5HP briggs fuel pump set up.

[Sprocket86]

I'm planning on putting together a 5hp I/C Briggs with a Tec carb and 691922 intake.

The mini bike I plan on powering with this has a nice small round fuel tank that will gravity feed the float style tec carb.

The problem I'm seeing here is that the carb height relation compared to the fuel tank outlet isn't great enough for proper
gravity fuel flow.

How many different configurations of fuel pumps are there? Do some flow more than others? I don't want to much pressure and volume and over power the needle and seat.

I plan on using a B&S 696126 crankcase breather with the fuel pump fitting but not sure what 3 nipple fuel pump to use.

Thanks.

 

[Sprocket86]

Here's the bike I'm din the build on.

 

[CarPlayLB]

You don't need a lot of flow from the pump for that carb. Does your intake manifold have a 1/8" NPT fitting in it? If not, you can use a pulse from the valve cover to run the pump.
The typical pulse pump with have 3 fittings and most are labeled. The one with the < facing the pump is the fuel inlet side and the one with the > is the output. The 3rd line gets connected a pulse source, like the valve cover. You can also put a pulse port in the sidecover of you wish. the Walbro pump is a good choice
https://www.OldMiniBikes.com/walbro-fuel-pump.html

 

[Sprocket86]

Does your intake manifold have a 1/8" NPT fitting in it? If not, you can use a pulse from the valve cover to run the pump.

No as it's the thremoplastic resin B&S intake. I do plan on using the breather cover for a crankcase pulse signal. Briggs makes a breather cover with an extra tapped fitting for fuel pump use.

That Walbro fuel pump looks like what I need.

Any idea how much pressure these generate and are they fixed displacement?

 

[danford1]

If you are worried about fuel pressure you can use the return line method. You put a Tee in the line going to the carb. Then run a line from the Tee to a new barb on the tank. The un-needed gas will recirculate back to the tank.
You add the fitting to the top of the gas tank. Make sure your gas tank cap is vented.
However, I have run these pumps straight to the carb on multiple engines and never had a pressure problem. They just work great.
Danford1
https://www.ebay.com/itm/Fuel-Pump-Briggs-Stratton-808656-Mikuni-808462-Engines-Pulse-Style/282452399844?epid=2141765796&hash=item41c37996e4:g:l1YAAOSww5NZBBo3:sc:USPSFirstClass!48386!US!-1

 

[Sport King Eric]

On one of my bikes I run the exact Setup your talking about using.. I have a stock Briggs & Stratton valve cover with the port fitting.. into a Mikuni 3 port fuel pump.. this setup is very reliable I have no known issues and its plug and play.. even if there was extra pressure the fuel pump is vented to allow for this.. I don't believe there is a displacement limit as these same pumps are used on a wide group of small engines, from snowmobiles to lawn and garden equipment.. I went with the Mikuni over the walbro because of the OE Briggs & Stratton Part number.. but I doubt there is much difference...

 

[Havasu Dave]

This bike used a Walbro pump that was mounted in the shroud, above the flywheel out of sight. It will fit. Holes were drilled for the two rear hoses, which were equipped with rubber grommets. Carburetor was a "Chi-kuni" and I had no problems with the pump over powering the float valve. Pulse input was via nipple on the intake manifold, but several have reported successful pumps using the crank case.

 

[Sprocket86]

Hey thanks for all the info and help. I'll call my local small engine shop today and see what they've got.

By Looking at the photo a few times, I'm wondering if I'll even need a fuel pump to assist with fuel flow. The tank might be sitting high enough in relation to the carb.

I'll do some experimenting today.

 

[Sprocket86]

This bike used a Walbro pump that was mounted in the shroud, above the flywheel out of sight. It will fit. Holes were drilled for the two rear hoses, which were equipped with rubber grommets. Carburetor was a "Chi-kuni" and I had no problems with the pump over powering the float valve. Pulse input was via nipple on the intake manifold, but several have reported successful pumps using the crank case.

View attachment 105682

Thanks Dave. That bike is a wild machine with that front end and I like how you hid the fuel pump in the fan shroud. Never though of doing that.

The layout of the carb and fuel tank is very similar to my "Sprocket" mini bike I posted above, heck even has the same power plant. Perfect to know this worked out for you.

 

[Havasu Dave]

Thanks Dave. That bike is a wild machine with that front end and I like how you hid the fuel pump in the fan shroud. Never though of doing that.

The layout of the carb and fuel tank is very similar to my "Sprocket" mini bike I posted above, heck even has the same power plant. Perfect to know this worked out for you.

I restored the bike, thanks. It's a Taco 99 with an original trail tamer on it. Randi (125ccCrazy) built the engine, and I bought it from him. It was a dual bearing IC engine, but had all of the hot rod internals, and radical Dyno cam. Forget which one, but I had to use leather gloves to start it. It made some great power, but I cant take credit for the engine.

 

[Sprocket86]

Leather gloves to start it eh! Some major compression with that radical dyno cam. I did a similar mod to a Tec HS-50 and it required the same starting technique.

It became a pain in the ass after while and I returned to stock.

I've though about doing a "mod" build on this I/C dual BB 5hp Briggs but my Camaro is stealing all the extra hobby funds.