M7 Fuel Pickups?

xmmm6 · Feb 28, 2011

I recently purchased a M7 and had it out yesterday on a long ride and ran great all day until I let a friend ride it back to the truck. When we hit a straight away I decided to pass him hard. When he punched the M7 it reved and then peaked at a lower RPM like it was not getting enough fuel. I rode it and could reproduce it on only on hard acceleration. I thought it was almost out of fuel. So I fueled it up and it only took about 7 gal. When refueled I took it up and down the street and it ran perfect again.

Do I need to clean or replace the fuel pickups in the tank? Anything special I need to know about inspecting them? Is this just the nature of the M7 fuel system, which I will have to live with?

offroadmatt · Feb 28, 2011

Sounds powervalve related to me. My older M8 does that very same thing sometimes. Usually in a drag race. Everytime its ended up being something with the powervalve cables. Just my thoughts.

xmmm6 · Feb 28, 2011

offroadmatt said:
Sounds powervalve related to me. My older M8 does that very same thing sometimes. Usually in a drag race. Everytime its ended up being something with the powervalve cables. Just my thoughts.

When back in the hills with more fuel in the tank I had no problems making hard WOT climbs and WOT tail pulls. It only did it at the end of the ride when the tank was lower. Could that still be a power valve issue? I will check them just to be safe though, thanks.

offroadmatt · Feb 28, 2011

I wouldn't think its fuel related. The only way you could check that is to install a fuel pressure gauge. The only time mine gives me trouble is when I punch it from idle or around 4000 rpm. If I feather the throttle thought the power valves opening it will work fine.
Not sure on the M7 but the cables get really hot on the M8 and melt away the housing. Which I think makes the cables sticky inside. Causing the servo to function improperly. Seems like the servo only pulls a certain amount of pressure instead of a certain amount of distance. (If that makes sense.) So when it feels that extra resistance from a fraying cable or melted rubber it quits pulling. Which could be 1000 rpm's from peak.

Hope it helps. Matt

xmmm6 · Mar 2, 2011

offroadmatt said:
I wouldn't think its fuel related. The only way you could check that is to install a fuel pressure gauge. The only time mine gives me trouble is when I punch it from idle or around 4000 rpm. If I feather the throttle thought the power valves opening it will work fine.
Not sure on the M7 but the cables get really hot on the M8 and melt away the housing. Which I think makes the cables sticky inside. Causing the servo to function improperly. Seems like the servo only pulls a certain amount of pressure instead of a certain amount of distance. (If that makes sense.) So when it feels that extra resistance from a fraying cable or melted rubber it quits pulling. Which could be 1000 rpm's from peak.

Hope it helps. Matt

This was more like a mild sputter not just a reduction in RMP. Checked the power valves tonight and everything functions smooth. Valves were pretty clean but now they are really clean. Cables are in good shape no kinking or fraying and moved with ease. Doesn’t hurt to check them out.

My next step will be to drain the tank and inspect the pickups. I read some pickups have a smart valve that can cause issues if dirty. With a full tank I was not able to replicate the problem, pulled really hard.

Mjunkie · Mar 3, 2011

I have pulled mine out a couple times to clean the screens on them because I once had them plug up with crud and caused me to go lean and sieze:face-icon-small-fro, so it is something good to do from time to time.

xmmm6 · Mar 4, 2011

Mjunkie said:
I have pulled mine out a couple times to clean the screens on them because I once had them plug up with crud and caused me to go lean and sieze:face-icon-small-fro, so it is something good to do from time to time.

Thanks for the advice. I was going to drain the tank the fun way but now I will siphon the tank and clean them before the next ride.

xmmm6 · Mar 5, 2011

Well I finally had a chance to drain the tank and remove the pump and pickups. Upon removal I found the front pickup was the only one letting fuel drain out. The rear two pickup valves were stuck in the closed position. I disassembled them and cleaned them up to where they operated smoothly. There appeared to be a barely noticeable amount of varnish buildup to cause the valves to stick closed. Filter screens were surprisingly clean. I am going to throw some Sea Foam in the tank today for good measure.

How often should one check and clean the pickup valves? Should it be a routine maint item or done when the sled starts acting up?

Mjunkie · Mar 5, 2011

I haven't always done it, but my goal has been once a year before I start the season to hopefully prevent future problems. I have no idea if there is a regular maintenance schedule from arctic cat or not as to how often it should be done.

SaberKitty · Mar 6, 2011

On the smart valves in the tank, stretch the springs out to more of a ballpoint pen length. This allows more resistance before it shuts off fuel and if they do pull up water or goo and stick closed, it helps them pop free more quickly.

Another little trick I did was pull the little white disc off the smart valve so if they do get suck closed due to water or debris, they won't shut the fuel off at all. Instead of smart valves, I've now got smart screens. :face-icon-small-hap

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M7 Fuel Pickups?

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