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Discussion Starter · #1 ·
Hello everyone,

With riding season around the corner, my buddy and I decided to get the sled back together and see if it would run. We knew we had a fuel supply issue from the previous year so I brought a funnel contraption to feed the fuel with gravity. With this setup the sled ran fine but as soon as I'd bring the funnel down at gas tank level ,fuel was no longer being sucked in and it would eventually die.

This would mean it's either a pulsing issue or a fuel pump issue. We rebuilt the pump last year so I imagine that was good to go, We checked for pulse by placing our thumb at the end of the hose; with plugs out we would feel a tiny pulse; with the plugs in we couldn't feel any pulse, this was done by pull start. Would this point towards a pulse issue which doesn't allow to draw fuel? Is there a vacuum test I can do to see what vacuum I should be pulling?

I'd check pressure that's coming out of the pump from one of the fuel supply lines but the issue now is that we broke the nipple off the pump when removing the pulse line.

If I run a compression test and everything checks out up there, it would most likely mean that the crank case seals are shot correct?

How much pressure does the pump actually put out when working correctly?

Thanks!
 

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Sounds like you are on the right track. Sometimes pump rebuilding works and sometimes it doesn't. Depending on the model fuel pumps are not that expensive and it may be worth it to just replace the pump. It would eliminate that as a suspect.

As far as crank seals, the easy test is to spray ether and listen for rom change. Be careful doing this, especially because you are already risking a fire running the sled on a funnel.

Sent from my SM-G996U using Tapatalk
 

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Discussion Starter · #3 ·
Sounds like you are on the right track. Sometimes pump rebuilding works and sometimes it doesn't. Depending on the model fuel pumps are not that expensive and it may be worth it to just replace the pump. It would eliminate that as a suspect.

As far as crank seals, the easy test is to spray ether and listen for rom change. Be careful doing this, especially because you are already risking a fire running the sled on a funnel.

Sent from my SM-G996U using Tapatalk
Thank you for your message, I ordered a new pump to eliminate that possibility so time will tell. I also got the compression tester from my cousin so now it's just to find the time to go to my buddies to run the tests.

Do you mean to spray ether at the seal area? Then if the revs pick up then I have a bad seal at that area.

Thanks
 

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Yes for the seals. It can be tough to check the mag side, opposite the clutch.

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Discussion Starter · #5 ·
Yes for the seals. It can be tough to check the mag side, opposite the clutch.

Sent from my SM-G996U using Tapatalk
I would have to pull the pull start cover for the MAG side. If I have good compression, with the new pump installed and still having the issue then I'm 100% positive it's the seals. The decision is do I want to do a full tear down or just throw a low pressure 12V fuel pump for this season lol
 

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if the seals leak enough to cause no pulse signal. then surely it will suck to much air , and run super lean , ie nuke it, remember one thing ,any short cut you take at this point will cost you double later , id just pull the motor and do it
 

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Discussion Starter · #7 ·
if the seals leak enough to cause no pulse signal. then surely it will suck to much air , and run super lean , ie nuke it, remember one thing ,any short cut you take at this point will cost you double later , id just pull the motor and do it
Good call, I didn't think about it that way.
Thank you for waking me up lol I have a feeling I will end up pulling the motor in the end.

I'll keep this thread updated as I go
 

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Keep in mind that being a triple, there are crank seals between the cylinders also.. I believe with the ultra engines you can't mix up the cranks with the cases or the seals don't line up properly ( I.e. use a 1997 crank in a 1996 case).. I've seen this on YouTube, there is a guy who only does polaris triples and he found out. ( search "wet basement" on YouTube)

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Discussion Starter · #9 ·
Update*

I was able to go over to my buddie's place yesterday and installed the new pump. To my surprise, the sled ran perfectly on it's own drawing fuel from the gas tank! What a relief, I don't have to pull the motor. I already have three dirt bike motors I'm currently working on lol

Next on the list is replacing the fluid in the chain case and taking her up to the cottage. I will be changing the track over the summer for the following season.

Cheers
 
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