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3 sets of fuel pumps failed

rporzio

New member
Joined
Mar 25, 2010
Location
Tampa, FL
I need some help. My 84 242 somehow got water in the tank and after we replaced both pumps, filter and all injectors my main fuel pump would start to whine after a few days and eventually fail. We're now on the 3rd set of both and just yesterday the main has started to whine loudly again although at this point it hasn't failed. I did replace both relays and noticed today that after the car starts the fuel pump relay vibrates slightly, don't know if that's normal. Would really appreciate some tips/help in troubleshooting to find the problem rather than replace the pump(s) again. Thanks, Ralph
 

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Have you had a good look inside the tank? My guess is that it is rusty as hell, and the fine rust particles are eating your pumps up in short order. This happened to me before, and I went trough 3 in tank pumps before I noticed. If it is rusty you can remove the tank and take it to a radiator shop to have them coat it.
 
You've replaced both pumps three times? What was wrong with them each time? Was the sock on the intank filled with crap?
 
No, my mechanic wasn't concerned about the tank after we added the new fuel components and 4 cans of HEET. I will bring it up when the car goes back in next week to try and resolve this. Thanks so much for the idea... R.
 
No the sock(s) looked ok but the main external pumps whined louder and louder then eventually stopped working. R.
 
Did you replace the sending unit? Aftermarket units are wired backwards causing the main pump to starve.
 
Confirm the in tank pump is pumping. If it isn't it will make the main pump louder, but I've never actually seen it kill them. Usually when I first get a new to me 240 the in tank is dead, and prob has been for years, who knows... Are you saying the main pump has died 3 times in succession, but the in tank has been fine?
 
Did you replace the sending unit? Aftermarket units are wired backwards causing the main pump to starve.

I replaced the sending unit on my '93 240. And while I replaced the fuel pump wiring itself (much bigger single pump in the tank) the untouched fuel gauge wiring was wrong and the gauge didn't work.
 
The safe way to test that the in tank indeed does flow gas(the right way!!!) is to take the hose off the sending unit, and attach a clear vinyl tube to it that is long enough to snake around to the tank filler neck. Energize the pumps by jumping them at the fuse box and confirm that an appropriate volume of gas is flowing out of the tank through the tube and back into the tank. I usually just pull the hose and then energize the pumps and look to see that some gas squirted out... but that prob isn't all that safe...
 
yes we tested the in tank pump by disconnecting the line to the main and visually saw fuel. The in tank pump was actually replaced twice, once because it was dead and the other just to make sure since it was an after market piece and not that expensive. The external has been replaced 3 times all with the whining and then dying symptoms leading to failure. R.
 
The in tank sending unit was replaced during the original build in 2010. I bought it from partsgeek.com 204.00 shipped
 
If the in tank isn't being killed it is prob not rust in the tank... What this is sounding like to me is a fuel pump relay issue... possibly it isn't giving good voltage to the pump? What about wiring? You need to pop the cover of the fuel pump relay and re-flow solder to all the connections. Then I would make a good test light with a incandescent brake light or similar that would pull pretty good amps, and hook it up to the power wire at the pump. See if it lights it up nice and bright... Check the wiring as much as you can for any shorting...
 
Thanks labyrinth, I replaced both relays just to be sure. What voltage should I see at the main pump itself, a solid 12V or will they run with less?
 
What brand of pumps are being installed? Cheap stuff or decent, sourced from chinabay or a reputable vendor?

The relay shouldn't be buzzing at all. I'd look at that as well. Either swap with another, see if the issue remains (if so, check your control circuit to it), of not, then you have a relay issue.

FWIW I've had a brand new Delphi sourced from one of the chain stores that crapped the bead on the test drive, so there is indeed some crap stuff out there, even thru legit channels.
 
Two from AutoZone and one from Advance. Is the control circuit the piece under the hood, front passenger side? I've often wondered about it contributing to this mess over the years. What points should be checked on the control unit? The relay is vibrating slightly but consistently, so did the old one. I was under the impression that it was either operated or released. R.
 
good point about the filter but my mechanic checked for pressure at the rail and found it to be good, does 80 something or other sound about right, can't exactly remember what he told me.
 
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