A couple of weeks back i wrote about my car starting hard. I have to crank it over for a bit before it starts. Before this problem, I had an engine light on. I had it coded, and it said corroded terminal or fuel filter. At the time I couldnt find the terminal, so I replaced the fuel filter. The light came back on the next day. I then asked where the high pressure switch plug was, and when I cleaned it the light never came back on. But a couple of days after I changed the filter is when the starting problem started. I thought I may have gotten something in the lines, and it had traveled to the injectors. Cleaned them today, and the problem still exists. Some post say that it could be the fuel pump as there is a check valve in there that holds the pressure. What are your thoughts on it being the new fuel filter, as it has a pressure regulator in it. Maybe its loosing pressure. Any thoughts?

Thanks,
Dave

 

Hey Dave looks like you may be on to something with the pressure loss idea.
Once the car starts and has been running. Turn it off for 10 seconds or so then start again.
Was there a pause or did it start right up?
If it started right up it may be that you are indeed losing pressure in the fuel lines somewhere.
Now you just gotta find out where!

 

Thanks tighed1,
Im going to put a fuel pressure gauge on it today and see also if there is a pressure drop. This Forum is invaluable. Will keep everyone posted,
Thanks,
Dave

 

I had the exact same problem. It's probably the check valve in the fuel pump. It's worse when the motor is hot because the fuel in the rail can vaporize with no pressure.

 

I just checked the fuel pressure at the fuel rail. 0 pressure with car shut off, then I started car and it rose to 28 lbs. of pressure, and when I shut it off, by the time i got to the front of the car, it was already o again. Anyone know what the regular pressure is supposed to be? So there is a check valve in the fuel pump? I was thinking that since the pressure regulator is also the fuel filter, and thats where the excess fuel goes, back thru the fuel filter, that that may be the problem. I just replaced about 1 month ago. Thats when I started having problems, about 3 days after i changed it. Any thoughts on that. I hate to change the pump if thats not the problem,
Dave

 

The check valve is in the fuel pump. The regulator is in the filter and the pressure is regulated to 54-61psi.
It's all in the shop repair manual.

 

That's right. The pump runs for a few seconds then waits for the car to start to resume pumping. Your check valve is stuck open in the pump. If you quickly turn the key (cold start) without priming the car it it starts right up right? Replace your pump or just live with it. That pressure seems low too. should be about 55psi with the car running.

 

If I try to start without hesitation, it still doesnt start right away. It has to crank a bit before it starts. Im thinking that my new filter/regulator is not working properly. But then im not sure if the pressure would drop to 0 so fast if it was the filter. The pressure drops to 0 as soon as i shut off the car. Just not sure which one it is. Trying to avoid buying a new pump.But if thats definetly the problem, I have no problem getting one. You guys are awesome. Thanks for all of the input,
Dave

 

Thanks tunaglove,
The more I think about it, if the check valve was stuck open, it wouldnt be able to build up the correct pressure. Im leaning towards the Pump,
Dave

 

I read the shop manual and it does give a procedure to find problems like this.
See the attached .pdf file.

 

Quote:

Originally Posted by onehundred80

I read the shop manual and it does give a procedure to find problems like this.

You and your silly reading!

 

DJ, when you get his age that is all you have to do.......



According to that diagnostic, rapid/immediate loss of pressure is usually due to failure of the check valve in the PRESSURE REGULATOR(fuel filter)..... slow loss of pressure is a line or the check valve in the pump.....

 

The filter is new and in all probability the old filter was fine as well. I would discount the filter as a cause of worries. The fuel pressure never gets to the spec pressure so the fuel pump is not capable of pumping up to pressure and not capable of holding the pressure it does reach.
I'd say replace the pump or submit it to further testing by checking the pressure at the outlet from where the gas enters the filter. If it cannot reach or exceed the spec pressure (54-61psi) and hold pressure as outlined in the .pdf it needs replacing.

 

I wanted to thank everybody for all of the great input. It ended up being the fuel filter/regulator. Go figure, it was bad brand new.. Anyway, shes runing good as new,
Thanks,
Dave

 

Another XF back on the road!

Thanks for following through the whole process. This may help someone someday.