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MG TD TF 1500 - SU fuel pump inlet valve

This was a surprise. Pic shows my SU fuel pump inlet valve. Outlet is normal disc/spring clip as per manual. Pump is about 10 years old and has AUA 4080 stamped on base and AZX 1332 on tag fastened to diaphragm retaining screws.
It's off the TF because it started to only click once or twice on ignition switch on. When both inlet and outlet pipes are connected, that's what I get. Disconnect the inlet pipe and pump ticks just fine.
Did SU/Burlen change the spec and are they still like this?

David


David Wardell

David - What you picture is not a valve, it is only the inlet fitting and tube that serves some purpose that is a mystery to me - I usually just discard it on the pumps that I service, since the only function that I can discern is to make it difficult to drain the fuel out of the pump. The inlet and out let valves are the two disks under the outlet fitting. The bottom disk and its seat comprise the inlet valve and the top disk is the outlet valve.

"It's off the TF because it started to only click once or twice on ignition switch on. When both inlet and outlet pipes are connected, that's what I get. Disconnect the inlet pipe and pump ticks just fine."

If the pump is stalling when the inlet pipe is disconnected, then you have some kind of a clog on the inlet side of the pump - could be a clogged line or the filter screen in the tank could be clogged with debris in the tank. See the article, Fuel Delivery Troubleshooting Guide in the SU Fuel Pump Articles section of my Homepage at: http://homepages.donobi.net/sufuelpumps/

By the way, with a clog on the inlet side of the pump, don't let the power remain on for any period of time when troubleshooting as the pump will be stalled in a current on condition, causing it to overheat and could ultimately burn out the internal swamping resistor. Cheers - Dave
D W DuBois

David, many thanks for your reply.
After I posted, I studied the diagrams again and worked out how the valves worked. I was working on the (mistaken) assumption there should be a valve in the inlet port as well.
When I took the pump off, petrol poured out of the fuel line from the tank. And I have bench-tested the pump using two bottles as fuel tank and carbs and the pump stalls as soon as the inlet pipe is connected. So I don't think it's a clogged inlet line.
Next I'll clean the valves and contact points and if that doesn't work, it will be a rebuild kit from Burlen.
David
David Wardell

Dave,
I too have seen these hoses on the end of the inlet fitting. I believe they were normally used on the later rear mounted pumps to allow fuel to be drawn up in the case where there is an air pocket at the top of the inlet chamber. Without it, there is the chance of getting an air bubble and subsequent loss of vacuum.

Just a speculation, however.
Lew Palmer

This thread was discussed between 20/07/2014 and 21/07/2014

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.