Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Fuel Vaporisation

Had my 1980 +8 for 40 years, runs a John Eales 3.9 on carbs and I have done a load of miles in the car 250k/400k kms, run it on E5 98/99 octane. Travelled widely across most of Europe. Mostly trouble free motoring.
Just back from another trip into Europe. Struggled badly today with fuel vaporisation (and had a few similar issues last year in Sicily on E5). Air temp 33-40C-90F./106F. The issue is when I try to restart the hot car after a very short stop it will not fire. It needs a couple of mins to cool down and will then start. Today on Eurostar, stopped then asked to move forward. Will not fire. Anyone else finding ethanol based fuel a vaporisation problem?

Yes. Not in my Morgan but in my Rover-v8-engined MGB. Partially cured it by re-routing the fuel lines away from the rocker covers and by wrapping the fuel lines to the two SU carbs in reflective insulating material. You can get it online and it's self-adhesive. I suspect even the high octane E5 fuel is more volatile these days. If the vapourisation is in the carbs it may be possible to help matters with some kind of heat shielding around the float chambers. Of course modern fuel injected cars have a fuel return system which keeps the fuel circulating back to the tank so it has no time (in theory) to vaporise.

I used to get vapourisation in my Bv8 years ago, but only at the MoT when it was standing for a while at tickover. I laid a mat of woven insulation under the carbs which helped a bit, but I also looked at fitting some sort of fuel return with a higher pressure pump. It could be done, but would need some trial and error I suspect.

On my Morgan, where both fuel lines run close to the exhaust, I've sleeved them with insulating weave, and up to now have had no trouble.

Hest sink is the issue, so even a fan ( blowing at the carbs) which runs at tickover and immediately after switching off might help. There are options if you look at fans used in IT systems, or competition cars.