Classic cars forum & vehicle restoration.

[badhuis]

One disadvantage of a mechanical pump is that it only pumps when the engine turns.
My TR4 has a bad habit of letting petrol disappear in the floats, especially overnight. So for the first start of the day the engine has to be cranked quite a lot in order to fill the bowls. Then it starts quickly. If I prime the fuel (manually pumping) the engine also starts immediately, but this is not a practical solution - having to put up the bonnet each time.

When the engine is hot and it stops for a short while, vapour lock happens. When started again the first minutes or so the engine runs quite bad - sputtering etc. After that, it runs fine.

So I am thinking about fitting an electric pump alongside the mechanical in the engine compartment. This could be the solution for both problems. I would fit a press button to actuate the electric pump.

Should I fit an extra electric pump? And if so, in parallel or in series? If in series, before or after the mechanical pump?
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a car stops being fun when it becomes an investment

[MikeEdwards]

Doesn't it indicate that the fuel pump could do with a refurb? I've had issues in the past with having to crank the engine for a long time, because the engine in mine is know for cranking over slowly. The problem was that over time, the fuel would drain back out of the fuel line into the tank. A new fuel pump (still mechanical) sorted the issue, partly because it had more "suck" and partly because it did a better job of holding fuel in the pipe. I think.

In any case, wouldn't be easier to fit a non-return valve in the fuel line, so the pump will have some fuel in the line without having to pull it all from the tank?

[Phil - Nottingham]

Our pre-war Rover P2 has always been prone to this but it gradually became worse particularly in long traffic queues even in winter presumably due in part to the winter fuel.

The carb and mechanical pump get really hot and I fitted a puller pump high up and away from the engine in tandem with the old mech pump and a thicker carb insulator block.

This made no difference!

I removed the perhaps worn mechanical pump and matters improved a lot. This year though it worsened. Perhaps the electric pump which should have adequate capacity was also wearing. Certainly, no air was being drawn in and filters and fuel lines were clear.

I have just fitted an SU hire pressure (pusher) pump under the rear seat but have left the engine mount one with an isolating switch so have extra assistance if needed. This set up is very much better but if left for more than 10 mins it still splutters for a few seconds on restart till the vapour clears.

I still believe its the petrol formulation
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Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2

[jp928]

With P2 and P3 models in Oz, they are very prone to vapour lock, due to temperature, and having a sucking pump - lowers vapour pressure in the line. We painted the base of the tank(exposed to road heat) silver to try to reduce its heat take up. If adding an extra electric pump, I would locate it as close to the tank as possible, and use a pusher model. Avoid the solid state units as they can be very noisy compared to an SU. You can get relays that run for a few seconds at switch on and then stop until they get another signal - might help. Try to get a late SU with diode/cap, and double points set.
We had an SU pump failure once at night, and my dad sat on the drivers mudguard , hanging on through the window, operating the pump with a small screwdriver to get home.
jp 26 Rover 9