carb overflow

F

fett

Member
Hi gents, I need your SU v8 expertise.

I have a pair of newly refurbished carbs (HIF 6) by andrew turner fitted and set up an ballenced. They have done about 300 miles so far.

I have noticed fuel is coming out of the overflow on the passenger side carb after a run. I had notcied the smell for a while but couldnt trace it, it seems that it may now be worse as after the last run of about 15 miles then some idling on the drive I switched off and came out after about 10 mins and it was dripping well and had disolved some of the asphelt from my drive!

I went in and took about 5 or 10 mins to gather some tools, came out and it was dripping still but perhaps not as much. I gave the carb a couple of light taps incase the float was sticking and then pulled the pipe off and it seemed to have stopped- not sure if it was beacuase of the taps or just petered out- presumably it can only drip what is in the float chamber?

Any ideas? , I am hoping they wont be problems with the internals as they are so new.

If it makes any differance it almost looked like bubbles of fuel at some points.

Thanks for any help you can offer
 
This problem will have one of two causes. First (and least welcome) if the needle valve and float in the dashpot/fuel reserve under the carb is sticking. Second is if you have a facet electric fuel pump, they are known to provide too high a fuel pressure and force fuel past the shut off. If the latter is the case you simply need to add a fuel pressure regulator set to around 5psi before the carbs.

Chris
 
chrisyork wrote,...
Second is if you have a facet electric fuel pump, they are known to provide too high a fuel pressure and force fuel past the shut off.
Click to expand...

I've never had that happen to me Chris, and I have both the mechanical and a Facet in series, although I don't run them together all the time, but when they do have never had an overflow.

The more likely cause Fett is the float in the float bowl. I had a new float fill with petrol, sink and then petrol poured from the overflow, and only after 4 days... :evil:

Ron.
 
Thanks guys, I do have a facet style pump with no regulator, is there a reason it would only cause this on the one carb when the pump is common to both?

I have to say I am not thrilled about the idea of the float leaking as these were not a cheap set of carbs and I didnt rebuild my old pair to avoid this very type of problem after install and set up, again at my expense.

I presume though if it were the float would I not have some running problems, and perhaps a leak when the engine is running?

Thanks again
 
Hello Fett,

I have also had a few drips after a run, more so when the weather is hot. I suspect it is just the fuel vapours condensing as nothing so far has come of it, and this is after 4 years. I'd be inclined just to keep an eye on it. You may well find that when the weather cools the fuel drips disappear.

If the float is taking on fuel, then it will eventualy pour from the overflow while the engine is running.

I sometimes switch on my Facet prior to starting the engine, to fill the bowls, and with no regulator fitted have never had fuel pour from the overflows.

Ron.
 
That sounds a much nicer option , I hope your right :p

I thought it was odd that it looked like bubbles with the fuel, it was hot and I have a stainless exhaust fitted so it gets very hot under there, I wonder if it was vapourising the fuel with engine off and no flow to cool it and therefore was forcing fuel/fuel vapour bubbles out of the overflow.

odd that it was only on the one carb though when they are fed by common line, although that carb is closer to the feed to the bonnet and water trap/filter.

I am going to try and use it more reguarly for work over the next couple of weeks so I hope I will get a pattern worked out!
 
chrisyork said:
This problem will have one of two causes. First (and least welcome) if the needle valve and float in the dashpot/fuel reserve under the carb is sticking. Second is if you have a facet electric fuel pump, they are known to provide too high a fuel pressure and force fuel past the shut off. If the latter is the case you simply need to add a fuel pressure regulator set to around 5psi before the carbs.

Chris
Click to expand...


can I ask where this shut off is and how it works ? thanks
 
Hi Fett.

This is the needle valve in the float chamber underneath the carburettors that we were talking about earlier, sorry, just my loose use of language!

I'm happy that Ron has never had the problem of facets pumping through. In the UK there are many different types of Facet theoretically avaiable. In practice most people seem to fit high pressure ones intended for racing and competition cars. Consequently this problem is quite common on UK cars.

Chris
 
chrisyork said:
I'm happy that Ron has never had the problem of facets pumping through. In the UK there are many different types of Facet theoretically avaiable. In practice most people seem to fit high pressure ones intended for racing and competition cars. Consequently this problem is quite common on UK cars.

Chris
Click to expand...

Good point Chris. I had one of the facets cube pumps fitted (the smallest 4psi one) and didn't like it. It was noisy and had a habbit of not priming if let run dry. I've since replaced it with a facet posi flow, which as the name would suggest is all about flow rates rather than pressure, after positive results on the white car.
Regards,
Dave
 
Are there any differences between the Range Rover(?) and p6 that should be taken into consideration too?

Rich.
 
Ahh , that shut off!

I have the bearmach "facet" style pump which I hate to say was the cheapest on LR direct but I am sure its the very bog standard one.

The old bendix one I took off which looked like a ball of rust when I got the car and was haning off on one mount, actually came up well on on the shot blaster at work and when I finally got it apart cleaned up well inside too :mrgreen:
 
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