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MG MGB Technical - losing power on hills

1978 MGB. losing power on hills yet the car goes like hell on level surfaces? has a Webber carb if that helps. New fuel filter; do I really need a new fuel pump?
SAB Brown

"do I really need a new fuel pump?" Probably not. Check the output from the pump by disconnecting the fuel line a the pump and stick into a container marked at the 1 pint level. Turn the ignition on and time how long it takes to pump 1 pint - should be 2.4 pints per minute. If the pump is putting out that much, then the problem lies somewhere else. Cheers - Dave
DW DuBois

I presume "up hills" not down. Hence maybe a gravity issue. i.e., fuel.
Fuel levels in float chambers, muck in float chambers moving and blocking a jet, muck in tank blocking pick up filter.
With wide open throttle I suppose an air leak could dilute the mixture.
Can't see a pump struggling with hills!
Allan Reeling

There is every reason to suspect the pump if the engine struggles when you ask it to work harder i.e. with a wider throttle opening, so David's delivery test is the most obvious first step. The factory quotes 1 Imperial pint per minute as a minimum, but in practice it should be at least double that.

If however it runs as it should at full throttle on the flat, then it is unlikely to be fuel deliver.

There could be several reasons for a pump giving reduced delivery, such as the inlet one-way valve leaking back, low return pressure from the spring, blocked inlet filter, and so on. It could also be caused by a choked tank pickup filter, pinched pipe, delaminating hose and so on, so even with low delivery changing the pump may not cure it.
Paul Hunt

Wide Open Throttle is irrelevant, on it's own, in relation to mixture therefore fuel delivery. Engine speed and WOT however is. If the car accelerates strongly on the flat using high revs (well high for a B), then pumped fuel delivery is not likely to be a problem BUT
See if you can repeat the symptoms either parked or jacked nose up.
Failing that clean the fuel system, especially the tank.
Also check the isn't a problem at the electrical end of the pump which protrudes into the trunk. i.e., loose connections.
Also look underneath for possible fuel pipe fouling on suspension. (Tail down).
Allan Reeling

I bought a TC some years ago that ran very well on the flat but wouldn't climb hills. I checked the timing to find it retarded, set to correct timing and it flew up the hills (for a TC that is). Just a thought.
Don TF 4887 (and TC and MGB)
D J Walker

I agree with DJ...98% of fuel problems in MGs are electrical...
Bob Dougherty

This thread was discussed between 08/09/2015 and 10/09/2015

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