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

[justbob]

https://www.racetronix.biz/p/universal-bulkhead-wiring-system-4-way/bcws-001?dfw_tracker=58263-BCWS-001&gclid=EAIaIQobChMIqZ24hqi39QIV k2xvBB38ZgheEAQYAiABEgIiEPD_Bw E


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[azgolfrat]

JB, thanks. I see this part uses 14G wire. Aero is recommending 10G (!) for the same wiring.
The fuse that came with the booster is a 40A; I think the Aeromotive can draw up to 30A.
Unfortunately, I am a chem E, not an EE, so I do not know if the 14G wire on this part that you sent me link to is sufficient for 30A.
Theory is one thing, but in practice, is it your experience that 14G is sufficient?
Thanks
-KK

[azgolfrat]

JB, thanks. I see this part uses 14G wire. Aero is recommending 10G (!) for the same wiring.
The fuse that came with the booster is a 40A; I think the Aeromotive can draw up to 30A.
Unfortunately, I am a chem E, not an EE, so I do not know if the 14G wire on this part that you sent me link to is sufficient for 30A.
Theory is one thing, but in practice, is it your experience that 14G is sufficient?
Thanks
-KK

How many amps will 10 gauge wire handle? (askinglot.com) (https://askinglot.com/how-many-amps-will-10-gauge-wire-handle)

[justbob]

All wiring is rated by the foot, and if in a house conduit, the number of wires also plays a part due to heat but that’s getting super deep.. So let’s simplify by experience.

I can’t recall offhand the highest amp rate/foot off hand besides somewhere around 10amp/10’ as being close. You are well under that between the FPDM and the pump.

If it helps you rest I used this kit on mine along with their added dual pump relay kit and all my power came from the battery on a fused 0G wire to a distribution box mounted just to the right of the spare tire on the back wall of the back seat. From there I fed a speaker amp, a sub amp, and power for the fuel pump relays.

The only part of the original wiring bung I retained was for fuel level sender. I took the other two wires and simply wrapped them around the assembly for the time being. The new bung that I showed you powered my twin 340’s with its four wires. I no longer used the FPDM as I went to a return style fuel loop. Anyways my pumps were so efficient that Jeff at Marty’s said we could easily dial her up mid to upper 800’s at the wheels and every supporting system was up to par (except the current clutch and lack of head studs) Plenty of fuel, air, maf…

They also claim it’s not to be used in returnless fuel systems and yet we’ve done it for decades without failure and adding boostapumps as well.

Anyways, here was mine.

https://uploads.tapatalk-cdn.com/20220117/5d9d3218ad9acbfdf9c4bd5ab53814 19.jpg

https://uploads.tapatalk-cdn.com/20220117/0ed795301fe64fc4cd14dce2e97060 07.jpg
https://uploads.tapatalk-cdn.com/20220117/b84097b32f93e6d06bc32e17db1dad 39.jpg


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[azgolfrat]

Great photos JB. Really very helpful. Got it.
Thanks!
-KK

[MyBlackBeasts]

Aeromotive is also plagued by counterfeit pumps being sold in USA via eBay and other sites. They have a high failure rate.

[justbob]

Aeromotive is also plagued by counterfeit pumps being sold in USA via eBay and other sites. They have a high failure rate.

Very true. I purchase almost all parts that matter thru Summit when possible.


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[azgolfrat]

All wiring is rated by the foot, and if in a house conduit, the number of wires also plays a part due to heat but that’s getting super deep.. So let’s simplify by experience.

I can’t recall offhand the highest amp rate/foot off hand besides somewhere around 10amp/10’ as being close. You are well under that between the FPDM and the pump.

If it helps you rest I used this kit on mine along with their added dual pump relay kit and all my power came from the battery on a fused 0G wire to a distribution box mounted just to the right of the spare tire on the back wall of the back seat. From there I fed a speaker amp, a sub amp, and power for the fuel pump relays.

The only part of the original wiring bung I retained was for fuel level sender. I took the other two wires and simply wrapped them around the assembly for the time being. The new bung that I showed you powered my twin 340’s with its four wires. I no longer used the FPDM as I went to a return style fuel loop. Anyways my pumps were so efficient that Jeff at Marty’s said we could easily dial her up mid to upper 800’s at the wheels and every supporting system was up to par (except the current clutch and lack of head studs) Plenty of fuel, air, maf…

They also claim it’s not to be used in returnless fuel systems and yet we’ve done it for decades without failure and adding boostapumps as well.

