FUEL PUMP

jp928

Well-Known Member
#21
If stopping hot causes restart problems that would indicate heat soak issues. An electric pump should help this by refilling the lines, filter and carbs at switch on, getting rid of vapour. I think some insulation on the fuel line across the engine rear and along the near side - a cover like Firesleeve should help - get a size that will slip over the nut on the end of the pipe, and run it all the way to the reserve tap (if fitted). Make sure there are no leaks anywhere also.
 
#22
Classicalgreen: Sounds like the dreaded vapourisation. Common with P6. MY 3500S was so bad that I was seriously considering selling it, as on hot days (in UK!) any traffic jam would bring this on.
Refer to information in Rover club literature to cure this. My problem was a blocked water return pipe from carburetor tower to radiator. Chris York of P6 club tech support pointed me in the right direction. Now the pipe is open I no longer dread driving on hot days.
My 3500S has ben fitted with Facet pump and pressure regulator.
 
#23
I use 95 octan fuel. Don't know if it would make a difference with 99....I will try. Why some cars work ok and why in same configuration don't.....
 
#24
99 Octane fuel will contain more dissolved gas than 95. This is how fuel manufactures get a higher Octane rating now lead additives are banned.
This gas will come out of solution as the fuel heats up, giving vapourisation. Lower octane will not cure Vapourisation, just hide it. Far better to cure the root cause. P6's should run without vapourisation even in hot countries
 
#25
Both P6 and SD1 V8s vapour lock here in Australia. The cure for the P6 is to use the electric pump from the air con cars which sits under the tank and pushes the fuel through. The inlet pipe for the mechanical pump is attached to the bottom side of the block under the exhaust manifold where it heats up the fuel. The return line then sends the hot fuel back to the tank, pre warming the rest of the fuel.... The SD1 with injection came with metal fuel lines which followed the exhaust pipes with the fuel filter can up top to catch the gas. They get so hot you can't touch them. Again the hot fuel went back to the tank so vapour lock was inevitable...The later plastic lines helped cure it on all but the hotest days. Jaguar used part of the airconditioning system to cool the fuel line on hot days.

Your problem still sounds like incorrect float levels though you could try putting the pressure regulator AFTER the carbs.
 

jp928

Well-Known Member
#26
I had an early (carbs) and a late (EFI) SD1 in Melbourne, never saw a vapour lock in 300k kms. Had failures of the ign lock (wouldnt turn) , cured by cooling with a wet rag. Killed 4 clutch masters due to bulkhead bending before dealer said 'no more of them under warranty'.
 
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