924Board.org

martin924 · Joined: 14 May 2006 Posts: 15

My 21 year old 924 runs mint, just serviced her and all is good apart from hot starting, when left for only a couple of mins no problems, but 5mins to an hour or over and she does like starting at all, is it a fuel evapouran problem? Is there a way to fix it, if not is it best to floor the gas pedal until she finally springs back to life or not??? Apart from that, its the most fun on four wheels i have ever owned

im well pleased,

Smoothie · Posted: Wed May 17, 2006 6:22 am Post subject:

There are several check valves that when working, hold pressure in the fuel system after shutdown to prevent vapour lock. One or more of them must be leaking pressure. One is a check valve at the outlet of the fuel pump. Another is at the primary pressure regulator that's built into the fuel distributor. Fuel injectors may also leak - both the 4 CIS fuel injectors and the CSV (cold start valve). The fuel accumulator/s are another possible source of the problem. Until you find the leaky component/s and fix, yes, hold the throttle to the floor while cranking to clear the vapour lock quicker.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

martin924 · Joined: 14 May 2006 Posts: 15

Thank you for your reply, sounds like a bit of a job, the fuel pump does wistle and whine on tickover, and i have found a brand new bosh 0 580 254 909 in the glove box!, but according to the web i should have a bosh 0 580 254 053. same connections and size and 5 bar pressure but the ## 909 is 148 liters per hour and the correct one ## 053 is a higher output of 175 liters per hour, will this work?? Thank you so much for any help, Regards Martin

timstar92404 · Joined: 22 Sep 2004 Posts: 2075 Location: richmond BC

don't touch the gas pedal when cranking it can backfire and blow off your intake hoses and then you could be stuck if you don't have a screwdriver.

someone told me fuel pump checkvalve or fuel accumulators are most likely the problem.
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78 924 sold.
85.5 944

Ozzie · Posted: Wed May 17, 2006 5:48 pm Post subject:

After shutdown the heat from the engine causes the fuel in the lines to try to vaporise and the pressure forces fuel to return to tank.
Areas to check are fuel pump non return valve, accumulator, fuel lines, and primary pressure regulator, warm up regulator, CSV and injectors.
Any of these or any combination which allows pressure to either return to tank or escape (into the intake manifold or atmosphere) will cause this problem.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

TheFuzz89 · Posted: Thu May 18, 2006 5:13 am Post subject:

Ozzie · Posted: Thu May 18, 2006 6:55 am Post subject:

I wouldn't take the backfire as gospel.. I would suspect Timstar couldn't time his car properly.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

leadfoot · Posted: Thu May 18, 2006 12:58 pm Post subject:

It says in the owners manual that this is exactly what your meant to do...
Put your foot to the floor and crank it over till it starts...
Leadfoot
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

Eturbo924 · Joined: 09 Nov 2002 Posts: 2212 Location: Londonderry NH

You can also wire a push button onto your cold start valve so you can fire it. It works perfectly in my 1977. I did not wire it up though.
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1982 924
1992 968
2003 C4S
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P924 · Joined: 14 May 2006 Posts: 57 Location: Belgium

skemcin · Joined: 02 Sep 2003 Posts: 1284 Location: Plainfield, IL

P924 · Joined: 14 May 2006 Posts: 57 Location: Belgium

Eturbo924 · Joined: 09 Nov 2002 Posts: 2212 Location: Londonderry NH

http://www.924.org/techsection/hot_start_problem_fix.htm
_________________
1982 924
1992 968
2003 C4S
Parts Parts Parts and More parts.
E-mail me for parts you need!
Drive Fast!

martin924 · Joined: 14 May 2006 Posts: 15

Thank you for the link about puting a switch on the cold start value, thats just what il do!

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

The hot start button will work if the fuel pressure loss is back into the tank. If the loss is due to leaking injectors, it will make it worse.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black