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MG MGB Technical - Fuel pump and E10 gas

I have had to rebuild my Bellows electric fuel pump twice after the last two times I run E10 fuel through it. I read earlier in the threads that people are not having problems but could the fuel be my problem and should I try a different fuel pump. If so which one should I use? If not what could be the problem. I don't drive the car that much. After rebuilding the pump it works fine. after sitting for a month or so it wont start and the pumps rubber diaphram inside is deteriorated.
David Whetsel

David. What vehicle are you driving? The MGB came, as standard, with an SU electric fuel pump. Mine have held up well on our fuel which has, depending on the time of year, either a 10% alcohol content or some thing similar with MTBE. My cars are driven on a regular basis and are used as my primary means of transportation. Perhaps you should drive yours more? Perhaps a change to an SU fuel pump? Mayhap David DuBois, who rebuilds SU fuel pumps, can add some insight.

Les
Les Bengtson

E10 doesn't seem to be a problem to the older SU fuel pumps, but anything with more than 10% ethanol becomes iffy. The SU pumps built in the last several years and the new diaphragms available for them seem to hold up quite well. The bellows pumps are made by the company that used to be called Welbro (and may still be). You would have to check with them as to what their bellows are built to work with. Cheers - Dave
David DuBois

My car is a 1969 model. I found out the pump I have is not rated for fuels with alcohol. So there is my problem. So one of the new electronic SU pumps should work fine? I attached a picture of one of the pumps I have been using. Any advice on a new pump will be greatly appriciated
Thanks,
David


David Whetsel

David. David DuBois is our resident fuel pump expert, having rebuilt SU pumps for a number of years as a side line. Now that Dave is retired, he rebuilds them as an after retirement job. Thus, he will be the best qualified individual to discuss with you what would work best for you and what else (such as the banjo fittings and washers) would be required to change over your current system to the original system. You might also ask him for a link to his website where he has some worthwhile articles. I installed the back up fuel pump system that he mentions on the website and am evaluating it. So far, it seems like an excellent idea, especially when one fuel pump failed and a single flick of a switch allowed me to continue on my journey.

Les
Les Bengtson

He gave a link to his website just a few days ago http://homepages.donobi.net/sufuelpumps/index.html
Geoff Everitt

The new Burlen electronic SU pumps have all of the good qualities of the original SU pumps without the problematic points. Excellent for cars that are driven infrequently. RAY
rjm RAY

E10 could well be marginal for the rubbers and metals used in our era of cars, E85 is very particular in what materials can be used. An Australian site http://www.fcai.com.au/publications/all/2006/6/3/can-my-vehicle-operate-on-ethanol-blend-petrol- indicates E10 is not compatible with MGBs, but E5 is.
P Hunt

I received my new AZX1307 SU fuel pump today. Since it's a totally different animal than what I had before I still have a few questions. First which one is the in and which is the out? I see where it says out and top on the side of the fittings area but I don't understand what it means. The second question, is there a certain orientation it needs to sit. If it sits on its side then the top and out make some scents due to the out hole is on the top. My third question is where does the power line connect? My old one connected on the bottom. This one has a connector on the bottom and one on the top (next to the fuel line connectors). I assume this one is the ground connector.
David Whetsel

The pump mounts on its side, under the car, just inboard of the RR wheel, on a bracket with a round rubber mount both available from Moss. Outlet up. Fittings all from Moss.
Dave, It's Walbro. That looks like a variant of the old Autopulse pump, sold under many names. They used to have brass bellows, which lasted about 100,000 miles and don't care about fuel - possibly still available. I have called Walbro a couple of times and demanded to speak with an engineer, who were most helpful, albeit stumped by my problem, which I figured out myself finally.

FRM
FR Millmore

12v supply goes to the spade at the electrics end with the plastic cap. Earth/ground lead goes to the spade screwed to the body near the ports.

On a CB car orientation and ports are as shown on the attached, inlet to the bottom and outlet to the top.





P Hunt

David - Here is another picture of the pump installation showing slightly different routing of the fuel lines. I believe that the picture that Paul provided is the more correct routing, but that is not the subject of your question. The pump is always oriented with the 'top hat' cover at the top - the lower port is the inlet and the upper port is the outlet. This is true of all models of SU fuel pumps - the outlet is always on the top. Cheers - Dave


David DuBois

Thanks for all the help.
I finally got it put in, see attached picture. I decided to put it in the extra battery box. First I moved the battery to the other side, behind the driver seat. and then had plenty of room in the one behind the passenger seat to make an easy installation. I don't think it should cause any problems here.


David Whetsel

I noticed that the point vent cap is missing from the fuel pump. It should have a check ball that only allows the heat to escape under the cap. RAY
rjm RAY

Ray
This is an electronic pump. I'm under the impression it doesn't actualy have points. Maybe that's why it doesn't have the cap your talking about. If that's not the case I don't know, that's the way it came. Am I missing something?

Thanks
David
David Whetsel

The vent cap is there, it just doesn't have the tubing connected to it that goes to a Tee in the boot, together with another vent tube from a nipple near the diaphragm. It's nothing to do with points, or heat, they prevent pressure each side of the solenoid from damping its movement. If they are left unconnected like that they will suck in dust and moisture.
P Hunt

Meant to add a pic from Clausager of the vents. This is a CB (although early cars only had one I think), on an RB there is only one vent as the electrics end is already in the boot.


P Hunt

So I just need to add a tee to the vent line that already runs to the trunk from the vent cap by the diaphragm and connect the other vent cap to that, correct?
David Whetsel

It is not necessary to run a vent tube anywhere for the vent spigot on the end cover. As Ray stated, there is a check valve in that spigot that prevents any external air from being drawn in. For more information on the venting of SU fuel pumps, see the article, SU Fuel Pump Vents in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/
David DuBois

If Abingdon saw fit to *add* the vent tube from the electrics end going into the boot, then that's good enough for me.
P Hunt

This thread was discussed between 25/11/2009 and 24/12/2009

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