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MG Midget and Sprite Technical - no fuel after sitting for few weeks

Hey folks, hope everyone is well and enjoying their spridgets.

I don't have a great deal to report as I have been ploughing on with trying to get all the body filler etc done.

Anyway, I decided to run the car today for a bit of light relief and take it for a first gear spin round the yard. Here is the daft question... After 3 weeks sat, should I be expecting there still to be fuel in the fuel line/carb?? Everything was totally dry, carb and fuel filter near tank, therefore it took ages cranking to get fuel up to the carb and for the engine to fire.

Or is there a smart and easy way to prime the fuel system?

1500 with mechanical pump BTW.

Cheers,
Malcolm
M Le Chevalier

I had a 1500 a few years ago and it was exactly the same. Leave it for a while and it took quite a long time to fire having to pull fuel from the tank and get it to the float bowls. The older the pump the longer it takes as well.

Previous midgets of course have electric pumps so don't suffer in the same way because they pump as soon as the key is turned.

Rob
Rob aka MG Moneypit

Check all the rubber connections from pump to carbs and the gasket on the front float chamber in particular. This chamber really only fills after the rear one so if its allowing fuel to evaporate and the rear is the same it causes quite a delay when the car has been left standing. The warm weather lately has caused mine to evaporate more than usual so like yours is a bit slow on priming after a few days standing. I have a new mechanical pump that is about 12 months old.
Dave Squire

Sounds like it could be a weak diaphragm in the pump or some sludge build up asome where

Prop

Prop and the Blackhole Midget

Yeah
I have the same problem with our elan
I've replaced all the carby gaskets and hoses but after parking the car you can smell fuel slightly in the shed
Carbs are bone dry, I've even tried clamping the vent hoses but can still smell it specially on hot days
After 3-4 weeks it takes a fair bit of cranking to get it started It has a clear glass bowl on the fuel pump and pumps instantly when you crank it so somehow the fuel bows are draining It's got me a bit
I'm starting to wonder if it is syphoning fuel up through the jet tubes Next step is I'm going to take the dashpots and needles out and monitor the fuel level in the top of the jet tubes
We'll see what happens and report back
willy
William Revit

Modern petrol evaporates faster than the petrol that was around when the Spridget was produced. Spridgets have vented tanks. Moderns have sealed systems, with valves to cope with expansion and contraction of the tank.

So says the blurb from a number of sources on the internet.

Not specifically about the loss of fuel from the tank, here though is a link to a quite interesting pdf by BP about modern fuel used in Classic cars.
http://www.bp.com/content/dam/bp-country/en_au/media/fuel-news/modern-petrol-vintage-engines.pdf

Or --- http://tinyurl.com/keksuqw --- if the above link won't work for you.

PS. My Midget 1275 does the same thing. Fuel pump ticks like a mad thing after car left in the sun for a day.

Lawrence Slater

An update to this...

On Sunday I went back after couple of hours after running the car. The carb and fuel filter near the tank were still both full.

When I looked last night (24 hours later), there appears to be no fuel in the system again. The filter near the tank is empty and carb has minimal fuel in.

I guess it is just evaporating from the carb and draining back from the fuel line into the tank(?). I have ordered a couple of in-line fuel check valves, I will probably fit one just before the pump and see if it changes the situation (although I thought the pump had such a valve in it anyway?).

Pump is new and seems to have no problem pumping once running, I just don't like the idea of having to spin it over for so long every time I want to go anywhere! (Not that I am going far at the moment! ha ha!)

Thanks for your thoughts and experiences everyone.
Malcolm
M Le Chevalier

Lawrence,

Thanks for posting the link - very interesting information. A few months ago I had a heck of a job to start my 1275 midget after leaving it for a few weeks. Never had a problem before. I thought it was down to "old" fuel but I am now convinced it was a "characteristic" of modern fuel.
Ray
Ray Rowsell

A final final update for those still reading and with the same problem.

I added a check (one-way) valve to the fuel line just before the pump last night and primed the system. When I went back today everything looked a lot better, i.e. still fuel where there should be fuel.

I didn't try to start it, but it looks to have cured the fuel line draining issue, although if I left if for three weeks again it would probably still struggle.

Cheers all,
Malcolm
M Le Chevalier

Malcolm
In that case it would mean that there is a fault with the one way valve in your fuel pump
willy
William Revit

Interesting thread. I've always assumed that the fuel evaporates through the float chamber overflows.

Though I have in the past dismantled a twin carb setup that had been lying forgotten on a shelf for weeks, and found the chambers half-full - despite the fact that the fuel line was chopped, and open to the air.
Nick and Cherry Scoop

I did think that Willy, am I just treating the symptom and not the disease?! Maybe. But the pump still works... hmmm! I will continue to monitor the situation! Maybe I am missing a small leak somewhere or something :-)

That said, I have bigger kippers to smoke at the moment. I tore down the front end last night chasing an oil leak from the front plate and/or timing cover. As there has been a lot of rain at the moment I can't push the car out into the open to do any bodywork sanding (I don't like sanding inside the garage due to dust!) so I am cracking on with mechanical bits and bobs.

Thanks for listening folks,
Malcolm
M Le Chevalier

This thread was discussed between 24/08/2014 and 29/08/2014

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