# 1967 MGB loses power when hot **URL:** \ **Category:** Power/Fuel\ **Created:** [March 22, 2019, 3:17pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982 "2019-03-22T15:17:50Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![msnbiz1990\_149787](https://avatars.discourse-cdn.com/v4/letter/m/a88e57/32.png) [@msnbiz1990\_149787](https://community.cartalk.com/u/msnbiz1990_149787)\ **Post date:** [March 22, 2019, 3:17pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/1 "2019-03-22T15:17:50Z")
I have a 1967 MGB that runs great, until it gets warm or if it is particularly hot outside. It will then lose power for several minutes, then it will get better. I can “floor it” and it will only go a few miles per hour. What could be going on? ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [March 22, 2019, 3:27pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/2 "2019-03-22T15:27:41Z")
Could be fuel boiling, or it could be an overheated part of your ignition system. What kind of carb(s) do you have? It could be a weak fuel pump, too. Have you posted this on an MGB forum? ---
**Author:** ![shanonia](https://avatars.discourse-cdn.com/v4/letter/s/9de053/32.png) [@shanonia](https://community.cartalk.com/u/shanonia)\ **Post date:** [March 22, 2019, 5:08pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/3 "2019-03-22T17:08:43Z")
Someone knows better than I do, but my hunch is that today’s fuels are a lot more volatile than those of yore. ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [March 22, 2019, 8:49pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/4 "2019-03-22T20:49:03Z")
Good point, hopefully OP is only using ethanol free gas, if not? ---
**Author:** ![msnbiz1990\_149787](https://avatars.discourse-cdn.com/v4/letter/m/a88e57/32.png) [@msnbiz1990\_149787](https://community.cartalk.com/u/msnbiz1990_149787)\ **Post date:** [March 22, 2019, 9:00pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/5 "2019-03-22T21:00:32Z")
Thanks for the suggestions. I will check for phase separation in my gas! ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [March 22, 2019, 9:01pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/6 "2019-03-22T21:01:36Z")
The problem is more that ethanol damages old rubber components in your fuel system. ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [March 22, 2019, 9:05pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/7 "2019-03-22T21:05:29Z")
How much of the car is original? All the rubber components should have been replaced by now, maybe twice. ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/48514_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [March 22, 2019, 9:14pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/8 "2019-03-22T21:14:46Z")
> [@texases](#): > > Could be fuel boiling, or it could be **an overheated part of your ignition system** If this ancient British car has its original ignition coil (possibly sourced from Lucas…), it is very possible that the coil is the source of the problem. ---
**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\ **Post date:** [March 22, 2019, 10:04pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/9 "2019-03-22T22:04:06Z")
edited… the 1967 had SU carburetors and my post referred to Zenith Strombergs. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [March 23, 2019, 1:20am UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/10 "2019-03-23T01:20:21Z")
I’d sure like to hear from the OP more about his car - what’s been done to it (carb swaps are common), what’s the maintenance been like, etc, etc… ---
**Author:** ![wentwest](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wentwest/32/6073_2.png) [@wentwest](https://community.cartalk.com/u/wentwest)\ **Post date:** [March 23, 2019, 5:41am UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/11 "2019-03-23T05:41:54Z")
The Prince of Darkness strikes again! Will it ever stop? ---
**Author:** ![anon86613489](https://avatars.discourse-cdn.com/v4/letter/a/ad7895/32.png) [@anon86613489](https://community.cartalk.com/u/anon86613489)\ **Post date:** [March 23, 2019, 12:37pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/12 "2019-03-23T12:37:51Z")
Please come up with some more info. Like Ignition system - points/condenser or electronic?, when was last service. Miles **and** months/years? One or dual SU carbs (or other brand)?, heat shield - is that present between carb(s) and exhaust?. Electric (which type) or mechanjcal fuel pump. And this is just the beginning. You cannot give too much info. ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [March 23, 2019, 2:42pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/13 "2019-03-23T14:42:57Z")
OP mentioned phase separation in the gas which leads me to think he is using gas with ethanol. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [March 23, 2019, 5:12pm UTC](https://community.cartalk.com/t/1967-mgb-loses-power-when-hot/136982/14 "2019-03-23T17:12:54Z")
He said he’d check if there was separation. There are so many possibilities…