injector hats
07-13-2007, 10:00 AM
#17
Rennlist Member
Its right after the fuel pump and it stops fuel from flowing back into the tank after the car is shut.This way the system remains pressurized and loses it over time instead of right away. This assists in restarts.
Raj
Raj
07-13-2007, 10:16 AM
#18
Rennlist Member
Not to go too far off-topic here, but I have been dealing with a persistent cold-start problem as well. The car never starts the first time: usually catches on the 2nd try. Check-valve tests OK. DME relay replaced recently and the car behaves fine otherwise.
Raj: FPR? Is that testable or does one just replace it?
Raj: FPR? Is that testable or does one just replace it?
07-13-2007, 11:08 AM
#19
Rennlist Member
John, you can test the fpr but it involves connecting a FP guage to the fuel rail. The rail has the male fitting with a cap on it, its between the intake manifold runners. You need to remove the cap, make sure you don't lose the ball that sits on the tip and then connect a fuel pressure guage. Run the car, shut it off. Initially you should be at 3.8 bar and lose pressure over the next 30-45 mins. If your fuel pressure drops right away, your fpr is bad.
I will see if I can take some pictures.
Raj
I will see if I can take some pictures.
Raj
07-15-2007, 12:27 PM
#22
Rennlist Member
Lord, as stated, you connect a fuel pressure guage to the fuel rail and monitor fuel pressure during running (3.8 bar) and after it shuts down. If teh fuel pressure in the rail drops right away, you have a bad fpr. It should take time for the fuel pressure to drop.
Raj
Raj
07-15-2007, 09:17 PM
#23
Rennlist Member
The picture below was taken after the vanitfy cover was removed. As you can see, the fitting is on the fuel rail between intake manifold runner #3 and runner #4.
Be very careful not to drop the ball when removing the cap. If the ball drops, good luck finding it. The ball is essential for sealing the rail and without it you will have a major drip.
As always with everything related to gasoline, please use precaution and proceed at your own risk.
Good luck.
Raj
Be very careful not to drop the ball when removing the cap. If the ball drops, good luck finding it. The ball is essential for sealing the rail and without it you will have a major drip.
As always with everything related to gasoline, please use precaution and proceed at your own risk.
Good luck.
Raj
07-17-2007, 04:22 PM
#26
RL Community Team
Rennlist Member
Rennlist Member
Thread Starter
If you buy a fuel pressure gauge from a parts store like Kragen, you will need to stop by a hardware store and buy a special adapter to make the gauge fit the Porsche fuel rail. Try home depot or a auto-specialty tool store.
About the FPR. On my first 944, the FPR was bad and I tried the test Raj described and it checked out fine. That's not always a definitive test of the FPR. What you should also do is:
1. While the car is running, and the gauge is connected, read the pressure, then disconnect the vacuum line to the FPR, and read the pressure again. It should jump way up.
2. While the car is running and engine is still COLD, read the pressure. When the engine gets hot (warmed up aaaaall the way) read the pressure again. They should be the same.
Beyond that and what Raj said I don't know if that completely covers the functionality of the FPR, but that's all I know of.
And about starting issues. When you try to crank, does the engine actually turn over - does the starter grab anything? Or does it just sort of sound like it missed and just spins freely, and there's a whirring whining sound of it spinning. My starter (as with many 968s, apparently) have issues where the shaft won't come out all the way all the time, so it doesn't grab the flywheel, and doesn't crank the engine. I need to open up my starter, clean all the crap out and relubricate it... or so I've been told. I read the info and procedure on clubstuttgart.com. Someone correct me if I said something wrong.
Oh yeah, and about the pintle caps. I called witchhunter first because Washington is quite closer than CT. The guy there (Gordon) told me he won't sell parts, he'll only do the whole service, including installing new caps. Then I called Marren (www.injector.com) and they were happy to sell me the parts I needed. They wouldn't sell caps alone, but a kit including o-rings and the cap. $6.50 per injector, x4, so $26 and I'm out of the ditch. When I first told the guy what car it was for, he said 'hmm... 968... that's the one with the funny looking green caps, right?' Now that is expertise.
About the FPR. On my first 944, the FPR was bad and I tried the test Raj described and it checked out fine. That's not always a definitive test of the FPR. What you should also do is:
1. While the car is running, and the gauge is connected, read the pressure, then disconnect the vacuum line to the FPR, and read the pressure again. It should jump way up.
2. While the car is running and engine is still COLD, read the pressure. When the engine gets hot (warmed up aaaaall the way) read the pressure again. They should be the same.
Beyond that and what Raj said I don't know if that completely covers the functionality of the FPR, but that's all I know of.
And about starting issues. When you try to crank, does the engine actually turn over - does the starter grab anything? Or does it just sort of sound like it missed and just spins freely, and there's a whirring whining sound of it spinning. My starter (as with many 968s, apparently) have issues where the shaft won't come out all the way all the time, so it doesn't grab the flywheel, and doesn't crank the engine. I need to open up my starter, clean all the crap out and relubricate it... or so I've been told. I read the info and procedure on clubstuttgart.com. Someone correct me if I said something wrong.
Oh yeah, and about the pintle caps. I called witchhunter first because Washington is quite closer than CT. The guy there (Gordon) told me he won't sell parts, he'll only do the whole service, including installing new caps. Then I called Marren (www.injector.com) and they were happy to sell me the parts I needed. They wouldn't sell caps alone, but a kit including o-rings and the cap. $6.50 per injector, x4, so $26 and I'm out of the ditch. When I first told the guy what car it was for, he said 'hmm... 968... that's the one with the funny looking green caps, right?' Now that is expertise.
08-03-2007, 10:01 PM
#29
6th Gear
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Might check the Throttle Position Sensor. Seems like they get dirty at the idle position. I had a problem with first starts. I started exercising the throttle each morning before I tried to start. Guess it cleaned up the wiper just enough as the car fired right up. Took it off and worked it back and forth a lot and reinstalled. No problem since. Probably should replace it one day.
