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Possible Fuel System Issues (Weird Noises)

2manyturbos said:
That may be your only choice for the in tank pump. Their quality control is also dismal. They have been making pumps that are wired backwards. That doesn’t give me much faith in them.
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Apparently they are not even an option from RockAuto (I'd order from IPD, but the two pumps are on "whenever we get them" status).
My options for an in-tank pump are Ultra-Power, AutoBest, GMB, and Carter.
 
CaliMeatWagon said:
1991 745T w/ LH 2.4

Yesterday I noticed this weird humming noise coming from the center of the car. I didn't pinpoint the sound, but when I put my hand on the inline fuel filter its vibrations matched with the sound. And when I filled up with gas, the sound went away.

So I'm guessing it was because I was low on fuel, but it only took 12.6 gallons to fill up and I know I have a 16 gallon tank. And my previous 91 740 never made those noises even when it was on E.

So what could be going on here?

For some extra info that may or may not be pertinent back in July I had to clean out the tank and replace the in tank fuel filter because it had been sitting for 7 years. And two weeks ago I replaced the inline fuel filter. Also, my gas gauge doesn't work (no signal at sensor wire) so I have no idea what it would have read when the noise was going on.
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Anyone heard of problems with the cloth strainer(filter) on the end of the inboard pump? I thought I read somewhere a guy was having similar fuel flow problems with a low fuel and a high fuel tank. Turns out the strainer was collapsing in a low tank and clogging the 'feed' to the pump.
 
Definitely sounds like a non functioning pre pump. When they go out, they don't provide a constant enough fuel supply to the main pump, and the main pump, then, makes those loud cavitation sounds, because it's just too far back to the tank, down the sender pickup pipe, to the bottom of the tank, and then,to the pre pump, and if it's not working, that then becomes a restriction in the system. This system needs a pre pump. The normal symptom for a failed pre pump, is a noisy main pump at 1/2 tank or less. The noisier, the lower the fuel level. Is it possible that the wiring got damaged when the pre pump sock was replaced. The fact that your fuel gauge also doesn't work, leads me to believe that, maybe, both problems may very well be wiring related, maybe the wiring plug loose? Think I'd get back there, and take another look at the wiring, and pull the sender back out to inspect, before I just bought replacements. Good luck!
 
I have yet to try this, but I've heard switching to a higher flowing, single unit in tank pump is a good option. I believe walbro is what the folks on here go for, maybe someone can chime in about switching to a single unit set up, or otherwise I'm sure there are lots threads covering it. With the limited supply of good pumps, that might be the best bang for buck. Something I'm starting to consider doing myself.

I hear you about the funds. Seems like the more my hourly wage goes up, so then does the price of everything.
 
moetheshmoe said:
Anyone heard of problems with the cloth strainer(filter) on the end of the inboard pump? I thought I read somewhere a guy was having similar fuel flow problems with a low fuel and a high fuel tank. Turns out the strainer was collapsing in a low tank and clogging the 'feed' to the pump.
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I've heard a couple people say that when they had their in tank pump that the sock fell off, causing pump failure. That could've been user/installer error but maybe something to keep an eye, if it doesn't fit quite right or something .
 
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