13 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
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YOUR RESEARCHStarting
Reported or suspected cause
still there
Reported cause
No successful repair reported for this finding.
1
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Suspected cause
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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 report identifying a cause
1
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Reported cause · Original poster
I ended up putting a new Fuel Vent Valve (Regeneration Valve) in yesterday and the starting problem is still there.
Leading evidence: 'still there' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'still there' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check bleed off in the fuel rail over time' (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
We recently had a 996 owner/Youtuber that went though this diligently and tested/replaced many many things to finally install an aftermarket check valve in the fuel pressure line to keep the fuel from bleeding back into the fuel tank, and that solved his problem..
Outcome qualification: Negation, uncertainty or missing explicit repair resolution overrides the raw extraction signal.
Test /
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
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
We recently had a 996 owner/Youtuber that went though this diligently and tested/replaced many many things to finally install an aftermarket check valve in the fuel pressure line to keep the fuel from bleeding back into the fuel tank, and that solved his problem..
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 contain suggestions
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.
Suggestion · Original poster
Actually I thought about that and need to get a pressure tester to check the bleed off in the fuel rail over time.
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 contain suggestions
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.
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 · Original poster
I did disconnect the tube at the FPR prior to starting the job, but you know with the limited space and with all the pulling and pushing you can disturb a number of things.
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 · Original poster
However I assumed it had something to do with me dropping the engine and lifting the rail when changing the injectors because everything was fine before I started the job.
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
We recently had a 996 owner/Youtuber that went though this diligently and tested/replaced many many things to finally install an aftermarket check valve in the fuel pressure line to keep the fuel from bleeding back into the fuel tank, and that solved his problem..
Outcome qualification: Negation, uncertainty or missing explicit repair resolution overrides the raw extraction signal.
Replace things he did in order
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
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.
Suggestion
You can search for the thread and do all the tests he did, and even replace the things he did in order to finally fix the problem...I can't remember his name , it was Finch or Rinch or something, maybe someone can give more clues to find the thread, and his channel is "this Tiny Garage" or something like that..
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 · Original poster
It�s now idling/running better than ever however when starting from cold RPM goes straight to 2000 and immediately settles down to 840, when hot it cranks a number of times before starting, sometimes needs throttle input.
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.
13 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 · 1 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T174436Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi, 99 996 3.4 H6 C2, 34,000 miles, changed Injectors, upgraded coil packs, new plugs, new MAF & O2 sensors.
Was running well prior to the work however I sensed a slight miss at idle. No CEL or anything on the scan.
It�s now idling/running better than ever however when starting from cold RPM goes straight to 2000 and immediately settles down to 840, when hot it cranks a number of times before starting, sometimes needs throttle input. No fuel leaks.
Thank you for the help in advance.
As Mike Murphy said.
Difficult hot start: Check whether the fuel vent valve is shut and does not allow fuel vapours through. Easiest check is by clamping the hose shut between valve and throttle body when engine hot and then start. If no add. throttle required then it's the valve (or the wiring to it). If not look further.
@hardtailer
I ended up putting a new Fuel Vent Valve (Regeneration Valve) in yesterday and the starting problem is still there.
it starts fine when cold and starts fine when hot within 30 minutes of shut down, however after 45 minutes won�t start first or second try but will eventually start.
We recently had a 996 owner/Youtuber that went though this diligently and tested/replaced many many things to finally install an aftermarket check valve in the fuel pressure line to keep the fuel from bleeding back into the fuel tank, and that solved his problem..
You can search for the thread and do all the tests he did, and even replace the things he did in order to finally fix the problem...I can't remember his name , it was Finch or Rinch or something, maybe someone can give more clues to find the thread, and his channel is "this Tiny Garage" or something like that..
That thread covers every "hard to start hot" scenario known....
Thanks for posting your result.
This is the video porschetech3 is referring to
You Tube
A fairly easy test to indicate faulty check valve at the fuel pump is to bridge terminals 87 and 30 (+12V battery voltage, always live) of the fuel pump relay after 45min before you turn the key to start the engine. If it starts like the cold engine, then it is indeed the check valve.
Easiest way to bridge 87 and 30 is to remove the cap of the relay and stick a thick enough feeler gauge blade between coil and 'lever'
Hi, ok start problem when hot, after about 45 minutes from shutdown fixed.
It was the pipe between the Fuel Pressure Regulator and the intake plenum which had snapped while I was changing the fuel injectors.
Thanks for the update.
Did you motice anything that could explain why the effect of not having the FPR referenced to the intake vacuum is so different between the warm engine sitting for 30 minutes and it sitting 45 minutes?
It almost sounds like the vacuum line held was able to hold some vacuum for about 30min but after another 15min of heatsoak it held nill and ambient pressure was what the fpr saw.
Actually I thought about that and need to get a pressure tester to check the bleed off in the fuel rail over time. However I assumed it had something to do with me dropping the engine and lifting the rail when changing the injectors because everything was fine before I started the job. I did disconnect the tube at the FPR prior to starting the job, but you know with the limited space and with all the pulling and pushing you can disturb a number of things.
This is a source reference. Confirm exact model applicability in the original material.
