I hear the fuel pump, but no fuel...

[Perkster029]

So, I'm not getting any fuel moving from the tank. Somewhere around 11.5V-12V when the ignition is turned "on" for a few seconds, then no voltage. And same voltage the whole time when cranking. So, the signal seems good.

I pulled out the tank and tried to get it to run with a 12V signal. Can someone double check me here? On the connector as shown on the pic below, from top to bottom, Fuel Pump +12V, Gauge, Gauge, Ground. Right?

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I hear the pump making noise, but still no fuel comes out. Tank is about half full. Bad pump?

Edit: stock c5 donor pump, 2001

[Shoeless]

I think I remember Shane telling me if you don't block the crossover outlet that is on the inside of the tank on the pump, you won't get any fuel pumping. Not sure if this is your issue or not.

[Perkster029]

Hmmm. That sure would be something, I don't see any mention of it in the manual, and that would be the FIRST time that's EVER happened.

[Shoeless]

I had to block mine off with a stainless bolt and hose clamp. I don't think I have any pictures of it, but I'll take a look and see. Just to note, I'm using the Lingenfelter High Flow Fuel Pump.

[Perkster029]

Oh! Is yours the 03-04 tank? Mine's from a 2000

[Ray]

Are you sure that you have the supply and return lines on the correct fittings?

I learned the hard way on our build to check the simple stuff first.

Ray

[Shoeless]

Oh! Is yours the 03-04 tank? Mine's from a 2000

I went with the aluminum tanks for my build.

[Perkster029]

Are you sure that you have the supply and return lines on the correct fittings?

I learned the hard way on our build to check the simple stuff first.

Ray

I wish it was that easy. I actually had the tank sitting on the ground, both the return and supply routed to a bucket, energizing the pump with +12V. No fuel comes out :/


I went with the aluminum tanks for my build.

Oh neat! Maybe I'll take my pump out and inspect, see if there are any obvious things that might be a crossover port.

[Shoeless]

Take a look at Step 76 on page 23. I think this is the clearest view of the jet line that I had to block off on my fuel pump. Not sure if yours is similar, but this is what I had to block off.

https://www.lingenfelter.com/PDFdownloads/L710140105.pdf

[EMO]

Maybe the pump is wired in reverse polarity?

[Perkster029]

Maybe the pump is wired in reverse polarity?

Ya know, I actually tried that! I swapped the +12V test signal and ground. Pump still made noise, still no fuel moving.


Take a look at Step 76 on page 23. I think this is the clearest view of the jet line that I had to block off on my fuel pump. Not sure if yours is similar, but this is what I had to block off.

https://www.lingenfelter.com/PDFdownloads/L710140105.pdf

I'll check this out tomorrow

[VRaptor SpeedWorks, LLC]

Pin A is power to the pump and Pin D is ground for the pump. You don't have the plastic check valve installed backwards in the external fuel line? If you have fuel in the tank and just an open hose coming off the pump to a bucket and you can hear the pump run, it seems like you should definitely have some fuel coming out...even if the pump wasn't working at 100%. The port that Shoeless mentioned is only on the '04 tanks. The inside of your tank is pretty simple....you have the pump attached to a flexible plastic hose and that hose is attached to the steel outlet port that you have your fuel hose connected to. There should be only 3 possibilities.....either the pump is somehow not getting fuel (which should be pretty much impossible if your tank is half full) or that plastic flex hose is broken or the fuel pump is shot. I just don't know that I've ever run across a fuel pump that you can hear running, but won't pump any fuel at all. Yeah....as they go bad, either it completely stops running or still runs but can't create enough pressure to run the engine......but to hear it running and not even have enough pressure to pump fuel out of an open hose into a bucket (zero pressure required for that)....just doesn't make much sense.

[Perkster029]

All, thanks for troubleshooting this with me! I may have found an answer:

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That spring doesn't seem like it should be like that..... should it? It's at a weird angle.

I think I'm just buying a new pump, at this point. I won't feel comfortable with this one, knowing it had issues in the past.

[VRaptor SpeedWorks, LLC]

That spring just holds the pump tight to the bottom of the tank so it's not just flopping around inside the tank. So that brown flex hose inside the tank is your pump output....and you don't have anything else in that fuel line connected to that port?....it's just an open hose and nothing comes out? If that is the case, then yes, I would say your pump is shot.

[Perkster029]

You got me taking a closer look at the pump output, and I think I realized something. Is the FFR manual wrong?

The one they label "cap" is the one connected to the pump...

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[beeman]

https://thefactoryfiveforum.com/showthread.php?34425-Help-please-OEM-C5-fuel-pump-line-identification&highlight=Corvette+fuel+pump