I recently got the 77 V12 running. The car got some water in it's fuel tank and the fuel injectors where rusted. We replaced the injectors and now she is running. This car wasn't running for over 4 years.

Apparently the cold start injectors are affected because we had to "pinch" the fuel hoses to them otherwise they were always on and we were seeing fuel leak out of the air cleaner. ( way too rich ) Where is the best place to acquire replacements?

Even with that problem behind us the car was still running way too rich. Standing behind it your eyes would burn from fuel in the exhaust. Also it is very sluggish to drive and after holding the throttle at some rpm's it would rather die then idle. If you slowly lower the throttle it will idle.

Can anybody offer me some things to check on why it might be running so rich? One friend of mine mentioned the "engine temp" sensor might be tricking the fuel injection that the car is always hot.

Thanks for your help.

Submitted by jason.eaton@gm… on Mon, 07/10/2006 - 01:08

Hurm, nobody mentioned that! So I should pull off the return line at the tank and put it in a gas can to make sure its returning properly?

I have replaced the oil/filter just to the gas out of the oil, and ordered two new regulators. But someimes its the simplest things.

Thanks for the advice, I will check it out.

Submitted by jason.eaton@gm… on Sat, 07/08/2006 - 12:07

I checked the fuel pressure by putting a fuel pressure guage between the cold crank injector and the fuel rail on the passenger side ( right side ). Adjusting either regulator did not make a noticible difference.

Thanks.

Submitted by dougdwyer@adel… on Sat, 07/08/2006 - 09:26

I think you need try try a different regulator, too....perhaps two of them.

If memory serves an early car such as yours has two separate fuel rails---one for each bank. If so, then it is quite possible, I'd think, to have one bank regulating down to the proper pressure while the other isn't.

How and where are you checking the pressure?

As an aside to William's post, the right side on *any* car is as viewed from the driver seat, not just British ones :-)

Cheers

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe

Submitted by bonnettoboot@e… on Sat, 07/08/2006 - 02:13

The fuel pump is not the problem, you have two options exchange the injector you removed with the one you didn't. The pressure has to come down to 30/35. Or perhaps you should just fit another new one! The right side in a British car is as viewed from the drivers seat. Change your engine oil ASAP. Jaguar affectionado and etc.

Submitted by jason.eaton@gm… on Sat, 07/08/2006 - 01:57

Thanks William. As I mentioned I did replace one of my regulators to get the pressure down. It was in-effecitve in reducing the pressure to 30psi.

If you read my post I asked these questions, maybe you can help me with;

What is the proper fuel pressure, and is it reasonable to use the regulators to adjust from 90psi to 30psi? That is a huge difference. If my pressure regulators dont seem to be effective should they just be replaced or is there something else wrong? I do have an XJS fuel pump in my car because the stock one quit working.

Thanks.

Submitted by bonnettoboot@e… on Sat, 07/08/2006 - 01:36

Hello James, clearly you did not heed my first suggestion but i'll try again. It sounds like you changed the wrong regulator. There is little point in changing any sensors or even driving the car until you get the pressure down to 30/35. The cold start and likely the other injectors are leaking because the pressure is too high! read my last response, Bill Jaguar affectionado and etc.

Submitted by jason.eaton@gm… on Sat, 07/08/2006 - 00:36

Thanks for the help guys. I checked the fuel pressure today and i was running around 90 psi. From what I can gather it is supposed to be 30 psi. I tried adjusting the pressure regulators but it didnt really do much. I replaced one of my regulators with another one and still didnt see much difference in the fuel pressure.

On a good note I replaced the water coolant sensor and she seems to run much better with that sensor replaced. Also the cold start injectors were still leaking fuel into the intake even though I had clamped the hoses shut. I instead routed the cold start injector fuel outlets together so that there is no chance fuel would get into the intake.

After these two changes the jaguar was running pretty good. However doing a test drive i find a hesitation when i accelerate from a steady cruise. It looks like I have more to diagnose but making progress.

What is the proper fuel pressure, and is it reasonable to use the regulators to adjust from 90psi to 30psi? That is a huge difference. If my pressure regulators dont seem to be effective should they just be replaced or is there something else wrong? I do have an XJS fuel pump in my car because the stock one quit working.

Thanks.

Submitted by bonnettoboot@e… on Wed, 07/05/2006 - 01:05

You will i'm sure, get lots of help with your problems but just a word of warning. When cars overfuel like yours a tremendous ammount of gas/petrol ends up in the engine sump, (SMELL IT) Do not run the engine too much until you find the problem, then, change the oil & filter. Jaguar affectionado and etc.

Submitted by dougdwyer@adel… on Tue, 07/04/2006 - 10:00

Check the fuel pressure with a gauge. Too much pressure will over-fuel the engine. The fuel pressure regulator may be faulty

The coolant temp sensor is also a common culprit, yes. However, you're friend got the problem a bit backwards. The sensor might be tricking the system into thinking the engine is always cold and thus more fuel is supplied....even after the engine is warmed up and no longer needs it.
As for new cold start injectors you could try XKs Unlimited, Coventry West, Moss Motors, SNG Barret.....the list goes on and on. get the part number then "Google" it :-)

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe