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MG MGA - Fuel system alcohol issues?

Recently gasoline with 10% alcohol made its appearnce at our local gas stations. Are there known issues with the MGA fuel system regarding the alcohol content (fuel pump diaphram, etc)?

G T Foster

Gerry - To my knowledge, there are no fuel system issues with 10% ethanol. Apparently problems start when the concentration is above 15%. Cheers - Dave
David DuBois

Does it make a good vodka and tonic?
Steve Gyles

I'd have thought you were more a G and T, Steve!
Neil McGurk

The alcohol can be a solvent and can dislodge deposits in the fuel system. I have had to use this blend in Illinois for years without problem but an in line fuel filter down stream from the tank is good insurance.
Keith Lowman


I have had a terrible problem with 10% ethanol fuel. It is not sold locally but on trips to PA and FL it broke loose a POR-15 fuel tank sealer I had done in 1992. Sheets of the stuff clogged the intake and the pump strainer. Early tank sealers are known to NOT be resistant to alcohol fuels. It is a real problem if not impossible to get all the old sealer out!!

I drove thousands of miles before encountering the ethanol but it only took 100 miles to clog the intake.

Hope you or a DPO didn't seal the tank 20 years ago.

Jim Ferguson

"...but an in line fuel filter down stream from the tank is good insurance."

Please, not between the tank and the pump. See the article, SU Fuel Pumps Facts and Myths in the SU Fuel Pump Articles section of my web site at: Cheers - Dave
David DuBois

Thanks guys...

I put a tank sealer in the tank on my coupe, which I'm not driving at the moment. I believe it was a POR product but I need to check. I did it about 5 years ago so maybe they have adjusted to the alcohol problem.
Alcohol problem.....naahhhh....

G T Foster

Alcohol is a BAD idea at any level. The only reason we have it is the Agriculture lobby got its way and some jerk in congress got to say how green he was. It Is NOT good for the environment. It is a bill of goods sold by liars and thieves. TERRIBLE for cars. If the fed cared as much about cars as it does for the safety of airplanes it would be illegal in cars to. The FAA knows how stupid it is to put in airplanes so they don't allow it at all. Who cares if it kills cars they just coast over to the side of the road.
R J Brown

Current (last 15 years) sealers are advertised to be ethanol resistant.

J R,

Jim Ferguson

This is serious stuff for some people, but almost amusing for me. I put Moss Motors slushing compound in my fuel tank with first restoration in the late 70's, putting it on the road in the mid 80's. I went through the transition to 10% alcohol fuel in the early 90's. The fuel tank and pump never noticed it, and I wasn't running any filter at the time other then the original screens in pump and carbs.

The trick I think was that I was driving the car a lot at the time, using 500 to 1000 gallons of fuel per year, two or three tanks full per week during the main driving season, and half a tank per week in the off season. I think the tank liner material was simply dissolved and gradually washed out of the tank along with the fuel, and I'm pretty sure the tank was bare inside by end of the 90's. There is no trace of the liner now, as the tank is pristinely clean inside and still in good serviceable condition after 52 years and 375,00 miles.

My personal opinion is that tank liner might be useful for people who expect to leave the car in storage for long periods with half a tank of fuel so it might rust inside. If you would store it for several months, leave the tank full of fuel. If you're thinking about parking it for some years, just don't do it, maybe sell it instead. If you drive it regularly you're probably better off with nothing but fuel inside the tank.

There were some other effects from the 10% alcohol. In 1989 the stuff dissolved the rubber diaphragm in a couple of Walboro fuel pumps, and each time it only took about 30 days when I was driving it regularly. Later on I noticed the Walboro pump was the only one in the J.C. Whitney catalog with a note stating, "Not for use with alcohol fuels". The SU fuel pump diaphragms are laminated fiber (cloth) reinforced (and nearly flat). The only sad stories I hear there are about the diaphragm going stiff after 20 years or so, but not usually leaking.

The alcohol also eats other rubber parts. For many years I was changing grommet seals on the SU H-type carburetor float bowls every year or two as the grommets would deteriorate dramatically and leak. Moss Motors recently offer a different part number for these grommet seals made with Viton, so maybe they will last longer now.

You might expect the alcohol to eat rubber fuel hoses as well. I have been changing the 5/16" bore fuel hoses on my aftermarket fuel pump every five years or so. I've never had a leak there, but they get to looking pretty bad after a while, so I do the preventative maintenance.

The large bore fuel filler connector hose should also be honest "fuel hose". I put a piece of coolant hose in there once, and it was shot in about 5 years, all soft and puffed up. Moss now has those in the proper material (last time I checked). Real fuel hose will last at least 10 to 12 years in that application, so I change it about as often as my car gets a repaint.

