Fuel Starvation

[Andrew_Fox]

Morning All,

It's been some time since I have got along to a FDMC event following an unsuccessful attempt to sell my MG, So I decided to use the MG today for work, bad idea !!!

Lots, of backfiring, misfiring, hesitation and even the engine dying under load (even going up small inclines). Good old AA man turned up, did nothing but look at the fuel filter, and then follow me home.

My thinking is to start by replacing the fuel pump, the AA man suggested I don't replace it with a MG part but a Facet Fuel Pump and replace the fuel filer for a metal one.

Is this a good idea ?

Suggestions gratefully received.

Andrew

[Paul Prescott]

Are you sure it wasn't just old unleaded causing the problem, or are you saying the fuel filter was dry or empty?

[Andrew_Fox]

Good thought Paul.

I did a quick test that maybe the AA man should have done by taking the fuel line off the carbs and put it in a container, turned on the ignition, the pump clicked away like billy-o and it delivered at least a pint in a minute. However, this morning I seam to remember thinking when I started it, Hum why did I not hear the usual click over of the fuel pump, but as the car started i thought nothing more about it.

I have had the car sitting in this barmy sunshine all day, and just driven around the block fine. Humph.... Joys of classic motoring.

Now thinking of your point on fuel, How long is too long for Unleaded to sit in a tank ? I've not used the car and it's been under covers since the MOT in Oct, so the dregs have been in the tank for say 4 or 5 months probably. I did fill up today before the misfiring started from under 1/4 of a tank to now 3/4.

[Rootes]

you using the old SU round shape pump?

[dw]

Andrew

"Primrose" my MGB GT has a slightly 'warmed' engine [1860 overbore, decent cam, balanced crank, etc] and so I run 99 octane fuel from Tesco. In four years I've never found any problems with it after it's been standing for two or three months in the winter. As regards the pump I replaced mine last year as the old SU had a weaping joint that was virtually impossible to seal. The Welsh MG Centre do an electronic [contactless] plastic pump for £35 which performs very well - recommended to me by a couple of the Luffield Challenge MGB boys at one of our sprints. The other thing is to make sure that the glass in-line filter is always at least 50% full or the carbs could pull the occassional gulp of air with the resultant hesitancy, momentary loss of power, etc.

"Primrose" is currently off the road awaiting the insurance go-ahead for a new rear wing, bumper, lights, etc due to a right foot that slipped off the middle pedal, got jammed and stuck throttle down whilst reversing in the drive - flew into garage and crashed into shelving unit and the workmate. Going to cost best part of 2 1/2 to 3 grand!

David Walton

[TeamToad]

Hi Andrew
Pump could well be giving trouble - the old SU models don't like to be left too long unused especially if damp gets in. They sometimes work intermittently afterwards. But a sharp tap with a spanner will often trigger them enough to get you home if it fails again.
It will only click when delivering fuel, so if the float chambers are already full, you won't hear it when you switch on. But it should click as soon as the engine starts running, especially on choke.
I have one of the plastic bodied electronic pumps on the V8 which was on it when I bought it and has, so far, given no trouble.
I'd definitely go for an electronic replacement, but have had bad reports and experience of the small square Facet models. One of my parts suppliers won't stock them any more due to returns, and the last one I fitted burnt out after only 50 miles (annoyingly, it was only a precautionary replacement - the old one still worked).
I think the problem is quality control - the old points pumps and electronics used to go on for years, but many of the recent ones fail very quickly. Good idea to bench test a new one before fitting it. Some MGB owners even fit two now which they can switch between in the event of failure.
I should exercise the pump on the new petrol and see if theproblem goes away. And perhaps buy a new one to carry in the boot - at least the RAC man can fit it for you then!
Cheers
Martyn

[Redmist]

If all else fails , I've got a competition Redtop plus spare ' new ' filter in perfect condition . It was fueling my 2lt zetec on webers before I changed to TB's ---- £20 will suffice