3rd Fuel Pump in a year?

Hey guys, I have a 1996 Chevy Silverado 4.3L C1500

Truck runs fantastic and is in great condition still but I've had this fuel gremlin for the last year that I can't figure out. I just had my fuel pump go out last year. It had prob 200k miles on it. We put a new pump in and the truck ran great for about 5k miles then the same issue happened, truck wouldnt start and the fuel pump wouldnt turn on when I turned the key over.

Thinking maybe I got a bad pump? I put another fuel pump in. This time the truck ran the same about 5k miles and then stalled out on me.

If I let the truck sit for a few days, the truck will cold start strong and fire up right away. Run for about 20 mins then die. And wont restart, and the fuel pump wont kick on when I turn the key over. If I wait a few days, cold starts strong, runs for 20 mins, then dies.

So something was up.

I looked in my relay box and started doing some electrical testing on the relay contacts. I saw I had a short under one of the relay wires. I repaired it.

Thinking this fixed my problem.

The truck is still doing the same thing. Runs for 20 mins, dies, and wont restart (the fuel pump wont turn on) untill I let the car sit cold for a few days.

Did I find the problem? And just now this fuel pump is worn out and just need to replace it with a 3rd and final pump? Also should my fuel pump relay get warm to the touch with the truck running? I know mine does but none of the other relays are warm to the touch. Also the relay is new.

Talk soon!

The most common problem that I repaired is the connectors of fuelpump somtimes it burns and loose Ground make the fuel pump damaged ,,,so make sure that connectors coonected properly also make sure ground is Good ..

In addition to what abe1204 said, I recommend a voltage drop test on the power feed, too.

This video shows ScanneDanner doing a voltage drop test on a computer. The same method is applied to the fuel pump.

I would also look for signs of arcing at the blade fuse connector

Ive checked the grounds, back near the fuel pump and they seemed fine? I just checked to see if the bolt was lose or any wiggle room and nothing, everything was tight. Is there any way to digitally check the ground? Is there any way I can check the connector? I did stab a t-pin into the back of the connector (engine side, non pump side) and tried to crank the truck with my 12v circuit tester touching the t pin and got nothing.. but I was thinking I wasnt doing it right or wasnt grounded the test light correctly (I just got it), and then the battery instantly died on the truck so I just moved on.

I can do a voltage drop test on it and see what happens. My multi-meter knowledge isnt the strongest

What will the arcing do? And are you talking about the relay or is there another smaller fuse? My relay pin slot is a little melted from the previous damage of the wire shorting out under it. But I repaired the short and exposed wires.

There is Oil pressure sensor that control the fuel supply going to the fuel pump ! the Orange wire and gray wire are contacted when engine start to power up the fuel pump relay . It is located behind the Distributor ., hope this make help !

What brand of fuel pump did you get? Hopefully something good?

Do voltage drop as suggested, check all wires for resistance, trace wires from back to front or opposite and make sure the wiring isn't hard and brittle.

IF there's any plugs, blocks check them for corrosion, brittleness.

Have you maybe tried bypassing the wiring from the relay out to the back or wherever the last point is before it heads back there?

Does it do it if it idles, driving only, combination in regards to the shutting down for 20min.

Did you replace the whole pump assy in the tank or just the motor part? I know not many people do just the motor part but never hurts to ask.

Check and compare voltages, grounds, etc.

IS it wiring? Could it be a warmed up internal collapsed fuel line? I know that's a long shot but better to ask than not.

What state is this vehicle in out of curiosity?

Sent from my SM-N975U1 using Tapatalk

Voltage drop test. If the pump doesn't work, substitute a load like a headlight bulb and turn on that light with the existing wiring at the pump. Then take a voltage reading of the feed and the ground to make sure feed side reads battery voltage and the other reads close to 0. Lower voltage requires more amperage to get the same work done.

jreardon wrote: Voltage drop test. If the pump doesn't work, substitute a load like a headlight bulb and turn on that light with the existing wiring at the pump. Then take a voltage reading of the feed and the ground to make sure feed side reads battery voltage and the other reads close to 0. Lower voltage requires more amperage to get the same work done.

What would this do, because you need some type of load to see if the circuit is working? And if the fuel pump is dead, no load, no circuit? I started taking some basic electrical circuit courses.

I've read about a similar condition some where else.
I think John is spot on here. I think the fuel pump ground is on the frame rail back there somewhere. It corrodes which results in voltage drop which further results in repeat premature failure of the fuel pump.

The bulb is used to load the circuit to get an accurate idea of circuit integrity under working conditions.

The top suspect in multiple fuel pump failures is generally crap in the tank, floating around, clogging the strainer and killing the pump.

Question has the fuel filter been changed ever?? Maybe it’s killing the pump. Also definitely check voltage drop

Noah wrote: I've read about a similar condition some where else.
I think John is spot on here. I think the fuel pump ground is on the frame rail back there somewhere. It corrodes which results in voltage drop which further results in repeat premature failure of the fuel pump.

The bulb is used to load the circuit to get an accurate idea of circuit integrity under working conditions.

The top suspect in multiple fuel pump failures is generally crap in the tank, floating around, clogging the strainer and killing the pump.

