Here is my prior thread on fixing my fuel gauge malfunction:

https://www.jaguarforums.com/forum/x...fusion-141696/

Well, yesterday the gauge suddenly dropped from 7/8 full to empty behaving like it did prior to fixing it by cleaning the contacts on both senders. Frustrated by the prospect of having to pull the back seat again and re-cleaning the contacts every couple of months, I decided to try an experiment.

I purchased a bottle of concentrated Techron and added it to the tank then topped it off to full. After sitting overnight, the gauge is now working properly again.

If your fuel indicator suddenly stops working properly, you might give this a try before the deposits on the contacts have a chance to barnacle their way to a more permanent condition. Here in the U.S. the Techron concentrate is widely available and it's under 5 bucks at Walmart.

 

That was a clever solution, well done.

Roger

 

Any feedback on what is happening with the Techron? I have never tried this additive.

 

It worked to restore the fuel gauge function, and at the time I bought it, I picked up two bottles in case one didn't work. I ended up putting the second bottle into my XJS V12 when it needed a refuel, and it now runs smoother than before.

So in those two isolated cases, it was effective.

 

Old Range Rover and XJ-40 owners are very familiar with Techron. I had a very trustworthy dealer recommend it for my XJ-40. They couldn't really prove that it worked, but they also said they never had injector issues with owners that used it vs those who did not. I never had any of the known injector issues on my XJ-40 or Range Rover Classic when I used it. It is recommend by the dealer and other mechanics to use it when I was going to use the full tank on a trip. There are many snake oils and "fuel treatments" out there, but I believe Techron is a legit product. I have never heard of it maintaining fuel sender contacts, but I never had sender issues while using it. Maybe it was maintaining the contacts the whole time.
I didn't use it every tank, only every couple of fill-ups from time to time.

 

Thought I'd give an update on this.

On the second to last fill up the fuel gauge once again started acting up. Once again a bottle of Techron added to the tank returned the function to the gauge.

On the last fill up I went out of my way to fill the tank with Chevron fuel, which has Techron as an additive. However, this weekend the gauge started acting up again. So the Chevron fuel likely doesn't have as high a concentration of Techron.

Short of adding Techron at every fill up, does anyone have any ideas?

If I pulled the senders again and cleaned the contacts, can anything be done to protect them?

I think part of the problem is my wife just doesn't put very miles on the car, and it goes quite awhile between fill ups. The issues are always at the high end of the gauge, so I'm guessing the sender areas that are exposed to air when the tank is less than half full are the problem.

 

Techron concentrate is about 2/3 light oil, with about 10% naphtha, and the remaining 1/3 being Stoddard solvent. $5.00 a tank and would equate to $160 for 32 tanks of fuel.

Marvel Mystery Oil is almost the exact same with a little less Stoddard solvent (20%~25%) and a percent or two of chlorinators that are used to remove carbon deposits from metals. MMO by the gallon is about $22.00 at WalMart and will give you 32 tanks of treatment.

Both are good choices for fuel additives in automotive applications. They are safe for all engine controls like cats and O2, they lubricate and cleanse. We cannot change the fuel we buy, but we can modify what additives we use to create a better running fuel system. Ethanol blends contribute most to sending unit issues.

Neither of these products even come close to a full-on fuel injector cleaning which can be done with the proper cleansers and equipment, but regular use of either of the products above will certainly help mitigate the need to get a full-on injector service.

 

The fuel gauge sender and float just clip onto the side of the pump

housing and I don't think new ones are expensive.

 

Mac Allan ,

I would seriously disregard the comments made in post #7 , it has no relevance to what you were asking and generally bad advise for your fuel system .

I would however agree and consider what post #8 had to say .

 

It may come that, though I haven't seen the senders available for less than $150US each, and my concern on used ones is that they might be just as susceptible to corrosion.

I wondered if the higher levels of ethanol now in California fuels, isn't a contributing factor. To experiment, I put in an ethanol fuel conditioner and stabilizer and filled up the car yesterday. It's cheaper than the Techron, and works out to less than $2 per tankful. I will report back if it makes a difference or the gauge malfunctions.

 

It certainly has relevance. Especially when your vehicle sits more than driven, and use of ethanol blend is used. (which is predominant at most stations) Do you know why they don't run ethanol in pipelines? Because of the acidic, corrosive qualities. The OP brought up the issue of Techron, I simply left some alternatives. Both items have decades of safe use in fuel systems. If you do not understand their chemical composition, you can certainly find it in the MSDS. If you don't understand what fuel detergents consist of, you can use Google.

I also suggest you may research what TopTier fuels are. If they don't add them, you and I can, by use of the products stated above.

"Since the minimum additive performance standards were first established by the EPA in 1995, most gasoline marketers have actually reduced the concentration level of detergent additive in their gasoline by up to 50%. As a result, the ability of a vehicle to maintain stringent Tier 2 emission standards has been hampered, leading to engine deposits that can have a big impact on in-use emissions and driver satisfaction."

 

There is a new one here:

JAGUAR XJ SERIES FUEL TANK SENSOR GENUINE PART NEW | eBay

Check it is the right one!

They are asking too much for shipping.

 

Wish I'd known while my daughter was still in the UK, could have had her bring it home. Thanks.