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MG MGA - Continuous clicking from fuel pump

With a whiff of spring finally in the air, I dusted off the cobwebs and started the old girl up yesterday. Everything looked good and she seemed to run just fine. What I noticed, though, is that the fuel pump continued to click quite vigorously with the car idling. I shut it off and with the engine stopped, I turned the ignition on. Away went the fuel pump...click-click-click-click-click.

Normally, it'll do that for a few seconds and once the fuel bowls are full, it stops clicking. However, now it just seems to go on-and-on. I checked the carbs. Both fuel bowls are full. Both floats are floating. Nothing dripping from the carbs. Crawled around under the car and found no apparent fuel leaks. I clamped the rubber fuel line coming out of the pump, expecting it to stop, but it kept on clicking.

I assume this is a bad thing that the pump doesn't stop. The pump is only about 3 years old. Is this an indication that it's on its last legs? Does it sound like something repairable or should I start looking for a replacement? Am I safe to go off driving with it like that or is it imminently doomed to fail?
Andy Bounsall

Not good, but it should be repairable. It sounds like some trash caught in a check valve (most likely the suction valve disc) allowing back flow and preventing the pump from building full pressure. You can service both check valves by removing the outlet union from the pump head. While you're at it, remove the inlet union to check condition of the inlet filter, which may have a hole in the screen allowing trash to pass. See the workshop manual for an explosion drawing of the pump.
Barney Gaylord

Could also be an air leak on the suction side of the pump. If all the fittings don't seal totally air can be sucked in. Not as likely as Barney's answer but easy to check.
R J Brown

Thanks very much for the suggestions guys.

RJ, you hit this one on the head. There are a couple of transitions between steel and rubber fuel line on my car where an inline filter has been spliced in between the tank and the pump. Two of the hose clamps at the junctions were a bit loose. After snugging them up, the pump is agin working properly and stops pumping once the line to the carbs is pressurized. Thanks again.
Andy Bounsall

You also could be just low on gas.
Steve Meline

Andy - You can do yourself a favor and loose that filter between the tank an the pump. If that filter becomes clogged it will stop fuel flow to the pump entirely, then instead of constant ticking there will be no ticking at all. If power is left on in this condition (such as during troubleshooting) you can very easily wind up with a burned out coil in your pump (I just received a pump in that condition from a client). When there is a clog on the inlet side of the pump, the pump will stall in a current on condition and you don't know that anything is wrong (other than the pump is not supplying fuel) until you smell smoke. See my article on SU Fuel Pump Facts and Myths at: http://homepages.donobi.net/sufuelpumps/Fuel_Pumps/SU_Fuel_Pumps_Facts_and_Myths.pdf
Cheers - Dave
David DuBois

This thread was discussed between 07/04/2008 and 10/04/2008

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This thread is from the archive. The Live MG MGA BBS is active now.