I got my V12 running but it has a lot of surging and stalling. I changed the fuel filter to no avail. As I changed the filter though I noticed the fuel was quite orange as it came out the filter.

I think my tanks are rusty. So is it worth trying to repair or should I replace them but my word the price of new tanks is obscene.

 

Some radiator shops do gas tanks repairs. They can clean 'em and solder-up any pinholes if they're not too bad. Hard to say until the tanks are removed and cleaned. Worth a try, IMO.

Cheers
DD

 

Did you check RockAuto for tanks? I picked up a pair for my 1974 XJ and I thought the prices were reasonable.
It's my personal opinion that it's better to replace rusty tanks, especially if you have fuel injection.

Here's what my original tanks looked like from the filler:


Here's what I drained out from the bottom of the tank into a green 5 gallon bucket. Sure the strainer and filter would have caught most of that, but given enough time those would fill up and you'd always be replacing them.

 

I have gone down this very same road with an XJ6. Yes, the tanks are not inexpensive, but in my opinion, this is one area that biting the bullet and replacing with new is well worth the cost, especially with the time involved with removing them. The best price I found about 6 months ago was right around $350.00 each. Of course, a lot depends on how and if yours are rusted. Buy an inexpensive borescope that attaches to a cell phone, pull the rear taillight and sender and have a look inside the tank.

 

I farted around with vinegar, tried electrolysis. Replaced mine with series 3 tanks. Requires new gauges for series 3. Using the old gauges, they only show 5/8 when full.

 

I agree with replace. If you can find some new that are not ridiculously expensive, definitely go for new. And then keep them full to avoid condensation on the inside walls. If you repair, they will probably need to be repaired again or replaced in another few years and replacements might be more difficult or impossible to find then (it happened to me about 15 years ago). Rust particles are a disaster for the fuel injectors, fuel pump, and the tank change over valves. Also, it's extremely difficult to flush them out of the fuel lines. Do everything and anything to avoid the nightmare!

 

I have cleaned and sealed many tanks over the last 30+ years with good success. However, I haven't seen many tanks that get as corroded as xj6 tanks, especially after this many years. I've done two xj6 tanks in the last several years and at the price of new ones I'll not ever do another one! Much, much too labor intensive, then you have a second rate tank compared to a really nice galvanized inside/out (are you kidding me?) brand new tank. I consider the $350ea on the last ones I bought for the xjc some of the best money I've ever spent. No more chasing gremlins, pristine clean fuel system. Btw... don't kid yourself into thinking you can clean and seal without removing the tank, may want to do some weight training ahead of time too as you will need to hold it overhead and shake it around with playground chain and (strong) phosphoric acid (not muriatic!) many times over several days. Nah, I'll do motorcycle tanks or small car tanks that are nla but only after I'm beaten into submission.

Geez, even cheaper now! https://www.rockauto.com/en/catalog/...fuel+tank,6268