Fuel pump pulse type

Must be some small engine gurus here. Got the latest toy home and been mucking around with it. Its a gokart with a modified honda gx200. At high revs it seems like its running out of fuel. Im a car guy so the basics are similar with a few different little things. Im wondering about this pulse fuel pump. Where would the best place for it be to run at high revs? Some people run them off the inlet manifold which I would of thought would be vacuume at high rpm, and I see some people run it of the crank case?

Wouldn't an electric high preasure lift pump be the answer?
I've got a similar problem i need to solve on a deisel landcruiser project that is nearly complete. I believe that in my case it should be just after the fuel tank

Where’s the tank?

What is the physical situation in which its feeling like it's running out of fuel? There's a few things in these that can create running issues, generally if there's a fuelling problem the little sods are a real bastard to start.

Can you describe the situation a bit more?

The go kart doesnt have a battery or charging system so an electric pump is out.
The tank is between your legs like a race kart.
Yep it seems a bit of a prick to start. Driving along it will be ok at low speed floor it and it will go for a bit and then die out take your foot off the gas and it will idle along at slow speed. Floor it and leave you foot down the engine will die and stop

Have you stripped the carby out and given it a proper clean? And, has the governor been removed or is it still fitted?

Govener is removed its got a billet flywheel and rod. 1 to 3 rockers stronger valve springs head had a bit taken off it and 22mm mikuni. Im going to take carb off it and go over it at work.

Yep - pilot jet not functioning correctly can do this, certain models of this engine can have the pilot jet rotate slightly which misaligns the holes in it.

Another test is rig up a small tank above the engine and plumb it in to check if gravity feeding cures the issue - that will tell you if a pulse pump might help.

Its not the standard carb. It already has a pulse pump on it. Was wondering if inlet manifold was the best place to run the pulse line

Crank case, no pulse on the intake

Thats what I was thinking

Yep, off the crankcase for a pulse take off. Same theory as a two stroke motor like the chainsaws... Probably need to drill/tap in, I don't think there is a factory port on these?

I can just tap the hole where the govener used to be

Been watching this thread with mild interest. What you are calling a pulse pump is a vacuum pump as fitted to various scooters, chainsaws, stationary motors et all. They are powered by the vacuum pulse generated by the intake manifold or crankcase of said engine. There will be a port on the intake manifold or crankcase ( above oil level )somewhere. If the pump fitted to your machine isn’t working correctly chances are the diaphragm or spring is fucked or been refitted incorrectly. Also, some engines such as yours are very sensitive to incorrect valve clearances and will give these symptoms. For context, I work in a Honda/Stihl dealer w/shop dealing with these problems regularly.

Cool thanks for the info. The pump im refering to gets a vacuume or pressure pulse from the engine that operates a diaphram that pumps the fuel. It seems to work if I lightly suck and blow on the pulse line.

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Originally Posted by blip

Cool thanks for the info. The pump im refering to gets a vacuume or pressure pulse from the engine that operates a diaphram that pumps the fuel. It seems to work if I lightly suck and blow on the pulse line.

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Yep, lightly suck on vacuum line. Not too hard, it’s only a light spring. If diaphragm has gone a bit hard it will pump but at a reduced volume. Make sure hose is tight on fittings. Pump kits are cheap as if needed. As said before, check valve clearances, they can be fussy little fuckers those engines. Good luck.

Exactly right, they can start being a pain in the arse with very little notice or warning - and then you might not find out what was causing the issue after the third time checking everything out and the damn thing starts running like nothing was ever wrong!!!

Having the aftermarket work that you'e listed on yours, I am going down the fateful track of assuming that the valve clearances, head condition, rings, cylinder are all good and obvious things like the spark plug and magneto/kill switch setup aren't playing stupid games.

I haven't seen one of these with a factory pulse take off as the factory carby relies on gravity feed to the fuel bowl, but the logic in tapping the governor rod hole and using that is sound. That should provide enough fuel to get the thing running right, but then again... A possibility is a marine style primer bulb in the fuel line, a couple of pumps before starting to get enough fuel in to get the thing ticking over?

Its a bit of a learing curve which is half the fun. I just prime it by blowing on the fuel tank breather