Random starting problems

[binaryc]

I've got a '99 Boxster, and every once in a while I have a problem getting it to start. The starter motor spins strong, but it just won't light. I've ruled out the battery by connecting another battery from a different car. I'm not getting a CEL or any fault codes.

The only way I've gotten it to start is to just keep trying. I normally crank for a few seconds, then let it sit for a while for the starter motor to cool, then try again. Eventually it'll start. Once it starts, it runs smooth. I'd guess it has the problem once every five starts or so. The only consistent theme is that it happens at the most inconvenient times.

I have a feeling it's not a spark problem, or I'd have running problems as well (and probably get a code). My guess is may be a fuel pump problem, but I would imagine I would also get running problems (and a code), wouldn't I?

[extanker]

i think you will have to find out if you dont have spark or fuel. arent ignition switches known to go bad ? without test equiptment its gonna be guessin .can you hear [here for cloud job] the fuel pump =

[m208334]

Could be the starter solenoid. Sometimes the solenoids start to not pull in. Temperature could effect resistance.

[binaryc]

If it were the ignition switch or the starter solenoid, wouldn't the starter motor fail to spin at all (I would just get a clicking sound)? I hear the starter motor spinning fairly strongly, but no ignition.

How can I tell if the fuel pump is pumping? I hear a bunch of sounds, I'm not sure which one (if any) is the fuel pump.

[extanker]

when its cranking over and not starting you can try to slightly turn the key back[but just a little bit]...the switch has a few contacts in it but you wont hear any clicks from it. the fuel pump is best heard [herd for surf job] by the fuel door wit da cap off,not a one man job...random and man made problems are the hardest to find...let us know ....off topic...hey houdy cloud howelz my syntax

[ARModen]

The fuel pump is only going to come on if the car is cranking which makes hearing it very hard. If you or someone near by has a PIWIS, PST2, or durametrics set up then they can turn it on and off with the car off for you very easily. The relay that controls it is the small one just to the rear of the double roof operation relay in the drivers foot well. You can short that out to force the pump to run also.

The starter solenoid engages the starter with the engine. If the starter goes bad you just hear the clicking of the solenoid trying to engage the starter. If the solenoid goes bad then the starter will spin but won't engage the flywheel/turn the engine. You can test that by turning the car over and having someone put there hand by the exhaust. Even before it fires it should puff air out of the exhaust as the starter rolls the engine. (Someone suggested that to me a while back when I was having problems, but I've never actually tested it, so... gl).

[TimAustinW]

Have you checked the flux capacitor? :troll:

[coolbreeze551]

Sometimes it is as simple at the floor mat being pushed up to far and not letting the clutch go in all the way. Check it out.

[spgribben007]

As of yesterday I'm experiencing the same thing... the car won't start (there were no warning signs), so I replaced the old battery with a new one last night hoping that this would be an easy fix but no such luck. I've replaced the ignition switch several years ago and in that case it was just a clicking noise. This time it's spinning and spinning.

Been on this site this morning and I've read something about a clutch switch possibly going bad, is it fairly common? Is it a inexpensive DIY job? How can you tell if it's bad? I'll try the solenoid experiment when I get back home (out of town right now).

[extanker]

if the starter motor is turning the engine over its not the clutch switch. check for spark and/or fuel

[spgribben007]

Thanks for the suggestion but without testing equipment how do I test for spark and/or fuel?

[binaryc]

Just got the car back from the shop. The problem was apparently pretty difficult to track down, but wound up being a weak/worn out engine speed sensor (part number 986.606.112.02).

[extanker]

crankshaft position sensor ?

[Pianohawk]

Originally Posted by binaryc

Just got the car back from the shop. The problem was apparently pretty difficult to track down, but wound up being a weak/worn out engine speed sensor (part number 986.606.112.02).

I've had this SAME issue for about a year and a half now. Money has been tight so I haven't taken it to the dealer yet (ind. shops haven't been able to diagnose it).

Would you explaining a bit more about what the mechanic said or PM me if you have a few minutes sometime. Thank you!

[binaryc]

From what I can tell, that sensor tells the computer the speed of the crankshaft, which controls spark timing and fuel injection. In my particular case, the sensor was putting out a weak signal, which is really weak in starting conditions (low RPM, low battery). The problem was also heat related -- if the engine was cold, it worked fine. If the engine had been running for a while, it worked fine. If the engine had been running, then shut off and sat for about 20 minutes, it wouldn't work until the engine cooled down further.

The actual part is relatively cheap, and replacing it is fairly easy. The hard part in my case was figuring out what the problem was. The tech had to hook up a break out box to the DME in order to track down which sensor was flaking out.

[marco]

Any results to share from your starting problem some time back? Iam having the exact problem.