3.8 S fuel tank pickup explanation / solution ?????

Started By: Curtis Wood on 2008-09-27 18:44:56

I recently bought a nice 3.8S that will not run for long periods of time under very high loads or high rpm due to a lack of fuel. I am sure it is a fuel pressure/volume issue. Have cleaned and cleaned and cleaned pickup tubes, tanks, installed filters, plug and screen, ect. ect. and even tried replacing one of the pumps.

Really believe that the pumps are drawing a little air instead of 100% fuel on the suction side. Can't see inside the tank and so don't understand how the fuel line on top is supposed to seal to the pickup tube in the tank. Can anyone explain this to me???

My car currently has a clear plastic suction line tube and a fitting that presses down on a collare to push the tube down into the tank. Because the tube only extends an 1/2 inch or so down until it hits obstruction (presumably the pick up) I can't imagin how it is supposed to seal to the in tank pickup???

Any explanations or assistance will be greatly appreciated. I am usually pretty competent with these things, but am missing something here.

Thank you in advance,

Curtis Wood
curtis at thiscrazygarage dot com

Comments

I'm sure someone will come up with the answer. Fortunately I've never have to deal with this issue in my 'S' , so I do not know where the clear lines connect to, but based on your description, they must connect to a nipple at the pickup as opposed to just being "floating".

I am familiar with the two compartments where the two pumps reside, and with the clear lines you describe, but otherwise I have no clue where or how they are connected.

Thanks JAM,

Was wondering this am if maybe the clear line is broken off at the top of the pickup and is actually supposed to be threaded down through the pickup channel to the bottom of the tank. Who knows? I can't see in there, nor will my fingers fit through the hole to feel around.

Hoping someone smarter than me will reply with an explanation today.

Sorry I couldn't be of better help. if noone answers, try calling and asking Tom Curren, Orlando's Jaguar Guru, who owns Coventry Classics in Orlando. Tom is very helpful and he knows these cars well.

What you say makes sense, I honestly do not think there is a clear plastic line floating in the fuel, it must be threaded to a nipple, just like they are at the fuel pump nipples.

As a last resort, join Jag-Lovers Saloons Forum and surely someone there will have the answer, many MK-II, S type, and 420 owners answer questions there.

http://www.jag-lovers.com

Also try Jaguar World Magazine Forums at

http://www.jaguar-world.com

I have both the Factory and Parts manuals which have great ilustrations but I am not near them at the moment.

here's a modification (mod) you might want to do to your S type's ASC (Auxiliary Starting Carb), after you solve the current mistery:

http://www.jag-lovers.org/saloons/asc/index.htm

My 2 cents on fitting an override switch: Years ago it was the only way we could get the choke to operate if the temp switch didn't work, as the switch was not available. That changed about 15 years ago. The original set up is simple and effective and also efficient as it shuts off the choke just when it should. So many people used to flood out as they forgot to switch the choke off. As for the original problem, when you get the car running is there fuel visible through the plastic line?

The fuel is visible in the plastic line before the pump and in the clear inline filter I added after. But there are bubbles in the line, on the suction side, that come up out of the pickup with the fuel. Can't believe the fitting pressure is all it needs to seal.

Is the clear line supposed to go all the way to the bottom of the tank through the pickup tube? Should there be some kind of fitting at the top of the pickup for the clear line to seal over?????

Story of my life. I always have the unique problems. :>)

Curtis check these things--are your fule caps vented or have they possibly ben replaced with non vented ones? Are the two vent lines on your fule pumps clear and free? Does your pick up possibly go so far down into the pickup filter it hits the bottom? If so it will pull itself down under load and effectively starve out! Does your car do this on both tanks? Do you have this problem with the tanks full?

George,

Vents are clear and I have tried it with both a full tank and with gas caps off.

Both sides are the same, although the line seems to get a little better seal and draw less air on the left side.

With regard to the pickup, that is what I don't understand. The plastic "pickup" line only goes about 1/2" down into the top of tank. the bare end of the line contacts something there and the amount of fuel or air that is drawn depends on how the line seals against this, whatever it is.

Is the line supposed to fit onto a union of some sort inside the tank? Maybe there is broken line there and my pickup line should thread its way to the bottom of the tank, but can't? Is there some type of fitting I am missing on the line that would allow it to seal to the pickup tube inside the tank?

When you have the tank filter off the pickup should be there at the bottom of the tank to fit into the receiver in the filter.

George, thank you so much for taking time to think about this and thankyou in advance for giving me another chance to attempt communicating more clearly.

I have pulled the drain plugs which have the screen built in and that the in-tank pickup sticks down into (where it draws fuel) That is all clean and clear.

That pickup, internal to the tank runs straight up, from the plug/screen area, to the top of the tank and ends just below where the fuel line fitting screws into the top of the tank. The question I am trying to articulate is: How does the fuel line going into the top of the tank seal to the top of the vertical steel pick? I am guessing that the air I am drawing is coming from a misfit of hose to top of pickup, way up top.

Thank you in advance to anyone who might be able to explain how the intank pickup hooks to, or seals to the fuel pump line.

Edited on 2009-01-13 12:49:38

Curis,
did you resolve this issue?? I can scan the illustration from my S type Service Manual showing the two fuel tank components if it will help.

George,
the two caps in my S type say "non vented" on them. They are stainless steel and appear to be the originals when I compare them to illustrations in the service manual which also read "non-vented" in the drawings.

JAM