almost done with this fuel dilemma on the ole jag, and im not hooking up the new fuel pump until everything has been sorted out. so far ive blew out the lines, cleaned the clogged injectors (that was fun), and added 2 fuel filters before the pump and got a new one for the pressurized side. now im on to the gas tanks, everytime i unscrew that bolt, rust always falls out, and i really dont want to buy yet another fuel pump. so the question is, how are you guys flushing your tanks with them still in the car? garden hose? pour in chemicals and letting it sit then drain? thanks in advance!

 

I took the bung plug (not just the bolt) out on each side and poured several gallons of gasoline through it, allowing it to drain into a bucket, until nothing else came out.
I am adding a filter on the suction side of the pump (highly recommended) as added insurance.
So far, so good.

 

thats what ive been doing, seems never ending though! anyone just stuck a garden hose in there to flush everything out?

 

before I poured the gas in, I saw the tanks were dry, so I blew some compressed air down the filler and blew as much out when it was dry as I could. You can't put any pressure on the tanks, though.
I also replaced the plastic screens on the intake pipes.
Hope this helps you. I have mine running good, but now I'm reworking the air conditioning. Looks like it will cool off before I finish...he whined.

 

Inert the tank with exhaust fumes. Then get 30$ worth of BB's or pellelts and load into the tank with a quart or more of soapy water. Seal it up and shake until you cant shake no more. Then remove the BB;s using a paint strainer to collect them so you can reuse for the other tank. Rinse the tank with more water or mineral spirit and let it dry thoroughly. Then you can convert the remaining rust in the tank with a product like R10 or any gun bluing solution. Don't use products that "seal" the tank, they tend to coat the tank and eventually the coating flakes away.

If you want to keep going with this...Then ditch the dual tank system and bridge the tanks so they both get used and cycled regularly. This keeps condensation from collecting and that helps prevent the rust from returning.

An after tank / pre-pump strainer type filter is always a good idea.

 

Thanks for the tip icsamerica! ill use that when I get to the fuel system on my 78 Chevy luv. ( putting in a 5.7 350) but, I would prefer not to drop the tanks and leave them in the car. I know I won't be able to get them as clean if I would, seeing what methods worked for people who didn't want to go through the trouble

 

I strongly recommend against your advice for "inerting" the gas tank with engine exhaust.
For one thing, engine exhaust has changed: in modern cars, it can be combustible, or at least so clean that it will not suppress combustion. For another, it can contain combustible amounts of unburned fuel; even carbon monoxide is combustible under the right conditions.
Our company had a welder retire; a few weeks later he tried this old trick to repair a gas tank. The explosion left his boots in their tracks and blew him up.
As for coating a gas tank: I rebuilt an old tractor about 20 years ago. The gas tank was rusty, so I boiled it out with lye until it was perfectly clean, then coated it with motorcycle tank sealer. Still going strong after all this time, with no problems.
I have mechanically assisted in cleaning a tank by putting a length of steel chain inside then shaking it to scrub the inside of the tank. Of course, leave the end outside the tank so you can pull the chain out.

 

A disposable fire extinguisher might be a good source of inert gas. Or a soda siphon.

Then again, if you completely fill the tank with hot soapy water first, the air has been displaced at least once. It would be wise to do it several times to lift any remain gas film that could make more fumes.

 

i think im just going to rinse them with soapy water, let them air dry and flush out any remaining soap with some gas. thanks for the replies guys!

 

Way back when, I was morphing my first car, a 23 Ford T roadster pickup into a more deireable fenderless 27 roadster!! I found such a bucket in a back yard. it had served as a parts car for the resident, a medical dr. that stuck to his immaculate T coupe, not wanting to learn to drive a 'modern' car! His mechanic OK'd the sale of the body. Somehow we detached it from the frame and got it on to my car and brought it home. The body swap went well. But, the 27 had the tank in the cowl. Better, in one way, not so good ion another. Yuk the first drive, the T stalled. No fuel to it's A carburetor. Opened the line, chunks of rust flakes. Repeated, no go for any time.

Solution, put a bunch of sharp tacks and a couple of gallons of Kerosene. Cheaper than cheap gas in those days. Added a two gallon out board motor tank as a gravity feed. % gallon GI can with a couple of more. Did OK. From time to time, drained off the cowl tank of the rust flakes til it ran clean. Hooked it up. Sanded and painted the body. Car did just fine for my first year of college. But, the gals had gotten more sophisticated, I needed a warmer car. So, the T left. New chick magnet, big black 31 Studebaker fordor. Gangsta!!

Bridging the tanks on the Jaguar is Ok, unless you live or go to a hilly city. SF is an excellent example. If one parks vertical to the curb on a hill, the fuel from the high side will migrate to the low tank. if there isn't enough room, it will overflow. Gas pouring over the side is asking for trouble.

If it stays on the flat land, OK.

I merely alternate tanks down to about just below half on each then refill.

Carl

 

well thanks for the replies guys, but after some thought i figured im just going to run my 15 gallon plastic fuel cell in it. no more rust, no more killing fuel pumps, and ill be able to take it out and clean if needed. only downside is there isnt a fuel sending unit, but the ones in original tank never worked anyway.

 

I always thought a vendor would make a lot by making a plastic replacement late model replica of the Jag tanks. Make it for S3, use the stock senders put in a good sock and drain system, incorporate feed and return fittings that would allow use in all models of XJ's.

I would buy them...new is always better than messing around with rusted tanks.

I have two good ones that I just took out the '84 V 12 Sovereign that I plan to use in my '71 XJ when converting to fuel injection for the needed return lines...but by then they will be rusted from sitting around empty...

 

My Series III tanks were a complete mess. I sent them out to a local radiator shop that does sideline work with gas tanks. They clean, and seal, and then pressure check the units. Comes with a lifetime warranty.

I noticed a few extra plugs in the tanks. It turns out, to gain access to the some of the tight spaces and ENSURE it is clean - and then to coat the internal tank in these tricky areas - they drilled additional access holes for injection. Then plugged them with steel threaded inserts.

 

That would solve a problem for sure. But just in case you are looking to free up that boot space - honestly, pulling the tanks is not that bad. You need to get them clean, and keep them clean. Once this is accomplished and you are aware of the danger of ignoring them- it will no longer be an issue. Changing the sending units out is a piece of cake once you lower the tank a little.

 

i been around old cars to long, rusty tanks and changing filters;; NOPE aint gonna happen to my XJS. polyethylene tank ,stainless pump and filter, aluminum lines,ETC.

 

that looks nice! how do you have your return line hooked up to the fuel cell?

 

the return line is on the left of picture,
the feed line goes into the small slosh tank(lower right to eliminate any air bubbles,FI dont like bubbles), then into replacable filter into pump, all 1/2" aluminum lines, up to engine ,then into custom fuel rails, all AEROQUIP flex lines, after fuel rail into FPR then returns to tank, via 3/8 alum. line.

simple and effective, most important its all adjustable,according to my needs!