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Ferret Fuel Pump Woes

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Hi

 

Have spent a bit of time (along with others) in trying to sort out a Ferret Fuel Pump problem.

 

The conclusion we have reached is that the pump is not pumping when fitted to the engine. The pump works fine when it off the engine. When fitted to the engine, Fuel filter bled and fuel lines primed no fuel is reaching the carb.

 

The fuel pump is driven via a push rod and cam in the engine, are these prone to wear ?

 

Also what 24V electric fuel pump can anyone recommend and where is the best place to fit one ?

 

Cheers

Richard

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Hi Richard,

an electric does improve starting, and gets rid of the flat spot when pulling away after idling in traffic. Plenty of cheap 24v pumps (ie ebay)

Mount it away from the engine, (way too hot) in an accessible place,(n/s/r crew compartment) lower than the pickup tube from the tank (close to floor) and use an inline clear fuel filter on the suction side. This keeps the fuel cool until entering carb, being lower it shouldn't air lock, will self bleed easier, and if crud comes through from the tank, you can see it and get to it!

I binned my old mechanical lift pump, and made a plate and gasket to go over the hole.

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I agree a electric pump is better than the mechanical pump .The vehicle starts straight away on the first flick on the starter.

Mechanical pumps can leak fuel into the oil due to a torn diaphragm caused with bad fitment or rot.

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I quite like the fact that my ferret after being stored a while takes a bit to prime fuel system , gives a chance for oil to get round the internals

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Hello, are you 100% sure the fuel line between tank and pump is air tight , I had lots of problems with my Humber pig which turned out to be poor connections in the fuel line preventing the pump from drawing the fuel from the tank . Replaced the faulty connection and had no problems since !

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Is the fuel actually running freely from the tank? Not unknown for the banjo bolt to become blocked with debris/asphaltines. There is a mod to extend the bolt above the lowest point of the fuel tank.

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I quite like the fact that my ferret after being stored a while takes a bit to prime fuel system , gives a chance for oil to get round the internals

 

yep I'm with you on this one, my pump was knackered but bought a couple of repair kits, fitted one and away she went. Also nice to know that it's as it should be. Being brought up on plugs and points system I think that so long as you have every thing set up properly then there shouldn't be a problem. I like to think that if I brake down and it's fuel or elecy I can fix it on the side of the road. But each to their own I guess.

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Hi

 

Thanks for the inputs and the advice on where to put an electric pump if we go down this route.

 

The banjo bolts are all free from debris, and as far as we can tell all the lines are airtight. We will double check and I will keep you posted. By the way the pump has had its diaphragm replaced.

 

Cheers

Richard

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Hi

 

Have spent a bit of time (along with others) in trying to sort out a Ferret Fuel Pump problem.

 

The conclusion we have reached is that the pump is not pumping when fitted to the engine. The pump works fine when it off the engine. When fitted to the engine, Fuel filter bled and fuel lines primed no fuel is reaching the carb.

 

The fuel pump is driven via a push rod and cam in the engine, are these prone to wear ?

 

Also what 24V electric fuel pump can anyone recommend and where is the best place to fit one ?

 

Cheers

Richard

 

Old trick we used to do in REME workshops, put an airline blowgun on the tank breather pipe and get someone else to slacken the banjo on the carb, this will push the petrol through the system. Sometimes when pumps are dry they do not suck well. Another common issue was the Vokes fuel filter, drawing air in the banjo unions and sometimes at the sealing ring on the bowl.

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It's not unknown to have to "wet the pump" on some of these old pumps. One of our trucks does this from time to time, so we have to remove a flexible hose and tip some fuel down the line. Messy, but gets her going. Pretty sure I had to do this on a Ferret too.

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Am i right in thinking it primes up manually, but does not pump fuel when running

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A few queries along these lines, if I may.

 

1. I've taken the (ferret) tank out to clean it. Not sure if the pump is 100% so I plan to connect the input hose to a can of fuel, disconnect the hose to the carbie and run that into a can, then crank the engine. Is there a measure of ml/min or PSI to see if it's working, or just be happy if fuel squirts out?

 

2. I've purchased a hand priming pump (the rubber bulbs that you get at marine shops) to put between the LHS tank outlet and the filter, with another filter on the suction side. This needs to be low down in the fighting compartment (i.e. near the bottom of the tank) so will need to get a short length of metal pipe with the swelling on the end, to save chopping up the existing pipe, to connect flexible hose. Imagine pipe is readily available (but haven't checked yet).

