consistant starting issue

[comicbook8@gmai]

Hi all !
my 89 944 s2 has a starting issue , when i try to start it after a couple of days i turn key and it cranks and cranks and cranks then splutters into life .if i turn it off then restart it within 15-20 mins it will start no prob any longer and it struggles into life again .if i crank it a couple kill it then crank it straight away it starts ok every time , she is running superb other than this , does any one have any ideas? could it be fuel prssure regulater , any input greatly appreciated thanks !

[Makis]

S2 does take 2-3 seconds of cranking before it starts. My does this consistently. The regulator may be the problem but doubt it as you say the car is running good once started. The fuel pump should pressurize the system quick enough. Only if the fuel has leaked out of the fuel filter will the pump require more time to pressurize the system. I can't see a faulty regulator to do this in 20 minutes. The regulator can loose pressure quick but cannot drain the fuel filter. So check to see if you have any fuel leaks.

Also when cold once started does the car run OK cold? Or is the car running OK only once is warmed up?

[Cking1975]

I would check the fuel system, prehaps you are losing fuel pressure over time for some reason ? I would be interested to see if you pumped the gas pedal a couple of times and then try to start the car, if it started right away.

[zedsn]

Hi, not sure on your S2 but my 944 has a check ball that is right above fuel pump that keeps the system pressurized. Maybe you have one and it is fualty and as the call sits for a long while and the fuel all leaks back into the tanK.

[marko]

Mine was doing the same thing awhile back, drove me crazy.
I had been messing with the throttle cable and set it too tight when I was done. This had caused the TPS to always be in the open position.

Worth a try. With the engine off, move the throttle cable back, you should hear a click from the tps, if not, you might have found the problem.
To make sure, you can take the tps connector off, put an ohm meter on the bottom two pins of the tps (not the cable end), it should measure a short, pull the throttle cable back a bit and after the click, you should read an open.

[comicbook8@gmai]

thanks for the replys guys !
car runs fine when cold and warm, but is defo running rich.could this be related?
when i pump the gas pedal b 4 starting this makes no differance same results.
is there a fuel line check valve on the s2 ? this sounds like something.
the t.p.s (throttle position sw.)? is this where the throttle cable connects to the throttle body ? i will check that tomorrow,maybe previous keeper messed around with it !

any more input much appreciated

[jmd_forest]

I had the exact same issue as marko. The PO had increased the idle using the throttle cam stop screw and it left the TPS idle switch open all the time. It started fine but ran like crap when cold. The TPS is a small black plastic box about the size of a matchbox on the underside of the throttle body (where the throttle cable connects). It should have a connector with 3 wires attached to it. Check out Clark's Garage for a detailed procedure on testing the TPS.

jmd_forest

[comicbook8@gmai]

thanks for that jmd i will check that , was she running rich when cold?
some thing else just dawned on me thow , during the winter when it was frosty / cold it would fire first time every time . hmm whats up with that now the weather has gotten kinda warm 20 celsius the prob has become very consistant !

[comicbook8@gmai]

there is a fuel check valve on the s2 just after the fuel pump !
just checked the porsche kat

[mikepellegrini]

Originally Posted by comicbook8@gmai

there is a fuel check valve on the s2 just after the fuel pump !
just checked the porsche kat

That's what I was thinking.

The leakdown pressure test procedure at Clark's calls for 2 bar (20psig) at the end of 20 minutes. http://www.clarks-garage.com/shop-manual/fuel-01.htm

What you described would be classic behavior for a bad check valve.

[Makis]

Originally Posted by comicbook8@gmai

there is a fuel check valve on the s2 just after the fuel pump !
just checked the porsche kat

The check valve can kill the pressure but will not drain the filter of fuel. The pump should then be able to build the pressure quickly, so somehow don't think the problem is the check valve.

[comicbook8@gmai]

hmm, hmm , good point ! the pump should be able to pressurize no matter what
if i sw on ignition get pump running and leave it for over a minute before trying to fire its the same. does any one know if it could be a leaking injector what the symptoms are of such a prob ?
sorry everyone your prob sick and tired of this 1 but tks 4 your patience , im a bit of a novice but am learning so much from you all .this is what porsche ownership is all about great stuff all consuming eat ,sleep, drink porsche

[jmd_forest]

Yes, she was running rich. But right now, she's running rich all the time (new O2 sensor reading .965V after warmup) and I don't know why yet.

Although the pump should be easily able to pressurize the system in a few seconds, the check valve is there for a reason, to assist in warm starts. Do a leakdown test on the fuel system. Clark's Garage has a good procedure writeup. Instead of the fancy connector to the fuel rail access port, I used a short 3/8 inch hose and 2 hose clamps to connect the pressure gauge to the rail.

Also, there was an issue similar to this on the 944online forum earlier today. Turned out to be the coil was weak and got weaker with heat.

jmd_forest

[comicbook8@gmai]

ok so i decided to order the fuel check valve and a fuel pressure reg. while i was at it , i changed the reg. last week still the same maybe a slight bit better , going to change the check valve this weekend and hope !!

[comicbook8@gmai]

aaaggghhhh !!!! "BUGGER"
STILL THE SAME WITH NEW F.P.R AND CHECK VALVE.
back to the drawing board ah well . any body out there with an opinion on this it really is driving me nuts now. it starts every time once i give it a couple of cranks then ignition off and ignition back on she fires and runs great .and if try to start within 30 mins its fine anything longer and have to do the cranking routine .
could it have any thing to do with engine temp sensor it has gotten completly consistant since air temp has increased , used to be fine on a cold frosty morning fire up straight away

any opinions and i mean any are greatly appreciated .
THANK YOU IN ADVANCE

[Makis]

When cold try to crank it until it catches and starts. Do not stop the cranking unless you crank over 10seconds. If it starts and runs great straight away then probably the temperature sensor is OK. If not then sensor could be suspect. Let us know if you can start this way and how long it takes to fire up.

[Makis]

Also check the battery condition, assess starter motor condition and battery wiring. Any weakness here can cause hard starting. The S2 is a big engine and requires decent spin in order to fire up.

[comicbook8@gmai]

Originally Posted by Makis

When cold try to crank it until it catches and starts. Do not stop the cranking unless you crank over 10seconds. If it starts and runs great straight away then probably the temperature sensor is OK. If not then sensor could be suspect. Let us know if you can start this way and how long it takes to fire up.

just went out to start her up now to c how many seconds it would crank before it fired . turn ignition on for about 10 -15 sec then turned key all the way to try and start it and it started straight away!!!!! bloody typical it has not started that good since the winter. i doubt it is fixed. normally it would take 5 or so seconds of cranking then when it fired it would splutter like it was clearing its throat then it would settle down and run fine , a bit rich thow!

[Makis]

Looks like you may need to just freshen up the electrics. If the car fails to start outright then is like most cars will be more difficult to start as you risk flooding the engine. Once this happen try to press the accelerator while attempting another start, this will allow more air in and may aid the starting.

[hpservertech]

It very well could be the injector harness. Could be shorting out some times. Only way to know for sure though is with a noid light. Had this happen on my late 85. Cheap to fix...you can get the new plugs at any napa. just took a couple of hours to troubleshoot.