fuel vaporisation
- Thread starter p6 john
- Start date
robin collis
Active Member
Could be vapourisation, but unusual in the cool weather we are now having. Has this just started happening?
usually vapourisation first occurs when you are stuck in traffic in hot weather. i.e. You would have been more likely to have experienced it last summer if you were using your car then,
Try Harvey's cure, which cured my 3500S of vapourisation. Blockage was in the narrow pipe going into the carburettor tower. I cleared it by gently drilling with something like a 5/32 drill, turned by hand with a tap wrench. Take some care as the inlet is steel which could corrode and i do not think there are any replacements available. Also it is likely to be corroded into the Ally carburettor tower.
Easy test is to check if the 3/8 hose from top of Rad to the Carb. tower is hot ( warm) when the engine is up to temp. That is, is there water circulating through the Tower.
If this cures the vapourisation you might consider giving your cooling system a good flush out with descaler I believe Chris York recommends dish-washer or washing machine cleaner.
Are you using the original mechanical fuel pump?
Alternatively, theri might be a restriction in the fuel supply and the engine stops when float chamber are empty and will restart hen enough fuel has got through to the carbs.
usually vapourisation first occurs when you are stuck in traffic in hot weather. i.e. You would have been more likely to have experienced it last summer if you were using your car then,
Try Harvey's cure, which cured my 3500S of vapourisation. Blockage was in the narrow pipe going into the carburettor tower. I cleared it by gently drilling with something like a 5/32 drill, turned by hand with a tap wrench. Take some care as the inlet is steel which could corrode and i do not think there are any replacements available. Also it is likely to be corroded into the Ally carburettor tower.
Easy test is to check if the 3/8 hose from top of Rad to the Carb. tower is hot ( warm) when the engine is up to temp. That is, is there water circulating through the Tower.
If this cures the vapourisation you might consider giving your cooling system a good flush out with descaler I believe Chris York recommends dish-washer or washing machine cleaner.
Are you using the original mechanical fuel pump?
Alternatively, theri might be a restriction in the fuel supply and the engine stops when float chamber are empty and will restart hen enough fuel has got through to the carbs.
i have only had the car a week the fuel pump is a electric one in the engine bay . the problem occurs after driving for 15 / 20 minutes then switch off for 5 or ten minutes start up again go a few hundred yards the it splutters and cuts out and it will start up and run for about 10 seconds then cut out even if i try reving the engine
I had a similar problem with a Triumph Spitfire some years ago with exactly the same symptoms.
At last, the problem was a rusty tank and small rust pieces blocked the pipe. A few minutes after the breakdown, I could start the car without any problems and drive a small distance. The next day, when I drove the car, it stoped within the same time or mileage (approx 7 Miles).
At last, the problem was a rusty tank and small rust pieces blocked the pipe. A few minutes after the breakdown, I could start the car without any problems and drive a small distance. The next day, when I drove the car, it stoped within the same time or mileage (approx 7 Miles).
Julian
Member
Coil! when a coil start failing one of the faults is as it warms up, it has a dry joint on the primary side that goes open open circuit. So worth checking the spark when it is failed state. I know this has happened to a older BMW and an older ford that i have repaired, both after about 20 minutes of running start misfiring and then cut out, wait for 10+ mins and starts straight back up again (and repeat and rinse as the saying goes)
You need to check that the pipe coming out of the tower is clear, all the way through to the inside of the tower, not just the hose.
Phil Robson
Well-Known Member
“Hazel” (series 1 V8) got to the point where it would splutter to a halt everywhere & in any weather.
Clearing the pipe as mentioned helped tremendously but a good carb service & then tuning the engine absolutely ‘per the book’ not only stopped the spluttering but transformed the car!
Clearing the pipe as mentioned helped tremendously but a good carb service & then tuning the engine absolutely ‘per the book’ not only stopped the spluttering but transformed the car!
classicalgreen
Active Member
can be combination .eg excess heat under bonnet which creates bubbles in ethanol fuels. after ensuring tower feed pipe is clear as per Harvey. we may have fuel supply issues or carb . I fitted a see through inline fuel filter ( the type you can take apart and clean and reuse) and found small black debris was getting to carb. cleaned carb bowls out as had debris. blew through fuel lines and ensure return line was clear. I also removed tank and cleaned .lined with epoxy tank liner ( no more corrosion) . so far no issues even in traffic . its more a case of doing changes until we find a solution. I only use premium fuel as far less vapour issues or none. I did notice after a run 15 mins or so with engine still running pop bonnet and saw bubbles being formed in fuel filter. (heat vapour ) so have also added a think aluminium shield to each exhaust header . wrapped fuel lines in heat proof shielding and though not a pretty sight I am happy to run car now regardless of weather.
robin collis
Active Member
My experience of vapourisation was that the engine did not cut out so much as run badly; coughing and spluttering, and could be kept going by revving, (for a time,) letting it cool down it would restart and run better for a few minutes, then symptoms would start again.
I find it difficult to imagine that it would be so bad in the cool weather we are having in UK at the moment.
You say you have electric fuel pump? With vapourisation, you would hear it running constantly, at full speed, as it tries to pump vapour. Can you hear this?
I find it difficult to imagine that it would be so bad in the cool weather we are having in UK at the moment.
You say you have electric fuel pump? With vapourisation, you would hear it running constantly, at full speed, as it tries to pump vapour. Can you hear this?