Hi

I thought it would be better to start my own thread compared to hijacking somebody elses. Fell free to tell me if I'm wrong...

The car was not smelling of fuel when I bought it 5 months and 2000 miles ago. It was maybe smelling more like a workshop than perfume, but now it's smelling properly of fuel.
I wonder if the reason could be that I fill the fuel tank completely when I buy fuel ? Maybe a leak at the top of the tank and the previous owner had learned not to fill it ?

Anyway: Yesterday I finished step one of the fuel-smell-in-boot survey: After 200 miles starting out with half a tank of fuel the fuel level is now really low. Good starting point, if I end up removing the tank.

I have read a bit in the Palm Kirby book and is honestly a bit intimidated by all these compression fit connections, which most likely will not seal properly after detaching them if I don't replace brass compression rings AND steel tubing.
I have removed battery and carpets to get a look. Thinks look pretty OK, but the wax applied to prevent rust makes it hard to see traces of leakage.

The fuel pump noise was by the way not noticeable on the drive yesterday.

Both Kirby and Haynes tells me to clamp the fuel hoses hoses when taking things apart. I really don't like to deform a hose, rubber or not, this much, but I guess there is no other way to prevent/reduce fuel spilling, which we don't want in our boot.

Here a few pics from my boot. I have not found the fuel pump relays, I guess they should sit next to the ECU, which by the way is the 16 CU DAC 6336-type. That should be the non-catalyst high compression type and thereby correct for my engine. Good to see a match...

The central connector from the bottom centre of the main tank does look a bit suspicious to me. It looks like it's the fuel tank itself, that is gving up, pretty annoying

I have read about using a fine dusting with flour to detect leaks, but I'm afraid the wax applied in '89 is still is 'wet' enough to give false indications. I will try it anyway...

Something completely else: I have noticed the gearchange from 2nd to 3rd with the pedal to the metal happens at around 5300 RPM. That's too early in my opinion. I guess the reason is either lack of engine power or some failure/adjustment issue in the gearbox.

I guess I should just pull myself together, pull the tank and change all tubing here during the winter. I have no idea of the age of the tubing, but most of it is likely to have been sitting there since 1989 (rebuild) or 1977 (build).

For now I would be happy if I could just trace the leak.

 

Why are you removing the tank? Is it venting properly? The fuel vent/purge system on these cars is a terribly restrictive and an overly complex design. Pull the line up front in the left wheel well and make sure low pressure air will blow through it, also check all is functioning properly up there. Do you gat a whoosh when removing the gas cap after driving a while? When it's warm out? Any smell I had was related to the vent/vacuum system not functioning properly not the tank actually leaking. Wrap/lay some paper towels/tissue around the suspected fitting, wax isn't going to soak up in a tissue but fresh fuel will.

 

No pops or whoosh when opening the filler cap, so I think ventilation is ok.

Will the ventilation system by the way be as complex as later cars ? This is a 1977 PreHE after all.

The reason to consider removing the tank was to ensure it's not rusting in the bottom and to get better access when doing preventive exchange of flexible lines in the system

 

Not sure on the pre HE, I know the system uses a vapor separator in the buttress pillar then up to the front, the tubing is small and prone to kinks, restrictions, purge valve failure etc. If the tank doesn't vent/vac properly through use or heat cycling fuel will find a way out where you don't want it to come out from.

 

Leo
There will not be just one cause. Thinking that there is only one cause of problems maybe one of the most common errors in XJS maintenance generally, I have found. Bite the bullet, remove the tank and pressure test it, radiator guys can do this for you, they can also repair the tank with solder, which is a really excellent repair. Renew all the flexibles you can, much of the stuff is still available. There is no need to worry about the compression fittings, new imperial olives are available and they will seal fine when replaced.
That tank exit looks like one of the sources, but I bet the tank underside is iffy too.
As for tank breathing, just buy a two way valve such as this (various pipe sizes available):
https://www.merlinmotorsport.co.uk/p...n-tails-m-trl7
and connect it to one of the three tank breather tubes on the top RHS of the tank. Block off the others and connect the breather to the RHS boot drain tube with a Y piece.
Greg

 

Like all maintenance questions, opinions will vary. Remember that 50% of your maintenance is generally caused by 50% of your maintenance. I always take the least invasive route first and work my way up. In other words don't fix what isn't broken or break it while trying to fix that, that doesn't need fixing. Check your vent system, easy, peezy, check the soft/hard pipes throughout the route, blow low pressure air and then if all is up to snuff pull the tank. Take out the sender and send in a mirror with a light on it to inspect around the seams and base. Why would one go through all the trouble of pulling the tank before checking the simpler culprits? In all seriousness, that's just daffy! My boot, interior smelled, I fixed the vent system....no more smells for the past 4 years.

