4 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHNo start ? failed new fuel pump?
Leading reported evidence
Inspect oil filter
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed · Original poster
Drained the fuel and cleaned out the tank, changed the oil and inspected the oil filter.
Leading evidence: 'Inspect oil filter' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Inspect oil filter' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Took our independent shop days to find it, and when they did, they reassembled it and installed a new pump….which lasted a few weeks before recurrence.
Replace fuel filter, fuel pump, fuel pickups and level sender
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
Replaced the fuel filter, fuel pump, fuel pickups and level sender.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Porsche dealer completely replaced all hose sub assemblies with a new, Porsche-branded pump, and we are still running now.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
Drained the fuel and cleaned out the tank, changed the oil and inspected the oil filter.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Took our independent shop days to find it, and when they did, they reassembled it and installed a new pump….which lasted a few weeks before recurrence.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
working with the stepson and replacing the fuel pump on his C2, it ran great for two weeks after replacing the failed pump and then a no start, had towed home and remove the new pump to find he didn't click the feed line all the way and had fallen off inside the tank.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
working with the stepson and replacing the fuel pump on his C2, it ran great for two weeks after replacing the failed pump and then a no start, had towed home and remove the new pump to find he didn't click the feed line all the way and had fallen off inside the tank.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
4 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T053112Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Trying to get a 2000 C4 started after it sat for several years. Drained the fuel and cleaned out the tank, changed the oil and inspected the oil filter.
Replaced the fuel filter, fuel pump, fuel pickups and level sender.
Put in 4 gallons of fresh gas in the empty tank.
Tried to start. Nothing. Cranked it maybe 5 times for a few seconds each time.
Found that the new fuel pump is not working.
There was fuel in the high pressure line, and pressure at the fuel filter inlet connection. So it tried to pump initially, but it won�t pump anything now. Not sure fuel was circulating thru the rails or returning back to the tank. Possible there is blockage in rails or lines (?).
Had tested the pump before installing, and it spun. But now only hums when hooked up to 12V. Filter sock is in place on the suction side, and no obvious reason to think debris was sucked in and jammed it.
Just a coincidence that the new fuel pump went bad when trying to start the car? Buy another and try again?
Could a blocked line burn the pump out that quickly?
Thanks for any insight or trouble shooting ideas.
Not sure if it will help, but we went through a tough time with fuel pumps on our 99 C4. There is a Venturi line or a jet line that runs down into the bottom of the tank, and a fitting came off in the tank while driving. This starved the pump and burned it out. Took our independent shop days to find it, and when they did, they reassembled it and installed a new pump….which lasted a few weeks before recurrence. Porsche dealer completely replaced all hose sub assemblies with a new, Porsche-branded pump, and we are still running now.
The parts I bought were from a dealership, so OE Porsche, VDO pump w/ made in Germany stickers. So hoping they were good quality. But that said, I have had a new/replacement 964 Bosch fuel pump fail after a few weeks. So not unheard of.
Cut apart the old/original pump. Its a little rotary/gear pump, and the gears were seized due to rust (moisture collecting in the bottom of the fuel tank over the years while it sat) so no surprise there. The contacts/wiring were wrecked, likely from heat when the motor was trying to turn the seized gear pump.
Because it's a positive displacement pump, if there is a down stream restriction, it will overload the motor, unless there is a high pressure relief or bypass of some sort. Which I don't know, but doubt the fuel system has that type of overpressure protection? Fuse or relay should catch a high amp draw.
Before I removed the new pump, I tried to test that it was working while still in the car. Jumped the #30 and #87 pins on the fuel pump relay socket, and heard no sound and the jumper wire got hot quick.
Not sure that cranking a few times for a few seconds would be enough to damage the wiring/motor. Anyone know what the resistance should be across the +/- terminals on a good pump? The new one (that doesn't spin) is 0.6 ohms, which seems like that should be ok.
So I guess my next step will be to ensure there is no fuel line blockage in the rails, FPR and return line back to the tank, before trying another new pump.
Is there a good fuel system schematic (factory manual or other source) to trace the various fuel feed, return and vent lines?
Sorry, I'm new to this series of Porsche cars.
working with the stepson and replacing the fuel pump on his C2, it ran great for two weeks after replacing the failed pump and then a no start, had towed home and remove the new pump to find he didn't click the feed line all the way and had fallen off inside the tank. reinstalled and been great since.
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