I'm at the end of a (very) long restoration, and my first test drive a few weeks ago lasted for about a minute before the engine stalled - it would start again after being left for about a minute, but would then stall again as before. I subsequently discoverd that fuel is leaking from where the fuel pipe connects to the top of the carb (the float chamber is very full...). It's a stock 28 pict 1, by the way.

The carb had been on a shelf in my garage for the last few years during the restoration. but looked clean (and worked fine before I took it off the engine). I have subsequently re-built the carb and am frustrated that that has made no difference at all.

I have checked the length of the fuel pump pushrod and that's OK (I have also tried two different fuel pumps and it's the same with both of them - in addition, one of the fuel pumps was on the engine originally when it worked well with this carb); I have checked the float and that doesn't have a leak; the cut off valve appears to work (in as far as when you press the t*t you can't blow through it!). I have fresh fuel in the tank, btw. Any ideas chaps? I really want to try and get on the road at last after all these years so would be really grateful for any help!!!

It could be the flote level hight that needs adjusting.


Andy W

Or a leaky float itself, it doesn't need much of a leak to not raise enough.
Maybe double check.

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Change the needle valve, this is almost certainly the problem. They can get 'sticky'.

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Thanks Guys, I'll certainly double check those tomorrow when I get back into the garage. I did replace the needle valve with the new one in the rebuild kit, and that has made no difference (but that said, I understand they are of "dubious" quality nowadays...). What I don't understand is the stalling - would a faulty needle valve induce that? Surely this would be a fault lower down in the carb that is inducing something along the lines of fuel starvation, wouldn't it?

It may be flooding the motor when going to idle



Andy W

Ps Were are you ???????

Thanks Andy - I'm in Essex.

When I test drove the car it went well (up to 3rd gear and revving nicely) and then it lost power and died. I will take the carb apart again tomorrow and check the needle valve and float, and then give it another go!

Ta

Tom

OK, just checked the float and there doesn't seem to be a leak in it. The needle valve seems OK too (blow in through the inlet tube and then press the valve and it shuts off).

When taking the top of the carb off, the chamber was full, so the float has raised up and closed the needle valve, causing the fuel to back-up and leak out of the inlet.

Any ideas anyone? I'm at my wits end! Could it be a setting on the carb that doesn't allow enough
fuel to flow through to the engine??? I have checked the main jet, the emulsion tube and the accelerator pump and they all seem to work OK...

What you need is the float adjusting on the metal strip so it shuts the needle valve be for the float chamber is full.When this happens then the falve is shut not letting any more petrol in to the flotat chamber and the petrol pump gose in to over run so dose not put presuer on to the needle valve.




Andy W

I would advise still changing the needle valve. Sometimes they shut off ok but can be a bit sticky when closing (intermittently)- I've seen this a few times. For a few ££, it is worth changing whilst you have the top off the carb.

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Andy, you mention that the fuel pump has an override - for sure when the needle shuts off the fuel is backing out over where the pipe connects to the carb and is flowing down the outside of the carb. Should it not be doing this?

Slightly embarrassing - it appears that the end of the fuel line was perished and therefore nothing to do with carb whatsoever...

We all live and learn. :thumbup:



Andy W

I think I would re new all the fuel pipes if they are all old!

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Without a doubt! I think I last replaced them 9 years ago and whilst I'd have assumed they would have lasted a bit longer than that, now that one bit has gone, I can't trust the rest of it now!