[Healeys] BN2 Fuel Pump

Bob Spidell bspidell at comcast.net
Sat Sep 4 19:27:31 MDT 2010


Listers, 

I'm most familiar with BJ8 fuel pumps--being able to assemble at least two working units out of a large collection of parts at any given time--but I'm having trouble with a BN2 fuel pump. The BJ8 pumps have a valve body with two thin reed-type valves--one on the suction side and one on the pressure side (they are set up differently, of course, but I believe the valves are the same). Anyway, my BJ8 pumps a few times when energized and settles into a steady rhythm of a pump every 5-6 seconds with the engine not running. With the engine running, the pump speeds up according to engine speed; a pump every 2-3 seconds at idle, a couple pumps a second during acceleration, and a steady pump every 1-2 seconds at cruise. Very logical. 

Our BN2's pump--a brand new SU electronic--is a different design. There is only one valve--a brass disk, basically--on the output side and nothing on the suction/inlet side (it almost seems like it's supposed to siphon as much as pump). This pump behaves erratically--it'll pump rapidly when the key comes on, and seems to settle down but then starts pumping erratically. It pumps almost continuously with the engine running--the engine runs fine, BTW--but it's still an erratic continuous. 

Is this typical for the BN2 pump? It appears this design is way inferior to the BJ8 pump design--in spite of the lovely brass machine work inside--and I'm glad to see SU improved the design (and probably make it cheaper, to boot), but it doesn't seem right to me. I haven't ruled out air leaks, but we've checked, tightened, and checked and tightened again and nothing seems to change. Not having a reverse-flow preventing valve on the inlet side just don't seem right, somehow. 

All info, SWAGs, etc. accepted/appreciated. 

Bob 

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Bob Spidell - San Jose, CA 


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