Aeromotive fuel pump might be the problem

[azgolfrat]

Well, we cranked the engine over for the 1st time yesterday. Sounded good!
But , no fuel.
Lots of troubleshooting indicates the fuel pump may be bad. We can hear it buzzing, but there is no fuel coming out of the tank to the fuel rail connector
Do you guys know, can I weasel that fuel pump out without dropping the tank?

When I put the aeromotive pump in, I did drop the tank...and that was NO FUN. I'd like to avoid if possible.

Thanks

-KK

[musclemerc]

Yes, it can be done. Unbolt the PS exhaust hanger, jack the car and look. the hat is 100% accessible.

Will require a cut and solder on the wiring harness or weather pack connectors

[massacre]

The hose from the pump to the hat might be leaking. Yes it can be removed without dropping tank

[justbob]

I agree on the fuel line popping off. Not the first one to happen if so but the couple of times I’ve read about it took a few days or weeks of use.

Is there any possibility you wired it up backwards?


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[musclemerc]

Just for clarity the fuel level needs to be lower than the bottom bolt on the fuel hat.

If the tank has a fuel level higher than the lowest section of the fuel hat, fuel will spill on the garage floor, and possibly on yourself.

This is a PSA........... That is all........

[azgolfrat]

Hey guys,
Thanks.
Well, Since I've pulled the tank before, I was familiar with the work, didn't want to cut wires (need soldering lessons...always screw it up), and hey, I wanted to get a look at that pump. So out came the tank.
It had 4.5 gallons in it.
Got the tank out, got the pump out.
Everything looked good. No fuel line popped off.
Previously, while troubleshooting (yesterday), we ran 12V from the battery directly to the pump by connecting the battery and a ground to the output/input connector of the FPDM. When we did that, we could hear the pump buzzing. We then disconnected the fuel line at the rail, and reapplied the voltage; same buzz, no fuel.
So..long story short, got the pump out today, put it in a bucket of water with a long hose on the output and whatyya know - buzz, but no water being pumped.
Still have the old oem pump ; wired it up in the bucket, lots of water pumped :-)
The brand new Aeromotive, which had never seen fuel , had sat in an empty tank since July of 20, is bad.
Chris is sending me a new one pronto. Chris is great, and I can't say that enough.

Hey justBob - alldatadiy really helped us several times in our troubleshooting (Daniel.Driver was here helping - wonderful guy & FAST Marauder). Thanks very much for pointing me there.
-KK

[justbob]

Good to hear! I’ve relied on Alldata for many many years mostly for diagrams and torque specs.


That’s pretty odd to make noise and not pump. Probably just needed a tap on the concrete from sitting LOL. Honestly it wasn’t sitting all that long to not work? I’ve had nothing but great luck with 340’s other than each one sounding differently. In the old taxi I had one somewhere around 10 years old?? Super quiet, switched to twin pumps 5 years later and the added one sounded like it was flowing sand thru it but pumped plenty fine.

Make sure to only use a quality clamp made for fuel injection and not a worm gear style. Seen a few of those pop right off.


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[blazen71]

I would use cinch clamps and plastic accordion hose for the pump. It’s the most reliable

[blazen71]

I’m also a big fan of Walbro 255’s

[azgolfrat]

Well JB, the worm has turned (for crying outloud).

I noticed in my video of the bench test with water wherein the pump made a hum, but did not pump,
that the prime hole - which is at the opposite end of the pump from the filter sock -
was not submerged. :/
So, I re did test making sure the prime hole was submerged, and the pump worked. GEEZ.

When we tried to start the car and got no fuel, I had approx 4 gallons of $4.15 per gallon premium in the tank.
The tank is approx 9 in wide by 38 in long (at base, and up for a bit). L*W & converted to cm^2, this is 2200 cm^2
Assuming 3785 cm^3 per gallon of gas (water)
3785 * 4 gallons of gas = 15140 cm^3 of gas

15140cm^3/2200cm^2 = 7 cm height of gas in the tank when 4 gallons are in the tank.
7cm is less than 3 inches.

Unfortunately, the prime hole sits 4 inches above the sock. Assuming the sock is right at the floor of the tank when installed, which I think it is not, the prime hole was not covered when we tried to start the tank.
:/
So, JB, you were right in this case (again)...something is weird about a pump buzzing but no fuel. And now you know the rest of the story. Hmm. Well, At least I am not buying a new pump.
My big question is this... lets suppose I run the tank down to 2 gallons. The height of the gas in the tank will be below the prime hole. Will the prime be maintained over night until I start the car to go to the gas station?

Recall, the pump was new, and had sat it my empty tank for 18 months while I messed around with everything else trying to get the car ready to run. Arrrgh.

[justbob]

Great find bud! I honestly never knew of a prime hole in them. For what it’s worth I as well as many others I assume have easily been down to literally the last gallon when parked for a night or several weeks for that matter and never once had an issue of a no start.


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[azgolfrat]

one more worm turn :
To make sure I was on the right track I called Aeromotive. They said "nope, the prime hole is on the bottom (very near the tank bottom when installed). The hole on top is a vapor purge port.
The pump should have worked when the prime hole (bottom) was in the water container, whether the pump was fully submerged or not.
Aeromotive then said, "send it back, and we will send you a new one."
Looking forward to the victory lap on this one...but, not at all sure when I am going to run it.

[musclemerc]

These pumps have proven to be hit-or-mis from day 1

[massacre]

You'll get it OP

[azgolfrat]

Guys, while I got everything to do directly with the fuel tank taken apart, I was thinking of increasing the wire size (ground and hot) out of the stock FPDM to the pump.
Is there a BKM (best known method) for doing this in light of the weather pack/grommet that runs through the circular gas tank hatch door? Not clear to me how I put larger wire through that baby.
Literature from Aeromotive that came with the pump suggested this wiring upgrade.
Thanks