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Replacing Mechanical Fuel Pump

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Gday all, I’ve got the classic fuel pump problems with my re built 4K-C, was wondering if anyone’s got opinions on the replacement fuel pumps available before I jump into a Supercheap auto Goss Fuel pump. Anything better about and how good are these Goss pumps as opposed to the PAT pumps they offer?

any help is much appreciated cheers.

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Hi James,

                  Welcome aboard !  Are you looking for a mechanical pump to replace the OEM one one the front LHS of the engine, or are you toying with possibly, switching over to an electric pump, which has some advantages, & disadvantages ?

The original OEM pumps were very reliable, but asked to suck fuel from a long way back.  I once had a mechanical pump that would not deliver.  After trying two other pumps, with the same results, I came to the conclusion, that my issue was not the pump at all.  Issue was a not perfect seal in the fuel line, that was almost undetectable, but pushed the pump beyond its limits.  Only found it by running a long piece of plastic hose from the tank to the pump input.  It worked perfectly, so hence I went looking for the point, where it was sucking in air.

It you go electric, & mount the pump in the rear of the car, this has the advantage, that the suction line is short, & the bulk of the fuel line from the back of the car, to the carby inlet, is under pressure, not vacuum.  However, the disadvantage is, that you must add some safety features to ensure the pump is powered down, if the car is involved in an accident.

Lets know your thoughts.

Cheers

Banjo

 

Edited by Banjo
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On 4/11/2020 at 10:24 PM, Banjo said:

Hi James,

                  Welcome aboard !  Are you looking for a mechanical pump to replace the OEM one one the front LHS of the engine, or are you toying with possibly, switching over to an electric pump, which has some advantages, & disadvantages ?

The original OEM pumps were very reliable, but asked to suck fuel from a long way back.  I once had a mechanical pump that would not deliver.  After trying two other pumps, with the same results, I came to the conclusion, that my issue was not the pump at all.  Issue was a not perfect seal in the fuel line, that was almost undetectable, but pushed the pump beyond its limits.  Only found it by running a long piece of plastic hose from the tank to the pump input.  It worked perfectly, so hence I went looking for the point, where it was sucking in air.

It you go electric, & mount the pump in the rear of the car, this has the advantage, that the suction line is short, & the bulk of the fuel line from the back of the car, to the carby inlet, is under pressure, not vacuum.  However, the disadvantage is, that you must add some safety features to ensure the pump is powered down, if the car is involved in an accident.

Lets know your thoughts.

Cheers

Banjo

 

Hey Banjo, I was thinking about going electric purely for the purpose of modernising the thing up a bit and to me this sounds like it might be my problem, I’ve checked all the diaphragms in the pump and they are sound. Any advice on what electric pump you went with, I haven’t toyed around with fuel systems all that much but it’s definitely the problem here.

cheers

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Hi James,

                  There is a very simple test you can carry out, to see whether the issue is the pump itself, or the fuel line between tank & filter & pump.

Get a couple of metres of suitable size  clear plastic tubing. Slide one end over pump inlet spout, & stick the other end in a can of petrol, which is sited local to the engine.

Run the engine, & watch the petrol delivery through the clear plastic tubing.  There should be no bubbles evident.

If the tube end is always held below the level of petrol in the can, then there is no chance of any air being introduced. If the engine is still starving, or running out of fuel, you might want to fit another bit of clear plastic tubing, between the pump outlet & the inlet to the carby.

If there are bubbles in this line, then there is a problem with the pump diaphram or internal valves. 

If there are no bubbles, but the problem persists, then it likely to be in the carby itself.  

Likely suspects are the inlet ball/pin valve, or the carby float.  

The most common problem is a blocked carby inlet filter.  Many users don't even know there is an inlet filter in the carby, as it is not visible.  You actually have to remove/unscrew the inlet valve assembly, & then pull it out.  It is a very, very fine gauze filter, & often clogs up over time. 

Clean this filter, & if that was the issue, your problem will be  eliminated.

If you still want to go electric pump, give us a yell, & I'll post a picture of a very cheap one I picked up on ebay, that works well, although a bit noisy.

Cheers  Banjo

 

 

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5 hours ago, Banjo said:

Hi James,

                  There is a very simple test you can carry out, to see whether the issue is the pump itself, or the fuel line between tank & filter & pump.

Get a couple of metres of suitable size  clear plastic tubing. Slide one end over pump inlet spout, & stick the other end in a can of petrol, which is sited local to the engine.

Run the engine, & watch the petrol delivery through the clear plastic tubing.  There should be no bubbles evident.

