WIth much help from the forums here I am happy to say I can now drive the jag enough to get a feel for her and she feels pretty good!

Now my issue is a noisy fuel pump and a sputtering engine when the throttle is needed at higher speeds.

I changed the fuel filter last night and it seemed to quiet things a bit but it wasn't long and the pump started getting loud again.

I need to know how too clean the sump?? If I disconnect the lines going to it fuel spills out. Is this because there is to much fuel in the main tank still?

Also should I expect the tank to be rusty inside? If so why is this a problem with these cars?
To recap this is an 85 with 40k miles on it.

 

Age, wear, and dirty fuel add up to noisy fuel pumps. Sometimes they soldier on for years, though, even when noisy.

And sometimes not :-)




Any fuel in the main tank immediately drops to the sump tank, by design. Get a wooden ½" dowel, whittle a point on one end, and use it to plug the supply hose as soon as you remoe it. If you're quick you won't have much spillage

As for cleaning I recall removing the sump tank and sloshing it out



Probably. When you changed the fuel filter did you drain and examine the fuel? If it's brown, you've got rust in the sump tank.



Rust in the tanks is a bugaboo with older cars in general, worse on Jags....maybe the type of steel used? I dunno. It's doubly worse if the car sits unused for long-ish periods, which is pretty common with old Jags.

Cheers
DD

 

Following Doug's advice, there is a sock filter slipped over the outlet spout inside the sump tank that will almost certainly be blocked. You will need a new one.

The sump tank can be unbolted once the boot has been cleared out a bit. I think it is best to disconnect the battery and remove it, as a spark could be disastrous. The sump tank is covered by a sheet metal panel under the battery. The sump tank output to the pump is fixed with a locking ring, same size as for the fuel sender. Easy to clean it out once the thing is out. Quite a bit of the noise (on mine anyway) was caused by the sock filter not flowing enough fuel under gravity for the pump.

If you are lucky, it might be that (having blocked off the fuel feed to it!) just looking inside the sump tank through the output hole may reveal the thing is clean, in which case, no need to unbolt it, just renew the sock filter.

 

So it sounds like I should order a new sock filter for the sump and then venture into opening it up.

Is the locking ring removed by rotating it possibly with a screw driver and some persuasion?

I am also considering just ordering a new pump. By the time I finished my drive last night the pump was so hot that it stopped. After it cooled down the car started right up and i pulled into the garage, but I a thinking this pump is on its way out.

No comments on the pics? I think she is looking good...

 

Locking ring is loosened by turning the lugs anti-clockwise. Use a wooden block and carefull taps with a hammer on the wood, one lug at a time in sequence.

The pump getting hot is a classic sign of a blocked/reduced feed from the sump. Normally the fuel cools the pump as it goes through. I think it is a VERY good idea to renew the pump and keep the old one as a spare (but there again, I always think renewing old bits is a good plan!). BUT do not renew until the feed and sock and sump have been cleaned / renewed.

Also, check that the fuel really pours out of the main tank / sump pipe OK, and that the feed pipe from the sump to the pump also is completely clear. It is not unknown to have blockages/reduced flow in any of the pipes leading to the pump. Particularly the nearly 180° bend in the pipe from the sump to the pump, just where the pipe turns upwards to enter the pump. If the pump has dropped a bit in its clamp, this can get restricted where it fouls the floor.

Still and all; once this is done the thing will be working just fine. renew the sock filter every 2 years and no more worries.

Greg

 

When you order that new filter, ask for a new seal for that sump tank opening, you will need it. NEVER use that seal a second time.

There is a drain plug arrangement on that sump tank, behind a rubber grommet in the floor. I push a 10mm hose over the spigot, crack the plug and let it drain into suitable container/s. Obviously proper fuel precautions please.

 

Finaaly had a few minutes to look at the sump tank today. Its not good. I see a rusty brown color in the fuel and the sides of the tank have a sort of rusty growth on the sides of the tank.

Should I expect the same in the main tank? Is there a way to clean this out without removing the whole tank?

I have a new pump and sock filter on order..

 

May I suggest that you start with the sump tank, and fix that.

Then while you are doing that and have the boot empty, you can inspect the main tank as follows:

1. run all the fuel out of the main tank into a safe container using the normal to-sump-tank feed pipe.
2. Then remove the fuel gauge sender. This is in the centre of rear vertical face of the main tank and is fixed with the same locking ring system as the sump tank exit pipe to the pump.
3. Get a torch and you can then quite easily look into the tank through the sender hole and see if there is rust and crud all over the main tank floor. There may well not be, as it may all be in the sump tank.

If the main tank is in a bad shape, then it has to come out to be fixed.

Do not forget to replace the fuel filter once you have fixed the sump tank, even if a nearly new one, it will be very important to change it.

Greg

 

Thanks Greg, this is what I was thinking I would do as the sender needs to be looked at anyway since the fuel gauge isn't working either. I was planning to try to use some of the fuel first though since I believe there is a fairly full tank and getting rid of 15 gallons of bad gas is a pain. Plus I don't have 15 gallon cans to keep it in.
Probably a better idea do drain it though, but I imagine the fuel making it past the filters is fairly clean.

 

Pulled the sump tank out tonight and it was full of a rusty muck. Pulled the fuel sender out and the tank isn't to bad. There is some minor stuff in there but nothing like the sump tank. i think it will clean itself up with a few tanks of fuel run through the car. If I ever get it to run that far....

 

Alright, clean out the sump tank installed new filter sock pulled fuel sender in main tank and inspected. Looked pretty good, bot perfect but should clean itself up in time I think. Put it all back together and she runs much better now with much more power. Cleaned up the fuel sender and now the gas gauge works cool!!!

 

Great job, congrats! New fuel filter too (behind the spare whee) I hope!
Greg

 

Not yet Greg, but the one that is there has about five miles on it.. Thanks For the help!

 

Five miles and loads of crap via the sump and pump! Bunged up filters are responsible for lots of EFI problems.

G

 

OK. Which of you chaps can tell me how to extract/examine fuel sender unit (gauge isn't working but works to ground/earth) in a 91 XJS Coupe????

 

Pretty easy to do and mine didn't work either. Make sure you are low enough on fuel to be below the access hole that is behind the carpet that is behind the spare tire. Loosen the holding ring with a hammer and wood dowel pr something that won't spark just in case. The fuel sender will pull right out. Mine was just jammed up. A little working and some oil and it works great now.