hard starting issue

Okay, I am still trying to track this problem down on my '98.

When the XJ has set for an hour or so it won't start up right away. It cranks and cranks but it won't start. On the second try it starts right up! I changed the fuel pump this past weekend and was sure that was going to be it but I guess not. The strainer filter was replaced as well. In the beginning I thought it might be O2 sensors and/or the catalytic converter so i replaced those as well. What do you think? TPS? CPS? This XJ has about 150,000 miles on it, but once it starts it seems to run fine and dandy.

Burley

Do the key on thing, turn it on and count to 15, if it fires right up then that usually a fuel pump thing as it builds pressure back up. You could also put a fuel pressure gauge on the schrader valve on the fuel rail and watch it after you turn it off.
Just out of curiousity, whose fuel pump did you use, Dealer OEM or aftermarket ?

I used a Carter from Advanced Auto Parts. The dealer wanted almost $300 for their pump. This is the only place I could find one around here. Either Advance or dealer....

What else is in the fuel system?

I tried to get that BMW external fuel pressue check valve at the BMW dealership...but the part number that I got from another thread on a HARD TO START seach on here...Part number is (16 14 8 068 988) is not a valid number on there parts list and no other parts stores carries an external fuel pressure check valve...can someone check if this is the right part number...The people at the dealership don't know what I'm talking about...They need to know year and model and or part number to find it...Any info is greatly appriciated...Thanks...

john4wd...

Burley said:

Okay, I am still trying to track this problem down on my '98.

When the XJ has set for an hour or so it won't start up right away. It cranks and cranks but it won't start. On the second try it starts right up! I changed the fuel pump this past weekend and was sure that was going to be it but I guess not. The strainer filter was replaced as well. In the beginning I thought it might be O2 sensors and/or the catalytic converter so i replaced those as well. What do you think? TPS? CPS? This XJ has about 150,000 miles on it, but once it starts it seems to run fine and dandy.

Burley

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It does sound like it could be a faulty fuel pump check valve even though you've replaced the pump. Check the fuel pressure at the injector rail to find out if it's low on first start-up. You could just turn the ignition to the "on" position and wait a few seconds while the fuel pump primes itself before starting.
At about 150k miles is the time when various sensors start to act up so it's not unlikely that the CPS could be showing early signs of failure. A bad TPS doesn't affect starting.

Would a bad CPS or CPS connection cause the fuel pump not to send fuel when I turn the key to on? or does that only effect fuel and spark while cranking or running?
thanks, Joe

I don't know if this will help other people with hard to start issues...I installed a BMW check valve from BMA Parts...It was 10 bucks shipped in 2 days...On my 97 Cherokee...And while I had the tank down I replaced the fuel filter/regulator at the same time...My hard starting which happens all day long and sputtering when it started in the morning...but it never sputters the rest of the day only in the morning after sitting for almost 10 hours...Is now I hope a thing of the past...It fires after only one revolution of the motor...which is saving the life of the stater...If anybody tries to install the BMW check valve make sure the arrow on valve is pointing to front of vehicle...I double clamped check valve to fuel filter/regulator and the hard line going to engine...no leaks so far...i hope this helps someone out...

John4wd

Dr. Dyno said:

At about 150k miles is the time when various sensors start to act up so it's not unlikely that the CPS could be showing early signs of failure. A bad TPS doesn't affect starting.

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I disagree slightly. While I don't suspect the TPS since it would produce more symptoms, I have experienced no start/ hard starts from a faulty TPS.