Electric pump conversion

R

rancher_mac

Member
I have a Briggs opposed twin 17hp and I’m looking to potentially swap to electric fuel pump. Main reason being I hate the design of the pulse tube going to the crank case (potentially thinning oil with leak). I use high grade ethanol free gas and baby my carbs, but these carbs seem to give me trouble with their pumps…maybe I’m just unlucky. I had a couple questions regarding the pump input if I converted. Would I be able to plug the pulse feed and just put the inlet into the existing inlet on the carb? Or would I need to drill out and tap in the hole I circled in green? I’m looking to use this specific pump which is 1-2psi. IMG_2500.jpeg
 
Forest#2 said:
I've done a mod to those carbs and instead of using a electric pump I used the cheaper Briggs type pulse pump.
I also got tired of replacing the pump kits and I also had a good carb with one of the pump mounting screw bosses broke off the carb.

Here is a link to the general procedure I used when modding.

Professional Power Equipment Technicians & Education Network (PPETEN) • View topic - HOW TO CONVERT A BRIGGS TWIN CARB FOR EXTERNAL PUMP.

ppeten.com ppeten.com
Click to expand...
Great, thank you for the help. When you put the 10/32 bolt in the old pump outlet, did you use sealant on the threads? Did the npt seal fine by itself on the 5/16” barb fitting?
 
You asked:
When you put the 10/32 bolt in the old pump outlet, did you use sealant on the threads? Did the npt seal fine by itself on the 5/16” barb fitting?

The 10/32 screw blocks the fuel from going back into the front pump section.
I think I used a homemade little copper washer. It won't take much to seal because the pump is only about 2psi max output.
On the hose barb. I think I used teflon tape so as I could get a seal without having to tighten excessively tight and also reduce chance of the brass 1/8 inch NPT tapered brass hose barb cracking the aluminum casting. Just be careful with teflon or any sealant because it will go into the carb if any excess.

I did notice the picture of your carb at the hose barb area (in the green circle) that I tapped and mine did not have the protruding section like in your picture. Mine already had the correct size hole molded recessed into the carb body for the 1/8 inch NPT tap.
Since yours has what appears to be a little 1/8 sealed hole you could probably just drill through into the internal like I mentioned in the link and maybe do a smaller hose connection to the carb because you are going to have to take caution drilling that section out for a 1/8 inch NPT threaded hose barb.

Use of non-ethanol gas helps save the pumps and carbs plus installing a WHITE or red fuel filter before the pump is a good thing. The Briggs white filter is finer mesh for pump systems. The white is too restrictive for gravity fed carbs engines.

You can find pulse pumps for around $10.

Also I keep a eye and ear open for them old Briggs Pulse pump CARBS as spare carbs for the old Twin engines. The only weak link in them old carbs is the wimpy front pump. China is now starting to have clone kits for the pumps at around $5 for two pumps with free shipping on fleece bay, but I have not tried any of the China pump kits yet.

Also you WILL FIND that when one of the engines with them old type carbs starts running little bit rough just remove the drain plug on the bottom of the bowl and then re-install and about 90% of time the engine is ok. Has little moisture in the bowl. Do this while the engine is cold because the exhaust is usually right below the drain plug.
 
Last edited:
If at all possible, gravity flow all the way. Nothing to break or wear out. Never leave you stranded.

You need to check your available amps to see if your charging coil can even supply a third party pump.
 
Forest#2 said:
You asked:
When you put the 10/32 bolt in the old pump outlet, did you use sealant on the threads? Did the npt seal fine by itself on the 5/16” barb fitting?

The 10/32 screw blocks the fuel from going back into the front pump section.
I think I used a homemade little copper washer. It won't take much to seal because the pump is only about 2psi max output.
On the hose barb. I think I used teflon tape so as I could get a seal without having to tighten excessively tight and also reduce chance of the brass 1/8 inch NPT tapered brass hose barb cracking the aluminum casting. Just be careful with teflon or any sealant because it will go into the carb if any excess.

I did notice the picture of your carb at the hose barb area (in the green circle) that I tapped and mine did not have the protruding section like in your picture. Mine already had the correct size hole molded recessed into the carb body for the 1/8 inch NPT tap.
Since yours has what appears to be a little 1/8 sealed hole you could probably just drill through into the internal like I mentioned in the link and maybe do a smaller hose connection to the carb because you are going to have to take caution drilling that section out for a 1/8 inch NPT threaded hose barb.

