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Post by slartibartfast52 on Mar 6, 2020 15:05:03 GMT
I took my 1971 P5B Coupe out for a spin the other day and after about 8 miles turned off the engine at a rural railway crossing as I waited for the train to pass. After 3 or 4 minutes the barrier rose and I attempted to start again without success. A rather embarrassing situation as some kindly souls pushed me off the road. After a 20 minute or so wait, I returned and tried again without success; so I disconnected the fuel line feeding the carbs and turned her over. Fuel pumped through and after reconnecting she eventually fired up. I'm guessing this is vapour lock as the fuel in the lines evaporates !?. I've read some of the threads and it would seem that by fitting an electric fuel pump (Bearmach?) this will sort the problem. Could someone much more knowledgeable than I confirm before I purchase a pump. I presume that this needs to be wired in to the ignition circuit and perhaps you could advise how this is done.
There is a good spark at the points and a new condenser and coil have recently been fitted. Any other suggestions most welcome.
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Post by ray on Mar 6, 2020 16:38:56 GMT
Hi, its always difficult to diagnose form this position. However it does not sound like vaporisation as that tends to happen on hot days after long runs. Has your car still got the auto enrichment device fitted? This would be a classic example of that devices weakness. They would not shut off at the appropriate times and cause engine flooding, if the car is switched off after only a short run. The symptoms you described.
My car has manual chokes fitted and a standard fuel pump and has never acted as you describe. Vaporisation causes poor running when the air and engine are hot. I can always overcome it with careful use of the accelerator on those rare occasions. But have never had a fail to start situation.
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Post by Phil Nottingham on Mar 6, 2020 17:07:09 GMT
The mechanical pump wears but may pump when no pressure so may be no good - tank airlock? Was this present before the ignition replacements
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Post by slartibartfast52 on Mar 6, 2020 17:08:07 GMT
Hi Ray. No, I blanked off the auto choke some time ago and fitted a manual choke. Any other thoughts ….perhaps the in line fuel filter clogged up? I refurbished the manual fuel pump about 4 or 5 years ago ….can the components fail again? I have heard that some of these plastic/rubber parts can perish quickly with these more modern fuels.
Getting pretty frustrated 
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Post by slartibartfast52 on Mar 6, 2020 17:11:00 GMT
Yes, to some extent these symptoms were present but seemed pretty good for a month or so then we seem to back to a "lumpy" drive & a tendency to stall when idling after a short run …..! 
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Post by Phil Nottingham on Mar 6, 2020 17:32:33 GMT
Refurbishing the pump rarely lasts long - if you have not replaced the inline filter - do so or bypass it as a temporary measure. Blow through the fuel lines but check the Reserve tap s not HALFWAY Electric conversion is the best solution if the mechanical pump is past it
There is plenty on SEARCH about electric pumps
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Post by lagain on Mar 6, 2020 19:21:34 GMT
Check the points, they can 'bed in' and close up. Electronic ignition is a good upgrade. Is the new coil OK.
Do you have the standard carburettors
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Post by slartibartfast52 on Mar 6, 2020 19:42:19 GMT
Yes, standard carbs, rebuilt a couple of years ago and retuned (I believe) at last service 2 months ago. I'll check the points though as suggested. I have a dwell meter and can set up to the manual spec: New coil ok as far as I'm aware; how can I check?
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Post by Brendan69 on Mar 7, 2020 12:40:24 GMT
I would suggest as George has done to convert to electronic ignition unless of course you wish to stay old style.
Regards,
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Post by lagain on Mar 7, 2020 18:26:44 GMT
Sorry don't know how to test the coil!
Have you had the car long ? if this is a new problem what have you done recently, I think that a coil can break down when it gets hot and be OK once it cools down. Could you put the old one back on to try.
A friend had a similar problem some years ago and it turned out to be the O ring on the fuel reserve tap on the chassis that was disintigrating and causing a blockage. Worth replacing anyway if it is the original, easy to do but disconnect the fuel pipes at the tank.
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Post by Sam Bee on Mar 7, 2020 20:10:48 GMT
Agree with George. Many older fuel system seals are 'eaten' by part ethanol type fuel so replacement of ALL seals is recommended, including the changeover 'O' ring. If you renovated your carbs and fuel pump recently with newly purchased parts then those are attended to. This can also apply to the seals on the fuel tank.
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