Anyways, here was mine.

https://uploads.tapatalk-cdn.com/20220117/5d9d3218ad9acbfdf9c4bd5ab53814 19.jpg

https://uploads.tapatalk-cdn.com/20220117/0ed795301fe64fc4cd14dce2e97060 07.jpg
https://uploads.tapatalk-cdn.com/20220117/b84097b32f93e6d06bc32e17db1dad 39.jpg


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JB, what would you say is the best method for making the hole in the hatch cover for the new bulkhead? Is a drill press required? Will and hand held drill do?
thanks


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[blazen71]

These work great for thin/sheet metal. You can use a hand drill.

https://www.irwin.com/tools/browse/drill-bits/unibit-step-drills
.

[justbob]

These work great for thin/sheet metal. You can use a hand drill.

https://www.irwin.com/tools/browse/drill-bits/unibit-step-drills
.

This is the best to use. Hand drill is fine but I like to drill a pilot hole and not burn up the step bit. I honestly recall it being a little difficult to drill thru. Could have been my bit I suppose. Get a Milwaukee brand step bit from Home Depot. All others are junk.


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[azgolfrat]

Blazen & JB,
Just back from 8 day golf boondoggle (4 days of driving, 4 days of golf), and getting ready to install the new fuel pump and new connector from racetronix.
I will go by a Milwaukee step bit.
Thanks for all your help. If you are looking for golf lessons, I'm in your debt and at your service :-)
I'll send photos of pump/connector install
-KK

[blazen71]

No problem. You're trying, so I don't mind helping!

[azgolfrat]

Hey guys,
Willy and Nilly are over and we were getting ready to drill into the hatch for the bulkhead / connector mentioned above. Then Will and Nilly suggested slowing down a bit. Ya know, think about it.
Well, when Willy and Nilly say slow down, it's a good idea to do so.
So here's the questions the three of us had:
52270
The oring in the photo would wind up, after install, on the top side/outside of the tank, while the silver colored push ring clamp would be inside the tank, correct? (This is what JB's photos above look like to me)
Also, the diameter of the plastic cylinder that goes through the tank measures just a teeny bit over 10mm diameter. So...its seems drilling a hole 10mm diameter is needed, correct?
Thanks guys.
-KK

[musclemerc]

What do you gain by installing a new wiring bulkhead?

Your using a single pump and IIRC the stock wiring is 12AWG the racetronix bulkhead is 14AWG.

Not an upgrade IMHO.....

[justbob]

Stock is 14g as well but I seem to recall the Racetronix 14g a bit beefier under the insulation.


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[justbob]

Hey guys,
Willy and Nilly are over and we were getting ready to drill into the hatch for the bulkhead / connector mentioned above. Then Will and Nilly suggested slowing down a bit. Ya know, think about it.
Well, when Willy and Nilly say slow down, it's a good idea to do so.
So here's the questions the three of us had:
52270
The oring in the photo would wind up, after install, on the top side/outside of the tank, while the silver colored push ring clamp would be inside the tank, correct? (This is what JB's photos above look like to me)
Also, the diameter of the plastic cylinder that goes through the tank measures just a teeny bit over 10mm diameter. So...its seems drilling a hole 10mm diameter is needed, correct?
Thanks guys.
-KK

If you chose to go ahead you are correct, o ring on the out. 10mm? I’ll pretend you said a hair over 3/8” [emoji6] Anyways just run the step bit in and start to easily wobble it just a touch from both sides once you hit the 3/8” mark on the step bit. Gives it a nice little seat for the O ring and a smooth surface on the inside. Slide the locking ring on and place a socket over it and carefully “help” it seat fully with a light tap.

Maybe check the actual wiring thickness, compare the two and school us. It’s been awhile for me and that really wasn’t a concern as I just needed wiring for a second pump. I swore the stock wiring was even smaller but wiring diagrams say 14G. Kind of curious now.


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[azgolfrat]

MM, you may be right. For me, new to all this, it's a good learning experience.
I'll measure the stock and racetronix wire size, but in any case, going to go ahead.
Thanks for the answers above JB!

-KK

[azgolfrat]

Hey Guys,

The Racetronix mic's at about 1.8mm, which translates to about 13g. The insulation is labeled 14g. 14g = 1.63mm

I had cut the power and ground wires to/at the pump in order to remove the defective pump. I stripped a little insulation, and both those wires mic'd at 1.65mm, so definitely 14g.
So the racetronix wiring is just a bit larger in diameter, at least in my case, 1.65 vs 1.8mm (as you thought JB).

If you do the math, since resistance goes down (1/x) as cross section increases and cross section is proportional to the square of the radius, the small difference in conductor diameter creates about 19% less resistance.

So, there you go.

Underway. Hope it goes well.

