Center fuel tank, pump needed??

[MidNightIllusions]

I have a 5hp briggs and stratton engine (older model) with fuel return (tank sits under the carb). I'm just wondering if I mounted a fuel tank between the legs of a driver will the stock fuel diaphragm pump suck the fuel up?

Basically what I need to know is if I mount a tank lower then engine will I need a fuel pump. Also if so what kind of pump shall I need?
Skidoo pump runs off vacuum, where do you get vacuum source if it would work/need?

Thanks gentleman.

 

[Gokartbill]

If you are relocating the fuel tank, you will need a fuel pump. Especially if its lower than the engine. I doubt the stock diaphragm will be able to pump the fuel that distance. So it would be wise to get a new carb since you are eliminating the under carb tank. Either a briggs ohv carb or a Honda clone carb with a custom intake. I had that same question awhile ago too

 

[MidNightIllusions]

Oh ok. I thought so. So would a Skidoo fuel pump work? If so where do you get the vacuum source from?
Or what kind of fuel pump do people use on them?

If I change the carb would I have to change the main fuel jet, cause I'm thinking it would be too much fuel???

Thanks for the reply

 

[Gokartbill]

Im not sure if a skidoo pump would work. The "pulse" would come from the tube coming out of the valve cover under the exhaust and intake ports on the side of the engine. Walboro makes a good fuel pump for 20 bucks on ombwarehouse.com. For the carb, get one around the same 5hp rating and it sould come with a proper jet size

 

[anderkart]

Pulse fitting in the Intake manifold:

 

[MidNightIllusions]

That's a sweet engine.
What do you mean by pulse fitting.

 

[Gokartbill]

You can hook up your pulse line either from the carb intake or the valve cover. Yes, the intake idea is cleaner meaning that no oil will be able to get inside your pulse pump. If you are doing the intake route you will need a intake designed with pulse fitting. A "pulse" is the action of the gas getting sucked up from the fuel tank. Its similar to a rapid sipping action you would use if your where drinking a think slushy through a straw. That's my only idea of how to describe it. Someone might have a better way of explaining it.

 

[jandj]

If you have an "old" B&S, it's a flathead and doesn't have a valve cover. For about $10 or less you can buy a fitting that screws in the oil fill hole and uses crankcase pressure to run the pump. Some folks don't like them because of the length of the line but there's about a million people using them without a problem.

 

[MidNightIllusions]

Thanks
I know what pulse is haha. It was referred as a fitting. That's why I asked. Is there a pulse fitting?

 

[mckutzy]

Not a specific part, but just a hose barb that fits the hose, drill/tap a hole for it to fit into.

 

[MidNightIllusions]

Yes it is a flat head.
So you'd need a different style pump that uses pressure rather then vacuum. This is why I was wondering what I'd need.
So what small pump is needed that uses pressure rather then vacuum.

I'm sure I could spend hours researching it, but I thought I'd ask the people that have already used this setup before.

 

[jandj]

Yes. There is a pulse fitting. You have to buy one and install it yourself....for example, look at www.pfmparts.com/4-Stroke/Flathead for the screw in type.

 

[MidNightIllusions]

Oh ok well that's easy enough I have hose barbs. Lol

Just need info on a small enough pump that uses pressure over vacuum.

I really appreciate the help from everyone.

 

[jandj]

For $30 get a Walbro or Mikuni fuel pump and the pfm pulse fitting and be done with it. You'll save yourself a lot of aggrivation.

 

[MidNightIllusions]

Oh ok great. So just spent a few mins on Google.
What everyone calls a pulse fitting looks to be just a brass hose barb like you said.
Why would they call it a pulse fitting when really it's not that at all lol. The first thing that comes to mind when I read that was a fitting with a check valve built in. Haha

Oh well thanks for the help clearing this all up

 

[jandj]

It's called a pulse fitting because wherever you install it, it allows you to run a line to your fuel pump that uses the "pulse" of alternating vacuum/pressure ( be it crankcase or intake) to get fuel from your tank through the pump to your carb.

 

[MidNightIllusions]

Awesome. Thanks for the helpful info buddy.

 

[mckutzy]

There are some barbs that do have a check valve ball in them. I had a look at some catalogs at the auto parts store awhile ago, there are some in the air/oil/gas fittings book.

 

[MidNightIllusions]

^^ Yeppers I have actually used them before. That's why I was all effed up lmao

 

[porsche930dude]

the pumps pump with a pulse. weather that pulse comes from the intake vacume or the crankcase pressure it doesnt matter. i dont know if youll be able to use the puleajet carb without the tank. i think people have done it but its not ideal. id use a tecumseh adjustable carb . but the biggest problem iv had with fuel pumps on carbs that cant handle the pressure and blows the float needle open flooding it up. iv fixed that problem by making a bypass hose at the carb inlet back to the line before the pump. it blows any extra pressure back to the tank. if at all possible you should avoid having to use a fuel pump. gravity fed is just so much easier and simpler