Those BMC pumps again

Canal Boat - - Back Cabin: Experts -

QI have a fuel leak from the throttle spin­dle on my BMC 1.8 en­gine. I have re­moved the link­age but there is a quad­rant plate that goes against the throttle stop that looks like it should lift off but it won’t move? Do you know how this comes off? I pre­sume there is a seal or O-ring un­der­neath.

PHILCOLES, via the CB web­site

ATONY REPLIES: All the BMC1.8s I have seen use a CAV DPA in­jec­tor pump but they do not have a quad­rant plate. Be­neath the lever there is a disc with small holes punched around the edge. Dim­ples in the back of the throttle lever fit into which­ever pair of these holes is in po­si­tion for that par­tic­u­lar use. This disc also has an ex­ten­sion that bears against ei­ther the idle screw or max­i­mum fuel stop. The lever has a round hole in it and the disc an oval hole with two flats that match the spin­dle. I don’t un­der­stand why you can­not sim­ply pull the lever and disc off once you have re­moved the nut from the spin­dle.

It is vi­tal on these pumps that the throttle ca­ble is ad­justed so the disc hardly bears upon the idle stop when the con­trol is set to idle. If there is any ten­sion/com­pres­sion in the ca­ble it forces the spin­dle hard against the O-ring so leaks are likely.

The O-ring is on the spin­dle, not in the hous­ing, so you could just pull the whole spin­dle and lever as­sem­bly out of the pump. To do this, lo­cate the gov­er­nor as­sem­bly lo­cat­ing screw and re­move it. Then the spin­dle with lever should just pull out of the pump. You must en­sure it is prop­erly lo­cated in the gov­er­nor valve when you re­assem­ble.

I would ad­vise that you Google for a hy­drauli­cally gov­erned CAV DPA man­ual be­fore go­ing any fur­ther.

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