[justbob]

I love math. [emoji1303]


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[azgolfrat]

So JB,
A couple things

1)Home Depot and Lowes here were pretty much out of step bits. But I did go to Harbor Freight and bought a 19$ 3-piece Bauer (like my old hockey skates?) set... worked really well. I drilled the smallest pilot hole I could, then used the appropriate step bit. No problems..very clean. Used a small file to clean back side. I wobbled the step bit as you said, and I think that did create a nice seat for the oring. Thanks very much for the advice.

2) The clamp ring on the inside was a bit of work to get down snug; I used a socket as you described above...needed an extra pair of hands, but got it done. Here's my question - The bulkhead is now snug, but can be rotated with a moderate amount for force applied. Do I need it so tight it cannot be rotated? I'm going to do a water leak test, but thought you might have some insight.
See photos

52278
52279

[justbob]

I think mine moved a bit too before I finally said enough was enough. Not the best of designs. Rest assured zero leaks.


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[azgolfrat]

Well, pretty much got it back together after confirming pump operation with 12 volts and a bucket of water.
But here is a question:

According to alldatadiy circuit diagram, the two wires that run the pump come from the FPDM (fuel pump driver module). One wire is colored Brown/White, the other is Pink/Black.
I have confirmed that there is connectivity on these wires to the pump using an ohm meter. Since I added new wiring (Racetronix) from the pump through the tank hatch, I now need to splice the two new from- pump wires to the BN/WH and PK/BK going into the FDPM. What I don't know for sure is which is the hot wire, the BN/WH or the PK/BK . I do know which of my new wires needs to be spliced to the hot.

The applicable alldatadiy diagram shows the BN/WH and PK/BK terminating into the FDPM, but nothing else.

I'm thinking that the Pink/Black carries the 12V into the pump (stock) and the Brown/White out...but not sure.

Thoughts?

[justbob]

I see what you’re saying. I probably just hooked a test light and hit the key to verify when I did it.


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[azgolfrat]

Well guys,

I've put all the pump wiring in place, included the slightly larger gauge wires from the FPDM to the pump. These two I connected in just out of the FPDM connector.
Along the way I checked for pump operation.
If I put 12 volts on the wires leading to the pump, using the car battery directly, the pump will run.

If I attempt to put 12 volts to these wires via the FDPM (stock set up...for now the booster and relay are out of the circuit), the pump will not run. In this situation, I have confirmed that the Pink/Black out of the FDPM has 12 volts on it.

That is, any time the FDPM is used for providing ground to the circuit , the pump doesnt run. In fact, a continuity check between the 14g Brown/White wire out the FDPM and ground shows no connection. The Brown/White out of the FDPM is the other wire, along with the Pink/Black out of the FPDM are the 2 wires that go to the pump.

I've confirmed 12 V in and out of the fuel shutoff switch.

So, at this point I think the FDPM is bad.

Does anyone know of way of bench testing a FDPM ? I'd like to do that before putting the spare FDPM I pulled from a junkyard car in its place.

Please, if you need more info to help, I can provide, as I have run lots of diags.

Thanks
-KK

[justbob]

Sounds to me it’s already pressurized so the PCM simply isn’t sending a command?


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[azgolfrat]

JB, well, there is no gas in the tank. nothing at the fuel rail. could i read the appropriate pressure signal using the obd2 / tuner gizmo ? ( xct?)


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[azgolfrat]

does the fuel pump run, at least momentarily, when the key is turned to on?


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[justbob]

JB, well, there is no gas in the tank. nothing at the fuel rail. could i read the appropriate pressure signal using the obd2 / tuner gizmo ? ( xct?)


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You could log FPvoltage or Fuel pressure

does the fuel pump run, at least momentarily, when the key is turned to on?



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Not always. If it is holding a certain pressure then no need to run. I have no clue what the threshold is but I know my old set up like yours didn’t run the pump every time you hit the key. I know RacerX (and others) used to build modified FPDM’s. Something you might want to consider to fully compliment everything else you’ve done.


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[blazen71]

http://www.black306.com/?page_id=13

[azgolfrat]

Blazen ,
Thanks! - I may wind up there.
-KK

[azgolfrat]

Hey Guys,
Well, got the pump going with booster and relay added to the circuit along with FPDM.
JB, I think you were on to it; even though there was no fuel pressure in the fuel rail, I think the sensor was telling the PCM there was pressure, and therefore I wasnt getting any hum of the fuel pump when the key was turned to "on".
I disconnected the frps from the main harness, put the key on and checked the voltages that were going to the sensor..all looked good. Turned off the key, reconnected the harness and the sensor, turned the key back on and ...."hum" from the pump for about 3 seconds.

I may have bent the level sensor float arm on the fuel pump module a bit, as I'm stuck on "F" on the dash gauge....so, I'll have to get in the tank one more time. It's getting easier :-)
Anyways, as always, thanks for all the help.