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Old 08-29-2013, 04:50 PM   #1
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Runs, stalls, runs, stalls every few miles

This morning out of no where car stalled at light, like fuel starvation. It is a sharp turn and as down hill to light. Would not fire up for 5+ mins then finally started and drove fine for 5-20 mins till I got to work.
Started fine and idled normally at lunch.
On my way home turned a couple sharp corners after 10 mins driving and same fuel starvation feeling. Again same 5-10 mins with no fire up then start and drives fine. This happened routinely 4-5 more times until I got home.
I was thinking water in the gas but with some researching I maybe seeing fuel pump failure.
Unfortunately Bentley manual will not cover 2002+ fuel systems very well.
The car is Not throwing any codes.
I did disconnect battery to work on my door 4 days ago but the car ran fine to work the next day
I put it away in garage running fine so I would have to diagnose running correctly until I can get it to stall out again
I don't have any fuel pressure testing tools so unless I can rent

any direction, experiences will be greatly appreciated
Of course I had some great driving planned this weekend

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Old 08-29-2013, 05:26 PM   #2
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When was the last time the clutch was replaced?
Mine had these symptoms when my clutch gave out
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Old 08-29-2013, 05:48 PM   #3
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As far as I know it is original (62K current)
I certainly can't rule out anything. The clutch engages well, mid-pedal and there is no signs of slippage.
I think I will get car to stall again and try jumping relay to see if pump works at that point.
I'd rather replace fuel pump than clutch
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Old 08-30-2013, 12:09 PM   #4
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If there are no codes, then start with the fuel pump diagnosis. Check the pressure and volume flow. Another possibility is the crakshaft position sensor.
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Old 08-30-2013, 09:01 PM   #5
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My race car is doing the same - intermittent poor power/stalls at idle. Then it runs fine. Then it runs poorly and stalls. Feels like fuel starvation. Replaced fuel filter, fuel pump, and MAF. Ran two tanks of gas from different stations. No CEL's. Considering crankshaft position sensor next but also looking at fuel tank vent/recirc system.
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Old 09-02-2013, 08:30 AM   #6
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So I hope I'm onto the issue. Of course it's Labor day so Dealer Parts closed.
So Had a lot time to think about this and it seems that something, pump, relay heat up and kill fuel delivery. Things cool down and it starts again.
So I started and got car warm. I could feel relay was getting warm. Drove around try to get car to stall. Came back to my house and car stalled in driveway after a few minutes (That was some good luck)
Felt relay and it was very hot. Removed and put jumper in. I immediately heard Fuel pump run. Started car and it ran fine with jumper. Replace still hot Relay and car would not fire. Took the relay into the house to let the air conditioner blow on and cool it down. Plugged it back in and Car started right up and ran.
So I'm crossing my fingers it's the relay. Will not know until tomorrow when dealer is open and I drive it around stopping every so often to feel the relay.
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Old 09-02-2013, 08:28 PM   #7
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Thanks for the tip! I did some testing this weekend and my problem also seems to be heat related (car runs fine cold but has more problems the hotter it gets). I finally got a pair of codes (P1128/P1130) that I am investigating, but will also check the fuel pump relay.
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Old 09-03-2013, 06:43 AM   #8
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While I have not gotten any codes for this fuel delivery issue, I was receiving those two codes for a vacuum leak. After I did a throttle body/tubes cleaning, the hose from the AOS to the throttle body was not seated correctly and I would get those codes. Those two codes, in my case, definitely indicated a Vacuum leak in the air intake system

Of course my local dealer doesn't stock the relays and they are 2.5 times more than Pelican. I just order 2 relays + over night delivery and it's only $10 more than dealer for 1 and it would take 3 days
I am having boxster withdraw
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Old 09-03-2013, 07:26 AM   #9
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Glad you got the relays. As an FYI though, often you can repair a repair. Resolder the contacts on the board if a cold/damaged joint or by using fine grade sand paper on the contacts if worn. Often heat build up and failure is a sign of poor contact surface area. I've never had to resolder joints, but have used the sand paper method on relays and ignition points before when stranded. I've always replaced them when an opportunity presented itself so couldn't say how long the fix might last.
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Old 09-03-2013, 08:01 AM   #10
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Quote:
Originally Posted by thstone View Post
Thanks for the tip! I did some testing this weekend and my problem also seems to be heat related (car runs fine cold but has more problems the hotter it gets). I finally got a pair of codes (P1128/P1130) that I am investigating, but will also check the fuel pump relay.
Of course, I drove it this morning for 30 mins and everything ran perfect. I hate intermittent problems. Called the shop and they are coming to pick it up today for further diagnosis.

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