SC Warm Start problem, Again!

[wfbal]

This seems to be a common problem with CIS 911, my car start fine when cold but it won't start when warm if I let it off for more than 15-20min.

I had this problem on my 79 SC for a year now, I already replaced the Fuel Accumulator (for a used one and added an inline check valve.
Didn't help one bit.

My mechanic did check the fuel pump and it seem to generate enough pressure. He did also check the resting pressure and my car still seem to be loosing pressure to quickly. This would explane my warm start problem.
He is now telling me to replace the Warm Up Regulator. No way I'm playing that game again with 600$ parts!

Any advice on what I should do next (other than selling the car on eBay)?

Also there something I don't understand, the Fuel accumulator is suppose to retain enough pressure in the fuel system for about an hour or so.
My car won't start until it is completely cold, this takes between 2 to 3 hours of cooling depending on air temperature!

What's wrong here?

Do I have another problem on top of my dropping fuel pressure?

Any help would be greatly appreciated.

[vash]

i think if the mechanic shuts off the valve of the CIS tester, and the pressure holds steady, it is the WUR. i dont have my book with me at the office, so i cannot be positive.

also, my rebuilt WUR cost $150, and it is working fine.

[wfbal]

Thanks Vash,

where did you get a rebuilted WUR from?

At 150$, I'm willing to try it out.

[Paulporsche]

Sounds like your used fuel accumulator might be bad. The FA is supposed to hold residual pressure of 16 psi (1.1 bar) after 30 min. Have the mech check that. If you open up the bottom of the unit and some fuel comes out the FA is bad.

Your WUR may be out of spec, but I don't think that's it. Have him check both the cold and warm control pressures. Your colc cp should be about 2 - 2.4 bar @ 20C and about 2.75 to 3.2 when hot w/ the vaccuum line removed. 3.2 to 3.6 w/ line attached.

[mca]

Originally Posted by Paulporsche

If you open up the bottom of the unit and some fuel comes out the FA is bad..

So, if the fuel line is disconnected from the bottom of the accumulator and fuel spills out from the accumulator ... then the accumulator is bad?

[Jim Williams]

Loss of residual pressure when a '79 engine is shut down can be attributed to:
1) Check valve in the fuel pump
2) Accumulator
3) injectors dripping
4) Leaking valve in the WUR return valve in the Fuel distributor
5) Leak in the Fuel Distributor main pressure regulator

The WUR on it's own can "leak" the residual pressure down to it's control pressure, and still be within spec.

When disconnecting the fuel line at the bottom of the accumulator and you get a steady dribble, the the diaphragm in the accumulator is leaking.

[wfbal]

OK guys, thanks for the tip for checking the Fuel Accumulator. I will do that.

But what about after 2 hours or so. I understand that it is normal that there is no more fuel pressure after that long.
I gess some system should detect a Cold Start condition but it is not happening with my car until the car is really really cold.

What could be wrong here?

[Jim Williams]

Walter,

The specs on residual pressure don't really tell us how long before there is NO pressure left. But you said that your system was losing pressure too quickly. It seems you would want to get this issue resolved first, then see if that helped your problem. The cold start valve is held off from operating until the engine temperature is below 45 Deg C or 113 Deg F, which doesn't seem to be "really, really cold". Since the thermotime switch controls the cold start valve, it might be a good idea to check the operating temperature of this device.

At 113 Deg F, the WUR should be in its lean mixture range, so if your current WUR is in spec with the proper control pressure at this temperature, I don't understand how a new one is going to help the starting problem.

[Paulporsche]

Any new developments on this?

[Scott R]

Originally Posted by wfbal

Thanks Vash,

where did you get a rebuilted WUR from?

At 150$, I'm willing to try it out.

You can get them here:

http://www.fuelinjectioncorp.com/

[wfbal]

Thanks scott, I will get my Fuel accumulator checked, if it is OK the WUR is worth invetigating.