Advice needed on fuel pressure

[Jurjenz]

Hi!
I have some difficulties to start the engine when it's cold. After a few cranks, (+15 seconds) the engine hesitates, and finally starts. When it finally runs, it runs very smoothly, and no problems with accelaration. It seems like it has something to do with the fuel pump? As you can see in the video, there is hardly any fuel coming out into the filter. Two years ago I put on a new fuel pump. Any ideas how to solve this? Might be an 'air lock'?

 

[AdamWilkes]

If it runs nicely after it has run for a short while, then the semi-empty filter may be a red herring.

Slow initial starting was a problem with mine - the fuel managed to disappear out of the carburettor after it had sat for a while - I think it was evaporating from the float chamber. The float chamber has (and needs) a small hole at the top to allow changes in fuel level in the float chamber, but it also means that some fuel can evaporate.

I'm not sure if this was a problem from new, but I 'fixed' mine by using a low-pressure electric fuel pump in the fuel hose to prime everything before trying to start the engine up. The electric pump could be on a push-button so you can run it only for a short time, which is all it will need. This then fills the carburettor and the car will start immediately after that. Probably best not to run an electric pump all the time, as often they produce too much pressure, which will overwhelm the float valve and cause flooding, leaking and fire

 

[angel]

Don't be confused by modern fuel injection cars, where a fuel pressure 10 psi lower than normal may cause the engine not to start at all. Any carburetted engine is totally insensitive of fuel pump delivery pressure, as long as the float bowl can be filled and pressure is not that high to lift the float valve off its seat.
The fuel filter appearing half full, full or almost empty has nothing to do with actual fuel delivery to the carburettor, it's almost a random situation. Poor cold starting has usually more to do with ignition than fuelling: when points are worn, condenser of poor quality, distributor cap/leads damp, and on top of this current draw from the starter is high, therefore voltage reaching to ignition coil is low (~9-10V), spark will be weak and may not be hot enough to fire the engine.
What I have done to ease load on the battery during cold starting, especially when the R4 has been stood unused for 2-3 weeks, is to install a rubber priming bulb found at marine supplies stores, in order to pre-fill the carburettor and not have it done by the starter motor - just like AdamWilkes' solution but a bit more crude :-)

 

[AdamWilkes]

"install a rubber priming bulb found at marine supplies stores, in order to pre-fill the carburettor and not have it done by the starter motor - just like AdamWilkes' solution but a bit more crude :-) "

Funny that, I have done just fitted a priming bulb to my Reliant Scimitar GTE rolling restoration to prime the carb after being stood Also as available for many diesel cars (eg Peugeot 205, 305) for low cost - ideal for you, but may need a stretch if bulbs have 8mm diameter hose ends (I think your hoses will be 6mm inside ?)