Hi, I've had my '91 964 for about sixs months now. It has been running fine until earlier this week...now, it will not start. The engine cranks, but no fire.

I have replaced the DME Relay, as it was easy to do. But still won't fire or start.

Checked my records, the ignition coils, coil wires, and spark plugs replaced while crank pulling timing readjusted after stalling problem. The work was done 4K miles ago.

Noticed one other thing. "Check Engine" light does not come on with other lights with key in #2 position. Always did before.

Any ideas? Thanks in advance.

bob964

 

Do you smell fuel at all?

What were the circumstances such as weather, Is it possible that the oxygen sensor was wet?

Do you get spark?

Please let us know as many details as possible.

Colin

 

I think that even if the O2 sensor was wet, or dead, it should still fire up - since it is not used/ignored for the first minute while the engine gets warmed up.

If you've got a timing light, do as Colin says, check for a spark in the plug wires; or if you're daring, pull a plug wire and stick it close to a ground to test for spark. If you've got spark, you don't have fuel. Your fuel pump may have kicked the bucket - do a search on this; as you should be able to hear it running under the passenger side of the car.

Make sure the battery is good - according to Adrian's book, the engine has to be cranked up to a certain speed before things starting exploding.

Just some ideas... keep us posted!

 

Hi Colin,

No fuel smell, even when pumped a few times and numerous start attempts (this was an extreme measure) weather is dry and warm, the car was out during the day garaged the rest of the time. Wife had it out during the day. I came home and went to put up the top, but decided since it was such a nice day to take her for a spin, but no go.

Spark, but not no fuel.

Bob

 

When mine has failed to start (s'been a good 6 months since I had a problem) its been low battery power. Check your battery 1st even if it sounds too obvious. When mine was not starting I thought it couldn't be the battery as everything electrical seemed to have enough power (radio, lights etc) following Adrians advice however I checked with my multimeter and found it was too low. A recharge (and later a new battery) fixed my problem!

Good luck, its a frustrating situation and you have my sympathy!

 

Garrett...thanks for the reply...I will run a search on fuel pump and post back.

Howard...I followed your post and it gave me some good suggestions. I've tried a number of times to start the car and run the battery down. Checked the records and it was replaced about a year ago. Voltage reads 12.3V. Did not check the voltage until today so I don't know where I started. Will recharge tonight and see what happens tomorrow. One thing that is nagging me from your post was the suggestion about removing the driver's seat. My wife and I differ quite a bit in height and neeed to move the seat forward and back. Since I was the last to move the seat back, I wonder if something came loose . I checked but found nothing obvious.

Thanks again and I will post after further investigation. Keep the advise coming, it is appreciated.

Bob

 

Uh oh... sounds very much like you may have crunched your harness going to the DME. The fact that the engine light no longer appears is strange, and may be due to munching it with the seat. Of course check the light bulb with a new one....

Seems that strange things occur when harnesses get smooshed. And with frequent seat movement, it's possible.

 

It is possible that you may have a bad DME relay. Do you hear the fuel pump running when ignition is on?

If you do not hear it, you can pull the DME relay and jumper the three large contact slots in the fuse box. you should immediately hear the fuel pump runnning at this point. If this works, try to start the car.

A word of caution! the jumper wires will get hot. Wait for them to cool off or pull them out with a pair of insulated handled pliers.

Where is Pa are you located? If you're close I may be able to come by and lend a hand.

Colin

 

Garrett...I could only hope it was the bulb, swapped it with a known good one, bulb was fine.

Colin, already replaced the DME with a spare (got one as suggested, opend the old one and it looks fine), even did the jumpers just in case. you can hear what I assume is the pump running. Funny, still don't smell fuel.

I'm up in Lakawanna County. It would be a long haul, but I appreciate the offer. Porsches appear to be few and far between up here. I used to live within 40 miles of Howard and you would trip over Porsches there.

Bob

 

For what its worth, I had a similar problem this past spring, after firing up after winter storage. After checking the usual suspects, the first of which was replacing the DME relay, it still wouldn't start. Finally, I had the car towed to my mechanic. As it turned out, it was a faulty spare relay. What are the chances of that. The first one fails and the spare is a dud. Seems to me that the DME relay is the culprit for many of the 964's woes.

 

Bob did you try starting the car with the jumpers in? I don't think you will smell fuel until you have the engine turning over. The fuel pump will run but the pumped fuel will return to the tank via the bypass.

If the car starts with the jumpers installed, then you have a bad relay.

Colin

 

Hi Colin,

Recharged the battery last night. Today I tried the jumpers again, same thing, crank but no fire. The sound of the pump running was obvious with the jumpers.

Any other thoughts?

Bob

 

Could be the flywheel position sensor. I believe some members have had their sensors just go bad.

My car exhibited the same symptoms as yours when the flywheel position sensor connector came loose.

Colin

 

well, the moral to the story is to always go back to the most recent change and work backwards...it appears my problem was due to a broken wire under the drivers seat that ran to the DME. Wire repaired, problem solved. Thanks to all for their ideas and support.

Bob

 

Nice follow up!