A problem with my pickup.

[LRV745]

Hello All.
I am at my wits end trying to find the problem with my 1961 pickup.
The problem is that the pickup has a 1098cc engine I think?. and I can drive it any distance, but if I park up for about 20 minutes
the petrol pump don't work, if I pull the choke out it starts an runs but is missing for quit a while then picks up and away we go.
If I park up for an hour the petrol pump works ok, it also works if parked overnight.
I have put a reconditioned petrol pump on but it will not stop pumping, I also tried a s/h pump, that also won't stop pumping either. Last night I drove it slowly round the lanes for about 4 miles, it then stops, the petrol pump is not working, I took the
carb top off, it was dry, I filled it up with petrol put it back together, it went untill the bowl was empty, I done the same again, started it
up and the petrol pump worked again.
Today it started I drove it 15 miles parked up for 45 minutes, it started ok and I drove it back home 15 miles with no problems.
Any sugestions.
LRV745.

[bmcecosse]

Oh dear! Loose wiring connections? I would rig a wire direct from the battery to the pump to see if that makes a difference. It's really odd that it 'stops' - when that happens - have you tested for a vacuum in the tank? Take the filler cap off - is there a sucking noise - and does the pump start ticking? Other possibility is some junk in the tank - periodically obstructing the inlet ...

[LRV745]

Thanks for your reply, I have had the petrol tank out, there was some rust in it, I cleaned it out and put the air line through the tank outlet and blew it through, and also the pipe through to the pump end with it disconected.
I will try the cap but I have replaced it with a locking cap. I will try a wire direct from the battery.
LRV745.

[bmcecosse]

Locking caps are sometimes not vented!

[alexmcguffie]

When you say at some times it doesn't stop pumping, I assume its pumping air not fuel? Does it run better with a full tank of petrol than say half or quarter? Could be a fuel pick up problem in the tank...

[LRV745]

No I said if I fit a reconditioned petrol pump or a good S/H one they don't stop pumping, but if I put the original one back on it works as normal, until I go for any distance and park up for about 20/30 minutes, then the pump don't work, it will start if I pull the choke out, it misfires for a while then picks up and goes as normal.
With regard to the locking fuel cap, the same thing happens with the original cap on.

[bmcecosse]

How do you KNOW the 'pump don't work'....and why do you think pulling the 'choke' helps that? This is getting confusing.......