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 Post subject: Has anybody ever tried to insulate the fuel lines and rail
PostPosted: Wed Feb 24, 2016 8:31 pm 
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Has anybody tried to do this to help with hot start issues. To stop heat vaporising the fuel.

Done all of the usual stuff, even taken it to opc and they say its normal with 944's as the heat vaporises the fuel.

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Wed Feb 24, 2016 9:21 pm 
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What's the issue? I have the same car as you and don't have any problems when the engine is hot (or cold).

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Bryan

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Wed Feb 24, 2016 9:40 pm 
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briggy wrote:
What's the issue? I have the same car as you and don't have any problems when the engine is hot (or cold).

Cheers,
Bryan


If I use the car through out the day, multiple journeys. Driving for a bit, stopping for a bit, starting the car, drive somewhere else, etc. Throughout the day it gets harder and harder to start, until it wont. If I turn the engine off and start it straight away its fine. If I leave the engine off for a hour its fine. Normally after leaving it for 15 mins there's a problem.

DME rely, check valve, tested fuel rail for pressure loss ( checking injectors and damper) all OK.

Starts straight away when cold

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Wed Feb 24, 2016 10:23 pm 
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HUBBA.HUBBA wrote:
Has anybody tried to do this to help with hot start issues. To stop heat vaporising the fuel.

Done all of the usual stuff, even taken it to opc and they say its normal with 944's as the heat vaporises the fuel.


You are highly unlikely to get fuel vaporisation as it's pressurised when it's in the fuel rail, even when parked.

Crank sensors can play up when hot, though.

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Thu Feb 25, 2016 9:54 am 
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Sounds more like the fuel return valve leaking a bit. Fuel under pressure can't vaporise.. but it can if leaking back to the tank. Just a thought.

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Thu Feb 25, 2016 4:18 pm 
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robmal wrote:
Sounds more like the fuel return valve leaking a bit. Fuel under pressure can't vaporise.. but it can if leaking back to the tank. Just a thought.


Do you mean the check valve on the fuel pump? If that's the case, I've changed it.

or do you mean the pressure reg (haven't changed that, but have inspected)

The thing is I have done a leak down test at the fuel rail and it holds pressure really well even after 20 mins.

My gut tells me its heat related.

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Thu Feb 25, 2016 4:20 pm 
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white944 wrote:
HUBBA.HUBBA wrote:
Has anybody tried to do this to help with hot start issues. To stop heat vaporising the fuel.

Done all of the usual stuff, even taken it to opc and they say its normal with 944's as the heat vaporises the fuel.


You are highly unlikely to get fuel vaporisation as it's pressurised when it's in the fuel rail, even when parked.

Crank sensors can play up when hot, though.


How would the crank sensor effect starting? Out of interest.

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Thu Feb 25, 2016 5:08 pm 
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HUBBA.HUBBA wrote:
robmal wrote:
Sounds more like the fuel return valve leaking a bit. Fuel under pressure can't vaporise.. but it can if leaking back to the tank. Just a thought.


Do you mean the check valve on the fuel pump? If that's the case, I've changed it.


Yes, the check valve! Now I've run out of ideas then... sorry!

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Thu Feb 25, 2016 6:12 pm 
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HUBBA.HUBBA wrote:
Do you mean the check valve on the fuel pump? If that's the case, I've changed it.

Hubba, Ive just bought a replacement for mine - how easy (or not) was it to change?

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Thu Feb 25, 2016 7:14 pm 
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HUBBA.HUBBA wrote:
white944 wrote:
HUBBA.HUBBA wrote:
Has anybody tried to do this to help with hot start issues. To stop heat vaporising the fuel.

Done all of the usual stuff, even taken it to opc and they say its normal with 944's as the heat vaporises the fuel.


You are highly unlikely to get fuel vaporisation as it's pressurised when it's in the fuel rail, even when parked.

Crank sensors can play up when hot, though.


How would the crank sensor effect starting? Out of interest.


No or an iffy signal to the ECU from the CPS and it won't fire the injectors. It's reasonably common for them (not specifically the 944, just CPS's in general) to start to give issues when hot. Although in your case is does sound to be fuel related given the heat relation. I would expect an iffy CPS to also cause some hot cutting out symptoms...

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Thu Feb 25, 2016 8:07 pm 
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IanK wrote:
HUBBA.HUBBA wrote:
Do you mean the check valve on the fuel pump? If that's the case, I've changed it.

Hubba, Ive just bought a replacement for mine - how easy (or not) was it to change?

It was simple enough really. Main issue I found was seized fittings that you can't get a blow torch on the crack. Penetrating fluid and time. Have a few catcher rags ready for the fuel spill as well (not loads came out to be honest, but I let the fuel level run low before hand).

Out of interest where did you get yours from? I had 3 which claimed to fit but only 1 had the right thread.

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Thu Feb 25, 2016 8:16 pm 
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How would the crank sensor effect starting? Out of interest.[/quote]

No or an iffy signal to the ECU from the CPS and it won't fire the injectors. It's reasonably common for them (not specifically the 944, just CPS's in general) to start to give issues when hot. Although in your case is does sound to be fuel related given the heat relation. I would expect an iffy CPS to also cause some hot cutting out symptoms...[/quote]

Following what you have said has prompted me to search for the sensors. looks like there are two of them, which one are you referring to?

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Thu Feb 25, 2016 9:35 pm 
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Only time I've had hot start problems as described , is when the Head Gasket started to go, albeit it was only 1 cylinder missing.How's your head gasket?Can't see how fuel vapourisation would only occour on your cab , when others ( myself included ) haven't suffered with it at all.

Toby


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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Fri Feb 26, 2016 1:12 pm 
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HUBBA.HUBBA wrote:
IanK wrote:
HUBBA.HUBBA wrote:
Do you mean the check valve on the fuel pump? If that's the case, I've changed it.

Hubba, Ive just bought a replacement for mine - how easy (or not) was it to change?

It was simple enough really. Main issue I found was seized fittings that you can't get a blow torch on the crack. Penetrating fluid and time. Have a few catcher rags ready for the fuel spill as well (not loads came out to be honest, but I let the fuel level run low before hand).

Out of interest where did you get yours from? I had 3 which claimed to fit but only 1 had the right thread.


Thanks for that.
I got my fuel pump valve from my OPC last week £16.37 inc VAT.

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 Post subject: Re: Has anybody ever tried to insulate the fuel lines and ra
PostPosted: Fri Feb 26, 2016 1:32 pm 
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IanK wrote:

Out of interest where did you get yours from? I had 3 which claimed to fit but only 1 had the right thread.


Thanks for that.
I got my fuel pump valve from my OPC last week £16.37 inc VAT.[/quote]

You'll be fine then

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