Fuel pouring from carb overflow

J

Jiminwatford

Member
Starting today fuel is pouring from the nearside carb overflow

I haven't had time to look into it yet but i thought i might ask you helpful folk for what might be causing it for when i get home
 
Last edited:
When this happened to my car, it turned out to be the floats in the carbs. They were old, and porous, and slightly cracked, and had sunk. In the end I had the carbs off, sent them away to a 'specialist' for rebuilding (but that's another story entirely, which I've detailed elsewhere on here!) and they were fitted with new floats, along with all the other seals etc. Sorted the overflow problem.
Don't drive it until you fix it, for fear of fire. I'm sure you know that already, I don't mean to patronise. I hope you get the problem fixed properly.
 
I have just spoken to Burlen and ordered a float rebuild kit

Apparently the original floats can't withstand ethanol, absorb it and become heavy and sink
 
Jiminwatford said:
I have just spoken to Burlen and ordered a float rebuild kit

Apparently the original floats can't withstand ethanol, absorb it and become heavy and sink
Click to expand...

Hi Jim,

Well before the use of ethanol, floats would take on fuel and sink. The tell-tale sign being fuel pouring from the overflow lines.

Ron.
 
Yeh I thought that and when I asked the guy at Burlen why they sink I thought he might say fuel gets inside. But he mentioned the ethanol

Do you know how or why they fill with fuel? Is it a crack in a join that just appears over time?
 
Jiminwatford said:
Yeh I thought that and when I asked the guy at Burlen why they sink I thought he might say fuel gets inside. But he mentioned the ethanol

Do you know how or why they fill with fuel? Is it a crack in a join that just appears over time?
Click to expand...

It is a failure in the seam. I have had one fill and sink after only one week, others have lasted well over 10 years.

Ron.
 
I am no expert but most plastics are to some degree porous to hydocarbons . I know that plastic petrol tanks are usually made from heavy duty polyethylene , but are moulded with one or more barrier layers bonded inside to reduce this loss, diesel is less of a problem. As the emission regulations have got tighter & tighter more & more attention has had to be made to the number of joints in hoses etc to reduce this " leakage" . The majority of vent pipes are now inside tanks rather than around the outside. I believe the ethanol can break down the bond inside the plastic structure so allow leakage.
 
In my case it was the needle valve. Looked in good nick. Seemed to work fine, indeed, it did, most of the time. Changed it, been fine since, no fuel in float.
 
This happened to me 2-3 years ago, right after a water=pump replacement. Not connected, but puzzled for days as both floats looked OK and cut-off valves working OK.
Again, thanks to Burlen, discovered that 'old' floats, brown-coloured plastic, were the problem, even though they looked OK. New white coloured, floats supplied by Burlen and no problems since.
Floats were so cheap that i would recommend replacing all old brown floats as a maintenance issue. There might have been warning signs I did not notice, but if I ever bought another P6 I would be replacing the floats asap.
 
You must log in or register to reply here.
Back
Top