im putting a perry oscillating pump on my 4cycle and im wundering if pressure will hurt it in any way. it doesnt say not to use it in the instructions, im just wundering what is the best way to do it.

thanks

The Perry oscillating pump doesn't create enough pressure to foul up the carburetor on your 4-stroke. It creates just enough to get fuel to the spraybar.

Muffler pressure not needed with the pump.

let me clarify, im not worried about my engine getting messed up, im asking how pressure on the tank will affect the perry oscillating pump. will it help, will it mess the pump up, will it do nothing?

thanks

It will work, I used one that way. BUT, the tank pressure from the muffler is often greater than the pump's output. So the pump will only be boosting the pressure at idle through midrange. Apparently the diaphram cannot take this pressure for long, as my pump only lasted a year and a half this way.

thanks for the info, ill try it both ways and post the results.

You may not know for a year or so, when the diaphragm has a hole in it!

well, if ther isnt a SIGNIFIGANT gain with the pressure then im not gonna continue using it.

Jody, it will do nothing for it, you won't be able to tell the difference. The regulator part of the pump will prevent the increased pressure from passing but it will expand the diaphragm and eventually ruin it. I was just too lazy to run a vent tube from the top of the tank to the bottom of the cowl. Since silicon will just flop around, you need to secure it, or use brass tubing from the tank to the bottom of the cowl.

Hello,
When I added a Perry Pump to my Saito 1.20 , I took the line from the muffler and ran it through a tiny "eye" bolt on the bottom of the fuse. This keeps the line secure. I was concerned about it siphoning fuel but it doesn't seem to be the case. I removed my muffler and just ran the header part of the pipe. Not sure if I picked up any by removing the muffler but it sure sounds better (no noise restrictions at the field). The engine used to run REALLY lean before the pump. One of the best purchases I've made this year...

The Perry pumps make about .25 lb of pressure, also the muffler pressure would not hurt the diaphragm at all, when and if the muffler pressure exceeded the pump pressure the fuel would simply flow through the pump like it does when you prime the engine. No big deal.

Hobbsy,
Perry's instruction sheet says not to install the muffler pressure. Since it works fine with the pressure and my pump failed early I am assuming that using muffler pressure does damage. Yes you can run fuel through it, the instructions warn against that also. Since there is definately a restriction that gets worse the harder you pump, I am assuming that the fuel flow is restricted to .25 lbs even if pumped through externally.

my instruction sheet for my oscillating pump DOESNOT say "do not use muffler pressure"

the instruction sheet on my pressure drivin perry pump DOES say "do not use tank pressure"

are you sure your talkin about the oscillating pump, i searched the perry website and still didnt find anything about the oscillating pump and tank pressure.

Jody,
As the old lady on Saturday Night Live would say. Neever Mind!
The oscillating pump does not use a diaphragm, or I don't think it does. If not I don't think there would be a problem using muffler pressure.

The Perry VP 30 has a diaphragm that responds to alternating positive and negative crankcase pressure pulses, the Oscillating one has weight that slides back and forth in response to tortional engine impulses and does not have a diaphragm, just a couple of one way check valves.