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MG MGB Technical - Use of non-SU fuel pump

There was a Carter P4070 fuel pump in the boot of my '77 when I aquired it. The PO had attempted to install the pump but, was unsuccessful. I was able to mount the unit and use it for a short period (off-and-on for 2 days) before I found that I needed to pull the motor. The pump is very loud.

There are sales on SU pumps and I am debating on whether or not I will make the swithch back to the original configuration or use the Carter. I have the option at this point to do either.

If I use the Carter pump I will make a more permanent, visually acceptable installation.

Any opinions or experiences appreciated.

-mike
Mike Zaffarano

Mike. Fuel pump pressure is important with MGs. The Z-S, which your car came with originally, and the SU carbs need no more than 1.75 psi of pressure. If there is more, you will probably have problems. The original SU pump provided the correct pressure and volume for either type of carb. The Weber DGV series will handle up to about 3.5 psi without problems. If your Carter pump provides greater pressure than the carb requires, you would have to install a pressure regulator in the system between the pump and the carb(s). I have always used the SU pumps on my cars with no significant problems. Any fuel pump will wear out, but I have had less problems with the SU pumps than most others. Les
Les Bengtson

Mike,

If the pump is very loud, its probably no good. It should purr, not make a racket. If a pump has had gas run through it and not used (ie.tested briefly, then left in the trunk), it will dry out all of the rubber seals and internals.

Keep in mind that you will most likely only need a fuel rate of 1-3 psi to your carb(s), thus if you use an "aftermarket" (non-SU pump), you may need to install a regulator.

Good luck,

Mike
Mike

On a previous MGB the PO had installed one of those solid state jobs shown in the Moss catalog. He had bolted right on the rear bulkhead in front of the battery box. I hated it! The noise was transmitted right into the cockpit. Most passengers would also comment on how noisy it was.
The stock SU is much quieter. A new SU replacement pump should last for many years. Opinions vary on points type vs the newer solid state type.
Andrew Blackley

Hey, could this fuel pump be the reason that the car would shut down after removing the key? I have not been able to "nail down" the root cause of the run-on, this might be it.

I will not know for some time as the car is in pieces right now. I also need all the fittings because the PO removed them.

By the way the Carter puts out 6-8 psi and I have a Weber DGEV (and old SUs in a box).

-mike
Mike Zaffarano

Mike,
I am taking advantage of that new SU that Moss has on sale, and dumping my Facet, that I've been running for the last few years. Hopefully, I'll eliminate the fuel bowl overflow problem I've been having. And it will be a hell of a lot quieter.

Tyler
Tyler Irwin

Tyler, Just my 2 cents, try http://www.lbcarco.com/

-mike
Mike Zaffarano

OK, so I'm not so bright. I'll just bet the pump shuts down when the power is off. So maybe this is not my run-on answer. ;)
-mike
Mike Zaffarano

For a noisey aftermarket pump you might try a piece of rubber between the pump and frame as a buffer.

Mike
'79B
Mike Janacek

BURLEN NOW PRODUCE A FUEL PUMP WHICH IS THE SAME ON THE OUTSIDE AS THE SU PUMP BUT IS ELECTRONIC ON THE INSIDE. THERE IS NOW NO PROBLEM WITH POINTS BURNING OUT. THEY ARE AVAILABLE VIA MOSS OR FROM THE MG OWNERS CLUB.
peter bramble

Mike-
I use the pointless (solid state) electronic version of the SU fuel pump. So far it hasn't missed a beat. It'll bolt right in, looks like an OE fuel pump, and even makes the customary clicking sound, just like the OE SU fuel pump that has points. There's plenty of MGBs running around with their original 22+ year old SU fuel pumps, which tells you all you should want to know about durability. Why mess around adapting something else?
Steve S.

mike,
check the arcives for the run on. mine was caused by a faulty alternator. the diode ( which is in the alternator)that goes to the ignition lite in the dash was bad, ut the alt. was still charging. i just disconnected the lite in the dash and run on went away.
andy heston

Thanks Andy I will check out your tip after everything is back together.

I ordered the SU pump. I'll keep the Carter pump handy for emergencies.

-mike
Mike Zaffarano

Steve S - The new all electronic pumps from Burlen fuel not only looks and sounds just like the original SU pump, it IS the original SU pump. It just has a hall effect trigger instead of a set of points under the end cover. I do a similar modification to pumps that I overhaul, using a magnetic reed switch and magnet to replace the points. So far, the reliability has been fantastic. By the way, for those unfamiliar with Burlen Fuel, they are the ones who took over SU, so the pumps and parts that they distribute are genuine SU parts. Cheers - Dave
David DuBois

This thread was discussed between 20/06/2002 and 21/06/2002

MG MGB Technical index

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