I am in the process of re-commissioning my 1985 Jaguar XJ6 Sovereign after it was laid up for over 10 years.
I drained the right-hand fuel tank of approx. 20 litres of smelly dark brown petrol/gas. I expected this.
What I did not expect was the black tar-like substance that also drained out of the tank along with the fuel.
It was black and sticky like treacle. See photo of remnants in drain pan.

Tar-like substance in drain pan

After I removed the drain plug and the in-tank fuel filter I discovered that they were both also covered in this sticky tar-like substance.
I have a couple of questions:
1. Is this tar-like substance a byproduct of the petrol/gas I was using, 91 Octane.
2. Any suggestions of how to clean up this mess, suitable solvents?


XJ6 Drain Plug and Filter covered in Tar

Next removing the fuel filler necks

Regards

Paul

 

Paul,

I have heard of this tar like goo, never seen it though.

Word has been it is from the fuel, mainly Ethanol blends, and with lack of use, you get what you got.

Cleaning it up, oh boy.
Since it dissolves in Petrol, that would be my best guess.

How for you need to go, FILL THE BEER FRIDGE, and start at the back and finish at the Injectors. It will be everywhere I reckon.

New filter, new pump/s (some S3 have 2 pumps), Injectors out and pro cleaned. Flush the lines, including the return line (LH side).

FPR, dunno, may be OK??

 

I'm not a chemist but for the last 15 years I've spent most of my time working on cars that have been sitting unused for years. I've seen that black goo only a couple times. Given that E10 has been commonplace in the USA for a long, long time I don't think it has anything to do with ethanol. I think it's related to the something else in the "additive packages" that are put into the base gasoline by the big retailers.

Another possibility, perhaps more likely, is microbial bacteria....which can grow in gasoline tank just as it can in diesel fuel. Most likely if water has found its way into the tank.

I dunno. Just thinking out loud.

Cheers
DD

 

Hi Grant
I have owned the XJ6 since 2008 (my first Jag) and during that time have only run it on 91 Octane with the occasional treat of 98.
Maybe the previous owner used one of the cheaper Ethanol blends, however I never encountered any problems with the fuel system previously.
I agree with your diagnosis that it will be a complete end-to-end cleanout of the fuel system.
The question is what solvent to use to get rid of this goop.
The black stuff seems to be suspended in the petrol, so I don't think that it dissolves well in that liquid.
I need something more aggressive that I can swirl around the tank and dissolve any residues.

I am sure that the combined knowledge of the experts on this forum will come up with something.

Paul

 

Thanks Doug, interesting thoughts.

 

Maybe get a bit of the goo and start experimenting? I would try acetone, and next white spirit.

 

Only thing I've found that will dissolve that substance completely is aircraft paint remover and it's still a major pain. EZ Off oven cleaner will do better than any solvents, still need paint stripper to get it clean, but the time out of my life ain't worth it anymore on the tanks when they make nice replacements.
Btw... 5gal paint sticks with red scotchbrite zip tied on the end, another paint stick sharpened off as a scraper, all done through the fuel level sender hole with tank in car and drain bung out is easier, use of a garden hose etc... Even tried driving the car for 3 days with solvent in one tank and running on the other, more stories here than I want to remember. Lesson learned, buy new tanks, clean from tanks to injectors and back thoroughly, put it all back as new and it will be happy again for a long time.

 

Hi Greg

I have Acetone left over from a previous job so I will try that first.

Cheers, Paul

 

Thanks for your reply slofut.
I will try Acetone first as I have that.
New tanks would be nice, but they are AUD $1200 each and I don't want to spend that much ATM as I have several other cars needing my attention.

Cheers, Paul

 

Maybe try using GP paint thinner. Cheaper than acetone?
All these solvents seem expensive these days.
Hydrochloric (muratic) acid is pretty cheap, but not nice on the lungs (or skin). Use a mask with carbon filter & rubber gloves.
The acid will also remove any rust, without eating into the steel.
Needs to sit in the tank overnite to work its magic.
You will need to remove/replace the plastic tank filter as the acid will liquify it too. And obviously the sender unit.
After flushing with the garden hose, immediately use a heat gun in the fuel sender port to dry it out & minimise any flash rust.

Pete

 

I certainly understand Paul. $1200 ea! That's tough. You do have a lineup of cars to keep you occupied, I feel your pain as I have a few desperately waiting for me to get done with my xjc. Hope you can get those clean. Acids will usually eat metal and leave the goo in place. It's an awful job.

 

Paul, any progress on your tanks?

 

Hi slofut
Finally managed to get the RH fuel tank out after spending days trying to remove the filler neck, What a PITA.
The tank has gone off to a fuel tank cleaning specialist and I hope to get it back next week.
Meanwhile I am trying to start the car using a cannister of fuel in the boot/trunk feeding directly into the fuel pump.
Tried going via the diverter valve but that appears to be blocked so I bypassed it.
Also installed a new fuel filter.
I am now struggling with a fuel injector problem but I will start a new thread to discuss that.

Cheers

 

Paul, all the fuel related components are probably victim to the gunk and rust that was in your tanks. The diverter valve, the fuel pump, the one way valve, up to the fuel rail, the pressure regulator, fuel injectors,cold start injector and return line and return valves in the rear wheel wells. You must clean all them very thoroughly and flush the lines and fuel rail or when you put your newly refreshed tanks back in, it will just put the gunk back in the new tanks. It's a lot of work but you've already done the worst of it. Thoroughly clean all components, don't think the filters are going to catch whats left.
Your fuel injectors have very tiny orifices and even the finest silt from nasty tanks will clog them. You may be able to have them cleaned satisfactorily but sometimes that's a crap shoot, new replacements may not be too expensive. You're probably going to end up replacing a valve or two if they won't clean up. Clean out that fuel rail and pressure regulator or you get crud right back into new injectors. It all needs to be clean at once, then you're golden.