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MG Midget and Sprite Technical - Fuel tank problem

I should have known that I was tempting fate when I wrote a while ago about fitting an electric fuel pump to prime the mechanical pump on my Frog and that would also act as a backup in case of failure.

Out for a drive yesterday enjoying the sunshine and about a mile from home the car spluttered for a few seconds and then died. Checked the usual suspects and there was no fuel delivery when cranking (I didn't fit the electric pump after all) but I knew there was at least a quarter-tank of fuel. I cursed the pump soundly and then organised a tow home.

Blew out the fuel lines, no blockage; checked for air-leaks, none. I hooked up an electric pump that I'd bought to fit to my Elan+2 and, oh dear, still no fuel delivery.

Seemed that I'd become a victim of a failure of the fuel pickup pipe inside the tank. Proved this by jacking the rear and sure enough the pump delivered pressure - falling away to nothing as the car was levelled again.

This is a relatively new tank, bought about seven years ago when I started rebuilding the car and has only been in actual use for about three years. Not much chance of complaining to the vendor.

I'm wary of buying another tank which may have a similarly short life and am thinking of taking this to a local tank repairer to see if he can do anything with it.

Anyone any experience of doing this?

Dennis


D Stanfield

Is that a 1/4 tank of fuel as read by the fuel pointer of lies in the dash? If so, don't worry, just recalibrate your brain so that 1/4 left is empty. Easy to tell by filling it up as full as it will go from where you are now and seeing how much goes in.
Rob Armstrong

Remeber... the fuel pump MUST be below the fuel level thats in the tank

If the pump is above the fuel line, then the pump will NOT deliver fuel to the carbs

Also the SU and some electric pumps have to be angled downward at an angle... he exit pipe at its lowest postion

Prop

Prop and the Blackhole Midget

"Remeber... the fuel pump MUST be below the fuel level thats in the tank"


Prop, how on earth are you gonna do that when the tank is already hanging under the car?
If the pump that is positioned higher then the fuel level cant "suck" the fuel out of the tank its a rubbish pump.
Or do you mean the feedingpipe towards the pump?

Dennis, when my fuelgauge reads 1/4 then its practicly empty... so dont trust your gauge.

Could it be the air suply to the tank is blocked and therefore causing a vacuum?
The tank normaly breaths thrue the fillercap.
Make sure ther is enough fuel in the tank and undo the fillercap and test again.



Arie de Best

Thanks Arie,

When the car stopped the gauge was reading 1/4 full, I should have said in my initial post that the wife brought me a gallon of fuel. When I put that in the tank the gauge rose to a bit over a quarter. But there was still no fuel delivery when cranking or, when I got home, from the electric pump hook-up (by the way this was a "sucker" pump) and I only managed to get fuel through with the rear end of the car raised.

However, I started to drain the tank this morning (using the sucker pump and a hose - very handy when there is no drain plug) and guess what - I drained just under a gallon!

So, the gauge is way out but the tank pick-up is not lifting at least that last gallon of fuel. That I can live with and am off shortly to get another gallon to add to see if she will lift the petrol. Adjustment of the gauge can wait for another day or maybe, as Rob suggested, just recalibrate my brain.

Dennis

D Stanfield

Problem resolved, sort of....

With two gallons of fuel in the tank the pump delivers pressure. The gauge reads half full.

I will try to recalibrate the gauge this evening but still wonder if there is a problem with the lift pipe in the tank as it must be sucking air when there's only one gallon left.

And I know that I have previously driven the car with the gauge reading a fair bit less than quarter full.

So there is still an issue, but that's a problem for another day, meantime I have a four gallon tank and am going for a drive in the sun to enjoy.

Thanks for the suggestions and help.

Dennis
D Stanfield

Yes I think you've got it. There is a pick up pipe inside the tank - usually with a filter in the end. When the pick up pipe corrodes it draws air when juice falls below a certain point, so you think you're out of petrol when there's still a gallon or so in the tank. OK you could recalibrate the sender, but really you'd be better off replacing the holed pipe.
F Pollock

Agreed Fergus, but I think I'll add the tank repair to the list of winter jobs. A local radiator repair company that that re-cored my radiator also do fuel tanks and have advised that they can fix this.

But for the moment I'm just going to enjoy the rare chance for sunny open-top motoring.

Dennis
D Stanfield

i have this same problem, i can tell when i'm nearly out of fuel by the wild ticking noises from the pump, but apply the brakes a little bit to slosh the fuel to the front, or go around a left hand corner and its ok for a while.
I got about a gallon or so out of the tank after i experimented by letting the car stall due to no fuel, then draining the tank.

i keep a jerry can in the back now...
Andy Phillips (frankenfrog)

"Remeber... the fuel pump MUST be below the fuel level thats in the tank"

Arie,
Dont bother Prop with logical thinking... you will just clutter up his brain with more useless info.. LOL!
Steven Devine

Hi there.interesting reading.i've just bought a 1978 midget. Drove 225 miles home.never missed a beat.however from cold start it's a bit lumpy but fine after a few minutes.any thoughts ? Also took my wife out one Sunday,and going up an incline the car started to miss badly.took a turn downhill and lo and behold she came to life.after reading the thread I want to check the pickup pipe in the
Tank.is it easy to take out? New carbs fitted last Christmas,so wondering if that accounts for the rough starting from scratch.oh one last thing if you will indulge me.took the rubber bumpers off,but leaves a triangular void under the rear lights.anyone know what to use to look half decent? Thanks everyone
P LATHAN

This thread was discussed between 09/07/2013 and 18/07/2013

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