Got one for you guys

[OnTheRun2]

Car has been running great until on my way to work this morning I stopped for gas.
After filling up I left the station, and right after pulling out into traffic she stalled. I tried to restart her but no luck. Now while waiting for my brother to show up with the car trailer I tried her a few more times. After sitting for a bit she would start, but not completely. She would sputter like she was out of gas and never get up to full.
After I got her home I changed the fuel filter, tested the fuel pump, changed the fuel damper and FPR. Still no luck. She is getting spark and fuel to the rail. I have checked and she didn't jump time. Now every time I try to start her I blow #34 fuse (fuel pump).
I have also tried the jumper to pins 70, 70b and 30 with no luck.
I am stumped on this one. Any ideas would be greatly appreciated.
She is my daily driver and work is calling me back.

Just because someone will ask:
1986 944 NA
Factory stock
over 200,000 miles
Last belts 6 months ago.

[John_AZ]

The dist rotor is loose.
Did you try your spare DME/Fuel pump relay?
DME Relay Information and Testing
Bad gas.
Sensor connections at the top rear of the engine. BTW--do you have tach bounce when you crank?
If you had an early car, my next guess would be the ignition switch ($5) but you have a late 944 and different ignition switch ($90!)
Coil bad?

to be continued....
GL
John

[OnTheRun2]

Dist. and rotor are nice and tight.
Tried 2 spare ralays.
I have never had a problem with the gas before. I have been filling up twice a week at the same place for over 2 years.
I do have tach bounce.
I don't think it is the ignition switch as every is working as it should, except for not starting.
I am getting good spark, so I don't think it would be the coil.

All good thoughts, but I have gone through all of them.
Please play again..........

[jpk]

Speed and/or refrence sensor signal is not getting to the dme correctly
Check the wiring where the sensors connect to the harness. These are hall effect sensors that generate a very low level signal, so they are extremely sensitive to poor connectons and interference.
The harness end connectors can be replaced, but the only way to get a new plug on the sensor end is to replace the sensor.

[kdjones2000]

I would say bad gas.

You just filled up, maybe they had a bad shipment with lots of water in it, and you got a bad deal. Sputtering and such also hints at this.

Good luck, Keith

[944 Ecology]

If you're blowing fuse #34, you have either a bad fuel pump or a short in the wires to the fuel pump from the fuse block.

[JonA]

Are you sure you have proper fuel pressure at the rail? If fuse 34 is popping you may have a fuel pump problem.
A quick and dirty test might be to break the electrical connections at the fuel pump and try to start it again. If the fuse holds, it would point to a pump problem and not something with the wiring to it.

Good luck,
Jon

[OnTheRun2]

Good idea JonA, Cranking the car with the fuel pump disconnected causes the same blown fuse.
As for the gas being bad I think I would have seen at least a few pulled over like me. They have 36 pumps for cars and another 18 for trucks at this station. And most are in use 24 hours a day.
And for the Speed and/or reference sensors, I just checked them on the scope and they are working as they should.
I think I need to work on the wiring for the fuel pump and where ever that comes from.

[OnTheRun2]

Update....
Running a hot wire to the fuel pump, Car starts and runs as normal.
So I guess I have a short in the wiring to the fuel pump.
If anyone had another idea let me know. I'll be in the car tracing wires.

[OnTheRun2]

We Have A Winner...... ME.

In studying the wiring diagram I noticed that the O2 sensor heater is run on the same fuse as the fuel pump.
I disconnected the O2 sensor and everything works fine again.
I had a new O2 sensor on my wish list, I guess now it has moved up to the top.
Thank you all for your help.

[John_AZ]

Thanks.
I learned a bit more.

John

[matty89]

if a fuse blows i would alway check what is on that line to check for a short positif or a ground short ! thats the way to go ! good to hear you found it !

[bug]

If your O2 sensor eventually proves not to be faulty it should be reconnected as it not only limits emmisions it also boosts fuel economy and preformance.

[OnTheRun2]

The new one arrived today, but running with-out it for the week My gas mileage went up about 20%.

[924RACR]

Wow, shows it was really due for replacement! Should improve further with the new one...

[OnTheRun2]

Funny thing is that it was only 6 months old.
Just a good lesson... Never try to save a few bucks by going with a cheep after market.
Some things require spending a bit more to go with OEM.
If you don't spend it up front you will spend more in the long run.

[Ussery85097]

Im having the same problem withthe fuel pump blowing fuses. I have checked the O2 sensor, unplugged the fuel pump, and put a 12 volt power supply to the fuel pump. Pump works and still blowing fuses. The car was running before it sat for about a year with a leaky water pump, now its fixed and it wont start.

[mytrplseven]

Like the man said, "see what else is on that fuse circuit." Get an electrical schematic and follow the paths. It's sometimes confusing, especially if the colors are in German.

[bell]

iirc the o2 sensor heater is the only other component on the fuel pump fuse.....

[nynor]

fuel filter could be plugged.