set up if its on a mostly daily driven, a-b, work truck VS truck with a pretty mildly built 350 or maybe 383, occasional light/easy 4 wheelin

Sent from my SAMSUNG-SM-G890A using Tapatalk

Urambo Tauro · Nov 25, 2017

swervin said:
I just put a wire with male spade connectors on either end in the relay its self in the pos batt term and the fuel pump term... basically the same concept- hardwiring. Then put my test light on the ground screw of the pump and poked each wire feeding the pump and i lit up on all 3 so im getting ground and pos

You're probably right about the pump being shot. But there's one more thing that you can check. If there's rust around that connection, there's a chance that while you got a good ground path between the frame, bolt, and test light, it might not actually be getting to the fuel pump wire. You might want to unbolt, clean, and reinstall that connection first. (You'll want to do that anyway when you go to install your new pump.)

swervin · Nov 26, 2017

Urambo Tauro said:
You're probably right about the pump being shot. But there's one more thing that you can check. If there's rust around that connection, there's a chance that while you got a good ground path between the frame, bolt, and test light, it might not actually be getting to the fuel pump wire. You might want to unbolt, clean, and reinstall that connection first. (You'll want to do that anyway when you go to install your new pump.)

Thats probably a good idea! I think im going to see if i can remove the bolts holding the box on fairly easily, and borrow my boss' mini excavator to lift it off then back on after! Haha then i can actually see whats going on and i know putting the box back on is alot easier then reinstalling the tank if i can use the excavator (My 90 has baling wire and zap straps holding the tank up...gave up trying to get the proper tank strap back on). And then i can halfass clean the frame up quick too while its off.

Stephen · Nov 27, 2017

swervin said:
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

Is there plastic melted around one of the pins on the relay. I had a problem that was intermittent a few years back on my 96 C3500 7.4L. I discovered it that the plug on the power center under the hood where the relay plugs in had some melted plastic around one pin. The pin itself had expanded causing a poor connection. I used a very pointed pair of needle nosed pliers to close the pin. Haven't had any trouble since. The same relay is used for the A/C also

Fuel pump

swervin

OBS Enthusiast

swervin

OBS Enthusiast

swervin

OBS Enthusiast

swervin

OBS Enthusiast

swervin

OBS Enthusiast

Keepinitoldskool

I'm Awesome

swervin

OBS Enthusiast

Urambo Tauro

I'm Awesome

swervin

OBS Enthusiast

Stephen

OBS Enthusiast

Similar threads

Latest posts

Members online

Forum statistics

Share this page