 

3. The other option is an electric pump in the same position as (2) - I guess a 12V pump is suitable, rather than 24V? However on Googling the warning is to wire it so that it stops pumping if the engine stalls. The tachometer circuit is one suggestion and it certainly seems sensible to not keep pumping fuel if the engine stops for whatever reason, but this is getting a bit complicated for me. You'd hope that the carbie would stop fuel flooding everywhere but I'm not sure.

 

4. Plan to modify the banjo connection as suggested by "Grasshopper" to increase the hight of the fuel pickup a bit. Haven't looked at it yet but assume a bit of flexible fuel pipe would be OK for this?

 

5. Agree absolutely with the problem of air leakage. The fuel pump needs to pull fuel from the bottom of the tank to the filter near the top of the tank before it starts flowing down to the pump. Any air leakage makes this difficult or impossible. I've found one culprit connection, which was part of my problems and is why I'm planning option 2.

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A few queries along these lines, if I may.

 

 

 

 

3. The other option is an electric pump in the same position as (2) - I guess a 12V pump is suitable, rather than 24V? However on Googling the warning is to wire it so that it stops pumping if the engine stalls. The tachometer circuit is one suggestion and it certainly seems sensible to not keep pumping fuel if the engine stops for whatever reason, but this is getting a bit complicated for me. You'd hope that the carbie would stop fuel flooding everywhere but I'm not sure.

 

 

Using the tachometer to switch off the pump will not work as it is cable driven ...... not electric.

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If you install a tachometric relay (as used in LPG vehicles) you can take the pulse from the distributor.

 

How it works is once the ignition is turned on the relay allows the fuel pump to run for a few seconds then shuts it down. This creates fuel pressure to start the engine, once started the pulse of the low tension circuit to the distributor keeps the relay operating.

 

Once the pulse stops (the engine stops turning over) it shuts down the fuel flow.

 

This means in the event of a ruptured fuel line after the pump the engine will stop and so will the pump.

 

Relays are avaialable on eBay and cost around 30-40 Aussie $.

 

I use them on modified fuel injected cars, but they will work with a carby just as well.

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Once you've fixed the immediate problem there's nothing wrong with retaining the existing pump arrangement. Personally I like the idea of turning the engine over to get the oil pressure up a bit before it starts.

 

Andy

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Same here Andy. If I give the accelerator a couple pumps it would fire right away. Instead I don't touch the pedal, and I crank it till the oil light goes out. Then I hit the pedal and it starts. I do this mostly with the 2 speed generator in mind since oiling that before a start is indicated in the manuals.

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Hi

 

Have spent a bit of time (along with others) in trying to sort out a Ferret Fuel Pump problem.

 

The conclusion we have reached is that the pump is not pumping when fitted to the engine. The pump works fine when it off the engine. When fitted to the engine, Fuel filter bled and fuel lines primed no fuel is reaching the carb.

 

The fuel pump is driven via a push rod and cam in the engine, are these prone to wear ?

 

Also what 24V electric fuel pump can anyone recommend and where is the best place to fit one ?

 

Cheers

Richard

Hi Richard when the mechanical pump is on form it works fine . problems occur as the cam that drives it wears or the diaphragm is torn due to bad / incorrect fitting or perished diaphragm. Smell your dip stick does it smell of petrol. I am with the guy,s get an electric pump . I fit two , one as a back up. I put the switches in obscure places they act as an ant- theft device. Starting is great . Its better than pumping petrol oil around and having to replace big and main ends not to mention cams , bearings ,push rods and oil passing past oil seals.

 

regards

Laurence

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Hi

 

Thanks for all the advice

 

We have finally got it working...

 

The pump has been on and off many times and the rebuild was checked, still not sure what we have done differently. I still think that an electric pump is the way to go, just got to persuade the others.

 

Cheers

Richard

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I've found some fuel pumps on old petrol vehicles like to have the valves wet before they'll work properly. I get very bored of the taste of petrol...

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Realistically, diaphragm pumps are very reliable and have been keeping Ferrets going for over 50 years so far. The only things that can really go wrong with them are torn diaphragms and/or a stuck valve. In either case, a rebuild is a fairly simple procedure.

 

http://ferret-fv701.co.uk/mnuls/david_pump.pdf

 

An electric pump really isn't necessary.

 

Cheers,

Terry

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