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TR2/3/3A More on Fuel Pumps.....

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K

karls59tr

Obi Wan
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A friend of mine with a TR3 says when he starts his car it has to crank about half a minute before it fires. My TR3 fires immediately but I have an electric fuel pump. I think there was a thread on hard starting and hot weather recently. My friends starting issues are not necessarily confined to hot weather starting. Is it possible to have a "weak" mechanical pump or do they either pump or not pump? Could it be an issue unrelated to the fuel pump? He usually keeps his ignition and electrical up to snuff. Also , could enough fuel in a float bowl actually evaporate to cause hard starting?
I told him to get an electric pump but it seems some 3 drivers prefer to keep the mechanical one.
Any thoughts?
 
Karl - just a thought. Does your friend have starting problems every single time he tries to start? or only if the car has been sitting a few days.

The original mechanical fuel pump has a primer lever; five or six hand pumps and it fills the carb bowls. And hopefully the fuel filter or lines aren't clogged.

Tom
 
If my car sits for more than just a few days I fill the float chambers with the manual lever on the pump. Otherwise it does require consideraly more cranking time
 
Great minds think alike - and at the exact same second!
 
I prefer the mechanical pumps myself. One issue could be a lot of heat from the exhaust evaporating the fuel in the bowls. But I have not had such a problem. A heat shield would be the remedy to the heat problem.
charley
 
Does his garage smell a bit like gasoline?

I know some think since we have vented fuel systems there will always be some smell but I generally think a garage that smells like gas has a car with a (possibly small) fuel leak.

A slow leak from the carbs may not leave much visible evidence but will stink and will necessitate extra cranking (or priming) after sitting for a few days.

An engine w/o carb leaks should readily fire up even after sitting for a long spell.

Obviously an electric pump side-steps this -- though the symptom of a leak there is that you may hear the pump run for a second or two when you switch on the key.
 
As others have alluded, my first thought is leaking float bowls. The rubber seals that the bowls mount on is a particular weakness in the SU H6 design. They rarely last me for as long as two years before they start leaking, and sometimes much sooner.

The engine should be able to start on the fuel stored in the float bowls. If the pump is not working, it won't run for long, but it should start and run for a few seconds. My TR3 fired right off yesterday after sitting in the driveway for two weeks, without even raising the hood.

Synchronizing the chokes is another operation that is sometimes overlooked. If one is too rich and the other too lean, it will be harder to start.

Also worthwhile trying a different set of plugs. With an engine that has been hard to start, the plugs can sometimes get 'glazed', which will make it hard to start even after the other issues have been resolved. Using too much choke can also cause this problem.
 
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