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MG Midget and Sprite Technical - midget fuel problem

hi. i went out in my midget (1500) today and drove it like i stole it 4 a few miles. while i was ranting the ass of it there was no problems at all. i stopped,went in the shop and when i restarted it for about 2 mins its ran lumpy as hell then it was fine again.i then drove it hard again and stopped,switched the engine off for 5 mins and again it ran lumpy for a min or 2. it feels like a fuel problem. now the car does not have a heat sheild on the carbs.im wondering if when i drive it hard the engine bay gets hot,when i switch the engine of the fuel pump stops working and im wondering if the heat is evaporating the fuel in the carb so it runs lumpy untill the pump fills the pipe back up. does this sound likly or is it something else?
roy judd

If the fuel evaporated, it would only be a few seconds to get going again not 2 mins? It might not be that obvious but check the carbs are still bolted tight against the inlet still. It sounds silly but my 1500 did that and the rear carb was a touch loose!

Steve
Steve Hipkiss

Yep, sounds like fuel vaporisation, The heat shields are there for a reason, I just bought a Stainless steel one off ebay, might fit it tomorrow but I am still working on the front end. have you seen the bumpers in Marlborough? the old fat type, I couldn't resist a bit on them.
N Sayle

nick you daft bugger,now im gona have to bid against you.lol marlborough is only 15mins from my house. ny brother lives there. i think i will get a heat shield and see if it helps.
roy judd

I will out bid you, I was about to buy new ones!! hahahaha!!!!
N Sayle

nick they are all yours,i like the bumperless look. all im after are the quarter bumpers for the back.
roy judd

Roy -

I'd also suspect that heat is your culprit. The harder you run, the hotter the exhaust manifold gets. And with it being located just under the carbs, that heat can cause issues.

So add that heat shield and let us know how it goes. I've run into heat problems with my 1500, which is fitted with the US-spec single Zenith-Stromberg carb setup. The best I could tell, the vaporisation was happening where the steel section of the fuel line ran just behind the head and over the transmission on its way to the carb. That's a pretty hot location, so I switched to a rubber hose for the entire pump-to-carb run, and routed it between the heater box and the battery. I got the idea from friend Lee Fox, who did essentially the same thing on his 1500, but routed his fuel hose behind the battery. The intent is to move the hose as far as possible from the heat source, and in the process, we replaced the metal line with rubber in an attempt to reduce heat soak.

Best,

-:G:-
Gryf Ketcherside

Roy,
I had a lot of problems with fuel vapouisation when I frst bought my 1500 back in 1981, I have done the same as Gryf, and also fitted one of Ashley Hintons heat sheilds, from Ebay. But the biggest facor in curing my problem was the route of the fuel pipe from the tank to the pump. it runs in the seat channel, under the floor on the drivers side and rises up into the gearbox opening and then crosses the gearbox as a metal pipe which is clamped to the gearbox with a metal clip and then onto the fuel pump. I rerouted the pipe to cross the gearbox at the back of the GB opening and cut the metal pipe and used a rubber pipe from there up to the fuel pump. This worked very well, curing almost all the vapourisation problems on its own.

HTH
Alan
A Pritchett

thanks everyone thats food for thought. iv got a heat shield ariveing tomorrow so 1st il fit that then see about maybe moving the fuel pipe if it carrys on. it seems daft to have a midget with cartloads of grunt that pops and farts when you drive it hard.
roy judd

This thread was discussed between 09/04/2010 and 12/04/2010

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