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MG MGA - Orange material in the gas line

1958 1500 coming our of winter hibernation. This car is stored undercover outside and is a five+ year restoration project. In season I run the engine every week or so for 15 minutes.

In it's first start of the season it ran very rough. After a few minutes the engine started to die as if it was fuel starved. Investigation turned up that there was no fuel exiting the pump.

When I removed the inlet pipe to the pump there was an orange plug the consistency of jelly blocking the way. I was able to easily removed the material, gas stated to flow, and the car ran OK... but not great.

I'm assuming this stuff was congealed gas material, which surprises me since I cleaned the tank 3 years ago and added Stabil to the tank in the fall before putting it away for the winter.

My plan is to drain the tank and add fresh gas, as well as making sure the gas line from the tank to the pump is clear.

Any other thoughts or suggestions would be appreciated.

Thanks.
Brian Denis

You already have the right answer, bad fuel. Modern motor fuel can decompose rather quickly in storage. Six months with a full tank may not be a problem. Any long term storage with half a tank or less of fuel may be a problem as the fuel evaporates. A a few years on one tank of fuel is most likely begging for this problem. Drain the tank completely, even rinse it out with another gallon of so of fresh fuel. Pull the tops off the float chambers and flush the crap out of there also. Check/clean the inlet screens in the float chamber covers and in the fuel pump.

Another thing to watch out for is decomposing rubber grommets where the float chamber attaches to the carburetor body. With 10% alcohol in most fuel these days (and some other noxious additives) those grommets tend to deteriorate in a couple of years. They might start to leak, or they might swell up inside to clog the fuel flow passage in the banjo bolt. Been there, and don't want it again. I keep some of those grommets on hand for a quick change whenever needed (which is always too often).
Barney Gaylord

I'm not sure if this is the whole story. It's well known that petrol degrades over months in non sealed storage and I've put this down to the higher fractions evaporating off first: in effect the octane rating decreases. This usually means the engine is more difficult to start. I used to run a car only in the summer in the 1970s with two star petrol (lowest octane here) and because of this storage problem I got used to using nearly all the fuel before putting it away for the winter and in the summer putting a gallon of four star in to get it going. The same thing happens with my lawn mowers which I usually can only get going with ether in the spring after the winter break. But I've never seen any petrol deposit similar to the one Brian describes. Is it possible that the tank has been treated with a sealant or there is some reaction with the Stabil (I don't know what this is) material put in.
I have had a glass bottle of petrol unused on my shelf for twenty years or more and there is no sign of any deposit.
I think Brian's problem maybe with the fuel being in contact with some other material. Mike
m.j. moore

From bitter experience on a previous car, Mike's comment might be a clue. Having replaced a fuel gauge sender unit on a petrol tank many moons ago, in ignorance I sealed the gasket with an orange coloured silicone sealer. Result, fuel blocked by an orange coloured jelly-like plug (just like Brian's?) which fortunately was able to blow out the main line and no other bits got anywhere. I haven't experienced petrol decomposing that way, even ancient cans of the stuff discovered in the garage after nany years, but all is possible I suppose.
Bruce
B Mayo

In my experience in the chemical industry, I have come across bacteria growing inside a hydrocarbon storage tank. While this is unlikely here, a simple test will show if it is organic or mineral in nature. Burn the deposit on a tray using a propane torch and see if there is any ash left.
Art Pearse

Brian,
Do you happen to know whether or not the fuel tank has ever had a sealer applied? I have heard of instances where some sealers can actually be desolved by fuel after a while, especially those with alcohol content.
I also have seen what Bruce suggests. My friends fuel line became plugged by silicone on the way to last year's GT. What a treat finding and fixing it...in the pouring rain!

Cheers,
Gerry
G T Foster

I am with Bruce regarding the orange jelly like substance. I had a Magnette a number of years ago that would stall from fuel starvation periodically. I don't know how many times I fussed around with the fuel pump trying to cure the problem, only to find a big glob of blue RTV lodged in the banjo fitting on at the top of the tank where the fuel line to the pump attached to the pickup tube. Some really dumb PO had gubbed nearly a whole tube of RTV around the fuel level sender flange to get it to stop leaking and of course, the excess cam off inside the tank and was floating around looking for some mischief to get into. I removed the tank and did a thorough cleaning and flushing and never had any more problems. I would suggest that Brian remove the tank do the same thing, rather than trying to flush it out with fresh fuel - a bit more work, but is more likely to cure the problem. Cheers - Dave
David DuBois

Thanks for all your posts... I learned something from each. I think I've identified the problem.

I drained the tank and filtered the gas, no foreign material to speak of. I blew out the fuel line from the pump though the pick-up in the tank, no obvious obstruction.

Then as I was looking at the side on the tank where the sending unit screws in, I noticed orange silicone sealant on the seal between the sending unit and the tank. RTV to be exact.. the one with the warning "not recommended for use on parts in contact with gasoline". No DPO here Dave, this was me! I don't know what bothers me more, that I didn't read / heed the warning, or that I could be that sloppy to allow that much excess material to be loose in the tank!

I've put fresh gas in and all seems OK. I have an MGB fuel filter between the pump and engine so I think the carbs s/b OK. I will be cleaning and resealing the sending unit. I will remove and flush the tank later in the restoration. I will also start draining the tank prior to putting it away for the winter.

Any other suggestions are most welcome.

Many thanks for your contributions!
Brian Denis

Brian,
Good that you found the problem. The rubberized cork gaskets are the proper way to seal the sending units. They work great. Use a little (fuel proof)gasket cement if you want.

Cheers,
Gerry
G T Foster

Brian, a very good fuel proof sealant is Hylomar Universal Blue.
I assume its available in the States and use a cork gasket not one of those synthetic rubber ones.
David
D C GRAHAME

This thread was discussed between 27/04/2009 and 29/04/2009

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