I let my XK-120 sit for two months. It ran fine when put away, but now it will not run. It starts, but will not continue to run more than ten seconds. I suspected the fuel filter, so I replaced it. I can see that fuel flows to the filter and looks nice and clear, but does not fill the filter and must not be serving the float chambers adequately, so I am beginning to suspect that the pump may be compromised. My Dad bought this car new and I have had it for 31 years. I do not remember him replacing the pump, and I have not. It ticks fine, but maybe the diaphragm, or other parts are just tired. There is a shop in Napa, California that offers rebuilds at what appears to be an attractive price. Has anyone done business with this outfit or have any other suggestions (Besides smacking the pump smartly; I tried that)?

http://sufuelpump.com

Submitted by howardbollinge… on Wed, 07/23/2014 - 15:54

To All:
I must apologize.
In my haste, I forgot this thread was regarding an XK 120. My above comments relate to my Series 1 E-Type, so some of my commentary does not make sense when discussing the 120 situation but does work well for S1 E's.

Submitted by howardbollinge… on Wed, 07/23/2014 - 15:47

To All:
If you have diagnosed a faulty SU pump to be the culprit in your fuel system and if you don't want to spend the time and effort pulling it, rebuilding it, replacing $$ it, and you are not showing your car where originality of boot innards are judged, do what I did about 25 years ago.

Pick up an inline electric pump w/filter at Advance, AutoZ, or Napa etc. and mount it inline with clamp,hoses, etc. supplied, right on the front wall of spare tire compartment. If it ever goes bad you can replace it with another in about 15 minutes or less, and it will click away for many more inexpensive years.

fyi, I've left the dead SU in the tank with no ill effects.

Submitted by coventryclassi… on Wed, 07/23/2014 - 14:39

Gary, I have one other thought. The center bolt, that holds the top on the float chamber, has a paper washer under the vent tube banjo fitting. It is a special washer. I have had customers cars that a copper washer was used or another of the aluminum washers. It doesn't allow the air to vent and the fuel to fill the bowl. Easy to check.
Cheers Tom

Submitted by gilroyggg@aol.com on Wed, 07/23/2014 - 10:20

Well, I pulled the float filters and they were clean. Reset the float levels, and made sure that the needles were free. Disconnected the fuel feed at the inlet to the main line filter, and the pump now puts out a pint in about five seconds! No incantations were used. It's good for now anyway and running well. Thanks for all the suggestions and support!

Submitted by NE48-24099 on Sat, 07/12/2014 - 12:46

Gary, I might also add that today's fuel with ethanol degrades the diaphram in the fuel pump, thus rendering it useless.

Submitted by SW03-09811 on Sat, 07/12/2014 - 00:40

Gary,
A couple of basics....
- "Smacking the pump" is usually recommended, as a remedy, only when the pump ISN'T ticking.
- If the car has been sitting idle for days or weeks, the pump ticks and then stops, as if the float bowls are full, but the car is reluctant to start and run properly , it is worthwhile giving the top of each float bowl a firm tap with a soft (wood or plastic) object to free a possibly stuck float valve. If the ignition was left ON, you may hear the pump tick a few more times as one or the other float bowl is then filled.

If this doesn't help, by all means disconnect the fuel line coming from the pump, where it joins the carburettors' supply line, and see if there is a steady stream of gas. (There are filters in both the tank and in the pump that could be obstructed.) A ticking pump, that is not delivering much or any fuel, likely has a faulty diaphragm.

Additionally, it would be somewhat miraculous if the pump itself was still reasonably functional after 31 years. A rebuild or replacement would not be a waste of time or $.

Good luck,

Submitted by bogot001@yahoo.com on Thu, 07/10/2014 - 09:59

Gary,
Buy a new pump from S.U. USA
It's the heart beat of the car. Make sure flare
fittings match. Replace floats with new ones
From S.U. And needles as Thomas suggest.
It will be one less thing you have to worry about.
Cheers,
G

Submitted by coventryclassi… on Thu, 07/10/2014 - 09:38

Gary, try the banjo bolt at the carburetors to see if you have fuel flow. Sometimes the needle & seat in the carburetors stick closed, or only a small amount of fuel flow. There should also be a filter screen behind the banjo bolt that you can remove & clean. I would check for flow before having the pump rebuilt. Good luck, Tom