5.3 no fuel

[Ken Davis]

My truck has 200 miles on new build yesterday I was driving and it quit and I had to trailer home. After it sits for about 15 minutes it wil start and run for about 1 minute the fuel pressure starts off at 50lbs then starts going down to 10lbs truck dies the pump runs for a few seconds then dies at the end the pump sounds different. The truck did this 100 miles ago I removed the tank which is a rock valley stainless tank I checked the pump it worked fine I put the tank back in and it worked.

[truckdude239]

Bad pump what brand is it?

[Ken Davis]

I do not know the pump brand it is the one rock valley installed.

[truckdude239]

Try an ac delco ep381 pump

[ls1nova71]

Hey Ken, I guess I missed your call yesterday. Anyway, I would check your power and ground to the pump. Where is the pump grounded at? If its on the frame near the tank, you could try running it back to the engine where the rest of the harness is grounded. Could be other things, but since it worked after you pulled the tank last time, it makes me think its a problem near the tank. Illl be around today if you want to call.

[solidaxel]

How is the fuel filter?

[BR3W CITY]

Sounds like either a pump voltage issue, or a restriction issue on the filter or line somewhere, causing the pump to lose output after a few minutes.

You can also try putting a multimeter on the power wire to the pump, and watching the voltage as the FP drops. If voltage stays consistent, then the pressure issue is coming further up the line (FPR, fitting coming loose). If the current drops, then it could be a grounding or power source issue. If the current goes UP, then a restriction is causing the pump to pull more juice to run as normal, and it can/will do so until it blow a fuse, cuts out, or just heats itself and locks (depending on the pump).

I have no clue what pump rock valley gives you, but if you can find the spec's on it we can figure out a little more. If the pump isn't setup for high pressure, or just doesn't move enough fuel, that has to be addressed.

[First c10]

Is the tank vented?

[Ken Davis]

I removed the supply hose at the fuel rail and the fuel ran steady. I removed the fuel pump walbro gss340 it looked like the wires had been hot. Is there another pump that will replace this one.

[BR3W CITY]

That pump is just the regular 255, so a like-for-like replacement is fine. Any of the the other 255-derived pumps would work the same way.

Hot wires don't mean the pumps' bad, and if the pump IS bad, you gotta figure out what caused it. Otherwise theres a chance you'll end up down the road 6months with a dead pump again.

[Ken Davis]

The fuel pressure is around 50 should it be higher.

[yossarian19]

Yep, fuel pressure with a 5.3 should be more like 58-62, in there.
When you say wires "hot" you mean "stuff melted" or what?
is it an in tank pump or an external?
How's the temperature of the pump itself while running?
Engine running, are you getting a lot of noise off the pump or is it fairly quiet?
It sounds like the pump is over heating & stops working, then cools down & it runs again.
You probably need a fuel pump & if you can find some sort of heat sink to mount it with, that's a good idea too. Sadly, external fuel pumps aren't known for long productive lives - notice that just about nobody OEM uses them.

[BR3W CITY]

Originally Posted by yossarian19

Sadly, external fuel pumps aren't known for long productive lives - notice that just about nobody OEM uses them.

Shhhhh, the diesel guys are listening and angrily holding their lift-pumps.




Ken are you using the ECM to trigger the fuel pump, or is it just keyed?
Are you using a FP relay, and large enough gauge supply wire? Small gauge wire will heat up with the loads an external pump puts on it.

[truckdude239]

if its an intank pump i used an ac delo ep381 puts out rigt at 70 psi which works great on stock sending units. put the pump might not be bad if you say teh wires are melted looking resisitation in wires increases with temp and heat