I'm at wits end here - fuel pump bends itself???

[BigD]

So the summary of what's been happening is after I completed my S52 swap, the car didn't have a lot of balls and then finally died after a WOT pull (the second one on that trip). After a lot of cranking it sputtered and restarted, and ran like nothing happened.

I figured this is a simple case of my 20 year old pumps with 400k on them having one foot in the grave. I got two new pumps.

Installed the outboard with no issues. Went to install the inboard and I couldn't get it turned enough counter clockwise to get it to drop into the grooves (like you turn it about 30-45 degrees past square, where square is the fuel sender cutout being parallel with the front of the tank, it drops into the teeth, and you turn clockwise to tighten). I tried the old pump again and it went in as it should. I was starting to lose my mind and I pushed on it. I felt something give, it dropped into the grooves and I tightened it.

It started and ran just fine. I drove it to get gas, about 5km one way, and about 90% of the way back it died like it did before. I did a WOT pull up a hill and right after I levelled out it sputtered and died. This time there was no restarting.

I thought something electrical got fucked. I checked spark, injector pulse, everything was a-ok, DME sent 1444. Remembering the "give", I pulled out the in-tank pump to inspect it. The pump motor was offset to the side of its outlet pipe and the rubber hose was pinched shut. Like the pump outlet nipple was to the side, and directly lined up with the nipple that goes out of the tank - and the hose was stretched across the two, pinched shut.

I thought ok, it must have jammed on something and me being an idiot forced it and bent it. I put the old pump in, it started and ran great (I checked the old pump and it was fine, with the motor just a bit to the side of the pipe, with the rubber hose being at a medium angle).

I thought I fixed it. But it was leaking fuel by the seal (reused the o-ring with old pump) so I pulled it and since I had to pull it anyway, I bent the new pump straight and dropped it in. Again started and ran fine.

Went to get an alignment today, and passing the same gas station where I got gas last time, again ***shortly after going up a hill*** (and giving it throttle to maintain speed) it sputtered and died with no signs of wanting to go again.

I thought ah fuck the new pump must have bent back into its crooked position - like softened metal or something. I went home to get the old pump and tools. Came back, did a roadside fuel pump swap. Pulled out the new pump and it was indeed bent again, with the hose pinched off. I put the old pump back in, it fired and ran great again... thought I fixed it.

Went to try to go get the alignment today again, died in the exact same place, exactly the same way. Pulled out the pump and sure enough, it's bent - BUT THIS IS THE OLD PUMP NOW!!! I used NO force putting it in and there was ZERO resistance.

**** One thing I noticed ever since I put the new pump in for the first time, is when I put load on the engine, the in-tank pump makes a sound like someone is frantically trying to light a match, or frantically blowing bubbles into their coke drink. I've driven with the pump cover off before and I've never heard this sound. It happens with any of the pumps. I know it's related.

So today when I did my second roadside pump replacement, I tried to push on the tank bottom, maybe it was bent, don't think I did anything. I analyzed the top of the tank, it doesn't *seem* bent but I can't really be sure.

I knew it'd die again but I straightened the new pump and put it in. It died almost home. I pulled the pump out of the tank enough to shove a screwdriver and blindly stab the fuel pump hoping to straighten it temporarily. That worked for about a quarter mile. I did it again and got home.

Guys, what the fuck... please help!

One ad-hoc solution that comes to mind is just to bend the pipe that the pump connects to, so the rubber hose doesn't get pinched off and just not run the tank empty... FUCK.

[jlevie]

Remove the in-tank pump and level sensor and use a stick to stir the bottom of the tank. If you feel a layer of sediment in the bottom of the tank you've found one of the problems. Under high flow conditions the sediment will get sucked up onto the in-tank pumps strainer and choke off fuel flow. Shut off the car for a few minutes and the sediment will fall off and settle to the bottom of the tank, until next time.

Unless the bottom of the tank is bashed in, which should be evident from an examination from under the car, I can't think of any reason you are bending pumps. Well, I guess if there were a ridiculously thick layer of sediment that could be an explanation.

[BigD]

I think the tank floor is bent, I'm just not sure exactly what it should look like. There's a clear dent on the outer edge of it (by the fender) but that wouldn't affect the pump. I think the tank is dented in the pump area too but less dramatically, maybe the whole bottom is pushed up.

There's definitely sediment on the bottom, I can see it through the opening. But not a whole ton, and not in the area where the filter foot goes.

[BigD]

I tried pushing down on the floor through the hole with my pump jack handle but I couldn't feel it give - not that I had a lot of leverage pushing on the end of a stick. I may try a rubber mallet or something tomorrow, just don't want to rip the tank off, then I'll be a very unhappy man.

[BigD]

I dunno, I bashed the shit out of my fuel tank (put the handle of a sledge into the fuel pump hole and bashed the business end of it with a big rubber mallet). The pump area was definitely pushed up. I got it to the point where it looked more or less level with the car (just a bit bubbled instead of flat) and the pump seemed to go in fine, with the only friction being against the rubber ring. I peeked through the fuel level sender hole with a flashlight and unlike before, the rubber hose seems to be almost straight - ie the way it was when I put the pump in.

But it still makes that fucking noise - where if I accelerate it sounds like there's an electric motor inside the tank with a metal brush on the end of it, and it's spinning it, brushing it against the side of the tank, faster with the engine rpm. It gets louder when I corner too.

Gonna take it to the track day I had scheduled yesterday. Gonna trailer it, I think it'll fuck up again as before, I have no more faith in this thing until I replace the fuel tank.