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TR6 Fuel pump problem

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pdplot

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While I was at friend's house checking my rear-end clunking problem, a guy pulled up in a pickup truck. He was a fellow TR6 owner and had a problem that he blamed on his front carburetor. He claimed it was flooding his cranckase with gasoline - 5 qts. to be exact - twice. My diagnosis was different. On level ground, if the carb was higher that the fuel level in the tank, there was no way for it to flood with a mechanical fuel pump while the engine was shut off. The low point on a TR6 is the fuel pump. (Don't ask me how I know). My guess was that the fuel pump diaphragm was defective allowing fuel to go directly into the crankcase. He told us the pump was a new one. We told him that means nothing these days and that he should check out the pump - or install an electric pump and be done with it. He also said that the flooding stopped when the fuel in the tank got below a certain level.

Was my diagnosis correct? Agree? Disagree?
 
Well...I'm no expert but I will weigh in. Yes, the diaphragm in the fuel pump is the first suspect. I do believe though that if there is a sticking needle valve in the carb, there is enough head pressure in the tank line to make it to the carbs if the car has sat for a while (especially with a full tank of gas ). Many of us have installed inline shut of valves in the fuel line before the pump. I turn mine off when I'm done driving for the day ....

Cheers
Tush
 
Ok - I was half-wrong (as usual). I measured the height of the fuel tank and the carbs. The top of my fuel tank would appear to be about 32" above the ground - the carbs at about 22". Ergo, a full or almost full tank of gas could indeed flood the engine with a stuck needle on level ground. I would try the old trick of hitting the float bowl with a wooden screwdriver handle. I stand corrected. Whew. A close call.
 
The best bet is to put a fuel shut off valve and if the car is parked overnight with a nearly full tank.. close the valve.
 
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