418C and 520h electric fuel pump conversions

[Billyboy 2]

Hi All from the UK, following years of starting problems with both my 418c and 520h I am going to bite the bullet and fit Facet low pressure electric fuel pumps to both. I have read up the subject on these excellent forums and am grateful for the sage advice therein particularly about correctly wiring and using a relay and various fuses.

A couple of questions however.

Firstly, on the 418c with a Kohler 18 Magnum twin. I have changed the original fuel pump a couple of times and it has failed again. When I reroute the fuel pipe what should I do to the open pipe connections on the old  diaphragm pump which will remain in situ? The arm in the old pump is driven internally by a rotating shaft and is presumably splash oiled. So I assume that, should the diaphragm ever split, oil could find its way out of the pump unions unless they are blocked off? Any advice from anyone who has done that would be gratefully received.

On the 520h Onan I'm not sure what drives the pump but I think it is vacuum with a pipe behind it when it is removed. Again is it recommended to just simply block off the vacuum pipe or with that potentially cause all sorts of pressure and breather issues in the engine?

Any advice gratefully received, thanks. 

[squonk 42,534]

I have left them on with no issues but I would rather plate the opening with a gasket.

[Billyboy 2]

Thanks Mike, did you block off the holes where the original fuel lines connected to?

[pfrederi 18,333]

You can make your own cover plate and reuse the gasket in there now or buy a cover plate # 240282

 

 

 

 

[Bill D 2,091]

I would replace the pump on the Kohler with a Briggs vacuum pump P/N 808656.  Make a blank off plate and gasket and tap a hole for a 1/8" pipe thread and install a hose barb fitting.  Find a spot to mount the pump on the engine.  Consider doing the same for the 520 if the OEM pump is failing.  The 520 would be easier to convert to an electric pump.  Power could be supplied to the pump from the positive terminal on the coil.  The pump would shut down if the engine is shut down by the safety switches.  This is harder to do on the 418 since it has a magneto ignition.  If the engine is shut down by the safety switches the pump would still be running which could be dangerous.  I have had good luck converting two Kohler M12's to vacuum impulse pumps using the Briggs pump.      Bill 

[Billyboy 2]

Thanks guys for your speedy replies. I did not realise Kohler even made a blanking plate.

Bill, I am a bit wary of going down the vacuum pump route as the issue seems to be the engine not turning over fast enough to suck up the initial required fuel from the tank. Once a small of fuel is poured into the intake after removing the air filter they eventually cough into life.

Can you explain why the Briggs pump is different to the originals please?

Apologies if this is a repeated message but the first did not show as having been sent.

Kind regards, Bill 

[oldlineman 1,495]

I just ran a piece of line from the inlet to the outlet on the fuel pump.

[wallfish 17,494]

Most of the time the fuel pumps fail because the check valves inside fail to check the flow and allow fuel flow in both directions. Removing the pump and covering with a plate is probably the right way to do it but I just add the new electric pump into the fuel line between the tank and the old pump and leave the old pump in place. No issues.

[peter lena 9,088]

agree with above on the pump swap, I  also used a Kohler blocking plate , also used the  CARBOLE MICRO ELECTRIC FUEL PUMP , found it a much better quality unit as compared to the first pump I tried , a very solid secure mount is vital for zero noise. also went over to fuel rated clear lines . pete

[Bill D 2,091]

The Briggs operates the same as the pump on the 520, just a different style body.  The 418 pump is a mechanical pump not a vacuum impluse pump.  I just tend to like the vacuum pumps.  They are very reliable.  Bill