Need help understanding something... : MGB & GT Forum : The MG Experience

Need help understanding something... #1
mgjoc Dennis Rainey Crossville, TN, USA Sign in to contact 1965 MG MGB "Roscoe"	Topic Creator (OP) Oct 24, 2014 04:12 PM Joined 18 years ago 1,769 Posts

I decided to turn to this forum to see if I could get an understanding of a recent experience. My wife and I just returned home from a months drive thru New England for the fall foliage. We put 4722 miles on our '65 B with only a little trouble, a flat tyre first night out and about half way thru the adventure we had a generator failure. But, we were forced to fuel up with ethanol laced fuel particularly in the northern states. After doing so, the car started to "buck & snort" for want to a better description, as I was accelerating. The engine ran pretty smooth in cruise. This condition was not so bad with hard acceleration but still present to a lesser degree. My first thinking was that it is probably time for a carb rebuild as I've never had that done in my fifteen years of ownership, thinking that it was probably sucking air somewhere. Anyway, when we did find non-ethanol fuel this situation seemed to vanish almost completely but would return later. We found ourselves stuck in very slow traffic on a freeway for about 40 minutes at one point and the engine did heat up but not a whole lot, maybe 200 degrees indicated. When the traffic finally started moving again, the bucking & snorting was gone and did not return for the balance of our trip.

My own suspicion is that maybe a piece of carbon build-up was the cause of the problem but after heating up more than usual from the slow traffic, it had burned off and all was okay again.

Any thinking on this subject?

Cheers - Dennis

"Quality is long remembered after cost is forgotten" - Sir Henry Royce

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Re: Need help understanding something... #2
rntanner Roger N. Tanner (Disabled) Oxnard, CA, USA Sign in to contact 1970 MG MGB 1977 MG MGB	Oct 24, 2014 04:37 PM Joined 15 years ago 4,348 Posts

All I can explain is what happened on my 1977 MGB. After not driving it for several months, the car wouldn't start. The problem was from the ethanol in the fuel.

When your motor fuel is just petroleum gasoline, the fuel floats on the top to the water.

Condensate in Fuel Tanks:

* I mark this because almost everybody that is working on a car that has been in storage...and even a year can cause grief, has had to have their fuel tank cleaned. Unless the car is in a garage with constant temperature, every night the cool down brings in a little bit of moist air. When the days and night grow to 100's or 1000's, you can have a little rust that can be cleaned, or you may need a new tank.

Most radiator shops can do this job for you or assess it as "junk" with a new one required.

More:

Copper Nickel Fuel Line

If you have the original steel MGB fuel supply line from the tank to the carburetor, and your area has alcohol in the motor fuel, you are set up for a problem:

Before alcohol was mixed in the gasoline, the gasoline "floated" on top of the water, and most of the time, there were no problems.

Alcohol and water "mix" together, into a solution, and then the "alcohol-water solution" mixes with the gasoline, which rusts steel parts.

MGB "original equipment fuel lines" are made from steel. When I looked at my fuel lines, they were almost completely filled with rust.

You will find that your local auto supply will have 5/16 inch outside diameter, copper-nickel alloy fuel lines, which will solve this problem.

You will need to have your fuel tank cleaned at the radiator shop, and probably have the steel fuel line that goes down the bottom of the tank removed and replaced with the copper-nickel alloy tubing.

Then replace the fuel supply line, all the way to the carburetor(s) with the copper-nickel tubing.

If your car has the charcoal canister and fuel tank vent line from the tank to the engine compartment, that line will need to be replaced as well.

Roger N. Tanner, Professional Engineer (retired)
Oxnard, CA

Roger N. Tanner
Professional Engineer, Retired

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Re: Need help understanding something... #3
dipstick Kenny Snyder (RIP) La Center, WA, USA Sign in to contact 1941 Ford N-Series 1958 MG MGA 1500 Coupe "Rosie" 1970 MG MGB GT "Pat's GT" 1971 MG MGB "Gifted To Me" & more	Oct 24, 2014 05:46 PM Top Contributor Joined 15 years ago 7,564 Posts

Ethanol absorbs the condensed water that collects in the bottom of the fuel tank with normal gasoline. If you use ethanol all the time this is not an issue as the water is continually drawn out of the fuel tank. The first ethanol use will absorb mass quantities of water and cause the engine to run poorly. When Washington State first went to ethanol blended gasoline we changed out lots of plugged fuel filters because of the goop being drawn out of the bottom of the tank with the water (all tanks have goop). After a few tanks of ethanol the problem would stop.

