She starts.But it may take 2-3 turns of the key to get her to start. Otherwise it runs fine. Any ideas as where I should start looking?

 

Few clarifying questions to get us started:

Does it spin on the first and second turn of the key?

Does it matter if the car is warmed up or cold?

Does it matter how long it has been sitting?

Does it stumble when it does start?

 

Yes,no,no,and yes.

 

Sound like the same fuel pump problem I, and several others, had.

What happens is that the check valve or the over pressure regulator (both in the tank as part of the pump assembly) fail which lets the fuel completely drain back to the tank. When you turn the key, the pump doesn't run long enough to fully prime the system so you get a long crank.

The way to check is to hook up a fuel pressure gauge to the rail and see how quickly it bleeds down when you shut the car off and how quickly it comes up when switching the key on.

It should come up to about 65psi as soon as you turn the key to position 2.

 

Thanks, I'll check it out when I get her back home. Half way there from florida.

 

+1, sounds like the problem many of us have had. Do a search d
For bad fuel pumps and you will find plenty of info, and where I recommend you have someone replace it, since Jaguar had admitted to my mechanic at the dealership that they are seeing a high failure rate on new pumps, I have had 6 installed by the dealership all within a 9 month period.

 

CC, I think you're on the money even without doing the fuel pressure check. My reason for thinking is this,is because as I was driving it back home from Florida I obviously would have to stop and refuel. As the car has to be shut off to open the fuel gate,I would turn it off, quickly push the fuel gate button,and quickly restart the engine. With the fuel not having time to return to the tank, the car started on the first crank of the engine. So I guess I'll be buying a new Airtex Fuel pump and putting it in.

 

If it's just the NRV why can't a standalone NRV be fitted in the line downstream of the pump?

 

was wondering that myself Steve. Do they make such a thing?

 

Very common.
We use them in our tractors (very similar to a Jag) and they work fine.

 

I'm afraid it isn't going to be that pleasant if it does turn out to be the pump. The 2003+ has a returnless system that is quite different from the earlier cars. The part that fails to cause this problem is part of the assembly in the tank and no one so far has found any aftermarket sources.

When mine failed I asked to have it so I could take it apart and see what broke.
https://www.jaguarforums.com/forum/x...nalysis-80018/

You have to have a pressure relief in parallel with the the NRV or the heat from the engine will cause the fuel to expand after the car sits for a time and you will get a similar symptom for the pressure being too high.

The over pressure is downstream from the check valve and is essentially a very simple fuel pressure regulator whose "return" happens to be inside the tank already.

Don't get me wrong, this wouldn't be that complicated to build but is a little more complex than just a NRV.

I'm on my second pump, the first replacement failed within 300 miles. The second gave me a scare the other day but seems to now be on good behavior. If it fails again, I might try fixing it outside the tank, since the pump itself has been fine in all of the cases, even the original.

My indie gives a 12k mi or 1yr warranty and has been very good about replacing them but its a lot of labor on his dime so he's as frustrated with all of this as I am.

The high fail rate on new ones is why SteveJacks recommended to get it professionally done, I'm glad I took his advice on that one.

 

So the regulator is downstream of the NRV and you reckon it is the regulator that leaks.
In that case an external NRV should work unless the regulator leak was so serious that it was dropping the fuel pressure.
It looks like a loop here, as you say this topic has been covered before
https://www.jaguarforums.com/forum/x...l-pumps-78107/
I can't find the Rev Sam's thread about excess pressure. Is the idea that the fuel pressure is too high for the injectors to open?

 

See this:

https://www.jaguarforums.com/forum/x...-please-44285/

 

CC, the Airtex Fuel pump is an aftermarket designed for the 2003 Jaguar XK8. $478.00 at Autozone and other places. But from reading Sam's post, the NRV valve inline,as close to the tank as possible should work. My current pump is obviously working fine. I just did 1400+ miles in two days.Like I said,on fuel ups I would just shut the car off,pop the fuel door and restart immediately,before the fuel could return to the tank. This makes me believe that its just the return valve and not anything else on the pump. Plus a $40 NRV from Jegs is a lot cheaper than the new pump. I think it's definitely worth a try.

 

If you can get the NRV, or a valve plus a pressure bypass to work, please follow up and post about it. A how-to for this problem will do a lot of people good.

I know I will be eagerly waiting to hear how it works out.

 

Thanks Paul, I knew I'd read that thread but, unusually, Google wouldn't find it for me.
What it wants is an NRV with integral back pressure regulator which is what Rev Sam tried to fudge.
I know such things exist for pneumatics - I'll have a dig around today.

 

Actually, there was a later post by the Rev where he further continued to investigate the problem and found the bad check valve on the in-tank pump assembly.

I didn't find that post but the problem is now more commonly understood.

As I recall, the external check valve did work, but not completely solve the problem (fixed when he removed the Pump assembly and repaired the internal Check Valve).

 

Rev Sam nicked the NRV O ring so it leaked a bit. It cured the problem but the O ring disintegrated.
I can't find an all-in-one NRV/regulator.
It could be done with them in parallel and the reg set to a bit less than fuel delivery pressure - when the pump was running the fuel pressure would, of course, prevent the reg venting fuel.

 

Well, the NRV valve is in! Placed it just before the fuel filter,using high pressure rubber fuel line. The car starts beautifully. I'll post pics when I get new batteries for my camera. Definitely a lot cheaper than pulling the fuel pump and replacing that. Thanks again Steve and Rev Sam for the input.