85 3.2 no start

[benzboy]

hey all last year my 85 wouldn't start. it turned out to be the the reference sensors. so now I have the same problem. it cranks over but no start, the tach moes a little bit, I switched dme relays, but nothing. I have spark, I checked it. I pulled a plug and wire grounded it and cranked it over, I sprayed starter fluid in it, it catches a little bit. so it seems like a fuel problem. I turned the key on, and I cant hear the fuel pump run. is there a way to check to see if the fuel pump is bad? it sounds like it has to be the fuel pump.

thanks
tony

[proporsche]

Hi Tony
to check you fuel pump use a little jumper wire and cross you no 6 and 3-5 fuses at your front fuse box .direction from windshield..No ignition on needed.

Ivan

[cabmandone]

The fuel pump doesn't run on key on. As mentioned above, install a jumper to make sure you have a functioning fuel pump. It wouldn't hurt to put a pressure gauge back at the nut on the fuel rail as well.

[ischmitz]

As others said, jumper the fuel pump and verify static pressure. Also might want to do a delivery test (verify that no blockage in fuel filter, etc.) Then, verify the pump comes on while you crank. If that is all confirmed get a NOID light or LED test light and check for injector pulses during cranking (in one of the plugs. If none you might have a problem in the DME or one of the injectors is shorted. Unplug all of them and repeat the LED test light test. If this no pulse the DME is bad. If pulses connect one injector at a time to identify the bad guy.

That about sums up getting fuel. Good luck and report back with findings.
Ingo

[benzboy]

ok, so I finally checked my fuel pump by jumping the number 16 and 17 fuses. all I had was kind of like a clunk sound. seems like the fuel pump isn't running. so does this mean it is the fuel pump???

[ischmitz]

that's a trick question, right.....

Let's put is this way. Without fuel pressure the car will not run. To develop fuel pressure the pump needs to run and be in good working order (amongst other things). If you got to the right fuses and what you heard was a bad pump trying to spin then: "yes it is the pump"

[benzboy]

ok quick update. I bought a new fuel pump and car still wont start. I pulled the line out of the pump and see if it pumps fuel, and it does. now I didn't do that while I was cranking the car. only when I jumped the 16 and 17 fuses. what can be my problem? I have spark also

[Rodsrsr]

I would put a fuel pressure gauge at the fuel rail port to see what you get. If no pressure than check at the filter, it may be clogged, but check at the farthest point first and work your way back. If you do have pressure then do a volume check at the same fuel rail port.

[benzboy]

ok another update. I have 12 volts to the injectors. but then I put a noid light on. im getting no injector pulse. also. I was standing around the car, with a Porsche mechanic, and all the sudden I heard a noise. out of no where the fuel pump began to spin. the pump got really hot and I pulled the fuse. now my new fuel pump is locked up. is all this a sign of the dme its self? if so, is there any one out there that can fix it??

[ischmitz]

The fuel pump is controlled by the DME relay and that is controlled by the DME. Assuming this is a stock 3.2 car the pump should not turn on by itself. The DME will turn it on (via the DME relay) if one or both of the conditions below are met:

1. Cranking (power to the starter relay from ignition key with key in START)
2. DME sees flywheel motion > 200 RPM with both flywheel sensors working well

The first question is why it came on by itself. Was the key in the ignition switch? If yes, in what position?

In the current condition (fuse to fuel pump removed) tell us if the ICV is vibrating when you turn the ignition to RUN.

Next test: Try another DME relay since maybe yours is bad (fused shut). Not likely but still worth a shot.

Next test: It could be the DME itself. Pull the DME relay, take the key out of the ignition and then use a test light or your NOID light in the DME relay socket: Connect one pin to 30 and the other to 85B. If you use the NOID light try both orientation since it cares about polarity. If the test light come on your DME is bad. To confirm pull the DME and measure with an OHM meter between pin 20 and pin 19. If you see a low reading in the 0 - 10 Ohm this confirms the DME needs repair.

The next question is why the new pump is locked up. The fuel system in a 3.2 is designed for the pump to pressurize the fuel rails by pumping against the rail and the fuel pressure regulator. The fuel pressure regulator lets excess fuel go back to the tank. So even if the pump runs for an extended period of time with the engine not running it should not get hot and certainly not get stuck. The fuel flowing through it cools it. You may have gotten a bad pump in addition to your other issues.

And to your last question: Yes the DME can be tested and repaired. Let me know if you need help. You can send me a PM.

Regards,
Ingo

[mysocal911]

Originally Posted by benzboy

is all this a sign of the dme its self? if so, is there any one out there that can fix it??

Just like for ANY issue these days, do a Google search for a rebuilt DME unit,
e.g. Porsche 911 3.2 ECM/ECU/DME. There are many sources these days for that
service. Even Pelican Parts provides that service, just do a search in the Pelican Catalog.

By the way, it's very very rare for the DME ECM to fail causing the FP to run continuously.