CIS hot-start problem - will this work?
 

My '74 2.7 with CIS has the classic hot start problem (yes, I know there are many posts on this subject). I have replaced the check valve and the accumulator, still no luck. The idling mixture is also correct. What else can it be?

A Porsche mechanic told me that I can overcome this problem (if I want a quick-and-easy fix) by manually providing electricity to the enrichment valve when the problem occurs. This entails running wires from the dash to the enrichment valve, with a push button within easy reach.

Anybody out there that can comment on this?

Your car should have a thermo-time switch that activates the cold-start when the engine is cold then doesn't when it warms up. I f it has gone out, you car may be getting the extra fuel when hot and flooding it.

The problem may be too much fuel not the lack of it like your wrench thinks. I had this problem on a MFI car, the thermo-time switch went bad and stuck open, if i unplugged it when hot it would fire right up.

If I were to just hook up a switch to avoid (rather than fix) the problem, I'd probably hook the fuel pump to the switch. At hot start tiem, I'd run the fuel pump for a half minute or so before trying to start it.

The classic CIS hot start problem is low residual fuel pressure, as I see you are aware. Running the starter for a half-minute usually starts the car because the fuel pressure rises in that time.

My guess is your injectors are leaking away the fuel pressure, onto the backs of your intake valves, after shutoff. You probably have the non-metal injector lines, so you could fairly easily pull those injectors and watch them leak.

Another source to check for residual pressure leakage is at the fuel distributor where the system pressure is adjusted. On the right side of the fuel distributor there's a hex plug that uncovers a spring and plunger assembly.

Regards,

Joe Garcia

If you really have a pressure retention problem, and you are experiencing vapor lock, then your mod (kluge) won't solve anything.

Get a CIS pressure tester and verify that your system is holding pressure. If it's not, then there are other components besides the accumulator and check valve that can be at fault (injectors, fuel distributor).

I had the same issue as Paul Thomas...I had to get my girlfriend to come tow me home in her Saturn. How embarassing. I read a couple of books on injection and hoped that it was just the cold start valve flooding the engine. Sure enough, a couple of weeks later, the engine was turning over and not starting, smelling up a parking lot. After pulling the wire to the cold start valve, the engine fired right up. Good luck.

Hello

enrichment valve ?

Thats the coldstartvalve and using a overide via a switch is the best way to blow the box.

I´m not sure about the abilitys and Knowledge from your mechanic but did he allready checked the basiscs and your fuel pressure is good ? No leaking or weak injectors ?
Did he checked what happend during the hot starts ?

Grüsse