7 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHstumbling - fuel pump intermittent fail ?
Leading reported evidence
Check relay
Performed · outcome unconfirmed
No successful repair reported for this finding.
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Leading evidence: 'Check relay' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check relay' (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.
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Performed · outcome unconfirmed · Original poster
Then again - there is no CEL and I replaced the coil packs less than 20,000 km ago.
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Performed · outcome unconfirmed · Original poster
Then a few weeks later I started the car one morning and it ran really rough.
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Suggestion · Original poster
Usually this manifests as the car not starting at all which I have solved by jumpering the relay and then replacing the relay.
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Suggestion · Original poster
I have always been able to hear the fuel pump running when I jumpered it before so I know what to listen for.
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7 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Outcome without a verified action link
Then I put in an old relay (long story - I had gotten a new and old one relay mixed up last year so the old relay may actually have been the new relay) and I thought I fixed it.
A developing problem - need some hive thinking.
My 2002 996 with 236,000 kilometres has a bit of a history of failing fuel pump relays. Usually this manifests as the car not starting at all which I have solved by jumpering the relay and then replacing the relay. That;s happened now 3 times over the past two years.
So about a month ago, the car wouldn't start on the first try, I jumpered the relay and it ran fine. Then I put in an old relay (long story - I had gotten a new and old one relay mixed up last year so the old relay may actually have been the new relay) and I thought I fixed it.
Then a few weeks later I started the car one morning and it ran really rough. I turned it off and started it again and it was fine.
Odd - that's not how relays behave.
Everything was fine for a week or so and then it happened again - this time at a gas station.Same thing - turned it off and started it again and it was fine.
Then last night, another week and a bit later it started stumbling
while I was on my commute home - not on a start but during operation
. It smoothed out after a few minutes and I made it home and here I am.
I'm leaning towards a fuel pump that is started to fail but I am also thinking coil packs because it's been a wet salty mess out here.
Then again - there is no CEL and I replaced the coil packs less than 20,000 km ago. Plus it doesn't feel like a misfire so much as a total loss of power when it stumbles.
The question s whether fuel pumps can fail intermittently over time like I described....a 996 buddy had his fuel pump fail but it failled suddenly not slowly.
thanks
Jasper
I'd think that with all the relay problems, it's possible that the fuel pump has been getting funky voltages and/or spikes - certainly possible that it is starting to fail intermittently. Also, has your fuel filter been changed?
That is *exactly* what I was thinking dporto - I even went and bought a fuel filter last week before discovering that the Mk2 996 have their fuel filters integrated into the fuel pump - it's a non-service item on this model and only this model.
In other news I have a BNIB fuel filter for sale for every M96 model Porsche ever made....except the Mk2 996.
But - more to the point - I am now fairly certain that we were both right.
I just went to the garage to start the car and it started and died immediately and would not restart. I jumpered the FPR and could not hear the fuel pump running. I have always been able to hear the fuel pump running when I jumpered it before so I know what to listen for.
Next steps:
1) Google the procedure for removing the fuel pump assembly
2) Remove and bench test the pump to verify negative function.
3) Order new fuel pump.
4) Go to my mom's house and borrow her dented red PT Cruiser.
5) Hang my head in a mix of shame and embarrassment while I drive the PT Cruiser to work for a week.
6) Receive and install new fuel pump when it arrives.
Thanks for validating my line of thinking sir.
OP, just about a year ago, my 2003 C2 with about 70k miles started to intermittently sputter and stall and not start. That happened for about two days before it would not start at all. Luckily, it was parked in my garage. I checked the relay, but it was fine. I removed the fuel pump from the tank and tested it using the car's battery. Sure enough, the pump was toast. New pumps aren't cheap, but it is an easy DIY.
Thanks Nick.
Exactly my situation. I have a new pump inbound from Rock Auto. It came to only $200 delivered so not all that bad. I bought a Carter pump though instead of the OEM VDO Siemens part.
Mine failed in my garage too. That's good Porsche karma.
That's a great price. I don't think I shopped enough. Speaking of karma, my pump started failing just one day after I flew down to Socal and drove my newly purchased C2 to Norcal!
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