I just got the fuel tank out and the fuel pump out of the truck. So I am waiting on a new fuel pump to get here. I understand the concept of plugging in a headlight, or a tail light (easier for me to remove) because they use the same 3 pin connector plug. But how do I check the ground on the frame of the truck? I visually inspected it and it doesnt look like any corrosion is on it. Just looks like a slight surface rusted frame.

Truck is in excellent condition btw. One of the cleanest c1500's around. Got 380k all original engine transmission.

Fuel filter is always changed. But I am going to put a new one in with the new pump.

Inside the fuel tank is spotless visually. No crap on the bottom. No crap floating around.

I've been working my way through the scanner danner courses. I'm like half way through the basic electric. Pretty cool stuff.

Also I get the parts from rockauto, and get the acdelco pro or the oem if its available.

Hook up the two leads from the bulb to the power and ground for the pump.
If so is well it should light nice and bright.
You can take it a step further and perform a voltage drop test. With your multimeter set to VDC black lead on battery negative, red lead on the the pump ground with the bulb in the circuit and lit up, you should read virtually no voltage. A few hundred millivolts at most.
You could do the same test with the pump in the truck running, but since it's already out the bulb will sufficiently load the circuit.

abe1204 wrote: There is Oil pressure sensor that control the fuel supply going to the fuel pump ! the Orange wire and gray wire are contacted when engine start to power up the fuel pump relay . It is located behind the Distributor ., hope this make help !

Do you know where this sensor is behind the distributor?

Alright made my little lightbulb rig , which is the first photo. I can get it to light up if I connect both ends to my dewalt battery



This is how I hooked it up, turned the key on, and attached one end to the Grey wire terminal and the other to a clean body panel. It didn’t light up.



Then did the exact same with my multi meter and got this





Checked the battery with my meter and it’s got 12v. I’ll be here all day, weather is beautiful

According to my Haynes Manuel, the grey wire is the power coming from the relay. I don’t think we are getting power back there. I’ve tried a ton of different grounds, and can’t get the bulb to light. It lights fine off my battery

Wait a min, the multi meter test I did was checking voltage... reading 0 meaning no drop, meaning either that wire isn’t getting power, or it’s grounded out. Right? I’ve been studying the premium videos every day!

So I just checked my relay, the bottom left (orange wire relay #87) gets power wth the key on



Shouldn’t the top left (dark green / white) wire get power as well since the ground is on the other side?

Or does it work like this

Orange is hot with key on, ready

Once I crank the engine, dark green white get power closing the switch, now orange flows through to grey down to the pump. That’s how it looks on here

I feel like I need to check that ground, black/white. Anyone know where it goes? Or how to check it

stylingpat wrote: Or does it work like this

Orange is hot with key on, ready

Once I crank the engine, dark green white get power closing the switch, now orange flows through to grey down to the pump.

You got it. That is how it works.

The relay should send battery voltage down the grey wire to the pump. If you are only getting 3.2v-4.7v, at the fuel pump, then that is your problem.

Check voltage on the grey wire, at the relay. If you have battery voltage on the grey wire the relay, but only 3.2v-4.7v at the pump, you have a problem with the grey wire. If you have battery voltage on the Orange wire, at the relay, and only 3.2v-4.7v on the Grey wire, at the relay (when closed), then you have a problem with the relay.

If you can, try to use the same ground source for all of your voltage readings. A pair of jumper cables might help. (You only need to hook up the Negative, and use that as your ground.)

Chad wrote:

stylingpat wrote: Or does it work like this

Orange is hot with key on, ready

Once I crank the engine, dark green white get power closing the switch, now orange flows through to grey down to the pump.

You got it. That is how it works.

The relay should send battery voltage down the grey wire to the pump. If you are only getting 3.2v-4.7v, at the fuel pump, then that is your problem.

Check voltage on the grey wire, at the relay. If you have battery voltage on the grey wire the relay, but only 3.2v-4.7v at the pump, you have a problem with the grey wire. If you have battery voltage on the Orange wire, at the relay, and only 3.2v-4.7v on the Grey wire, at the relay (when closed), then you have a problem with the relay.

If you can, try to use the same ground source for all of your voltage readings. A pair of jumper cables might help. (You only need to hook up the Negative, and use that as your ground.)

Damn good call on the jumper cables to battery negative for a consistant ground!!!

So I imagine then, I have to test this while the car is cranking? Because it cant run, the entire tank is out.

What should I do about the battery dieing from the cranking? Can I hook jumpers up from the truck to another battery and crank that way? It would pull the power from the second battery in a running car?

And how would I check the voltage of the grey wire AT the relay? Wouldnt I have to have the relay taken off? Or do I need to get one of these so I can hook the relay up, so we can get juice from the orange wire.

www.amazon.com/Lisle-56810-Relay-Test-Ju...p%2Caps%2C173&sr=8-1

The voltage was in millivolts on dvom. If the key is turned on he will need to look at the bulb / multimeter at that same instance key is turned otherwise pcm shuts it back off. Only other way to do it is jump the relay terminals for the fuel pump feed and test power and voltage drop