Be safe out there.
Kenny

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Re: Need help understanding something... #4
Rick Fawthrop Richard Fawthrop Langley, WA, USA Sign in to contact 1960 Austin-Healey Bugeye Sprite 1974 MG MGB 1994 Mazda Miata	Oct 24, 2014 05:49 PM Top Contributor Joined 12 years ago 6,720 Posts

I would suspect contaminated fuel. If your tank hase a drain plug I would drain the fuel and check it for rust and comtamination.
If you do find water in the tank change the fuel filter and clean out the fuel bowls with spray carb cleaner.

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Re: Need help understanding something... #5
fast-MG.com Dave Headley Cortez, 4 corners, Colorado, USA Sign in to contact	Oct 24, 2014 06:10 PM Top Contributor Joined 15 years ago 9,605 Posts

The ethanol may have just leaned things out enough to get a lean misfire. confused smiley

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Re: Need help understanding something... #6
barry s Barry Stoll Alexandria, VA, USA Sign in to contact 1972 MG MGB GT 1974 MG MGB 1976 Triumph TR6 1980 MG MGB	Oct 24, 2014 06:15 PM Top Contributor Joined 14 years ago 7,461 Posts

There is another current thread concerning Diesel fuel as a 'stabilizer'. Read posts #42 on. This suggests that the amount of water that can collect in the tank under normal conditions is quite small and unlikely to cause performance problems. Water in the tank is usually a corrosion potential issue. I'm very skeptical that adding E-10 gas and driving normally could account for the "bucking" experienced. While I'm not a fan of ethanol enhanced gas, I've never experienced this type of problem. My E-10 issue is the short storage file. Ethanol free gas is not readily available in the US and never will be again. I use a stabilizer over the winter storage period. For very long storage, the fuel system should be drained.

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Re: Need help understanding something... #7
Gary G Toronto, ON, Canada Sign in to contact 1979 MG MGB MkIV	Oct 25, 2014 12:16 PM Joined 9 years ago 398 Posts

I agree to a point. I suspect the contaminated fuel was at the gas station. This happened to me once.

Either water got into the underground tanks, the station operator wanted to increase his profits so they mixed in a cheaper additive (more ethanol perhaps?), or it was an independent station. Some suppliers pump out the crap at the bottom of their huge storage tanks and sell it to independent retailers. After all, they are not a name brand, what's one little independent guy gonna do?

In reply to # 2833106 by Rick Fawthrop I would suspect contaminated fuel. If your tank hase a drain plug I would drain the fuel and check it for rust and comtamination.
If you do find water in the tank change the fuel filter and clean out the fuel bowls with spray carb cleaner.

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Re: Need help understanding something... #8
pinkyponk Adrian Page Berwick, NS, Canada Sign in to contact 1958 MG MGA 1500 1961 Austin-Healey Bugeye Sprite 1971 MG MGB GT 1973 MG MGB MkIII	Oct 25, 2014 01:58 PM Top Contributor Joined 13 years ago 14,759 Posts

You probably purchased gasoline with some water in it. I'm told that once gas with ethyl alcohol has absorbed as much water as it can, liquid water will appear at the bottom of the tank. The fuel pickup is at the bottom of the tank so it will suck up the liquid water and try to get the engine to burn it. Add a little methyl hydrate to make sure you have cleared out any water in the tank. If it's something else causing the bucking the alcohol won't cause any harm.

Adrian

Home built Eaton M62 Supercharger with 8psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, custom ground high ratio "stock" rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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Re: Need help understanding something... #9
ironpony Dan Howland Park Rapids, MN, USA Sign in to contact 1977 MG MGB "The "G"	Oct 25, 2014 02:47 PM Joined 13 years ago 1,350 Posts

Well, Barry, availability of "real gas " depends on where you live. Here in up north Minnesota it is common for our gas stations to have good gas for use in off road engines (old boat motors, farm tractors, ATV''s, snow mobiles and collector cars). drinking smiley

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