Duromax 16hp dual fuel pumps

nujac

It looks like I found a solution to my fuel delivery problems without purchasing a new larger fuel pump. I had a spare fuel pump that I installed in line with the current fuel pump. The first pump uses vacuum from the carb main intake and the second pump uses vacuum from, the valve cover. I also use a T in the line before the carb to send any extra fuel pressure back to the top of the gas tank.

I took a 6 mile ride up and down a lot of long steep hills and it did not have any problems. I also removed the governor to see if it would run out of fuel at full RPMs going up steep hill and it did fine. I always wonder if this would work and it does.

Its better to be lucky than good.

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JcXtreme72

Thanks for the tip

sho305

If it works it works! Kind of strange it had that issue to start with, those pumps should be able to supply a lot of fuel.

nujac

After having problems with the standard fuel pump I borrowed a 10hp vacuum fuel pump off my 10.5hp pull behind brush mower. With the top speed set at 25 MPH I had no problems. However I normally have the top speed set at less than 10 mph for safety when the kids ride the golf cart. It may be that taking vacuum off the valve cover at low RPM is not the best thing.

I plan on removing the 10.5 hp vacuum pump and installing another of the 8 hp pumps I have laying around to see if I can keep all of my stuff running without swapping parts.

sho305

A pulse off the rocker cover or anywhere on the block will pump more fuel with higher rpm. Pulse on the intake will pump more at idle and less at higher rpm. Have to be careful with the rocker cover as part of it is vented and part not, which would change the signal.

nujac

May be with this dual pump setup I have the best of both RPMs for pumping.

army

Good info nujac. Thx for posting it. I like your double coverage thinking. The intake option seems the best bet for me. I make the occasional banzai run down the road from my place to my old dad's but I do 95% of my riding at slower speeds around our farms. I had open heart surgery a few years ago and they messed up my chest nerves. Fence lines and ditch bank areas are too bumpy to drive fast now and no Dukes of Hazard creek jumping for me either. I tried an electric fuel pump and a regulator on my 390 clone but it overpowered the carb float/needle valve even with a 3/8" bypass line back to the tank. I'm gonna try a pulse pump today. I already have an intake adapter and pump so it's just matter of hooking it up and seeing what happens.

Has anybody tried using one pump and two vacuum sources at the same time, like a pulse tube tee'd off to both the intake and valve cover?

nujac

I did not think about the T idea.

army

Should work Nujac but it's just a theory. Never tried it myself. My intake pulse pump set up is working great. I used the pump that was on the cart (90 EZGO) when I got it. Didn't know if it still worked but it seems fine. I put several miles on the cart after hooking the pulse pump up. So far so good. Idles along nice and will run wide open without fuel starvation.

Here's a trick I learned years ago for priming the fuel pump on lawn tractors by lightly pressurizing the tank. To do that I drilled a small 1/2" hole in a spare gas cap that was the right size for the golf cart tank, then I put a short piece of 3/8 ID rubber hose on the tip of my blow gun. Next I started the engine (still had gravity feed gas tank hooked up) and put the modified gas cap on the tank, then inserted the rubber line on my blow gun in the modified gas cap. I squirted a little air in the tank and nothing, so I squirted a bit more in there and the fuel started flowing out of the pump's outlet hose. It was slow but steady. Just right for a 390 clone carb.

Be very careful and only use small amounts of air. You could burst the seam on the tank if you use too much pressure (not good with the engine running!). You just want to gently coax the fuel up the suction line to the pump.