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Old February 21st, 2004, 10:25
Scriff Scriff is offline
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Question How can I tell if the fuel pressure check valve is shot?

I've been having some intermittant starting problems. It'll crank but not turn over, once I hit the gas pedal to the floor it'll sputter and then eventually fire up. Once started it runs fine. I'm throwing code 17 which is 'engine is running too cold' but I think that is from an unrelated problem (my temp gauge is not working) which I had long before the starting problems.

The fuel pressure is about 42 psi in the on position and 49 running (its a '96). I tried leaving the pressure gauge on and turning it off; when I came back to check it an hour later, it had dropped down to 38 (so I lost roughly 4 psi in an hour). The FSM doen't say how much pressure should be lost so I don't know if this is normal or not. Should I try leaving it overnight maybe? How much pressure should be left in the rail when its been off for a few hours or overnight?

Also, if I need to do the BMW check vavle fix, where in the fuel line should I put it?

Thanks
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Old February 21st, 2004, 10:34
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RichP RichP is offline
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You should NEVER have to touch the gas pedal to do a cold start. I would pull the throttle body and remove the sensors then give it a real good bench top cleaning as well as the sensors themselves with a non-plastic hazardous cleaner. Sounds more like a bad connection or bad throttle position sensor to me. Loosing 4 lbs of pressure over an hour is not THAT bad and in my 98 FSM there is a rate of decrease vs time under the test procedures section for the fuel system. Unfortunately my daughter has my XJ and my FSM is still in the back seat from doing the gauge swap along with the old idiot light gauge pod 'just in case'. When she gets back I'll try to post the curve...
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Old February 21st, 2004, 15:52
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Matthew Currie Matthew Currie is offline
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When the check valve goes bad it will take longer to crank, but that's the only thing that really differs. I have never seen this affect the manner of starting, only how long it takes. My 95 is now sufferning from check valve malaise after 200K miles, but if allowed to pressurize it starts right up. If you need to play with the gas pedal I'd look elsewhere.
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Old February 21st, 2004, 18:29
Scriff Scriff is offline
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Well, here's an update... I turned it on and off again and tried leaving the pressure gauge on for about 7 hours this time and it dropped all the way to 0. However, I tried to start it going straight from the 'off' to the 'ignition' position and it started right up. So I guess it's something else.

The TB is relatively new but I had to use all of the old sensors on it, maybe one of them is starting to go. How much does the stealership charge for the three TB sensors? Or can I check them with a multimeter first?
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