Another CIS Question-No Start

[PeteT]

I am pretty much at wits end. First off, I think I have read pretty much everything I can on the forum to no avail. A bit of background, the car (83 SC) has been off the road for about a year for a trans rebuild. I replaced all the fuel lines from Len, replaced all vacuum hoses and replaced all the other hoses that were looking old and tired. Before I pulled the motor the car ran great and in fact I had just passed CA smog so things were doing well. I have been chasing a no start issue for the last couple of days. What I have done:

1: Check fuel system pressure, pegs the scale. Over 7 bar (100 psi) PROBLEM

2: Conducted FP relay tests outlined in Bentley, and all seem well. I can jump 30 and 87a and the pump runs fine.

3. Checked the 85 terminal on the FP relay ground and when I lift the sensor plate I get continuity so I am assuming that's ok.

4. Pulled all the injectors and inserted them in plastic bottles and jumping the FP relay while lifting sensor plate I get a great spray from all six injectors.

5. Pulled the pressure relief valve and cleaned it and replaced o-rings. It looked fine with no varnish. Also temporarily removed the shims to see if the pressure would go down and since the gauge pegged I can't really tell.

6.The car will "start" on the CSV and run for 2-3 seconds and then die. Obviously I think the pressure is WAY too high.

7.With the valve on the fuel pressure gauge open I can't really check the control pressure since the car doesn't run, but it shows off the chart pressures.

What are my next steps?? I have a feeling my fuel distributor is FUBAR and will need going through but am hoping there might be something else I can check.

Thanks
Pete
1983 911SC

[356911930]

You might want to check your fuel pressure gauge. Too high fuel pressure is a little unusual. Could be fuel distributor but that is unusual also. Pull your spark plugs to see if they are wet. this could mean too much fuel or too little spark.

Use an inductive timing light to see if you are getting spark and or pull plugs to see that they have spark.

1983 911 SC had some idle control components. Bob Contac (SP) is a PP resource for this MY Porsche. I would pM him. Last name could be Contak? ..not sure.
Rahl

[boyt911sc]

Pete,

What are your cold and system fuel pressures? If you are getting the same value for SP and CP, you have a clogged return line.

Tony

[RDM]

The car does not have to run to check warm / cold control pressure. With the electrical connector disconnected from the WUR, open the valve on your pressure gauge to let fuel get to the WUR and see what the gauge reads. To check warm pressure, simply reconnect the wires to the WUR, wait, and watch.

That being said, your gauge sounds flaky.

[Bob Kontak]

Originally Posted by boyt911sc

Pete,

What are your cold and system fuel pressures? If you are getting the same value for SP and CP, you have a clogged return line.

Tony

+1

Fuel pumps put out quite a bit more than system pressure. If no way to bleed off the excess with designed parts, your entire system will reflect pump pressure.

[ossiblue]

Originally Posted by PeteT

I am pretty much at wits end. First off, I think I have read pretty much everything I can on the forum to no avail. A bit of background, the car (83 SC) has been off the road for about a year for a trans rebuild. I replaced all the fuel lines from Len, replaced all vacuum hoses and replaced all the other hoses that were looking old and tired. Before I pulled the motor the car ran great and in fact I had just passed CA smog so things were doing well. I have been chasing a no start issue for the last couple of days. What I have done:

1: Check fuel system pressure, pegs the scale. Over 7 bar (100 psi) PROBLEM

2: Conducted FP relay tests outlined in Bentley, and all seem well. I can jump 30 and 87a and the pump runs fine.

3. Checked the 85 terminal on the FP relay ground and when I lift the sensor plate I get continuity so I am assuming that's ok.

4. Pulled all the injectors and inserted them in plastic bottles and jumping the FP relay while lifting sensor plate I get a great spray from all six injectors.

5. Pulled the pressure relief valve and cleaned it and replaced o-rings. It looked fine with no varnish. Also temporarily removed the shims to see if the pressure would go down and since the gauge pegged I can't really tell.

6.The car will "start" on the CSV and run for 2-3 seconds and then die. Obviously I think the pressure is WAY too high.

7.With the valve on the fuel pressure gauge open I can't really check the control pressure since the car doesn't run, but it shows off the chart pressures.

What are my next steps?? I have a feeling my fuel distributor is FUBAR and will need going through but am hoping there might be something else I can check.

Thanks
Pete
1983 911SC

You may have several problems, as mentioned by others, including the accuracy of the gauge as well as how you tested the fuel pressure. However, I have a question about the item you posted, #3, in bold.

If you were testing terminal 85 of the relay socket for continuity to ground, when you lift the sensor plate you should lose all continuity to ground, not get a reading as your post implies. Did I misunderstand your testing of terminal 85, or does, in fact, the terminal go to ground when you lift the sensor plate?

Here's why this is an important question. When 85 is grounded, the relay switches power to the fuel pump to the START circuit and the pump runs (and the CSV injects) only when the engine is turning over with the starter motor. As soon as vacuum is detected in the intake from a rotating/firing engine, the sensor plate lifts and the ground connection is lost causing the FP relay to switch power for the pump to the RUN circuit. If your testing is as I understand, grounding 85 when the sensor is lifted will not allow the fuel pump to run with the ignition in the ON position.

Your start issue may be related to the FP relay if, in fact, your post is accurate and 85 becomes grounded when the sensor plate is lifted.

[gomezoneill]

It's not your fuel distributor. If the car ran good before you pulled the motor it's something you did wrong while reinstalling the engine or something you forgot to reinstall correctly.