Engine won't Hot Start

Created: 2/17/98

Last updated: 

Author/source: DML Benson, Clark

dmcnews-digest V3 #331

Received: 2/17/1998 8:31 PM

Fist - a Quick Fix 


Date: Sun, 15 Feb 1998 12:56:31 -0600

From: "BRUCE BENSON" <delornut(AT)postoffice.worldnet.att.net>

Subject: DML: Re: Hot Start solution?


> Like many others I'm sure I've had occasional "hot start" problems. From

> the previous discussions I gather this is likely a fuel system problem,

> probably the fuel accumulator. I'm going to get that looked at by a

> mechanic, but in the mean time, if I am stuck somewhere, is there

> anything I can do to get the car to start quick, without waiting a

> couple of hours? Something like "quickstart" I can spray into the

> engine? I saw the mechanic do this to the car once before I bought it to

> solve a cold start problem.


> -sean

On the drivers side of the engine there are two prominent electrical


A grey one going to the control pressure regulator and a blue one going to

the cold start valve. Unplug them both and then plug the grey plug to the

cold start valve and leave the blue one unplugged. This tricks the cold

start valve into firing and gives an extra shot of fuel to the engine. A

word of caution: don't crank the engine more than about 30 seconds or

you'll flood it and after the engine starts, rev it up a few seconds and

turn it off. Replace the plugs to their original plug-ins and the engine

should re-start. If this works the problem is more than likely the

accumulator. If this doesn't get a balky hot engine started, the problem

may be ignition related.

Bruce Benson



And some Diagnosis Help:

Subject: Hot Starting Problem
Sent: 01/20 2:23 AM
Received: 01/22 6:15 AM
From: Chase Clark, stormrider(AT)socketis.net
To: Sudaesh1(AT)aol.com
CC: dmcnews, dmcnews(AT)goodnet.com

In reference to your problem starting your car, I have a Porsche 924 and a DeLorean. Last summer the Porsche had problems starting when hot and I was told it was a sign that the fuel pump was going bad and a vapor lock was being created. Porsche 924s also use a Bosch K-Jetronic Fuel Injection system like in the DeLorean.

In the case of your problem, a Tech Tip from Performance Products Porsche parts catalog may help the investigation:

HARD STARTING WHEN HOT "If your engine cranks for a long time before it fires up when hot, but starts fine when it's cold, you may have a leaking check valve in the fuel pump. In order to start immediately, fuel needs to remain in the fuel lines. A faulty fuel pump check valve will allow the fuel to flow back into the gas tank leaving the air in the fuel lines. When you attempt to start the car, all the fuel lines need to be filled first to build up enough pressure to start injecting. This takes especially long when the engine is hot since the injection system runs leaner when hot. Find out if the fuel pump check valve is the problem by getting someone to clamp the rubber fuel line to stop the flow of fuel on the engine side of the fuel pump right when you turn off the engine. Wait 20 minutes, have your friend remove the clamp and immediately try to start your car. If it starts up right away, it's the check valve and time for a new pump."

The Performance Products catalog (1-800-423-3173) also has a troubleshooting section for the Bosch K-Jetronic and L-Jetronic Fuel Injection systems. I would reprint it for everyone, however, it is copyrighted by the Robert Bosch Corporation.

Well, I hope that helps you in your search for answers.

~ Chase



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