I have been using the two carburetor fuel hoses that are lined with Teflon, and no problem at all with those for 22 years and 225,000 miles on the same parts. That is one lifetime guarantee that is serious and believable. Ditto for the oil pressure gauge flex line hose (but I do keep a spare for that one, just in case).

For the last 100,000 miles I have been running twin Teflon 0-rings in place of each of the carburetor main jet seals with no leaks or sticking. I have installed several sets of these for other people with no problems. Very good conversion bits for cheap. The cork seal for the jet bearing always does well, and cork seals on my fuel tank sender unit have likewise never failed.

The most serious problem I have with 10% alcohol in the fuel is the tendency to boil easier and make the carburetors go unbearably lean in hot weather. Some people have devised various tricky heat shields to keep the carbs cooler, and some may actually help. I have a neat scheme for fuel recirculation to cool the carbs, but I haven't gotten around to trying it yet.

Sometimes you can learn good things by driving a lot.
Barney Gaylord

Can you give us a brief description of your idea for recirculating fuel to cool the carbs? I have been toying with that idea for some time but have not come up with a really good way to do it. I did wrap the fuel line and float bowls with insulating material. It seems to help so far, but I have not been stuck in traffic on a really hot day to give it the extreme test. I blame the vapor lock tendancy on the new fuel with alchol, but there may be other fuel propertys that contribute to the problem. I don't remember having vapor lock issues when I drove the car in the 60s and 70s, but getting caught in traffic was not a problem then. Lots of open road and I didn't go to town very often. Now town is all around me and the traffic is horrible!

Ed Bell

Just another experience to consider.

We've been running 10% ethanol forever. All cars including the MGA. There have been no problems at that level.

However 2 years ago we received a written notice from Costco that they had inadvertantly put E85 (15% alcohol) in the "regular" underground tank and we had purchased gas on that day for our suburban. If we had any problems we should let them know.

Sure enough the car started having problems starting when the fuel tank was less than 1/4 full. Took it to the mechanic and he had to replace the fuel pump because the alcohol had melted all the rubber bits and rendered them in suspension which ruined the pump.

Costco stepped right up and covered the $800 bill, no questions asked. I've had a lot of regard for Costco since then.

I have no proof but the catalytic converters went bad on that car this year at 100k miles, which is a little young. I suspect that the emissions of the burnt rubber/gas mixture gummed up the honey comb.
T McCarthy

Ed, -- Without too much picky detail, here's the short version of carb cooling fuel recirculation.

Where the original fuel hoses connect to the carbs with banjo fittings, copy the rear "Y" banjo onto the front carb, install an in-line 1.5 or 2-psi pressure relief valve there, and pipe any excess fuel flow back to the fuel tank. The fuel pump needs slightly higher pressure output than the relief valve setting, and that's the recirculation function.

On the carbs wrap some copper tubing around the float chambers, probably flatten the tubing for better thermal contact, maybe add some heat sink goop, maybe put an insulation sleeve around the outside. Connect the two tubing wraps in series with the fuel return line, and that's the cooling function.

When engine is running hard enough, normal fuel flow through the float chamber and main jet will cool the throttle body as usual. When engine is running slower at light throttle or idling, any surplus fuel flow available will run through the tubing wraps to cool the float chambers and the fuel inside. The fuel tank will serve as a large radiator to absorb and dump excess heat from the returning fuel flow and keep the fuel cool (cool enough).

Simple enough, just not urgent enough for me to give it a go (yet). Not many people would bother to try this on their own, but if it came in a box as an easy bolt-on kit for under $100 it might be an interesting gadget.
Barney Gaylord

E 85 is 85% alcohol NOT 15% and as T McCarthy found out it is deadly. Any ALCOHOL is bad. All is from bad government decisions based on greed.
R J Brown

Most of our stations here in Essex-Windsor
have printed on the pump in small letters "May Contain Up To 10% Ethanol".
I have not had any problems with either the MGA or MGB. I don't know how long the signs were there before I noticed them. I had filled the MGA twice at a gas station near last year's NAMGAR GT in Seven Springs PA and at that station had 15% ethanol I believe. There weren't a lot of choices, so I used it and had no problems.
I wonder if some of the suppliers like Moss and SU will come out with rubber components that are alcohol resistant....
It was mentioned at the GT to use fuel stabilizer to prevent the Ethanol from separating from the gasoline. This happens more in cars that are not driven much, so thats a good excuse to get out and drive those cars.


This thread was discussed between 29/06/2009 and 02/07/2009

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