Fuel pump may be putting out too high a pressure. A fuel pressure regulator
on the fuel line keeping the fuel pressure below 3 psi might be a possible
solution.
-----Original Message-----
From: JagMkV@aol.com [mailto:JagMkV@aol.com]
Sent: Monday, November 10, 2003 8:18 AM
To: mg-t@autox.team.net
Subject: SU Carb problem
Hi Listers... I have a problem with the carbs on my Mark V Jaguar. Maybe
one of you have had the same problem on a MG.
I noticed that the car was running rich and fouling the plugs. I removed
the caps and pistons from both carbs. When I turned the ignition on, I
noticed that fuel was seeping from the jet in the front carb, and the pump
kept on clicking slowly instead of stopping. Thinking it was a bad float
or a stuck float needle, I dismantled the float chamber. The float was
perfect, no gas inside. I even checked it in a glass of water, and it
"floated" perfectly. I checked the needle valve, and it was clean. I put
the lever back on, checked the adjustment (7/16" bar across the rim of the
top) and it was perfect. I held it upright, and blew hard into the inlet
while raising the arm, and it stopped allowing air to pass through. Released
it and air passed through. Satisfied that everything looked good and was
in adjustment, I reassembled the float chamber, turned the switch and again,
gas seeped up through the jet accompanied by a slow "click...click" of the
pump.
I did not remove the float chamber from the body of the carb, but, if I
remember correctly, there are no moving parts in the connection between the
float chamber and the body.
I am at a loss as to why the gas continues to seep through the jet. It
seems to me that if the float needle was seated properly in the valve body,
and air under pressure couldn't get through when the float lever was in the
up position, how could gas get through?
Note, I have new float needles and valves, the new ones with the rubber
points. The valves are tight and, as I said, don't leak under air pressure
with the lever in the up position. The only thing I did not do was to swap
float tops and see if it still leaked from the other carb jet when the tops
were switched.
Any suggestions?
Craig CarraganSouthbury, CT USA
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