If the tube end is always held below the level of petrol in the can, then there is no chance of any air being introduced. If the engine is still starving, or running out of fuel, you might want to fit another bit of clear plastic tubing, between the pump outlet & the inlet to the carby.

If there are bubbles in this line, then there is a problem with the pump diaphram or internal valves. 

If there are no bubbles, but the problem persists, then it likely to be in the carby itself.  

Likely suspects are the inlet ball/pin valve, or the carby float.  

The most common problem is a blocked carby inlet filter.  Many users don't even know there is an inlet filter in the carby, as it is not visible.  You actually have to remove/unscrew the inlet valve assembly, & then pull it out.  It is a very, very fine gauze filter, & often clogs up over time. 

Clean this filter, & if that was the issue, your problem will be  eliminated.

If you still want to go electric pump, give us a yell, & I'll post a picture of a very cheap one I picked up on ebay, that works well, although a bit noisy.

Cheers  Banjo

 

 

Hey mate I’ll be sure to give this a go when I get to actually access the car (which with all this corona virus action doesn’t look like the near future) it’s certainly getting fuel to the engine as I can drive for say 10 minutes but then I’m stuck trying to get fuel going again, rinse and repeat and I finally make it home. Would you mind chucking up a link or something to the electric fuel pump for some research to cure my boredom and help me make the right call. The plan is to go electric really and has been from the start so I might as well have a look in the meantime. 

Cheers heaps for your help

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15 hours ago, Banjo said:

Hi James,

                  Try this basic one for starters.

https://www.youtube.com/watch?v=2ilRYuGcPkI

ebay cheapie !  They work, but need to be isolated mechanically of rubber mounts.

image.png.c0b627c6fc4d11d0608e1c105fb3d475.png

Cheers Banjo

 

Even then they are noisey. Used an old Facet brand electric pump and moved it three times to make it bearible.

 

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rattle rattle rattle. once i got sick of that I put an intank pump in my ke70 tank as a lift pump, there is a how to around somewhere...better off doing that with a suitable low pressure carby pump. which i dunno if exists, but it probably does somewhere. 

but whats wrong with the mechanical pump? I'm all about modifying but a new mech pump should last you another 30yrs if you don't intend on needing more fuel than it needs. 

 

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Hi Dave,

Rattle, rattle, rattle !  Biggest problem with "rotary" electric fuel pumps, is definitely, the noise & vibration.  I only fitted one to my Rolla, so I could use a mechanical fuel pump, "modified", to experiment with as an easy way to produce a synch pulse, from the fuel pump lobe on the camshaft, for my electronic ignition system. 

There are in-tank electric pumps with low pressure outputs for carby engines.

https://www.hotrod.com/articles/aeromotives-tank-pumps-carburetors/

The great beauty of an electric fuel pump, is that they can be fitted at, or near the tank, so that the majority of the fuel line between tank & carby inlet, is under pressure, not vacuum.

The other electric fuel pump, that is electric, but not rotary, is the British SU, as fitted to many early English cars. These produce a tick, tick, tick, rather than a rattle/rattle/rattle.

Plenty of these available second hand, & you can still purchase repair kits, & recondition one.  Biggest issue with SUs, was the "points", which like our Rolla dizzy points, used to burn, & pit, & stick.  I note now that these SU points, can now be fitted with a solid state electronic "points", which overcomes this problem.

However, many of the early British cars that used SU electric fuel pumps, that were imported to Australia, had the SU attached to the firewall in the engine bay, & the line from the fuel tank in the rear, was under suction. Worse than that, these English cars ran their fuel lines  parallel to the exhaust system, to keep the petrol warm, in their northern hemisphere winters.  Unfortunately, in Australia, that created vapourisation in the fuel line, & the solution was to fit the SU in the rear of the car, & reroute the fuel  line, away from the exhaust system.

I used to have an olde SU fuel pump here somewhere. My Dad used to have a Morris 6, in the early days, & could remember, often having to get out of the car, lift the bonnet, & give the SU a good few taps on the side, to free the points from sticking.

https://www.mgexp.com/forum/mgb-and-gt-forum.1/su-or-hardi-fuel-pump.3251831/

There are a couple of German brands of electric fuel pumps, in the SU vein.  They are the Hardi  & Huco.

Here is a video with some good basic advice & formula, for sizing.

https://www.youtube.com/watch?list=RDCMUCI3fKpfLBb9NegrWPWI2k_w&v=O06TpVafwIo&feature=emb_rel_end  

Cheers Banjo

Edited by Banjo

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