Use of non-ethanol gas helps save the pumps and carbs plus installing a WHITE or red fuel filter before the pump is a good thing. The Briggs white filter is finer mesh for pump systems. The white is too restrictive for gravity fed carbs engines.

You can find pulse pumps for around $10.

Also I keep a eye and ear open for them old Briggs Pulse pump CARBS as spare carbs for the old Twin engines. The only weak link in them old carbs is the wimpy front pump. China is now starting to have clone kits for the pumps at around $5 for two pumps with free shipping on fleece bay, but I have not tried any of the China pump kits yet.

Also you WILL FIND that when one of the engines with them old type carbs starts running little bit rough just remove the drain plug on the bottom of the bowl and then re-install and about 90% of time the engine is ok. Has little moisture in the bowl. Do this while the engine is cold because the exhaust is usually right below the drain plug.
Click to expand...
Sounds great, thanks for all the advice. I was wondering, which pulse pump did you use? I hear people say it can be particular which pump works best with a certain carb.
 
slomo said:
If at all possible, gravity flow all the way. Nothing to break or wear out. Never leave you stranded.

You need to check your available amps to see if your charging coil can even supply a third party pump.
Click to expand...
From what I’ve been able to find, my AC circuit runs 5A while the DC runs a 3A charge to the battery. Can’t find much info on it but it’s the Briggs 691063. The pumps I’ve been looking at draw around 1-2A.
Gravity fed would be awesome, but unfortunately I can’t accomplish it with my setup.
 
You have to keep a heads up when going to a electric pump due to pressure.
Needs to be low pressure, in vicinity of not over 2 psi and a reliable pump is usually $50 or more. The low pressure pumps are not constantly run so a 3 amp DC charge system would run them ok and still charge the bat.
A 12v pump is nice if the eq sets for long periods of time so as to get immediate gas to the carb so as to prevent long crank times on/off the starter and not have to remove the breather for a prime, run bat down etc.

Just some more general info.
The main reason I'm modding the 3 screw carbs is the pump kits are wimpy, vintage and usually have to remove the carb to do a kit because of the small parts inside. (and pulse pumps are more long term reliable as compare to the 3 screw type pumps)

Whereas also a Briggs 4 screw carb PUMP can Usually be kitted while the carb is still on the engine and the complete kits even with the pump body are more readily available. (3 screw pump bodies and parts are not as user friendly and not as cheap).
First most any small engine pulse pump will work with the modded carb. I have used the $5 China pulse pumps with good results.
I was working on some Briggs carbs yesterday and seen one that looked like your pic as a 4 screw pump type.
The ones I've been modding are the 3 screw types so the 4 screw will be little bit different in the steps, but basically going for the same thing.

Next
I seen that China is NOW cloning the COMPLETE 4 screw Briggs carbs for around $30 as 693480, 693479.
4 screw Fuel pump kit 693502 @ $11
complete pump body 693487 @!5
4 screw Carb overhaul kit 693503 @ $10 This includes both the carb gaskets and the pump kit.
 
Actually Arkie you can put the fuel pump inline with the existing carburetor pump I have seen it done on an old Lowes MTD rider here. The carburetor's fuel pump check valves will not prevent the external pump from working.

These horizontal opposed carburetors quite rare around here now.
 
Right them old Briggs twins with pump are getting rare but I just happen to see that China is cloning the 4 screw for around $30 as posted above.

I do not remember just why but I tried the pulse pump on a three screw by just connecting to the existing pump and I did not get any gas to the carb. I might could have cut the little flappers off the pump section gasket inside but the 3 screw that I converted had one of the pump casting ears broken off and it came to me with no pump and no way of attaching a pump.

That is a good point, the OP might try just connecting a pulse pump to his input 4 screw pump's input and might even be able to do a mod to the inside diaphragms and see if he can get a pump through plus no external leakage using a cheap pulse pump.

Like you indicate them old Briggs pump type carb's carb's are like playing with a dinosaur egg and we already know what happens when some of the China cloned dinosaur eggs HATCH.
 
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