QuestionThe car has about 157000 miles we just bought it full of cobwebs and dirt. charge the battery and drove it home. one head light work then it stopped working. what was funny about it was it ran fine. we where just tring to figure out if it was still leaking and over heating. So i drove it to work and my son drove it home. Seem to run good no cutting out or overheating. Woke up the next morning wouldn't start just turns over. I don't know anything about the cars history Paid $200.00 for it so could pass it up. I knew it would be a project car. I'm not completely stupid when it comes to cars but don't know much. My dad told me how to check for spark.I tried looking for vac leaks eveything looks good.Ground wires seem to be good ones I no of anyways. will look for airflow tomorrow after work.I'm waiting for a manual in the mail to help with learnig.Just seems wierd that it was running then just stopped like that. Thanks will let you know what i find tommorrow.-Ken
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Followup To
Question -
We bought our 944 and it started just fine. Has a water leak and it shows over heating. We change the thermostat. Drove it 2 miles to work and then back. Now it won't start, it turns over but wont start I beleive it has gas.Just bought this car and do expect it to be a project but this seems like something I'm being dum about. Do you have any suggest for me to try email me or even call me 530-899-3806. Thanks Ken
Answer -
Hi Ken,
I'll wager that the cooling issue has nothing to do with the no-start...unless... in the process of swapping themostats, some electrical connection or vacuum line or such was bumped or dislodged from its normal resting place. Perhaps the vibrations of that next drive caused a disconnect. That would be the most obvious first step. Take a flashlight and follow every wire and line nearby the front of the engine verifying the connections remain secure.
Other than that, a so-start can be quite daunting, as the number of possible cause are many.
If you boil it down to the four main components, you can start eliminating big chunks of possibilities. Meaning this:
You need: AIR, FUEL, SPARK, and COMPRESSION. Generally speaking the tests for these are straight-forward. Air means the filters are clean, the inlet tubes/piping are open, not crushed, and there is not any "false air". The Bosch fuel injection system you have uses this terminology to keep our focus on the fact that the right amount of air is good, too much or too little can be bad. The way the airflow gets too much air is to have air enter the intake manifolds without having passed through the air filter and the air measurement device known as the air-flow meter. If you have a vacuum leak, for example, the intake manifold is sucking in "false air" (non-metered air), having it mix with metered air, then the engine will run poorly. A very bad vacuum leak could be a no-start, but usually appears as a backfire first.
This is an example of the kinds of things you'd look for in the AIR category. There are similar tests, some easier and some more difficult, or requiring special tools, for the other three categories. Before I tell you things you already know, why dopn't you tell me more about the car and yourself. How many miles and how well maintained? The car, not you! When was the last maintenance and what kinds of things were done? Are you at all experienced with cars and Porsches or would you like some more assistance with the FUEL, Spark and Combustion categories?
Write back and let me know what you find during your evaluation of AIR.
Dave
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Follow-up 9-2-06
Ken...I misspoke earlier...I suppose I was so wrapped up in figuring CC to quart conversions, I didn't clarify something. For the gush test go ahead and crank the starter. But if you do any "volume" testing, DON'T run the starter that long. Activate the fuel pump using the fuel pump relay, not the starter...it'll get too hot. I've got to run right now, but I'd be happy to explain this process when I get back.
Dave
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Hi again,
Ken, thanks for all the good info...that helps. While you are there you might as well test for fuel too. Just find the connection of the hard line and flexible rubber fuel lines near the engine. Or disconnect the fuel line at the "service port" at the"fuel rail".
When you crank the starter you should be seeing quite a good "gushing" of fuel. The amount of fuel delivered (onto your garage floor) can be more precisely measured if to can catch it and measure it. The 944 requires 850cc (almost 1 liter) fuel in a 30 second fuel pump run. Frankly, if you get that good gush above, it means the fuel is arriving at the engine...it should start.
But the measurement test is really a good thing to do. If you don't have a 850cc container laying around, use whatever you have and convert the output...sort of like this:
Run the pump for half the time (15 sec) and try to get 425cc of fuel, which is .45 quarts, almost a half of a quart. Get the idea?
I'll be anxious to hear what your testing reveals.
Dave
