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MG Midget and Sprite Technical - I'm ready to pull my hair out...

Here's my story. I purchased a 72 1275 that had sat in storage for 16 yrs. Drained fuel tank, flushed lines,changed filter, changed all fluids, changed dist. cap, rotor, spark plugs, wires, oil, filter, installed carb kits (2), checked compression- front to back- 135-130-125-125, pistons and cylinders looked good, although it does smoke. Front three plugs are clean and the rear one is black. Had valve job done, installed another intake manifold as the one that was on it was cracked. It will start and run for a while and sounds good. Then it will die and I can't get it re-started. You can smell the gas and hear the electric fuel pump running. Plugs are then wet. I can stick my finger in either carb and it comes out wet. Certainly looks to me like way to much fuel. I bench set the carbs by directions I got from a fellow forum member who has worked on little british cars for 40 years. When I push the car back in the garage there was a wet spot (looks like gas and oil) underneath it where it had run out of the exhaust manifold. I greatly enjoy these little british cars as I have two others (76-79)which only have one carb and they didn't give me near the headache this one has. Any suggestions would really be appreciated. Thanks in advance.
GF Greg Smith

Hi, Greg -

Any car that has sat unused for that long will present all sorts of surprises.

Sounds to me as if the float valves aren't sealing properly, and are allowing the float chambers to overfill. Crud from the fuel tank can gum up the float valves, etc.

Best of luck!

-:G:-
Gryf Ketcherside

I think you're on the right track Gryf.

Greg- when you had the head done, did they also do the guides? with having oil on the exaust manifold, you could be sucking some oil down through the guides. That could be the smoking. Check the oil level too, that you don't have gas in it.
Tim Michnay

i was going to say the same as Gryf, it sounds like your float valves are stuck open so they over fill and the excess poors into the carbs, makes it hard to start because there isn't enough air in your air/fuel mixture. i recently had this happen, but just cleaning the float bowls and making sure the valve moved freely took care of mine. since yours has been sitting longer, i would probably just replace the valves. if you can hear the fuel pump and it doesn't stop pumping within a few seconds then you have a problem.
Chris Edwards

>>> if you can hear the fuel pump and it doesn't stop pumping within a few seconds then you have a problem. <<<

Bingo. The float chamber, to use a familiar analogy, works just like a toilet tank. As the chamber fills, it lifts the float, which shuts off the flow when the fuel reaches a specified height.

So if you've ever dealt with a toilet that won't shut off (and haven't we all...) you understand the process already. Make sure the floats are floating for starters, and then ensure that when they reach the top of their travel, they shut off the float valves positively.

Gunk in the float valves is most likely the culprit here. The needles are pretty small, so all it takes is a little bit of debris to keep them from shutting properly. I highly recommend fitting a fuel filter, preferably one of the clear ones so you can see at a glance if you're getting adequate fuel flow. In fact, I have two on my midget - one just upstream of the (mechanical) pump, and another right at the carb. Having said that, I've been into my fuel tank and I know it's clean. Yours, on the other hand, sat for a long time; and the contents may well be interesting.

Note too that if a fuel tank has been cleaned out at some point in its existence, the process may have destroyed the pickup screen inside. I know mine's like that. And if that's gone, then any crap in the tank can end up in your carbs.

Best of luck - By the way, what part of Illinois are you from? There's a pretty active club scene around Chicago, and you may be able to get some hands-on help.

-:G:-
Gryf Ketcherside

Amen to all the above - with one comment.

Get the Viton-tipped jobs from Moss. Seal great, and won't hang open on a piece 'o grit like the metal-tipped needles will. Also, make sure your vents are open (beneath that little tin sucker encircling the brass hose nipple on the float-chamber lid).

Joel
JM Young

This thread was discussed between 21/06/2010 and 26/06/2010

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