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+--- Thread: AC Fuel Pump (/showthread.php?tid=4763)
AC Fuel Pump - Alan Course - 05-08-2020
I would be very grateful for any advice as to how to prime the pump on my RP saloon. It should of course have an AC Type T pump but many years ago someone put a type U pump on which looks much the same but has a blank where the bleed screw is located on a type T. The car has undergone a very major restoration & we fully refurbished the fuel pump (I assume the new diaphragms fit both T & U it looked to fit but of course came from an A7 supplier. The tank has been cleaned & lined with POR 15 the original tank filter removed & fuel sucked through the pipe up to the pump. We have manually filled the pump with fuel but still no luck with the priming lever. I wouldn't have thought it essestial to have a type T as the type U was working when we got the car. Any suggestions would be greatly appreciated please.
Many Thanks Alan.
RE: AC Fuel Pump - Bob Culver - 05-08-2020
Great care is necessary to assemble with the arm on correct side of camshaft. If wrong I dunno if the arm can lock the diaphragm at one extreme, but can damage when engine turned. Operated in the hand by either lever the suck and blow can be felt, and should ditto on the car. Will self prime. Esp with the plugs out easy to carnk over by hand. There are right and wrong pump arms with very subtle differences. Air leaks on suck side of system thwart operation.
RE: AC Fuel Pump - "Slack Alice" Simon - 05-08-2020
Take the pump off and check for suck and blow when the lever is operated.
These pumps usually work ok, so either, as Bob says, it isn't being operated by the lever, or something is holding a valve open.
Are you sure the diaphragm rod engaged in the rocker arm correctly, it can be a bit of a fiddle?
RE: AC Fuel Pump - AustinWood - 05-08-2020
If the camshaft stops on the pump lever the manual prime won't work. Turn the engine one turn and try again.
RE: AC Fuel Pump - Reckless Rat - 05-08-2020
You lift the lever to prime, against the spring pressure, not push it down.
RE: AC Fuel Pump - Alan Course - 14-08-2020
Many thanks for all your very helpful sensible & logic responses - I then worked through them all & became very frustrated with myself (as everything seemed fine) when I failed! In despair I contacted a longstanding mechanic I used to know. After going through all your suggestions too (he didn't trust what I had done & I don't blame him!) no luck. Then he checked all the unions from the tank (I had already done that) all tight. Then he undid them; guess who when rebuilding the car had managed to tighten one of the unions, not cross threaded but the olive was not seating properly! I wont forget that lesson in a long time!
Your advice was nevertheless much appreciated.