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Use of ELECTRIC FUEL PUMPS on older vehicles?


N.O.S.

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Good idea? Bad idea? Thinking vehicles like GMC or Jeep which are not used weekly, and so always require priming or, if no hand primer on lift pump, cranking over to get fuel up.

 

Problems with over pressuring? If so, how to resolve?

Keep existing mechanical pump or bypass?

What about availability of 6v pumps?

recommended makes - e.g. S.U. pumps?

 

Comments welcome :-)

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Canadian Military Pattern Ford trucks had optional electric fuel pumps - "India Army only" according to the spare parts list. I have one on my F15A and it works brilliant. Turn on ignition, flick the pump switch and wait a few seconds, then the engine starts right away! On 6 volts too. . . .

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Thanks for the reply, Ruxy. Looks a really neat unit. I have now found pumps which deliver at 1.5 psi so hopefully too much pressure should not be a problem, but the unit might be worth considering.

 

Hanno - thanks for the info. I wonder if the Indian fitment is due to high ambient heat and fuel evaporation? Does your CMP have an electric pump only? If it also retains a mechanical pump, can you advise how the two pumps are piped in?

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Hanno - thanks for the info. I wonder if the Indian fitment is due to high ambient heat and fuel evaporation? Does your CMP have an electric pump only? If it also retains a mechanical pump, can you advise how the two pumps are piped in?

 

Yes, the electric fuel pump or "Autopulse" as it was called were fitted as an option to Fords built for the Indian Army and for those in use in hot climates.

 

But they were also tested for cold weather operations after the war. The "D.V.D Vehicle Trials Winter 1948 - 1949 Northwest Higway Report" concluded they were of "considerable assistance, particularly after draining of fuel filters, cleaning of carburetor or replacement or repair of fuel lines, due to the fact that the entire carburetor filter and pipelines can be refilled with fuel without using engine starter as a means of actuating the fuel pump. It is believed that they also assist in starting the vehicle engine at all temperatures due to the fact that they maintain fuel at proper level in the carburetor at all times wheter or not the engine is operating." It recommended "that these be considered a requirement on gasoline engined vehicles."

 

On Canadian Military Pattern Ford the Autopulse is fitted on the right hand chassis rail behind the battery tray (see attached picture) , plumbed in after the fuel tank and in series with the main mechanical fuel pump.

 

HTH,

Hanno

fordautopulse.jpg

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Good idea? Bad idea? Thinking vehicles like GMC or Jeep which are not used weekly, and so always require priming or, if no hand primer on lift pump, cranking over to get fuel up.

 

Problems with over pressuring? If so, how to resolve?

Keep existing mechanical pump or bypass?

What about availability of 6v pumps?

recommended makes - e.g. S.U. pumps?

 

Comments welcome :-)

I have used SU pumps on all my jeeps with no problems at all,took off the mechanical one and blanked off the hole. I nrun my jeeps on 12 volts. John.

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As well as MVs I've got a couple of a particular classic car. The standard mod on these is to fit an electric pump instead of the original AC mechanical pump, the hole for the mechanical pump being blanked off or used to fit an extra breather. Pick the right pump and it gets round all your priming problems as well as any issues with fuel vapourisation in use.

 

I don't see any difference between these and an MV using a mechanical pump, and I'd recommend it as a mod if you have fuel issues, provided you use a reliable pump and set it up properly.

 

We typically use a Facet or similar type pump rather than SU. If the pump exceeds the pressure the carb will cope with - say 1.5 - 2.5 PSI - use a pressure regulator, but I think they're beneficial even if the pump pressure is 'correct'.

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why do the pumps fail?

 

I wonder if it is through constant yanking on the hand priming lever which moves the diaphragm much more than the mechanical lever does maybe, thus shortening life?

 

Also I used to get a lot of trouble with repair kits in that the non-return valves would often have a powdery oxide deposit or something on the metal valve face which prevented good sealing and consequent run-back.

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Hopefully your vehicle manual will give spec for the lift pump - maximum allowable pressure and mimimum flow rate. If you replace the mechanical lift pump this is the spec you need.

 

I hope to find out soon (when I get a chance) whether you can put an electric pump of smaller capacity in series with the lift pump to use just to prime the system before starting, and then switch it off but allow the mechanical lift pump to draw fuel through the electric pump at a higher flow rate then the electric pump will deliver. Should be feasible to do for pulsating types of pump.

 

Larger capacity pumps get disproportionally expensive!!

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I am having this problem with the RL, once it is running it works fine on the mechanical pump but if it sits for a while (week +) it will not self prime. Putting a small electric pump in line works well but is a bit of a pain. I have just bought a priming bulb, same as you get for boats. The plan is to fit it near the tank so I can hand prime when needed but run on the mechanical pump, it should also stop fuel draining back to the tank.

I have used electric pumps in line, for priming, on a few things over the years with no problems. I am going to have a go with the bulb and see how it works as a simpler solution.

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Croc, I tried the hand primer in line on my Range Rover, bring fitted with a 2.8 Isuzui the one pain in the A** is if you need to bleed it. I got genuine disiel ones a fair bit of research , and the **** things kept splitting! :banghead: I tried two both split the same way after about a week. I have gone back to tow start if nessacary. So I'm not impressed by them. One useful electric pump I've found is the old Mini type 6 to 8 psi. Seems to work quite happily on a number of old engines.

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  • 1 year later...

I was going to update this ages ago but forgot about it. The bulb pump I used wasn't a success. I fitted it inline, near the fuel tank, and it worked to prime the system. The truck would tickover quite happily but once there was a bit of load on it the bulb collapsed under suction from the mechanical pump and blocked the flow.

In the end I fitted an SU pump inline, with a switch in the cab. It now works perfectly, prime system with SU, start and run on mechanical pump.

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What type/size electrical fuel pump would be suitable to fit onto a saracen?:undecided:

 

I had to fit other electric pumps to my sarry as the Tokheim submerged fuel pumps in the fuel tank were shot. Problem was that the sarry is 24V and has two pickups, one from the reserve tank and another from the main tank. So I put two 12V Facet pumps in series on each pick-up and joined the two lines.

 

 

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The pumps acts as one way valves when one set is pumping and the other is off. I still need to fit a regulator though as I think the high fuel pressure leads to fuel wastage. The regulator is on hand but just needs to be installed. I haven't had a problem yet and since the pumps are hidden underneath the floor panels, it is not an eyesore either.

 

In my opinion it is a definite winner!

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