1984 944 starting problem

wellstrung · 08-26-2009, 04:25 PM

Hi Folks!
I am seeking help with a perplexing problem. I have a 1984 Porsche 944 that was stored for the last six months. Now it will not start. I have read several forum threads and can't get a good handle on the possible cause(s).
The car has a new ignition coil, battery, and ignition switch. The engine turns over but I get no ignition.
Here's the kicker. I opened the hose between the air flow sensor and the intake manifold and shot in a quick burst of starter fluid. I then reconnected the hose and turned the key. The car started and ran smoothly at idle. I drove it around for 1/2 hour, returned home, and shut the car off. Seconds later I turned the key and it won't start. ???
Any suggestions from a qualified tech?
Thanks!

Icey1174 · 05:54 PM

Did the car at least turn over to try to start when you got home?

At start up the DME relay turns on the fuel pump once you start turning the car over to start it. Any time I have my fuel lines open it takes a few seconds for it to prime the fuel line while I start the car. All my American cars turn the fuel pump on as soon as the key is in the on position. These 944s wait till you are cranking the car till they turn on the fuel pump. If the car ran well once it was easily started with the starter fluid, then I would bet the farm that the problem is that for some reason the car is not turning the fuel pump on when it is cranking but is turning the pump on once it is running.

Try starting it again with the starter fluid.

Try a jumper for the DME relay. Maybe that is bad?

www.clarks-garage.com has a lot of info.

Link for the relay and jumper:
http://www.clarks-garage.com/shop-manual/fuel-05.htm

Icey1174 · 08-26-2009, 05:58 PM

I just read you have an 84 944. I would still guess that the problem is that the fuel pump is not being turned on while the car is cranking. You do not have the DME relay, you have a fuel pump relay. Could be a bad wire somewhere while cranking it.

Any other input???

Techno Duck · Techno Duck's Garage

Most definetley fuel related. Check and see if your injectors are firing while cranking, use a noid light or pull the rail off the car.

The other thing is to check if the fuel pump runs when you crank the car. If not, hotwire it directly off the battery. If that's the case i think your
ignition switch is suspect.

Lapponia · 08-27-2009, 05:37 AM

wellstrung! +1 to Icey and Thecno Duck. Remember though your fuel pump probably is 25 years old and have given up now like mine did the other week. My car started fine in the morning like it usually does and I run 25 km to a scrap yard to look at some car parts. Car started fine again and I drove to a café in the countryside and cut of engine and had that coffe break, an our or so. Got back to the car, put on safety belt an turned the key. Engine sputtered and stuttered several times when cranking and didnt fire up as expected. Lastly engine only cranked without any cylinder firing.
Hmm, 25 km from home I put in my spare DME relay and cranked but no fire. Removed DME relay and put in the jumper instead but in vain. Pulled the big nut in end of fuel rail, cranked engine again but no fuel in the rag. So by then I was pretty sure fuel pump was shot and no wonder, it was 25 years old like yours. Had to call truck with flat bed to get the car home, no business at all.
Day after I got a new pump for 499 skr (70 USD) in exactly same shape as OEM, put it in and BANG it started right up again and have done so since. AND this pump is almost dead silent compared to the old one. So now I have my spare DME relay in as well as a new fuel pump. Hopefully I will have no more issues around these parts as long as I live....or the car. There is a chapter 2 in the same business of wich you can read in a thread "Fuel smell........" earlier this week.
Also, I will recomend you to get Haynes manual for your car and read, read and read again.
Good luck and welcome to this great forum!
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Lapponia 1984/944 NA

wellstrung · 08-27-2009, 09:39 AM

Thanks for all the recommendations, links, etc! I appreciate everyone taking the time to help me get to the root cause of this starting problem.
Last night I did remove the fuel pump relay and checked the resistance readings. Everything is OK. However, when reinstalling I noticed that the cable harness behind the relay socket chassis moved when the relay was being plugged in.
I now suspect that a wire or two may not be properly anchored within the relay socket. Therefore the proper connections are not being made.
My next chance to work on the car will be this weekend.
I'll let everyone know what I find.
Thanks again for all your help!

Icey1174 · 08-27-2009, 10:31 AM

Please let us know what your results are.

Lapponia · 08-27-2009, 11:26 AM

Was it hard to get DME-relyay out? I would guess so sitting there for 25 years. When I bought my car I pulled all relays one by one, rubbed relay contacts with fine sandpaper and coated them with vaseline but was recomended in this forum to use "Dielectric Grease". Now they will be pushed in or pulled out quite nicely when nessesary. And all contacts are protected from corrosion for time on.
You should do this to every contact yuo can find in the car especially the ground contacts found in all possible and impossible places...its true. Good luck!
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Lapponia 1984/944 NA