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To answer your question, there was NO residual fuel pressure. Alternately, it could be because my pump failed and as such, hadn't generated any pressure for the whole drive home so there couldn't be any residual. .
One of the symptoms of a slowly failing HPFP is the long/multipule crank attempts to get a start, and viable idle.
While still able to start and run the engine, if the engine has been stopped, residual rail pressure is fully bled off in a short time, perhaps through faulty internal HPFP valving.
Hence Hindsight's experience of no residual HP fuel rail pressure during dud HPFP pipe disconnection, this could be verification the faulty pump can't hold fuel rail pressure very long.
I suppose leaking injectors would drain the rail pressure also, but there would be other accompanying symptoms such as oil dilution, raw fuel out the pipes, very rich rough start etc.
When there is no resudual pressure in the fuel rail, starting the engine requires more cranks to establish minimum rail pressure before signal is sent from the control module to actuate injectors and supply ignition voltage to the plug coils.
A catastrophic HPFP piston/diaphragm/seal/drive failure however, would prevent any engine start, as minimum rail pressure would never be reached.
A catastrophic HPFP piston/diaphragm/seal/drive failure however, would prevent any engine start, as minimum rail pressure would never be reached.
I read somewhere that when the HPFP goes, the ECU runs the car in limp mode by increasing fuel injector dwell time and running fuel pressure completely off of the in-tank electric fuel pump. It can only generate very low power levels this way, but it's enough to get you home. I don't know if this is accurate, but it is what I read somewhere.
Great job on your R&R fuel pump. I paid an indy shop $1612 to replace pump,I know the shop had to remove left muffler as they broke a bolt. I understand been that the new pump have been updated. 2009 C2S 38K miles
Great job on your R&R fuel pump. I paid an indy shop $1612 to replace pump,I know the shop had to remove left muffler as they broke a bolt. I understand been that the new pump have been updated. 2009 C2S 38K miles
I hope you're right. Let's see how long these new pumps last! Hopefully 50k +. The job wasn't too bad and I wouldn't be upset if I had to replace it again in 50k more miles.
Pics of near failure before repair, but after the housing was cleaned of older leaked oil to determine where exactly it was leaking. It explains why some surrounding bits are also oily but kind of patchy.
Mine "failed" at 95k km so near 60k miles mark, but probably even bit earlier as I only noticed it when oil was dumped on floor.. It didn't FAIL as such, because car ran fine but there was a little longer crank and it was also slightly tricky during full throttle as I felt the car not as eager. I drove with these symptoms about 3k miles without making much of it, as oil level was ok, pressure ok, and car passed inspection and 111pt test. Yet one fine day few weeks ago, it left a small puddle on the garage floor and I saw oil dripping. Panicked, I shut the car off. With further chat to my indy, he told me to start the car to see if pressure was ok in oil - it was. And oil leak was gone, but I did see leak around the pump's housing (on the left side) of the car, and housing was oily on the bottom.
May it was not the pump? It could have been either a small o-ring, or smth else, so mechanics washed the oil off, and we drove for about 25km to see if the leak developed - yes, it came back. It was determined that the leak was coming from one side of the pump, and oil just was squirting out at high pressure. The pump was working of course, and car was driving OK (same). And did not dump oil again.
Still, even if car was fine for now, though leaking oil a bit, I took the decision to get the work done at the dealer rather than with my usual indy - simply for that 2 year warranty benefit, and a discount the dealer gave was pretty good that made it irrelevant where I serviced. The piece of mind of course getting it done with dealer is there. I also replaced the thermostat while there, and saw a small leak in PDK - so the PDK was also fully serviced. Had a nifty bill in the end, but happy with the car being back in shape and not having to worry.
After replacement of the pump the throttle response seems to have been a little better, the car starts very easy also (cranks), not that bit longer as it did before.
So yeah, there we go, the failure at 60k, replaced at indy along with thermostat. Cost of part is below 1k USD, so it is not massively crazy for these cars, but dealer said its good to get it sorted and not wait for failure as in best case you lose pressure and engine is in limp mode, worst case it might just squirt hot oil on the exhaust below and who wants that...
Repair took few hours (4?) but I left the car a night before as oil needs to be cool before the procedure.
Hope yours is healthier but hey, at 10 years of age, it is normal our cars going through certain number of parts, par for the course!
Last edited by pascalemod; 10-29-2020 at 08:20 AM.
Great videos - thank you for posting. What I saw in that first video made a lot of sense. I saw a thin oil coming out of the expansion diaphragm on mine, and it wasn't engine oil. Based on the info from the video, it seems that one mine, and many others, the corrugated steel pistons fail for some reason and likely allow fuel to mix with the oil. I would guess that either the chemicals in the fuel degrade the diaphragm until it ruptures, or the excess pressure caused my the mixing of pressurized fuel and oil causes the expansion diaphragm to rupture, puking fuel-diluted hydraulic oil out the hole in the end of that diaphragm. Hence the leak we so commonly see when these pumps fail.
Bottom line: This is an internal failure - likely in the corrugated steel bellows, and really doesn't seem there is anything we can do about it as far as preventative maintenance goes. The good thing is that a failed pump won't hurt the car or cause any other serious issues so one just has to live with the fact that the pump will likely fail at some point and need to be replaced. I'd much rather this than other issues like hydraulic valve lifters or chain tensioners or chain tensioner guides. Replacing the pump isn't too hard of a job, comparatively speaking.
Thanks for the write up! Mine just took a dump , can't start the car code P1023 and P1026. No warning, just does not want to start or run for more then 3 secs. Around 70k miles/ 110k km on this pump since replacement in 2015.
Thanks for the write up! Mine just took a dump , can't start the car code P1023 and P1026. No warning, just does not want to start or run for more then 3 secs. Around 70k miles/ 110k km on this pump since replacement in 2015.
70k is a long tie for one of these pumps to last from everything I'm seeing. Good luck with your replacement. All has been great with the miles I've put on my new pump. Track days coming soon.
70k is a long tie for one of these pumps to last from everything I'm seeing. Good luck with your replacement. All has been great with the miles I've put on my new pump. Track days coming soon.
I've got 136K miles on my original pump. Hard to say how long they are good for or if preventive replacement is appropriate.
I've got 136K miles on my original pump. Hard to say how long they are good for or if preventive replacement is appropriate.
Preventative maintenance has been discussed but there really isn't anything known that you can do. These cars have a permanent fuel filter that is in the front tank and part of the front fuel pump that transfers fuel back to the HPFP. It's not a serviceable or wear item per Porsche.
About the only common wisdom as to cause of failure for these is water in the fuel or contaminates. But there isn't really anything you can do to prevent that aside from getting fuel from a reputable station that sells a lot of fuel (IE doesn't have and old leaky tank that they only get enough business to have re-filled once every few months and that they likely don't service properly).
Thanks for instructions , it was helpful. I was able to do it with just removing the muffler! Took about 5hrs as my muffler hardware needed to be torched off !
Pump is done, but after driving for an hour, seems like the upper hose that comes off the thermostat housing split so got a little coolant leak. You've mentioned a part number: 997-106-832-32
08-05-2020, 05:53 AM
