1987 Sovereign 3.6 XJ40 Fuel Tank
 

When cleaning out the fuel tank prior to coating with POR-15 sealer, I used an air gun to dry it out but the air gun moved when I was absent and burnt a small 2mm dia hole in the top of a blue plastic tank(??) within the main metal tank. The outlet and return hoses are connected to this blue plastic thing but I can’t see whether it’s actually a tank or just a baffle.

The tank does not have an internal fuel pump, that was on later models. I haven’t been able to find anything on the internet and local Jaguar dealers have been unable to assist. Only the complete tank is shown in the parts catalog with no internals.

Can someone tell me if this is actually a tank and is it pressurized, or is it just merely a baffle?

Thanks

Hi ruggers,

Our member Rob Evenson renovated the fuel tank on his '88 or '89 and may know the answer to your question. I'm going to send him a private message to see if he may be able to chime in. He's been very busy in life and hasn't been able to participate in the forum much lately.

I assume from your description that part 5 in the diagram below is not the part you are inquiring about. It's called the "fuel tank seal."


https://cimg8.ibsrv.net/gimg/www.jag...590bb23fad.png

Hopefully Rob will be able to respond.

Cheers,

Don

https://cimg6.ibsrv.net/gimg/www.jag...84448f35fb.jpg
Fuel tank
https://cimg0.ibsrv.net/gimg/www.jag...12a99c3a40.jpg
Hole burnt though plastic - was blue originally but now covered in sealer
Hello Don,

The blue plastic tank/baffle is actually inside the tank and can't be replaced without opening the tank by cutting through the spot welds, or by cutting a large hole in the tank. See the attached photos - the blue plastic has now been coated by the silver POR-15 sealer.

Ruggers,

From what I could discern from the lack of info available regarding the interior of these tanks,I also concluded it to be a baffle. I do believe mine is metal, but could be wrong.

I urge you to be cautious before installing the tank. I also purchased the POR15 interior sealer and decided not to use it because of the baffling. In my mind, there was no way I could assure there was perfect coverage on the entire interior of the tank. All you need is a small gap of incomplete coverage, or very thin/weak coverage, for the sealant material to start dislodging from the surface and float down to the fuel supply lines to the pump. On my model, the filter is after the pump. I envisioned the sealant material clogging the fuel pump, so I elected to not coat the interior of the tank. From what I could see, the interior on mine was very clean, further the tank rusted from the outside, not from within. If there was no baffling system, I would have used the sealant product. You may want to consider filling the tank with water and vigorously sloshing the water inside the tank a few times before re-installing.

I have a photo album of my completed tank refurbish in my profile if interested. What I decided to do was add the layer of fiberglass on the bottom and then several generous coats of POR15 paint to the exterior, especially the bottom. Word of caution on the extra paint layers, it was a challenge to re-install. Amazing how a few layers of paint made re-fit very tight.

Best of luck to you

Don....anytime!

Thanks Rob and Don

I will rinse it again thoroughly before reinstalling, and while I am quite confident the metal tank is coated properly, I am not confident the sealer may not flake off the plastic. I looked into the tank with an endoscope a few times throughout and I initially assumed the plastic bits were baffles for the pick-up tube, even though it looked like it already had metal baffles - it's difficult to see inside with the plastic fitting in the way. That's why I raised the question about the purpose of the blue plastic fitting.

I'll try pouring some fuel onto the plastic to see if any sealer comes off before I go to the trouble of reinstalling. I can't believe it's not even documented.

Hi all
have not posted much lately. Just reading this thread looking for an answer. Have the same model with external fuel pump. the problem is the car sat in a garage for 20 years unused so tank had a lot of rust and debri on the inside. Without having to move the tank I have managed to drain it out several times and believe I have rid of 95% of it. When cleaning it I put an vacumn cleaner into the sender hole and also blew compress air back into the tank from the fuel line at the tank side of the pump. But I have stuffed something up. Tank has 30litres of fuel in it yet nothing is coming out of the fuel line. If i put compress air back into the tank it just blows air and still not fuel comes out. What have I done it was working ok prior to cleaning it except for changing the fuel filters all the time. Any ideas?

As they were discussing above, the baffle inside is just that. It is designed to slow the sloshing of fuel to provide a steadier flow for the pump. As such, it will tend to catch "stuff" floating around in the tank and become clogged. I had a similar problem with tank rust on a 62 Chrysler in a past life and did just as you have done. My fuel filters lasted me about 30 minutes. I ended up changing the tank out.
As an aside, I wonder if the later tanks for use with the internal pumps will swap into that space in the car......
Good luck, I know these tanks are a PITA to work on, I had one collapse on me.

hi Jerry
Thanks for the reply
I know there are baffles in there but they should not stop the fuel from flowing? When i blow air backwards into the tank all I hear is air so that tells me its not clogged. Its though the drain filter is above he fuel line and I know ther is 30 litres in there?? Im Baffled! (excuse the pun)

I dont know, but to "grasp at straws" maybe the hose to the pump is off? I think I recall that mine (with in-tank pump) did not drain with the hose to the motor off because of the internal design.

When I removed my tank to repair my fuel pump, no fuel drained/dripped from the hose connectors.

There was still about a gallon or two of fuel in there when I took it out and I had to pour it out through the top. No fuel came out of the fittings on the bottom of the tank, so you probably have normal behavior!

Larry

Hi jagcoupes,

If yours is a 3.2L or 4.0L car with the fuel pump inside the tank, the pump itself prevents much fuel from escaping the outlet port, and on the return line there is a check valve where it enters the plastic tank or "module" around the fuel pump, and that check valve prevents fuel from draining back out of the return port.

If yours is a 2.9L or 3.6L car, the fuel pump is external, so I think fuel should flow out of the outlet port of the tank when the fuel line is disconnected, though you may have to loosen or remove the fuel cap to release the negative air pressure in the tank so the fuel can flow. I can't recall whether the return port on the 2.9L/3.6L cars has a check valve.

It is helpful if you use your User Control Panel to edit your signature and add the year, model, engine and possibly the last six digits of your VIN so this information will show up in all of your posts so others can provide the most accurate replies.

Cheers,

Don