Vapour lock/fuel starvation!

D

DAV8

Member
Hi All, I'm sure this has been run before but, had a run recently in warm weather and heavy traffic and my 3500 auto suffered from the dreaded vapour lock, I have fitted some hose round the fuel line over the bell housing so I wondered if anybody has come up with a rock solid way of preventing a repeat. I still have the original mechanical fuel pump fitted as I don't really like the idea of fitting an electric pump.
DAV8
Dave
 
Hi Dave.
Its strange that some cars suffer more than others, at one stage i was running 2 3500s one would suffer/the other didn't.
Apart from the norm electric options i would rebuild the original fuel pump /kit on ebay and wins.
Depends on age of pump to what size valves are fitted so ones in kit may not fit.
Vapour lock can be brought on by engine temp being too high but not at the overheating stage/ an uprated rad with electric fan is a good upgrade.
Also the unleaded fuel now causes engines to run hotter.
I cured my car by using 2 pumps look at the electric pump threads on here for details.
Clive.
 
I recently fitted a Huco pump to mine. I wasnt sure if it was the fuel pump at fault, however when i disconnected the old pump i left it with the pipes in to test the new one. It took about 15 minutes of the engine running for the mechanical pump to start expelling the petrol that was in the pipe along the sump. It was very lazy - I'm guessing the diaphragm was past it.

Super unleaded should help. Clearing the little water output pipe on the carb tower can really help. Flushing out the engine and rads with a hosepipe can help. Making sure your fuel line is free of debris can also help.
 
Hi All, I have recently had new gaskets fitted in the fuel pump (by Dan at Priory Eng) the pump does have the small valves as the car is a 1971 V8 however the pump is working fine. It is quite some time since I changed the coolant so a good flush out could be the next step, I will also try the super unleaded (I presume this is 97 octane as opposed to the 95)
Thanks for the help.
Regards DAV8
Dave
 
Hi All, Has anyone tried the following. I have run the engine up to temperature and I have noted that the fuel line where it runs near to the engine sump stays quite cool, there is a small clip where the engine earth strap is bolted to the engine and I suspect that this could cause a "heat transfer" at that point, (the clip and bolt do get very warm) so I have removed the clip and I find that there is no appreciative movement in the fuel pipe.
DAV8
Dave
 
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