• Hi to everybody.
  recently I bought an jag xjs 1985. Car was sitting for 9 years an now I'm trying to start it. I cleaned the fuel tank, small fuel tank, changed all fuel lines an return too, spark plugs, wires set, cleanead all injections, checked all harness from injection, but the car starts ( I think not all 12 cylinders) and when I pus the accelerator it turns off. Did somebody had the same problem?
  Also I have a question: after star fuel pumphave to turn on permanently or just for few second?
  Thanks.
  Ion

 

Firstly welcome to teh Forums.

When time permits, please do an Intro in the New Members Area.

The list is loooooong after 9 years of sleep.

Have a read of the "stickies" I wrote at the top of this section, it will help you nail some of the issues down, and if there are questions, NEVER be afraid to ask.

 

Yes I read it. But I don't wanna spend a lot of money just on changing part by part to find what is the problem. That's why I asked maybe somebody had the same problem. Now my big question is if th fuel pump have to be on all the time after start or not. Because in my case fuel pump is working just when I turn key on and after it turns off.
thanks for understanding.
Ion

 

The pump will operate for 2-3 seconds, to prime the system, when you turn the key 'on'. It then turns off until you crank the engine with the starter...which turns it on again. It then remains on as long as the engine is running

Cheers
DD

 

Ok. Thanks a lot. I'm going to get a new pump to see maybe that is the problem.

 

Will it stay running if you don't press the accelerator?


Cheers
DD

 

I'd hold off a bit.

You may end up needing a new pump...9 years of non-use may have done it in..... but make sure the problem isn't in the control circuit first.

Locate the orange ground wire at the fuel pump relay and run a redundant ground wire to it. With the relay grounded like this the pump should run, and stay running, any time the key is 'on'. If it does, try starting the engine and see if it runs better.

If the pump doesn't run with the orange wire grounded, post back

Cheers
DD

 

It still far a few second, maybe 5 maybe 10, depends how high is pressure in system. Before start the engine I turn on/off 3,4 times to make some pressure in system. I tryed to connect fuel pump directly to battery and then car still on for a longest time but is not all 12 cylinders on, I can't find which one doesn't work.

 

P.S. fuel pump is not the original one.
Ion

 

It stayed running with the fuel pump wired directly to the battery? Which post of the pump did you connect to the battery, negative or positive?

"+" voltage to the pump comes from the pump relay. If you connected the pump to the "+" battery post and the engine stayed running then you need to find out why the relay isn't supplying 12v "+" to the pump.

Do you have a 12volt test light?

Cheers
DD

 

I connected both wires from fuel pump to the battery. I changed relay but this doesn't help. And yes when I connect fuel pump to the battery engine stay on for a few minutes.

 

Yes I have a 12 volt light and and multimeter too.

 

Ion Balau, please post pics of your Jag. Some of us are simple folk (me).

 

I don't know how to upload here pic. I uploaded some pic on my profile. Please tell me what you mean when you tell me to upload pic.
Thanks.
Ion

 

I tryed like you said an this is the same thing like I connected to the battery, it is staying on but when I pus accelerator it turns off.
thanks.
Ion

 

When you are ready to post, go for Advanced option. Then you should see an editor window open with a white space where you type text (your message). At the top of that window (in the grayed out area), there are bunch of icons, just like in your favorite text editor (MS Word, for example). One of them is yellow, looks like mountains with a sun in the top right corner. Click on it and follow instructions to upload your picture.

Well, that's how I add pictures, at least...

 

ok I got that. Here are some pic.

 

Hi again. Today when I tryed to measure the presure on fuel lines I saw that the air cleaner from passenger side doesn't suck air. What is the problem on that case?
presure on fuel lines is 39 psi when it is off and 45 when it's on.
thanks.
Ion

 

That's normal

Where did you take the pressure reading?

If that's the unregulated reading, it's low.

If that's the regulated reading, it's a bit high @ 45psi

Cheers
DD

 

I measure in unregulated reading. From the start presure is 43 psi after in 2 min it goes down to 39. When fuel pump is on presure is almost 50psi. I'll measure today between presure regulator and fuel injection system.
thanks.
Ion