seems as though whenever i leave my 2000 jag s type sit for 2-3 days without starting it, when i try to start it, it runs for a few seconds and dies. then it will crank but not turn over. sometimes i will try again later and it will start. sometimes i have to spray into the manifold and eventually it will start up run rough and even out. I replaced the fuel filter and fuel pump 4 months ago. I replaced the battery 1 month ago. any suggestions why it behaves like this?

 

Which engine?

I'd read LTFTs (see below) at idle and 2500rpm e.g. to see if there's an air leak.

 

the engine is a 4.0

thanks for the info!

 

Were both pumps changed or just the main fuel pump? The issues you describe certainly sound fuel pump/fuel pressure related. There are actually 2 fuel pumps in the 2000 S Type - main fuel pump and auxillary or "transfer" jet pump. If the "transfer" pump was not changed out this could be your issue.

Finally, was the fuel pump replaced as an assembly, new or used? If the latter - this could be an issue as well. These pump assemblies are expensive new - many times they will be replaced with a used unit from a scrap yard and that's taking a "roll of the dice". Also, some shops hack into the OEM fuel pump assembly and replace the pump itself botching up the entire fuel assembly causing more issues.

Just my $0.02

 

i replaced the fuel pump assy with new. i did not replace the transfer pump assy because: i could not remove the fuel pump assy with breaking the grommets that fit in the troat where the fuel hose goes into at the top of the pump assy. i ended up buying a used assy just to replace the broken plastic grommets. SO i didnt replace transfer pump. i can replace it, but do you have a suggestion on how to loosen the grommets so the hoses slide out of the throats? i tried a tool the auto store recommended but i did not have the length needed betwwen the top of the pump assy and the 90 degree turn in the hose to fit the tool. I really don't want to break any more. AND, to no surprise, the grommets cannot be purchased individually! Thanks!

 

There should be 2 retaining push in tabs that release the springs holding the fuel tubing to the fitting. I can tell you from experience the white fitting on the transfer pump for some reason is very prone to the little plastic tab (one or both) breaking not allowing the spring to depress the bark allowing the tube to be removed.

What you need to do is pry the outer assembly of the white fitting loose with a very small flat blade screwdriver. (Don't puncture the fuel line!) Once you get the outer housing off - the springs will pop out and you'll be able to get the tubing out.

No worries here as: clearly the tab is broken and you'll be using the replacement transfer pump anyway.

One more thing - when depressing the tabs - you are supposed to push the line further in and then yank up...

Yes, those aren't sold separately... but mine were good on my old transfer pump and took them off and kept them... good thing I did cause I needed it for another transfer pump that had the issue you described.

 

Could you not see this problem with a fuel pressure gauge?

 

i know this may sound silly, but here is my question. it is possible for my car (2000 jag s type 4.0) to lose 'prime' of the fuel? I only have a problem with the car not starting (it turns over, have a new battery and fuel pump and fuel filter) when the car sits without starting for 2-3 days. And when i push the gas pedal in before i try to start it, it will backfire but not start.

 

No codes present ( fuel ) Backfire out manifold or out exhaust?? Manifold lean fuel.

 

What you describe is indicitive of a failing fuel pump, unfortunately... like I said before I would suspect the jet pump before meddling with the main fuel pump.

 

It sort of is possible, with leaky fuel injectors. (They can be removed and checked but overall maybe not that cheap?)