Petrol Supply To Carb

[Guest Mike G]

Guys

Having laid the car up for a few months during the Winter, my Exmo took a good number of cranks of the key before bursting into life. Thereafter it has started instantly. This happened the previous winter, but I thought I may have cured it with various tweaks. All the petrol plumbing is new, and nothing leaks. The pump is a mechanical one. The carburettor is a Weber, 28/32 I think, which has been reconditioned by one of the specialists, with a mechanical choke conversion which all works a treat.

 

Two thoughts come to mind:-

1) either the liquid gold evaporates, and it takes a while for the pump to shove more through to the carb, or

2) the stuff syphons back into the tank.

 

Anyone got a magic cure?

 

Regards

Mike G

[Guest MikeD318]

If it is syphoning back into the tank, what about adding a one way valve to the fuel line?

[Guest Mr Pid]

Its probably evaporating, I had a can of left over petrol in the garage (safety first!) and i went back to it after a few months and it had disapearred! This canister was supposed to be airtight aswell.

 

You could also fit a primer pump in line so that you can make sure the fuel is ready to feed into the carb.

 

Stu

[Big Jim]

It's doing both.

So you either do nowt, that's OK if your battery is up to it, and it's not a problem if you'll use the car now & again.

Or you could fit a none return valve. up to you!

[Guest Mike G]

Thanks Guys for the suggestions. Where do I get a primer pump and/or a one-way valve? Any ideas of costs?

 

Thanks

Mike G

[Guest Guy]

Did this problem ever get fixed?

 

The reason I ask is that my VW Golf is doing the same thing now I'm using the RH more often.

 

If I leave the Golf over night it starts fine next day, if I leave it for a few days it is hard to get started, if I leave it for a week it's a real bugger. It turns over fine.

 

It has got a see through filter in the petrol pipe that I noticed was full of air. Will a non return vlave help, are such things available?

[Guest Russler]

maybe it would be worth replacing your float valve in the carb, as the fuel will return if air can get in and so it could be the valve not sealing sufficiently

[Peter Bell]

Trouble with that is as soon as the fuel level in the carb drops with evaporation the valve opens anyway. I wonder if the problem lies in the cheap one way valves fitted in the cheap fuel pumps we use?

Peter.

[IanS]

I have used an old SU pump to prime the system on a previous car that had similar problems.

Put a T in the line to the mechanical pump and a T in the line from the pump to the carbs. and connect the SU pump (from a morris 1000 in a scrap yard) in parrallel.

 

The electric pump switches on with the ignition and primes the system, mechanical pump tends to give a higher pressure and holds the electric pump off in normal running. The mechanical pumps are a bit more reliable than the SU pumps which is why I used both.

 

Ian