Electric Fuel Pump

I'm about to go and try an electric fuel pump, my motor is running brilliantly after the ACR head and cam fitted but is running out of fuel under revs/load. Though it still managed 70mph up hill starting from 50 yesterday on M62 between Brighouse and Ainley top (quite steep long drag) and only pulling about 2,500rpm. Would just be nice to trust it overtaking though...

I've got one of these fuel pumps : SOLID STATE ELECTRIC FUEL PUMP / FACET CUBE TYPE PETROL LIFT PUMP | eBay and have made a bracket for it. I also got one of these pressure regulators: Pro-Flow Fuel Pressure Regulator SYTEC 8mm Tails [PRO54]. I really wanted a better one with a return but the bloke in the shop didn't know what was what and this one was the only one that made sense!

I'm going to wire it up like the attached diagram. Idea being when ignition is on but OIL pressure low the relay will pull in and switch OFF the pump. When started the OIL pressure will go up and switch OFF the relay and the pump ON.

I've got a dash mounted switch for priming the pump if need be.

Will this be safe enough? I might try and get hold of a fuel cut off switch but not sure where to look or what to get.

Looks feasible - can you get a return feed from the carb?

any particular reason you want a return ? Facet (bendix) pumps can be bought in various pressures, IIRC 4-6psi is the one you want . Are you going to pump thru the standard mech pump ? The standard mech pump in good condition is perfectly capable of supplying enough fuel for your engine . What carb have you got as SU would be best option .

The return I fitted after having problems with vapour lock last summer, it was a simple nipped up bit of steel T-piece. It completely solved the vapour/hot start problems but worsened the fuel-starvation problems.

I've not been through a whole set of mech pumps (2 pattern, 1 genuine LR) and they have all failed to deliver enough fuel and seem to either draw in air or make vapour. I've also replaced fuel pick ups and all piping to no avail. It still would crap out under high revs, I could only reasonably get about 3,800 in 2nd.

I fitted the electric pump yesterday along with a fuel regulator (set at 3.5 psi, no idea what it should be set at or if it is actually needed) and there was an immediate improvement. the inline fuel filter is no full of fuel instead of air/vapour, I can rev up to 5000 rpm (not that it sounds nice so I won't regularly) and it feels a bit more responsive under medium revs / high load (i.e. 50-60mph up hill in top still has a bit left rather than having to change down).

I suspect that pump I have is a bit poor but good enough for this job. I might look round for a rotary one at some point.

The carb is a Weber 34ICH, I'm planning on either getting an SU or I might have a go at making up a manifold and fitting a 32/36DGAV I've got on the shelf. I know they are difficult to set up but I love messing around with that sort of stuff!

The circuit works as intended though I'm not sure I like the fact that if the wire falls off the oil pressure switch the pump comes ON. I might get hold of a NO pressure switch and rewire for that and run the light from the relay...

The mech pump is quite often the source of vapour locking , thats why they had a insulation block between pump and engine .They also lower pressure in the pipe to pump so that fuel vapourises more easily if pipe hot . This was common on lots of army vehicles as well from my experience with them , I always found that fitting a electric pump at tank end and using as a boost pump (ala aircraft) pumping thru the mech pump sorted the problem , the basic landy pump will supply enough fuel for a 4 ltr engine working hard .
Re oil pressure switching just wire the relay so that it earths thru the oil switch , as thats what the warning light does . No need for prime unless you intend to run without mech pump .

Some Weber carbs have a fuel return on the carb itself, usually on the opposite side of the fuel inlet/filter chamber. Most have a blind hole - you could always drill and tap your own.

Cheers lads. Well I've just been on a long run to "prove" it from Halifax up to Whitby and Scarborough and back on the back roads. Plenty of stops with it hot and no problems. I think I'll just leave out the mech pump altogether. If you have a leccy pump feeding a mech pump with a broken diaphram you'd end up with a sump full of very thin petrol/oil mixture.

I don't think the ICH carbs have a return but I think the DGAV that I'm going to try does. When I try that out I think I'll get a bigger bore exhaust and manifold. Not sure about inlet manifold but I might try and make a water heated one...

Anyway I think I'll omit the return now as this setup hasn't suffered any problems and I deliberately got it nice and hot on a fast run and parked in a petrol station in the sun and out of the breeze. That would make the mech pump vapour lock guaranteed before I fitted a return and would require a bonnet open for quater of an hour to cool down.

I didn't go mental but gave it a good run at the windy B roads, steep gradients (sutton bank etc) and a few fast 70mph+ dual carriageways and averaged 25mpg....that's far better than I was expecting....must need a bigger main jet

I must say I'm dead pleased with the ACR cam+head it was pricey but the Landy is now a real pleasure to drive. It's not a lot faster in top-speed terms but its a lot quieter and I don't walk round in circles after a long drive with a buggered clutch knee!

I take it all back, sodding crappy electric pump packed in today. Had to get a lift back to my garage to get the old fuel pipes and swap back to the mech pump. Crappy copy facet pump. Will probably try again later this year with a proper rotary pump instead...

what was wrong with mechanical

see post #1

doubt running short of fuel was a problem with a mechanical pump unless pump was faulty ,they will deliver far more thans needed

Thats why i suggested that you use the electric pump thru mech pump setup , like used on light aircraft , during takeoff and landing , and of course in emergency . Belt and braces . BTW cessna use (bendix/facet pump) .

PS do you have ainline filter prior to pump , as crap can get into pump valves and stop them working properly HTSH

I don't have a filter before the mech pump - I did before the electric one.

I'm going to stick with the mech pump for my trip to france, at least when they go wrong I know how to fix them. I've got a reasonable amount of experience with these - I've had a few motors with almost identical ones. Including a 6,000cc bus and that keeps up.

The problem has always been air getting drawn in and I just fitted the electric pump to prove that it was fuel starvation that was causing the high revs problems. I at least now know its not the fuel pickup or carb that are at fault. I doubt its the mech pump as I'm on my third now. I'm also on my 2nd tank to pump pipe....

Anyway I'm off up to garage to re-check what I hurriedly did at road side last night. I'm going to use plenty of PTFE tape on all the unions and maybe a good dose of sealer on the outside of the unions. I'm really sick of ****ing around with this, its not something I've ever had a problem with before. Though my bus's pump did stop working that was due to the lever being worn down by a half a million miles worth of work!

I have a section of clear pipe before the lift pump so able see that no air is coming from the tank end.Even a pin hole lets in a lot of air.