I have a 1969 FHC. Fairly stock, Lucas CEI ignition and the air conditioning has been removed. Not that either of those figure into this issue.
Several weeks ago I tried to start it after it had been sitting since November. I turned the key and the fuel pump started clicking I waited 10 to 20 seconds and started cranking. It started but only ran 5 seconds. I then noticed that the pump was running continuously. I turned the ignition off and opened the bonnet.pulling the feed off of the carburetors and turning on the ignition I got no fuel flow just a spurt every 5 or so seconds and the pump was running continuously. I removed the bowl from the fuel filter and turned on the pump. Again a spurt of fuel every 5 or so seconds. I turned everything off.
I returned to troubleshooting today. I opened the rear and removed the spare so I could check the fuel lines between the tank and the pump for leaks. Everything looked good. I turned on the ignition and the pump ran for 10 or so seconds and stopped. I started the car and it ran normally.
I don’t like that now its running normally and I see no issues. Does anyone have any ideas on what I should be checking?
All types of pumps prefer to push the material they’re pumping and not suck it. If, after sitting for some time, the fuel in the line between the pump and the tank had drained, on the first attempt, fuel in the delivery side of the pump and ahead of it was probably enough to start the engine for a short period. The pump would then have to prime to be affective and when pumping air, that can be difficult, particularly if the pumping mechanism of the fuel pump is worn and not 100% effective.
You could try and recreate the same situation by draining the fuel line and pump and see if the same event occurs.
You could check to see if the pickup screen has broken up and become lodged in the intake pipe. It’s possible that some debris is caught in the inlet valve of the pump. Finally, it could be that the diaphragm is punctured. I’d start by putting a clear plastic line on the pump intake and see if it can pump from a bottle of gas. If it can’t, then get a kit for the pump and rebuild.
i have an XJ6 S2, what you described is typical of what my car does when i haven’t started for some time, i’ve got used to turning on and waiting & waiting & waiting till the pump stops, then i know it’s primed, i even added another fuel shut off solenoid up front hoping this would eliminate the drain but still didn’t help…just a case of start more often or just wait.
I guess it could be a dry line. Between taking the fuel lines off and checking the filter the pump likely ran a total of three minutes and never pumped any real volume. A week later it built pressure about 10 seconds after turning the key.
have never heard of a fuel pump getting better, only worse
If I was you, I would remove and carefully dismantle & inspect the pump, there may be trash in the intake, there is little brass plate valves, and you can examine the points and other parts. If all is well, they can be put back together with filed points and be good to go
It was mentioned the intake tube can draw up trash in the tank
I dont know whether you can drain or clean your tank, but I have seen trash in younger tanks than that
AT this age, if that pump is OE, you can check it out and possibly rebuild it. SU does now offer an electronic pump… same form factor, fittings, etc. bolts right in. I replaced mine with the electronic unit and had the OE rebuilt as backup, in case. The electronic one ticks like the points unit, so you can still check its operation while starting.