[whakiewes]

I am pretty familiar with all other Porsches other than 968's, and this is my first 968. The car has 160k miles, recent belts/waterpump, stock chip, stock injectors, stock mostly everything.



In the morning after letting it sit for say 10-12hrs straight, the car is hesitant to start. It starts, jumps to 1000, 800, 600, then off. Second time I start it starts perfect and pretty much any other time I start it throughout the day its perfect. The starter was replaced about 1000 miles ago. From sitting in it, it sounds like there is crap built up, and it takes it a second to work through that? Any ideas? As soon as I get done enjoying the car (which may be never), I am going to pull the head and get it all sorted; probably mid summer.



Thanks in advance,



Wes

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[flash]

does the engine crank fine, but just not start?



if so, you probably have a leakdown in the fuel system, and it needs to catch up - could be the "anti drainback valve" in the rear (can't remember what they call it), or leaky injectors (i had one at 43k)



at 106k, if it hasn't been done already, change the fuel filter and valve anyway



then run some techron through there and see how it goes

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[frank moran]

[quote name='whakiewes' date='May 12 2006, 11:11 AM']I am pretty familiar with all other Porsches other than 968's, and this is my first 968.  The car has 160k miles, recent belts/waterpump, stock chip, stock injectors, stock mostly everything.



In the morning after letting it sit for say 10-12hrs straight, the car is hesitant to start.  It starts, jumps to 1000, 800, 600, then off.  Second time I start it starts perfect and pretty much any other time I start it throughout the day its perfect.  The starter was replaced about 1000 miles ago.  From sitting in it, it sounds like there is crap built up, and it takes it a second to work through that?  Any ideas?  As soon as I get done enjoying the car (which may be never), I am going to pull the head and get it all sorted; probably mid summer.



Thanks in advance,



Wes

[right][post="20891"]<{POST_SNAPBACK}>[/post][/right][/quote]

it is probably loosing fuel pressure during the lay over, I don't know where the check valve is located on this unit. It is after the pressure regulator and possibly in the tank sending unit, bottom line it is nothing to get alarmed over, if you leave the key on a moment or two longer before you crank it the pump will charge the the fuel rail and this may start it quicker. Definitely sounds like a drop in fuel pressure.

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[flash]

it's in the back by the fuel filter

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[frank moran]

[quote name='flash' date='May 12 2006, 01:15 PM']it's in the back by the fuel filter

[right][post="20906"]<{POST_SNAPBACK}>[/post][/right][/quote]

flash, help me understand, fuel is drawn out of the tank by the FP, then pumped through the fuel filter and the check valve, up to and through the fuel rail, through the pressure regulator back to the tank. When it's shut down and vacuum drops off the regulator etc. now what holds the pressure between the filter check valve and ????is there a return line i'm not accounting for?

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[flash]

there sure seem to be an awful lot of lines going back and forth - i haven't traced them all yet to see what goes where



the regulator, injector seals and the check valve are supposed to keep the lines charged - in fact, thee is even a spec of how much pressure it is supposed to maintain over a period of time



a leak in either one would result in fuel potentially draining out of the line - if it were the injector seals though, i would think you should see some fuel in the oil, and/or a bit of smoke when starting - i had a slightly leaky injector, and it would dump a bit - you could smell it when it fired up after it had been sitting - occasionally it would also fire and stall



the check valve is known for failing - bruce did a write-up on the DIY - a common symptom is coughing when first starting and going in the morning, especially up a hill - a few seconds of running first, and the problem is "resolved"

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[whakiewes]

Thanks for the replies. I tried this morning before I posted letting the fuel pump run about 30 seconds before starting...not really any difference??



Wes

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[frank moran]

[quote name='whakiewes' date='May 12 2006, 10:13 PM']Thanks for the replies.  I tried this morning before I posted letting the fuel pump run about 30 seconds before starting...not really any difference??



Wes

[right][post="20933"]<{POST_SNAPBACK}>[/post][/right][/quote]

The best thing to do is put a pressure gauge on it and see what it is doing, there is port on the fuel rail for this, otherwise it's just a guess, confirm/eliminate the question of a fuel problem with a gauge reading, let it sit and see how much pressure leaks down. I have seen many non Porsche that leak down to 10-15 lbs. but start very quickly.

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[flash]

the spec is: 2 bar minimum at 20 minutes

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[whakiewes]

I will try that when I get home. Its really finiky...sometimes doing it, sometimes not. Sometime its hesitant to start...not like that, but like there is a weak spark. On Monday I am doing tranny fluid to Redline to see if it helps the ever so slight clunk, changing the oil, changing to coolant for the summer, new spark plugs, new fuel filter, and run some good gas through it. Down here at the beach I can only get 91/92, so thats not helping the fun factor <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" /> .



Another problem that just appeared was the electrical system. I am going to clean all the grounds and see what that fixes. My interior dome light doesn't work, and I was pretty sure there is a short in the system as the second I put a new fuse in and open the door, it blows. Last night with the door closed, only the hood open, keys in my pocket, etc... it through a major arc when I tried to replace it with another 15a. Melted a good portion of the fuse. Anyone ever see this before <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" /> . My PPI didn't pick up anything...so much for that $200.

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[S_Cal968]

First I'd make sure the DME relay is in good shape. A flaky relay can make if seem like there's a fuel pressure issue.

As mentioned I'd check the pressure on start-up - this is exactly what a what a shop would do. If the press. is low, the next suspect would be the regulator or pump. Check the vac line going to the regulator too.

I seriously doubt it's a c/v problem unless you're having a hot start issue. The c/v is not intended to hold pressure for a long period of time, but rather to aid starting when the engine is hot.

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[ether_joe]

[quote name='whakiewes' date='May 14 2006, 09:11 AM']On Monday I am doing tranny fluid to Redline to see if it helps the ever so slight clunk[/quote]



just put redline in mine over the weekend. My clunk is still there - like you said, it's real slight and intermittent. My buddy also gets it. I'm not too worried at this point.

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[whakiewes]

Yeah, Redline no help here, although it did help with shifting. I am going to replace the bushings, and while on the lift check everything else. I hope its not a 92' problem only that is internal. I agree though, the only time it really 'hurts' me is the maybe 1-2 times that I have speed shifted.



Wes

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[gbarrier]

I seem to have the same starting problem when the car sits overnight. I disconnected the fuel lines to remove the valve cover and there was no pressure on the fuel line. tells me that something is not holdinjg. Now two questions. What size and type is the fitting on the fuel rail so I can make up a connector to put a gauge on it and tell me again where that leak back valve is. Can't seem to locate it on PET. On the other hand, that's not the first thing i haven't been able to find something there.

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[gbarrier]

OK, I found the checkvalve P/N 944 608 951 01. Still need to know about the fittings.

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