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MG MGB Technical - Won't start, fuel pump?

Hello All,

'75 GT wouldn't start today. fuel pump seems to be ticking louder than usual and the ticking doesn't stop......pump not priming? Fuel isn't reaching the fuel filter, just before carbs. I put a gallon of petrol in the tank in case it was lower than I thought. Is the fuel pump knackered? Its an electronic pump fitted about 3 years ago so tapping it with a hammer won't do much good!
Would appreciate your input.
Thanks, Clark.
Clark

Clark - You don't say which make of electronic fuel pump. Some of hte aftermarket fuel pumps are fitted with a bypass valve to extablish the correct outlet pressure and these pumps do run all the time - The little square Facet pumps are famous for this typeof operation. If your electronic pump happens to be one of the Auto Pulse pumps from New Zealand, check the plastic around the inlet and outlet fittings, as these pumps are all plastic and will develop cracks around the inlet/outlet fittings over time, which will allow the pump to suck air on the inlet side. Check the fuel line from the tank to the pump for any holes, cracked hoses or loose fittings (particularly the one at the side of the tank. See my article regarding fuel delivery troubleshooting guide at: http://www.custompistols.com/cars/dave/ddFuelDeliveryTroubleshooting.htm
for more on troubleshooting the problem. If you still have problem, e-mail me directly and I'll try to help you isonlate your problem. Good luck - Dave
David DuBois

Check the fuel lines going to the pump, making sure they are not cracked allowing air into the lines.
Kimberly

Thanks Dave, Kimberly,

I'm pretty sure the pump doesn't tick audibly all the time, and the fuel tubing was renewed recently. I'll have a proper look underneath at the weekend.

Clark.
Clark

Sounds like a pump problem, maybe stuck non-return valves. However I have had a pointless (electronic) pump on mine, and that developed a problem whereby it ticked but was short-stroking and wouldn't pump enough to run the engine, till it decided to start pumping properly again. It's now chucked into the depths of a drawer in the garage and I have a proper pump with points on the car.
Paul Hunt 2

Clark,

I had a 'little square Facet pump' on my GT. It ticked really, really loudly when there was no fuel in it or when it wasn't pumping, much quieter (more of a throb) when it was pumping.

Anyway, it packed up on the start line at Wiscombe! Before that on many occasions (particularly if the fuel level was low or I hadn't started the engine for a while) it used to have some trouble priming itself - ticked loudly, wouldn't stop ticking loudly, I had to resort to filling the tank really full and/or rocking the back of the car to get some fuel into the pick-up line. Check the inlet side for a tight connection. The square pump has to have the inlet higher than the outlet, or vice versa, I can't remember which, so to fit it in a GT in the place of the old pump the inlet was towards the front of the car and the outlet towards the back. The inlet had to take a tortuous path to achieve this. That exacerbates the priming problem, the inlet going 'over the top' so not getting any fuel under gravity unless the tank is really full. Tried raising the rear of the car? Obviously being careful due to the risk of a fuel leak, disconnect the outlet pipe from the pump (not as easy if it sounds if you do have the little square pump) and feel it with a finger for output. You could try disconnecting the inlet side and siphoning some fuel into the pipe to help the priming, but then you have to be really careful not to get fuel everywhere - including in your eyes!

When it failed, two years ago, lots of people told me that there was a 'bad' batch of pumps in circulation.

Before that I had a 'pointless' pump that looked like an SU pump but was 'electronic'. It performed badly with the added disadvantage over the SU pump that you couldn't thump it.

Hope this helps, but of course will be useless if you haven't got the little square pump!

I'm now using a 'red top' which is the motorsport standard and hence should be pretty reliable.

Neil
Neil Lock

Paul,
It is a "pointless" pump about 3 years old, but as you say it may have failed.

Neil,
You describe the symptoms exactly! Will rock the car, try to prime and have a good look underneath at the weekend, before splashing out on a new pump.

Thanks, both.
Clark

This thread was discussed between 26/11/2006 and 28/11/2006

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