V8 Fuel starvation

#21
Many thanks Colin for your rapid response and sound advice. I've now read through many of the previous posts and will try the remedies mentioned. There was a great deal said about vaporisation in and and around the carbs but air bubbles in the fuel filter indicate the vapour is in the fuel line so I'll concentrate my efforts in this area. David
 

GRTV8

Well-Known Member
#23
I would also make sure the fuel filter is in good condition. Worth renewing if in doubt.
Its got an unusual filter- cylindrical made from some porous material. I soaked it and blew it out with a small air compressor . Not much crud was visible to give concern so I put it back in.
 

mrtask

Well-Known Member
#24
ukmax, you surmised correctly, there are two outlet pipes from the petrol tank. The normal outlet pipe is a bit higher/taller. When the fuel level drops below that height the car stutters, you pull the reserve cable, and then you're using the second outlet pipe, the lower/shorter one.
 
#25
are we aware ethanol in fuel creates gas bubbles . when fuel line is heated?. they are increasing levels to from 5% to 10% I believe. so much easier top get fuel vapour issues .mine always suffers that after I stop and 10 mins later try and drive off.. just about enough power to. get up to 28mph ( in a v8 ) for anything form 20 seconds to about 50 seconds..then like a switch ..broom and zoom .
 

cobraboy

Well-Known Member
#26
are we aware ethanol in fuel creates gas bubbles . when fuel line is heated?. they are increasing levels to from 5% to 10% I believe. so much easier top get fuel vapour issues .mine always suffers that after I stop and 10 mins later try and drive off.. just about enough power to. get up to 28mph ( in a v8 ) for anything form 20 seconds to about 50 seconds..then like a switch ..broom and zoom .
Does the fuel pipe that runs between your 2 carbs loop down and rest on the inlet manifold ? If it does it will be heating the fuel in there and will give the symptoms you describe. The answer is to slacken the unions and loop the pipe forward away from the heat.
You could also put a thermal wrap around any fuel pipe that is exposed to heat and a couple of squares of heat insulator under the float chambers wont go amiss.
 
#27
put heat shielding around some of my fuel piping. not all ..yet. aware its simply vapour issues but will be. convening to. all electric pump soon and removing mechanical pump , which also get warm on side of block not helping temps. not blown through pipes yet but have disconnected the reserve and ensured tap isn't moving ..it did once and cable wasn't returning it fully so had fuel starvation !! new. o ring and set in position fully open .so far so good.
 
#28
Thanks again for all the advice. Today, whilst I had the car up on a lift to do put some wheel rotation sensors in place I had a look at the run of the fuel line but I'm not sure whether it's standard or not. The fuel line runs down the left side of the engine and there is another in-line filter in the straight run about 300mm before it goes up to the lift pump. The whole run (including the filter) is very exposed to heat radiating from the exhaust and is almost certainly the cause of the vaporisation. I shall make a heatshield to protect this pipe and the the filter and see if this corrects the problem. I had already moved the pipe between the carbs when I serviced them a few weeks ago.
David
 
#29
I think that most issues have already been covered, but on my 3500S, when I bought it the reserve did not work, so local garage blew down the fuel line and cleared it. Suggested that 'crud' accumulated in the tank had blocked the inlet (lower in the tank)
Result was reserve working but later the symptoms of fuel starvation on normal setting. Crud blown from reserve was in he main fuel and blocked the in line filter. New filter cured all problems, but remember if the reserve inlet is blocked and blown clear, normal approach of a garage, then the muck has to go somewhere and will stay in the fuel tank and cause problems when is most inconvenient.
I suggest that if your reserve is working it does no harm to run the car on reserve once in a while. At least it stops the change -over tap from rusting in one position.
 
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