Fuel Line Plumbing on Twin SUs

DaveEFI · Post by **DaveEFI** » Thu Aug 19, 2010 10:55 pm

Carb SD1 Rpvers have an electric pump inside the tank. They suffer from fuel evaporation. So do the EFI models. External electric high pressure pump. The EFI only after being parked up on a hot day with a hot engine. There is a factory mod to help overcome this.

RoverP6B · Post by **RoverP6B** » Fri Aug 20, 2010 3:29 am

DaveEFI wrote,...

Carb SD1 Rpvers have an electric pump inside the tank. They suffer from fuel evaporation. So do the EFI models. External electric high pressure pump. The EFI only after being parked up on a hot day with a hot engine. There is a factory mod to help overcome this.

Well I never knew that...

My P6B runs both the mechanical fuel pump and I have a Facet electronic pump mounted close to the tank which I switch on only if required.

Even on hot summer days here in Sydney,..36 plus degrees C, coolant temp not far off 100 degrees C, engine oil temp in the sump running over 120 degrees C,..no problem with fuel vapourisation, and no need to use the Facet.

The only time it is likely to be required is towards the end of Winter when a warm day arrives and with Winter grade fuel still in use.

Ron.

primer · Post by **primer** » Fri Aug 20, 2010 7:34 am

RoverP6B wrote:DaveEFI wrote,...
Carb SD1 Rpvers have an electric pump inside the tank. They suffer from fuel evaporation. So do the EFI models. External electric high pressure pump. The EFI only after being parked up on a hot day with a hot engine. There is a factory mod to help overcome this.
Well I never knew that...

My P6B runs both the mechanical fuel pump and I have a Facet electronic pump mounted close to the tank which I switch on only if required.

Even on hot summer days here in Sydney,..36 plus degrees C, coolant temp not far off 100 degrees C, engine oil temp in the sump running over 120 degrees C,..no problem with fuel vapourisation, and no need to use the Facet.

The only time it is likely to be required is towards the end of Winter when a warm day arrives and with Winter grade fuel still in use.

Ron.

Just out of curiosity, what kinda of carbs? Are we talking HIFFs or the earlier HS type, with the side bowl?

RoverP6B · Post by **RoverP6B** » Fri Aug 20, 2010 8:10 am

primer wrote,...

Just out of curiosity, what kinda of carbs? Are we talking HIFFs or the earlier HS type, with the side bowl?

HIF6.

Ron.

DaveEFI · Post by **DaveEFI** » Fri Aug 20, 2010 8:20 am

RoverP6B wrote:DaveEFI wrote,...
Carb SD1 Rpvers have an electric pump inside the tank. They suffer from fuel evaporation. So do the EFI models. External electric high pressure pump. The EFI only after being parked up on a hot day with a hot engine. There is a factory mod to help overcome this.
Well I never knew that...

My P6B runs both the mechanical fuel pump and I have a Facet electronic pump mounted close to the tank which I switch on only if required.

Even on hot summer days here in Sydney,..36 plus degrees C, coolant temp not far off 100 degrees C, engine oil temp in the sump running over 120 degrees C,..no problem with fuel vapourisation, and no need to use the Facet.

The only time it is likely to be required is towards the end of Winter when a warm day arrives and with Winter grade fuel still in use.

Ron.

I dunno the P5B well and I'd guess it depends on the installation - ie how high the underbonnet temp gets and what the airflow over the engine and fuel pipes is like.

I also dunno if we get summer and winter petrol in the UK.

I had several P6s with both types of SUs, and there didn't appear to be much between them vapour lock wise in standard form. I did fit an electric cooling fan to the 3500S, and that helped. But never got round to really trying to address the problem.