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Having a fueling issue on my 07 660 rhino. I replaced the fuel filter a couple weeks ago. Just used a 1/4" inline filter from autozone. But it feels like it's starved for fuel at 3/4-full throttle. Surges more or less. I've cleaned the tank out and waiting on a new billet pickup for the tank.

My question is, any ideas on the surges? Also the inlet to the pump from tank is a 5/16 nipple, should I have a 1/4-5/16 filter? The pump/fueling system is factory as far as I know. Only had it a few weeks and I'm trying to fresh'n her up a bit.
 

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never had a problem with the filter being to small and I run fram g2 I believe from Walmart, but mine had a similar problem once that turned out to be bad old fuel, the size maybe a restriction when running wot
 

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........ Also the inlet to the pump from tank is a 5/16 nipple, should I have a 1/4-5/16 filter? ........
It is quite important that you do not have any air leakage into the suction side fuel line from tank to pump. Too small of a barb for the hose makes it difficult to clamp the hose small enough to actually fully seal the gap between barb and hose I.D. This will aggravate the difficulty in the pump establishing a prime after the machine has sat unused for a while. This likely not to be the problem that you see now, but may be a problem further down the road.
 

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Well I actually have had that issue and found a couple places that have were drawing in air. The short hose that was between the filter and pump actually sealed well to both the 1/4" and 5/16 barbs but was very weak and thin. I'm going to pick up a 1/4-5/16 filter and replace that hose w a longer piece to allow easier access to the filter for now.

Eventually I'd like to up grade the fuel system. With a stock set up (motor exhaust carb etc) are there any suggestions you might have? I've looked at the high flow kits, but didn't know if that was the right choice.
 

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While I think Steve is spot on here (he has a great wealth of info) with an air leak issue, I want to add my recent short comings with fuel. Last year, we had many dnf's (did not finish race) due to fuel issues and wasted thousands of dollars attempting to cure the problem. Finally after a year of research, we make our own filters, cartridges and housings, in house. Our filters range from 40 microns to 10, all stainless steel. What we found is that the more ethanol is used in our fuels, the more water tends to be absorbed. It is the water in the fuel that breaks down paper fuel filters and cause clogging/surging just like you have described earlier. My advice is to steer away from paper filters if you can, especially critical for fuel injection.
 

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While I think Steve is spot on here (he has a great wealth of info) with an air leak issue, I want to add my recent short comings with fuel. Last year, we had many dnf's (did not finish race) due to fuel issues and wasted thousands of dollars attempting to cure the problem. Finally after a year of research, we make our own filters, cartridges and housings, in house. Our filters range from 40 microns to 10, all stainless steel. What we found is that the more ethanol is used in our fuels, the more water tends to be absorbed. It is the water in the fuel that breaks down paper fuel filters and cause clogging/surging just like you have described earlier. My advice is to steer away from paper filters if you can, especially critical for fuel injection.
Great info. Thanks.
 

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Well I actually have had that issue and found a couple places that have were drawing in air. The short hose that was between the filter and pump actually sealed well to both the 1/4" and 5/16 barbs but was very weak and thin. I'm going to pick up a 1/4-5/16 filter and replace that hose w a longer piece to allow easier access to the filter for now.

Eventually I'd like to up grade the fuel system. With a stock set up (motor exhaust carb etc) are there any suggestions you might have? I've looked at the high flow kits, but didn't know if that was the right choice.
When you upgrade the fuel system, replace all of the hoses with clear (tinted is fine) polyurethane tubing. Polyurethane is gasoline resistant and is UV resistant and will last a lot longer without hardening up or degrading. The see-through hose allows you to see the fuel flow bubbles which makes diagnostics much easier.

The loss of prime is the biggest issue with most people. You can put in a marine squeeze bulb pump between the tank and the pump. Or, put a low pressure electric pump in between tank and existing pump to use (momentary switch) just before cranking the engine. Both of these approaches address the priming problem well and provide an emergency means of getting you home if the pump fails while you are out in the boonies. The high flow vacuum operated pumps help, but do not really solve the long cranking issue with loss of prime, but are liked by a lot of people. And of course, the existing pump can be replaced with a low pressure electric pump. This approach has the disadvantage of continuing to run with the engine off, should you be unable to turn off the ignition switch.

Do not eliminate the Y fitting, with it's fuel return line. This is actually what regulates the fuel pressure to a quite low value to simulate the gravity fed fuel system in a motorcycle, which is what the stock carburetor was designed for. It is a good idea to reroute the return line to be angled upward and loop up several inches above the stock fuel pump location before angling downward and returning to the tank. This gives the fuel level the appropriate "head" pressure to simulate that tank just above the engine on a motorcycle. An annotated snip out of the 660 service manual below graphically shows this looping:

 
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