Hi Everyone. My 99 996 has a peculiar habit of hard starting while running errands. Car ALWAYS starts fine when cold. Car also starts fine within minutes of being turned off.

However, if is run then shut off for more than 1/2 hour or so, it is very hard to restart. Cranks great, just won't start. Using takes 10 sec of cranking while flooring the pedal. Once it starts, it idles smoothly and runs great.

ANyone have this behavior? ANy leads on what it might be?

 

Same thing happens to my 04 996 whenever I fill up with gas. That' the only time it happens so I never really think about it until next time I get gas. Something to do with the gas tank venting or gas cap?

 

The issue doesn't seem to correlate with getting gas. Just when it has been driven and still warm (but only after sitting for 1/2 hour +), prior to that it starts right up.

 

I'm facing the same issue, from my research here and the guys the issue can be one of two things:

1 - Corroded starter cable, the one that runs from the alternator to the starter and the jumper block in the engine bay

2 - Bad starter

Seeming your car is older i'd say it might be the cable.

The way Asahi recommended I check is to do a voltage drop test. So test what the output is at the alternator and what the voltage is from the jumper block.

However with this procedure

- Car needs to be warm
- A/C needs to be on as well as the radio and the headlights (this is so you use some voltage and can simulate the car starting) then test if the cable has gone bad and is losing voltage preventing the car from easily turning over when warm.

I'm yet to do this test as I haven't had the chance

 

you may need some special testing equipment after KNOWING it is NOT a battery/starter issue. you would want to check for spark and fuel while it is cranking with no start. on some cars if you floor the gas pedal while cranking they go into "clear flood mode" cutting off fuel which could mean a fuel injector is leaking after shut down . bottom line is to find out if it is fuel or spark .there is just too many things that it could be ....fuel pump,relay,ecm,crank /cam sensor,fuel check valve,cranking voltage etc

 

Interesting. Pretty certain it is not the starter. The starter cranks free and fast while cranking. It just doesn't start. I do find that if I floor the gas pedal while cranking (only in this warm / won't start situation) it does eventually start. Anybody else experience these symptoms?

 

This is a not uncommon thing. My 99 did this. We replaced the Y cable and that seemed to help, although that was not a cheap fix. It can be really maddening to track down.

 

Ahh right sorry disregard my diagnosis steps if the voltage doesn't drop and the starter works well!

 

I had the same issue when my car was running.

I suspect that in my case, it's related to a bad crankshaft position sensor.

Heres my sensor:


I figure cold starts were fine but once it got hot, the broken plastic expands and screws with it.

 

Did you have any other problems from that or was it just hot starts?

 

there's a slight hesitation when 1st taking off on initial start up but I can't say thats CPS related as I suspect a bad variocam solenoid or spark plugs caked in oil (from scored cylinders).

I'm hoping it was just spark plugs caked in oil causing a miss.

 

are you starting [pun] to see a pattern here.........gas cap/radio?/replaced cable and SEEMED to get better/expanding plastic/i suspect/hoping/vario/plugs. these are commonly called shot gun repairing....scatter parts at it in hopes something with fix it. given enough time you will read.....bad gas/ims/wrong oil/parked on an angle .take the car to a shop that has the latest test equipment.....they will plug in to the obd port and look at the data while cranks no start......radio on....yeah dats a good one. tinkerbell auto repair

 

Your IMS bearing has failed. Replace that.

 

You should check your spark-plugs. I had this happen to wife's BMW, hard to start and foudn out the spark plugs were bad. I was also thinking about CPS, so worth checking it out. I had that problem with the bimmer as well. Good luck... Cheers,

 

Without seeing the vehicle and running some diag it is hard to tell but based on the information you are giving us I see 2 possibilities.

As mentioned by AWDguy it could be the crank position sensor. However when this fails it will typically cause the car to stall and not restart until it cools down. Since you said you can turn the car off and start it right back up I do not think this is the likely source of your problem.

You mentioned if you hold the accelerator pedal to the floor it will start easier, based on that info I would suggest it is a problem with your EVAP purge valve. Essentially this valve is failing and flooding the cylinders with raw fuel preventing it from starting again unless you lean it would with lots of air (full throttle on the accelerator pedal). This part number is 99611012953. It is about $210 for the part.



You can prove this by shutting the car off and pinching off the rubber lines after the valve. Wait the half hour and then try to restart. If it restarts without any issues then you can remove whatever you have used to pinch off the line and try to duplicate the problem again. If it is present then you know you found the culprit.

Let us know how you make out.