Vapour Lock Problems

jules greenway · June 29th, 2009

hi Guys
Pleased to report that the 8-90 is finally on the road (pic attached)after sailing thru our DMV test but having to be trailered to into our County Town so that another DMV department could confirm that the Frame No was what we said it was! and accepting the BHA research confirming the build date as 1931!
We have been experiencing problems with fuel Vapour Lock in our Jaguar XK120 during hot weather-I understand that modern Unleaded fuel is very prone to this as it easily vapourises at quite a low temperature. It always happens if you are stationary in backed up traffic for more than a few minutes-fuel supply ceases, engine dies and you have to wait 10/15 minutes to cool down.
I wonder if any of you have had similar problems in any of the Buicks? and if so any recommendations for curing them? I am going to try insulating the fuel pipes on the XK but think maybe the 90 may have more of a problem with the exhaust being on the same side as the fuel pump and carb-maybe wrap the exhaust as well?
Any thoughts gratefully received
best regards
Jules

eric_b_1937 · June 30th, 2009

I was recently discussing fuel problems on the General Forum. Take a look.

Calling Fuels Experts

jules greenway · July 1st, 2009

Eric thanks-seems to confirm what I was thinking
cheers
Jules

Rooster · July 3rd, 2009

I had big problems with my 1929 in the early days with vapour locking.
I tried all sorts of remedies but the only successful one was to fit an electric fuel pump. Mount it close to the fuel tank in the existing line. When you feel the engine dying simply turn on the switch to clear the vapour then turn off and revert back to mechanical pump ( until it happens again )

austincar6 · July 4th, 2009

The Elelctric Fuel pump is fine, Make sour you have one that will be less that 4 PSI. This is so you don’t over power the jets. Please do not put on a fuel regulator. They don’t hold up well with the todays gas.

jules greenway · July 5th, 2009

Ken/Rooster
Many thanks-do you fit the electic pump in the existing line? ie does the mechanical pump suck thru the electric one?
Mind you the XK120 already has an electric pump and still suffers from this problem?
cheers
Jules

Rooster · July 6th, 2009

Yes, cut the existing line and fit pump. It will push fuel through the mechanical pump no problems. The electric pump may have a little metal filter on it. I like to fit an extra plastic aftermarket one between pump and tank. The electric pump is also great for priming the carb for starting after sitting for long periods.

jules greenway · July 6th, 2009

thanks guys-will let you know how we get on
Jules