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> Won't start when it's hot
pcdarks
post Jun 5 2019, 02:44 PM
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I have a stock 1972 914 that has been in the family since 1976. In that time it has always had an intermittent starting issue. When the car is shut off when it's hot or has just sat in the sun it won't start. It doesn't do it every time and It will turn over but won't start. Mt mother had the car in the 70s-90s and when she would come to visit It would do this in the sun so she got in the habit of parking it under a tree and would never have a starting problem. I have a suspicion it's the computer. Any thoughts? thanks.
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Dr. 914
post Jun 5 2019, 02:57 PM
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if it has spark, it is probably a defective head temp sensor. That would be a good place to start.

QUOTE (pcdarks @ Jun 5 2019, 02:44 PM) *
I have a stock 1972 914 that has been in the family since 1976. In that time it has always had an intermittent starting issue. When the car is shut off when it's hot or has just sat in the sun it won't start. It doesn't do it every time and It will turn over but won't start. Mt mother had the car in the 70s-90s and when she would come to visit It would do this in the sun so she got in the habit of parking it under a tree and would never have a starting problem. I have a suspicion it's the computer. Any thoughts? thanks.

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Tom_T
post Jun 5 2019, 03:16 PM
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QUOTE (pcdarks @ Jun 5 2019, 11:44 AM) *
... a stock 1972 914 that has been in the family since 1976. In that time it has always had an intermittent starting issue. When the car is shut off when it's hot ....


George - this sounds to me more like the classic 70-74 fuel pump vapor lock starting problem, which would be remedied by your AA fuel pump relocation kit!

Not sure where he's located, but if sunny days are very hot coupled with hot pavement or other heat absorbing surface, then that too could be due to vapor lock.

In any case PCdarks - IMHO any 70-74 914 should have the fuel pump relocated up front under the steering rack cover with the factory kit off which yours is based, as per the Porsche Service Bulletin back in 1974-75 (IIRC its date timeframe correctly).

Cheers! (IMG:style_emoticons/default/beerchug.gif)
Tom
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pcdarks
post Jun 5 2019, 04:26 PM
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QUOTE (Tom_T @ Jun 5 2019, 03:16 PM) *
QUOTE
... a stock 1972 914 that has been in the family since 1976. In that time it has always had an intermittent starting issue. When the car is shut off when it's hot ....


George - this sounds to me more like the classic 70-74 fuel pump vapor lock starting problem, which would be remedied by your AA fuel pump relocation kit!

Not sure where he's located, but if sunny days are very hot coupled with hot pavement or other heat absorbing surface, then that too could be due to vapor lock.

In any case PCdarks - IMHO any 70-74 914 should have the fuel pump relocated up front under the steering rack cover with the factory kit off which yours is based, as per the Porsche Service Bulletin back in 1974-75 (IIRC its date timeframe correctly).

Cheers! (IMG:style_emoticons/default/beerchug.gif)
Tom
///////

Right now it's located under the passenger side in front of the rear wheel. The location that I remember it doing this was at my home at 6000ft elev. the air is cool up there but the sun is intense but the heat wouldn't get to where the pump is.
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Dr. 914
post Jun 6 2019, 08:25 AM
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I would have thought that also except they are talking about coming out on a hot day and not starting. Vapor lock is caused by hot fuel boiling


QUOTE (Tom_T @ Jun 5 2019, 03:16 PM) *
QUOTE
... a stock 1972 914 that has been in the family since 1976. In that time it has always had an intermittent starting issue. When the car is shut off when it's hot ....


George - this sounds to me more like the classic 70-74 fuel pump vapor lock starting problem, which would be remedied by your AA fuel pump relocation kit!

Not sure where he's located, but if sunny days are very hot coupled with hot pavement or other heat absorbing surface, then that too could be due to vapor lock.

In any case PCdarks - IMHO any 70-74 914 should have the fuel pump relocated up front under the steering rack cover with the factory kit off which yours is based, as per the Porsche Service Bulletin back in 1974-75 (IIRC its date timeframe correctly).

Cheers! (IMG:style_emoticons/default/beerchug.gif)
Tom
///////

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tessmar
post Jun 23 2019, 02:33 PM
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QUOTE (pcdarks @ Jun 5 2019, 12:44 PM) *
I have a stock 1972 914 that has been in the family since 1976. In that time it has always had an intermittent starting issue. When the car is shut off when it's hot or has just sat in the sun it won't start. It doesn't do it every time and It will turn over but won't start. Mt mother had the car in the 70s-90s and when she would come to visit It would do this in the sun so she got in the habit of parking it under a tree and would never have a starting problem. I have a suspicion it's the computer. Any thoughts? thanks.


Some years ago I managed to acquire, copy, and receive permission from Bosch to publish the full original and complete servic manuals for both the D and L Jetronic electronic fuel injection systems for the 914. You can access them here:
Rennlist post of Bosch EFI manuals for 914

This should help you evaluate the system as well as the responses and suggsetions by experts such as Dr. 914
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corby26
post Jul 14 2019, 08:05 PM
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Howdy! We're looking at a '73 with almost the same issue. How's your research so far?
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