Leaking SU Fuel Pump

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Napoleon Boot
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Leaking SU Fuel Pump

Post by Napoleon Boot »

Noticed a smell of petrol under the bonnet, so investigated and found a leak from the outlet union on the SU fuel pump:
Fuel pump 1.jpg
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Fuel pump 1.jpg
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2021:08:30 14:27:53
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At first I thought the leak might be a loose hose connection, so I refitted it and wiped everything dry, but when I turned the ignition back on, petrol could be seen rising up from the threads on the pump body:
fuel pump 2.jpg
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fuel pump 2.jpg
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2021:08:30 14:28:03
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As it's my only car, I'll get a new pump to fit and then refurbish the old one to keep as a spare. Is there any advantage to buying an electronic pump over a traditional points version? There's only £25 difference in cost from ESM, so just wondering if I'd notice the difference. Presumably the only difference is no need to reset the points gap when they wear, though I've read some things saying the electronic pumps are more prone to failure. I fitted an Accuspark electronic ignition kit and it made a huge improvement to the car's performance, so I'm not bothered about electronic upgrades being unoriginal.

Any advice greatly appreciated!

Seb



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Custard
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Re: Leaking SU Fuel Pump

Post by Custard »

You shouldn't see any difference in running as the pump should switch off as soon as the carb float chamber is full so that all stays the same.

I would probably do what you suggest get an electric one as long as the fittings are the same so that you can change back easily to your rebuilt one.

Though if the car is running ok the pump pressure must be ok so I would probably unscrew the fitting to see if it was just a washer that was required.

Its a while since I have had one apart I think its a fibre or copper washer. If fibre it could have perished.

If getting a new pump I would confirm if its E10 compatible.

Sean.

Just zoomed in on your photos. Hard to tell the angle of the car, but are you 100% sure it is the union leaking and not the gasket closest to it. That looks quite perished and depending on the angle a leak at the top could run over and round the threads.



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Napoleon Boot
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Re: Leaking SU Fuel Pump

Post by Napoleon Boot »

Cheers Sean,

Yep, the car has been running fine, so I think it's just a washer that's failed - after replacing the cylinder head I recently went for a three day road trip with lots of high speed running, which probably came as a bit of a shock to it after living life crawling in the slow lane!

I've been gradually upgrading parts of dubious provenance and the fuel pump is one of the few things untouched since I got the car. Will be good to have peace of mind that the pump is E10-proof, then I can rebuild the old one at my leisure.

All the best,
Seb



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Re: Leaking SU Fuel Pump

Post by Napoleon Boot »

Custard wrote:
2 weeks ago
Just zoomed in on your photos. Hard to tell the angle of the car, but are you 100% sure it is the union leaking and not the gasket closest to it. That looks quite perished and depending on the angle a leak at the top could run over and round the threads.
I think the photos a bit deceptive - in person, the fuel definitely looks like it's coming up from between the silver metal pump body and the rusty hex headed outlet port - it seems to be rising up the threads between them. It's leaking quite fast as I only turned the ignition on for a moment, and that was enough to cover the rest of the pump, which is why is looks like it's coming from the gaskets on the right. They do look pretty rotten though; a lot of the parts on the car were second or third hand when they were fitted which is why I'd rather fit a new SU pump and then rebuild this one thoroughly!


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Napoleon Boot
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Re: Leaking SU Fuel Pump

Post by Napoleon Boot »

Well, I bought a brand new SU fuel pump and fitted it today, very straightforward and I didn't even spill fuel everywhere! However after going for a quick test drive, I stopped to check it and noticed a weep of fuel. I wiped it up and drove a bit further, stopped again and by my highly scientific method of 'dabbing blue roll until I find the wet bit', found that the fuel is coming up from the outlet union, just like the old pump :banghead:

As I say, this is a brand new pump - the rubber outlet hose is on tight and the fuel isn't dripping from there, it's rising up the threads that screw into the pump body. Should I try screwing it into the body a bit tighter, or use some sealant, or send it back?

Apart from the leak, the new pump is quieter and doesn't seem to click as frantically as the old one, so a worthwhile upgrade.

Seb
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3.99 mm
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F-number:
f/1.8
ISO speed rating:
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Flash did not fire, auto mode
Camera-manufacturer:
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Camera-model:
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Custard
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Re: Leaking SU Fuel Pump

Post by Custard »

That seems a shame.

I would probably try a bit of PTFE tape so if it doesn't work it can be removed leaving no trace on the pump.

Sean.



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Napoleon Boot
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Re: Leaking SU Fuel Pump

Post by Napoleon Boot »

Thanks Sean, I was thinking pfte tape too, I'll give it go!

Seb


Learning to live with "Peggy", a 1971 Adderley Park Traveller

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