Help! fuel delivery

[garyg]

My 1988 C4 would start then shut down and was indicating a code 36 on the OBD readout, this is a MAF problem. I removed the MAF unit and cleaned it with CRC spray and remounted it. OBD code now reads 12 which is normal. Car would start strong then shut down, I expected a blocked fuel filter so after removing the fuel pump fuse, relieving fuel pressure at the fuel rail I installed a new fuel filter. Now the car cranks but no indication of firing, I suspected fuel pressure hasn't built up in the system, but still not firing.

Any suggestions?

 

[ecss]

My 1988 C4 would start then shut down and was indicating a code 36 on the OBD readout, this is a MAF problem. I removed the MAF unit and cleaned it with CRC spray and remounted it. OBD code now reads 12 which is normal. Car would start strong then shut down, I expected a blocked fuel filter so after removing the fuel pump fuse, relieving fuel pressure at the fuel rail I installed a new fuel filter. Now the car cranks but no indication of firing, I suspected fuel pressure hasn't built up in the system, but still not firing.

Any suggestions?

On the rear of the passenger side fuel rail is a schrader valve. There maybe a screw on cap like a
tire valve stem.

Crank the engine for a few secondes.
Remove the cap if there is one. Press down on the schrader valve using a small screw driver.
Fuel pressure should be around 40 psi so the gas should shoot out. Have a rag handy to cover the
valve while you press on it.

Otherwise go to Advance Auto or Autozone and see if they have a fuel pressure gauge you can rent.
You put some money down and get it back when you return the item.

You could also remove the MAF sensor. Manually open the throttle body blade and shoot a small amount
of starting fluid or gasoline into the throttle body and see if the engine fires. That would confirm you probably have a fuel problem.


Here's a picture showing the location of the schrader valve.
You could also try using a tire pressure gauge to read the fuel pressure.

 

[garyg]

Thanks, after I did mount the fuel filter I left the ignition in the on position expecting the pump would be running to build fuel pressure but to no avail.
I will try your suggestions.

 

[garyg]

I have now checked the fuel rail valve and gas spurted up impressively, I then went to start the car, it started strong but then immediately shut down. An immediate repeated effort to start was not successful. The only OBD readout I am getting is 12, no other symptom is shown.

 

[garyg]

I ran a pressure test at the fuel rail with the ignition only in the on position, the gauge read 40 lb. After removing the fuel pressure gauge connection I sprayed starting fluid in the intake and the car fired up strong but then shut down.

 

[ecss]

I ran a pressure test at the fuel rail with the ignition only in the on position, the gauge read 40 lb. After removing the fuel pressure gauge connection I sprayed starting fluid in the intake and the car fired up strong but then shut down.

The fuel pump only runs for 2 seconds when you turn the ignition on.
The fuel pump runs continuously if there are distributor reference pulses indicating the engine is rotating.

Have you tried running the engine with the MAF sensor disconnected?

Near the schrader valve is the fuel pressure regulator. It has a vacuum hose going to it. Unplug
the vacuum hose and verify there is no gasoline in it. If there is that would indicate the fuel pressure
regulator diaphragm is leaking.

If that appears good.
Unplug the connectors going to each fuel injector.
Use an ohm meter and measure the resistance of each fuel injector coil.
Should be close to 17 ohms.