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911SC '82
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Hot start issue. Warm up regulator?
Hi everyone,
A year ago, I posted about a hot start issue with my 1982 Porsche 911 SC. After driving in traffic for an hour at low speeds and then parking for 30 minutes to an hour, the car struggles to start, despite a strong battery and starter. This only happens in city driving, never during highway trips. Over the past year, my mechanic has replaced the thermostat, spark plugs, cables, injectors, fuel pump, check valve, accumulator, fuel filter, and installed a high-torque starter. The oil temperature is stable. Since the warm-up regulator hasn’t been replaced, could this be the next step? Has anyone else experienced this or replaced it? How much did it cost, and how long did it take? I’d appreciate any advice to resolve this once and for all. Thanks! |
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03-22-2025, 06:53 AM
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Join Date: Feb 2014
Location: Lomita, CA
Posts: 2,689
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You need to monitor the control & system pressures using a CIS test gauge (Amazon), when the problem occurs.
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Dave |
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03-22-2025, 10:03 AM
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Yes, the pressures will tell you what is going on - WUR or FA. I see the FA is replaced - but that may not mean it is actually working OK. Lots of suspect bits out there these days. You are wasting your time (and $s) until you get that info.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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03-22-2025, 10:27 AM
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PCA Member since 1988
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Agree with Alan. Usually a new FA fixes hot start problems, but at this point, you need to measure the pressures, especially the residual pressure.
DO NOT throw parts at the problem! Not only is it unnecessarily expensive, it also complicates your troubleshooting by causing new variables and potential problems. Troubleshoot first. I'm pretty sure I've said this to you before.
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! Last edited by PeteKz; 03-22-2025 at 12:20 PM.. |
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03-22-2025, 12:17 PM
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Location: Lomita, CA
Posts: 2,689
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Quote:
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Dave |
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03-22-2025, 12:24 PM
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Hot Start Troubleshooting………….
The most common culprit for a HOT start is the loss of residual pressure in the system. You could have good control and system pressures but if the residual pressure is out of spec, it would be a struggle to do warm start up. These are the known culprits for SC’s residual pressure loss:
Tony |
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03-22-2025, 01:59 PM
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Quote:
Need to know what is going on rather than guessing. Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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03-22-2025, 03:05 PM
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Registered
Join Date: Feb 2014
Location: Lomita, CA
Posts: 2,689
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Quote:
Read the first reply (mine) again: You need to monitor the control & system pressures using a CIS test gauge (Amazon), when the problem occurs.
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Dave |
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03-22-2025, 05:18 PM
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Replacing the FA doesn't eliminate anything.
Alan
__________________
83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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03-22-2025, 06:12 PM
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Dave, You could monitor the control & system pressures till kingdom come and that would not HELP. What you need is test the residual pressure. There is a specific test procedure for different CIS components regarding residual fuel pressure loss. Tony |
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03-22-2025, 07:38 PM
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PCA Member since 1988
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Quote:
__________________
1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! |
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03-22-2025, 09:46 PM
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Join Date: Feb 2014
Location: Lomita, CA
Posts: 2,689
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This results in a bad warm start mode. I just solved a warm starting problem for an independent Porsche shop just this week doing this test. Let's avoid twisting one's wording and intent.
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Dave |
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03-23-2025, 03:25 AM
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