911sc guys help it wont start!!!!

pnzr911 · 08-26-2002, 01:58 PM

Help! My 1983 911sc refuses to start! I have had this car for 6 months and it has always started on the very first crank. Now the car just turns over and over and over and...nothing. I checked for spark and its ok. I did a quick fuelpump check and it sounds like its working. I have voltage at the thermo time switch but have not yet checked the cold start valve itself. Can anyone give me any typical suspects??? Thanks in advance!!

pbs911 · pbs911's Garage

Has there been a major back fire recently? Do you have a pop-off valve? Even though you have the 3 necessary elements (gas, spark and air), if there is a blown air box the car may not start. Also confirm that the fuel pump is delievering fuel. If you lift the sensor plate can you hear the fuel?

surflvr911sc · surflvr911sc's Garage

Pull off the air filter and see if you have a pop-off valve. It shouldn't actually pop-off so if it did, there you go. If you don't have one, someone else will need to help out. I know a few things that will make this happen but this is the most obvious and I'd probably have you running in circles with the others.

Paul beat me to it!

83SC in PA · 08-26-2002, 02:24 PM

Fuel pump relay?

Superman · 08-26-2002, 02:28 PM

If the spark is okay, then check to see if the fuel system is getting pressure. Run the FP and lift the air flow sensor plate. You should be able to hear the injectors squeal. That being the case, go quickly to the cabin and start the car. If this works, then your cold start system may be unfuctioning. There. I invented a new word. Unfuctioning. Or Unfunctioning. Something like that.

pnzr911 · 08-26-2002, 04:42 PM

HMM the pop-off valve is OK. I tried lifting the airflow sensor plate and yes I could hear some strange squeal sound from the injectors. I did not try to start it at this point. I will go back and try that again. Im beginning to think its the cold start valve....darn it should have replaced it when the engine was out!!! Thanks for the input so far guys!!

BoogieOnSkis · BoogieOnSkis's Garage

Your description sounds very similar to a problem I had about 8 months ago.

I was sitting at an intersect waiting for the light to turn green when my car just died and wouldn't start. I had to tow it home and debug the problem. I had fuel, vacuum, and spark, but something seemed wrong with the spark -- it was not arcing as much as it should and it seemed week. I replaced my ignition coil and my car runs fine.

A good tell-tale is if you find a black oily substance on your coil, then there's a good chance that it's bad. Search previous posts for this.

Also, if your coil is bad, then there's a chance that your CD unit is damaged.

pnzr911 · 08-26-2002, 08:39 PM

I am recharging the battery overnight. The spark seemed very weak but I thought it was because the battery was getting low. Tommorow once the battery is full charge I'll check again and this time also checkout the coil. Thanks!!

Superman · 08-26-2002, 08:53 PM

The reason I suggest your hurry up and start it after you've heard the injectors squeal is because this will put fuel in the intake for starting. It will replace the cold start valve. The CSV only sprays for a short time. Up to 7 or 10 seconds in the coldest of weather. Much less now. So, it should start. Or try to start. someone holding the sensor plate up would have the same effect.

For all their complexities, engines are simple in that way. If there is a snappy blue spark at the right time (around TDC or just a little after...static timing that is) and you add fuel and air, Viola! Just like they do on Junkyard Wars.