fuel pump flow rate

[LAMBRETTLAD]

Hi How much fuel should an SU fuel pump ,pump per minute,or the time per 1/2 litre ? Help much appreciated

cheers Alex

[mole42]

18 gallons per hour.

[LAMBRETTLAD]

Thanks so 1 gallon =4.54 litres so 18 * 4.54 /by 60 =litres per min =1.36/2 = 0.68 per half a minute Any corrections very welcome

[Goldstar]

0.681 to be precise Alex good luck measuring the 0.001

[mole42]

Unless they are American gallons…

[mole42]

The Stag fuel pump would empty a Lambretta fuel tank in nine and a half minutes......

[wilf]

Funny - I only measured mine yesterday, after fitting new filters. 300ml in 30 seconds, or 1 pint per minute. 7.5 gallons/hour. Newish SU pump.

[Goldstar]

80 litres or 140 pints per hour according to the ROM so 0.666666666667 in your 30 seconds Alex

[mole42]

Funny - I only measured mine yesterday, after fitting new filters. 300ml in 30 seconds, or 1 pint per minute. 7.5 gallons/hour. Newish SU pump.

That’s less than half the specified flow rate from SU (18gph) and from the Triumph ROM (140 pints = 17.5gph)

[wilf]

Hmm.

Going to have to investigate this. Pump sounds healthy, and isn't old.

[mole42]

It might be the installation - filters, muck in the tank pipe, dirty electrical connectors or something like that.

I replaced my filters with cleanable metal ones which do seem to flow better than the old type.

Richard

[wilf]

Just fitted clean fillters, more digging needed I think.

[wilf]

More digging reveals the pump is supplying more air than fuel, must have a leak on the intake side, despite checking everything/renewing all seals there.

[wilf]

Scary now.

I eliminated all possible air leaks on the suction side, fed the pump from a jug of clean fuel to eliminate the in-tank pickup as well, and still got air from the outlet.

I called Burlen this morning, and they told me that some internal seals/gaskets on pumps more than two years old have proven to fail due to the ethanol content of modern fuel, and one of the symptoms is sucking in and pumping air. So I have an overhaul kit on its way (which has ethanol-proof seals) and will report back once that is fitted.

The scary bit is that this means that many of us may have this problem in time........................

[mole42]

Well done for identifyng this issue. It could possibly go into the Technical section so that other people are aware....

Richard