So I have given up trying to fit the mechanical pump. I have bit the bullet and bought a Huco pump, it's low pressure so doesn't by all accounts require a pressure regulator, but on receiving the pump today it says it is recommended that a emergency cut off switch be incorporated in the electric system. For people that don't know it's a switch that in case of a accident the fuel is cut off automatically.
Sounds like a reason to fit one so ordered one from Ebay but it takes three weeks to arrive.
I don't plan on having a accident imminently.
The only other thing I think I need is a filter but does it go on before the pump?
Most cars have a filter built into the tank pickup to catch the worst of any crap before it gets to the pump. Dolomites are not blessed with one of these, so best to fit a line filter between the tank and the pump.
I use fuel shutoff inertial switches on my high pressure EFi powered cars, it's a sensible precaution in that case, where you have 40+ psi running through the lines. Not really so needful on a carburettored car with only 3 or 4 psi on tap. Switching off the ignition will stop it in any case. So the only time you might NEED an inertial switch is when the car is upside down and you are unconscious. In those circs, you are already in big trouble! Though I was always a fan of the concealed manual switch in the powerline to the pump. It makes a good thiefproofing device! On my GT6 MkII convertible, I used the redundant HRW switch (clearly labeled as HRW) to power the pump, hiding in plain sight on the dash!
By an odd coincidence, the white Sprint shuddered to a stop on me today! I took it for a little run to blow out the cobwebs after first warming it on the drive. After about 15 mins running and 5 miles driving it started running rough, refusing to rev above 2000rpm and spluttering, I coaxed it another mile or so before I found a spot to turn round then started back, doing another 2 miles at slowly decreasing speed till it cut out on a slight uphill bit and refused to restart.
Lucky me, i'd just rolled it back onto the verge when a neighbour passed by and stopped to see if I needed help, so I blagged a lift home, got some tools and another car and went back to see what the problem was.
Because the rev counter had been steady throughout the rough running, I tentatively eliminated points, condenser and coil from my enquiries and went first to the boot where I physically checked the presence of fuel in the tank by removing the sender unit, half a tank at least there so next to the carbs, I removed the pipe from the front carb and switched the ignition on and, though the pump was clattering furiously, no fuel emerged. Ignition off again and the float bowl lid removed to show, as expected, a dry float chamber. I obviously had a line blockage and my thoughts turned to the fuel hoses under the car, they were all fairly new when I got it, but were they REAL R9?
Back to the boot and pulling the pipe off the pump allowed fuel from the tank to flow freely from gravity, no problem in the tank then! Pipe returned to filter and pump, I tried the other side of the pump, less flow but still enough, I replaced that pipe too and moved to the PRV, access was a bit poor but I managed to get the pipe off the engine side of the PRV without too much cussing. At this point, there was no flow from gravity (not that I expected any, at that point I was higher than the top of the tank) switching the ignition on got me no more than a feeble trickle despite the pump racketing away. So I turned the PRV up from it's default 1.5psi setting to 4 psi, that increased pressure to what I considered might be workable. I reconnected the pipe and a swift recheck of the float chambers showed them full now.
However, the car STILL refused to even try to start, not so much as a cough and the battery was going flat. I checked the points gap and opened it slightly, carefully inspected dizzy cap and rotor and checked the plugs, all OK but still no start, even with my (Ex Jeep Cherokee Chief) huge slave battery connected via jump leads. Until suddenly, just as I was about to give up and get the car recovered (no easy feat as mine is auto too) it burst into life, strong and sure on all 4 pots, WEIRD! I drove it the last 3 miles home and it was like nothing had happened, pulled strongly and idled fine. I switched off at home and it restarted immediately.
Now it's glaringly obvious that I have a problem in the fuel lines, it shouldn't need 4 psi to open the needle valves (there was no flooding at this pressure setting which I half expected) SOMETHING is slowing the fuel down, so I will replace all the soft lines with known real R9 and blow out or replace the hard lines as needed. I also need to check the other side of the PRV to see what sort of pressure is there, it may be that the PRV is malfunctioning (my fault for praising it in a post further up this page!) Why once it HAD fuel, it wouldn't start, until suddenly it did, I will postpone until a) I've fixed the lines and b) it does it again and I can check other things! But if the PRV IS duff, i'm definitely going for one of those recon SU pumps which, by rights, shouldn't need a PRV!