fuel starvation - lack of fuel

C

colin

New Member
hi all,

recently been having fuel problems with my v8 once i get a few miles from home decides to stall and refuses to start for about 10 mins in the most inconvenient places. No fuel can be seen in filter. If left alone for a bit it will start but wont pull away or pulls away slow and grudgingly, Rac man said most probably knackered fuel pump.

I have overhauled fuel pump with a service kit and refitted it to the car started and runs ok as it did before when cold but fuel level in filter is still low only a quarter full looks almost as if it could run dry. Just wandered if anyone could advise before i take it out on a good run if this level in the filter is normal, dont want to get stranded again, the pump and filter are the standard AC type.

I have heard of p6s suffering from vapour lock ? when hot would this cause these symptoms, or air in the lines.


any comments much appreciated


colin
 
is the filter mounted on the pump with a glass bowl.if so it should be nearly full...when u serviced the pump was the arm worn or the cam worn as this will make the pump not do its full travel..another thing could be the fuel reserve tap leaking air.
 
Colin,
cannot imagine it could be vapour lock in this weather!
Use the fuel reserve to change fuel feed pipes (this used to work on one of my previous V8 cars) and the car would pick-up again. Suspect dirt in tank or fuel lines.
Hope this helps.
Regards, John.
 
just a thought ,have you checked to see if the inlet manifold by-pass pipe isn,t restricted(manifold to radiator),theres a small steel pipe on the front of the manifold which can get blocked causing the manifold to overheat and vaporise the fuel before it can get into the engine,run a small drill bit down it ,...failing that try replacing the condensor in the distributor,
 
Adding to John Glinn's reply I had this problem and was told there is something on the fuel pick up in the tank that can block the pick up pipe Mine ran perfectly on the reserve setting but only 100yds on normal
Cured by removing the pump and blowing back down the fuel pipes with compressed air. Been OK for years , touch wood
 
Just for the record...

Fuel vaporisation normally occurs in warm weather. It is exacebated by sucking fuel down the fuel pipe rather than pushing it. This is why some cars have a remote electric pump near the fuel tank.

Sucking the fuel from the front of the car, typically by using a mechanical pump, causes low pressure in the fuel line. Reducing the pressure reduces the boiling poing point of the fuel, leading to vaporisation at a lower temperature. Modern fuels also have a higher benzene content than when these cars were built, which also increases the likelyhood of vapour lock.

Additionally, with age, deposits will form on the inside of the fuel lines. This restriction of the flow will also lead to a lower pressure in the line, when sucking the fuel along the line (increased pressure when pushing).
 
hi all,
thanks for the advice have had a go at it today and hope i have found the root of the problem.
The fuel level as i said before in the filter is always hovering around the bottom, watching it closeley while reving the engine to see if is would rise i noticed what i thought to be air pockets rising in the fuel in the filter.
Remembering advice given about air getting in through the reserve valve, took the air filter off to have a look at it for the first time. To my surprise it was not connected to the cable but held in the reserve position with a peice of wire wrapped around the lever. I undid the wire and moved it to the normal position by hand, great bet thats cured it i thought, shoved some compressed air down the main fuel line incase it had not been used for years connected it back up
and fired her up.
Unfortunately no better fuel level still low in filter i had a look at the reserve tap with engine running and saw fuel dripping all over the place from it moved it back to reserve position still the same.
So i am in need of more p6 wisdom, could the reserve tap have been the culprit all along by letting in air or have i just busted it by disturbing it after being unused for many years.
Any tips on getting the dam tap off the car without spilling fuel every where i can only just see it nevermind get my fist and a 1/2inch spanner to it, thought the fuel pump was a bit fiddly huh! that was easy.
Has anyone ever bypassed these taps? i would like to repair/ replace it properly just occured to me as i was staring at it bypassing it would be easier if it was going to be trouble in the future and if i couldnt manage to get it off to replace it.

any comments much appreciated

thanks

colin
 
hi colin,
it is possible to undo the little screw and slide the end out without taking the whole reserve tap out as that is very difficult in the V8. you will then find an 'O' ring inside and that is all that stops the petrol from coming out, renew that and that will cure that problem.

ianp6man
 
hi all,
just a note to thank everyone for the recent advice on my v8 fuel probs. I have managed to find a replacement O ring locally for the leaking fuel tap and fitted it.
The leak is cured and the fuel starvation problem seems to have gone, fuel filter is staying reasonably full of fuel and i cant see any air rising in the filter as before.
I will take her out for a good run tommorrow just to make sure everything is ok, fingers crossed !!



thanks again to everyone
colin
 
Hi all,
took v8 for a spin today went 25 miles to my parents house with no problems, even let my Dad have a go he used to have a 2000tc in the early seventies he said he doesnt remember p6s being this nice to drive, i think he wants one.
Set of on my way home about halfway, lost all power in ended up crawling along side of the road. Finally pulled over when she stalled and refused to start checked the fuel filter and not a drop of fuel to be seen thought about doing a "Bazil Fawlty" thrashing her with the nearest tree branch but the paint work is bad enough already, smoked a cig instead and scratched my head for a bit.
Restarted after about 10mins and managed to get home by stopping every so often to let fuel build up in the filter/carbs so its back to the drawing board tommorrow, more petrol on the drive and my hands !!

regards

colin
 
have you checked the fuel lines have no blockage..it does sound like something may be in the tank like rust flakes floating around and blocking the fuel pipe outlet from the tank.I bet if u blow back up the fuel pipe the car will run well for a time then will start to play up as the rust settles..if it does this then maybe its time to take the tank off the car and get it cleaned..
 
We have this power-loss thing occasionally on our V8 & reading this thread has given me the notion of fitting one of my spare P4 SU twin-pumps to her. Mainly as I replaced the pump-points in our 110 the other day which has completely cured our fuel supply problems in her, which were, admittedly, entirely down to the pumps condition. They tick away merrily now. Putting one on the P6B with a bit of extra plumbing would give us a fail-safe by having another pump to switch to (the P6's reserve system being left as is) should one fail as well as overcoming the power-loss problem hopefully.
Sounds good to me, how about you? ???

Also, referring the the carb-swap thread on the Forum, I have aquired a Holley set-up for a reasonable price, to try out on the V8. Would the electric pumps be benificial for this too?
 
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