XJ6 & XJ12 Series I, II & III 1968-1992

Changed Fuel Lines and Vacuum Lines-Advice on Testing

 
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Old 03-31-2019, 03:48 PM
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Default Changed Fuel Lines and Vacuum Lines-Advice on Testing

I finished replacing all the fuel lines and Vacuum Lines on the car (1984 XJ6 4.2 USA). I don't know how much was original but some lines had "BL" stamped on them so I think they might have been. \

Observations for future people. I distilled a list of fuel hoses and still ended up short on the 5/16". Buy extra.

I bought the fuel hose type clamps. But the sizes are really tough. I think 12mm-14mm is the most common, so buy lots of them.

Now for my request:

I will want to test for leaks. I took the battery out while doing all this.

When I put the battery back in, I know I have to turn the key to "on" but not "start" a few times to build pressure back up. How many times and how long to leave it at on?

Also, will this be enough to reveal leaks or do I have to actually start it? I want to be safe so I like to take baby steps after completely opening the system up.

I will have a fire extinguisher handy.
 
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Old 03-31-2019, 05:27 PM
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i start my '84 by placing the shifter in First Gear, then turning the ignition switch to max (START) and holding it there for 5 seconds while listening to the fuel pump. Then back to OFF. I do this 4 times, then I place the shifter in PARK and vrroom it starts from the first crank, actually it does not even crank, it just starts.

keep the hood open, once it starts, check the f.i. hoses for any leaks. Tighten clamps as needed. Also check every other replaced hose wherever they were replaced.

NOTE: if you did not depressurize the fuel system per the service manual instructions, and it does not start, the Inertia Fuel Cutoff switch may have tripped to OFF. Check it by pressing the reset button on top.
 

Last edited by Jose; 03-31-2019 at 05:33 PM.
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Old 04-03-2019, 07:46 AM
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Originally Posted by muttony View Post
I
When I put the battery back in, I know I have to turn the key to "on" but not "start" a few times to build pressure back up.

This won't work to pressurize the system; the fuel pump does not operate by simply turning the key 'on'....unless someone has modified the circuit.

You'll have to do as Jose described.

Cheers
DD
 
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Old 04-03-2019, 10:14 AM
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in my old S type, the system and the pressurizing is almost the same except it has 2 fuel pumps and they tick very fast when pressurizing and as they reach pressure the ticking slows until it stops, you do it to each tank, then you start the engine. A bit more primitive than the Series 3 XJ-6 but you have two pumps if one fails.
 
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Old 04-03-2019, 01:54 PM
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Doug and Jose are correct. On the XJ6, 'KEY ON' does not turn on the fuel pump.
As Jose stated, put the car in 'D' and turn the key all the way to the crank position. One other way is to prop open the flap at the MAF.
On my lump, I modified the fuel circuit so that the EFI system get primed as soon as you turn the key to the 'ON' position.
@Muttony: Happy to hear that you are making progress with your car.
 
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Old 04-03-2019, 05:08 PM
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@Sanchez Thanks!

Everyone, thanks for the info. Will try it this weekend and see how I did.
 
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Old 04-04-2019, 06:40 AM
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Hi Sanchez,
Can you post the mod you did to the pump circuit to energize the pump with the key to "ON"?
 
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Old 04-05-2019, 07:53 PM
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@ IAN: I will post the mod with some pictures within the next few days. Right now I am working on refurbishing my seats.
 
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Old 04-06-2019, 09:15 AM
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Hi Everyone

Just tried it out. Only a single leak and that was where I forgot to tighten a clamp on. Tightened it up and all's well.
 
 
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