 

Good for you in finding it. My real point is that so many people just chase after the magic bullet to fix a problem, when in reality it is a whole cluster of related items that together cause the trouble.
Thereupon, many people get discouraged because, instead of reconciling themselves to getting stuck in and making quite sure all is dead right, they do piecemeal "fixes", lose the thread of what they have and have not assuredly fixed, are consequently unable to accurately diagnose and work methodically through a given system, and then wonder why the problem persists.
I have found, for me obviously not for everyone, that doing it all and doing it thoroughly gives me the best results and the most reliable outcomes.
Greg

 

It's not a magic bullet, it's a fairly easy check that can be confirmed by checking it, making some adjustment/improvements to it and seeing if the smell dissipates. I hardly see where one could get discouraged by that.

 

Thanks Greg and JTsmks

Comparing the picture in post #4 and my first picture there is no doubt I have three breather hoses going up into the right buttress, so the system is probably the same. It looks like 3 parallel hoses going from same place in the tank to the same purge valve, but that would not make sense. One hose would do that job just as well ?

Thanks for the link to the tank vent valve, Greg. Basically an open connection combined with a check valve in case liquid fuel wants to get out. That will surely do the job, but I guess it's not available in green...
I suppose the original system ensures that tank fumes are going through the engine ?

I agree that it's stupid to expect to find one fault to solve a problem on an old car. More or less everything in a system should be evaluated. I plan to do this starting with the fuel supply, and I'm happy the previous owner seems to have used same approach with brakes and cooling recently, although I fear he forgot to have the engine flushed properly. Temperature gauge tends to move up 2-3 mm above center in traffic jams...

 

How do I identify the line in the engine bay ? Could you describe the routing ?

 

If your car is a UK/European spec, I think you will find that the tank vents to air and does not have the US spec venting to engine intake system. If you look underneath, just forward of the rear LHS wheelarch, you may well see (if the car is like the same spec HE model in this matter) a thin pipe emerging and venting to air. This is the fuel tank vapour vent, that comes via the canister thingy in the RHS buttress, via a Rochester valve (a two way affair), along a thing tube that runs along the back of the tank space and out.

You can just see the pipe in this photo, running along the bottom back of the tank space:
Greg

 

My car is originally sold in Germany, so Euro spec it is.

 

Leo,

If it were me I would pull the tank. There a pop rivet under the tank on the RH side inserted from underneath and it will eventually rub through the bottom of the tank. My car is much younger than yours and my tank had a definite rub mark.

To fix it remove the rivet and reinstall from the top. Also replace the foam pad under the tank with closed cell foam.

While you have the tank out clean it and the swirl tank, they will almost certainly be full of crud.

 

I do agree with not fixing something that isn't broken.

But my take on something breaking something while I fix an issue is that what I broke is obviously going to fail so I'll fix everything while I'm in there.

This has served me well, as my car is reliable enough for me to drive around Australia.

 

Not worth my words, carry on.

 

Then it need to be replaced

 

Once again, not worth it, carry on.

 

Leo as I said earlier I would pull the tank and fix it properly.

There is a pop rivet under the RH side of the tank that rubs on the bottom of the tank. Remove this and re-install from the top. If it has rubbed through the bottom of the tank you will need to have the tank soldered.

Clean the tank and swirl tank. Replace the pad under the tank, this will most likely smell of fuel, mine did.

While you have it all out replace the fuel filter.

 

That's more or less my plan, except from the fuel filter, which is not present in my car. I suppose it's an addition to XJ-S after my build year.
It's also a little bit hard to understand what the purpose is, when the next filter is found maybe 3 meters downstream in the engine bay...

 

Leo
Later cars had the filter you have in the engine bay repositioned to the boot. Both are downstream of the pump, so no real difference in their effect.
Greg