Failing aftermarket fuel pumps
My 3 rd aftermarket fuelpump failed (Bosch) after only 1 month. So far, I had an Airtex (9mo) 1st Bosch (3mo) now the 2nd Bosch has failed. 12VDC is there at startup. Is the voltage modulator unique to the SVX? The fuel tank is clean. Car is a daily driver. Fuel sources are the same as our other cars. Fuel filter replaced 30k ago, before the rash of failures. Strainers replaced after each failure.
Theories anyone? |
Re: Failing aftermarket fuel pumps
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The Modulator has the resistor in the circuit at idle, it only gives the pump a direct ground with the pedal down, for full flow. So when you check the pumps voltage, the ground wire will be at a voltage of say 6V, instead of 0V. Harvey. |
Re: Failing aftermarket fuel pumps
Hi Harvey! I measured 12VDC only at 1st turning the key on, then it drops...the last two were under warranty, so I didn't disassemble them...The last one wouldnt work even when I disconnected I think the yellow wire from the modulator and grounded it. The pumps would not kick over at all...
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Re: Failing aftermarket fuel pumps
Is the voltage modulator system used on all Subaru's? Could low voltage be burning out the pumps?
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Re: Failing aftermarket fuel pumps
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As you have had a few with the same problem, I would think the problem lies in the cars wiring/relay/modulator area:), but if you find that the pumps won't run, even out of the car with applied voltage, I've NFI. Harvey. |
Re: Failing aftermarket fuel pumps
I have seen some corrosion on the connector to tge tank cause misdiagnosed pump failures. Could also be a wiring issue from tank pigtail to the pump. Hace you been able to bench test the oumps failed?
Tom |
Re: Failing aftermarket fuel pumps
Hi Tom!
The more I think about it, the more the pigtail to the pump sounds like the culprit. I had ground voltmeter probes to fit the connector to pump, and had measured voltage there, but did not bench test the removed pumps. Is that connector sold separately? Arcing in the tank sounds scary... |
Re: Failing aftermarket fuel pumps
Are you getting resistance across the pump motor? You can check pin tension for the connector to be sure. Dont worry too much about arching in the tank... air to fuel ratio has to be just right to make a bang. Gonna have to pull the pump and bench test it and the wiring to be sure
Tom |
Re: Failing aftermarket fuel pumps
Pushing the topside connector on and off got the car to start and run, perhaps the flattened volt meter probes opened up the connection- Im going to use contact cleaner and a stylus to bend the connector sockets for more tension...
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Re: Failing aftermarket fuel pumps
Howd you make out gordon?
Tom |
Re: Failing aftermarket fuel pumps
Hi Tom,
A bad connection was the problem- I wonder if the original pump was even bad! I cleaned and flattened the sockets in the connector on top, car is running fine... Forcing the probes into the connector was a bad idea, have now ground a set of probes to the size of the male pins in the top connector. |
Re: Failing aftermarket fuel pumps
Glad to hear it... i never actually saw a pump fail... all were misdiagnosed... so your case definately caught my interest. Good fix!
Tom |
Re: Failing aftermarket fuel pumps
Thanks for leading me to it!!!
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Re: Failing aftermarket fuel pumps
Guys, this sounded like the most likely culprit in my latest SVX saga. Drove the car home last Friday with no issues whatsoever. The next morning it wouldn't start. The starter ran and the engine turned over. I "think" I didn't hear the usual fuel pump noise. Should this be the first thing to check? If so, how do I get to this connector?
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Re: Failing aftermarket fuel pumps
It is under the back seat. Actually if you fold down the seat and look under the carpet you should locate the pump..
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