Jet outboard troubleshooting

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Crankbait

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Hello guys. New to owning a jet outboard and I'm having a small issue and I hope I can get some input here. I bought a new blazer 1752 with a 60/40 4s mercury this year and love it, but the last few trips out I noticed my rpms are higher then normal. It usually runs 5200 but now I'm pushing about 5300 or 5400. I've made sure the bottom of the boat isn't dented, the grate is clean and none of the teeth are bent. However the liner does have some grooves and the leading edge of the impeller has some dings but isn't that bad compared to the ones I've seen online. It has about 40 or 50 hours on it. I've had a couple of accidents where it had sucked up some gravel in the river but I wonder if I need a shimming and sharpening of the impellar. Will a worn impellar and liner affect rpms? I haven't took the impellar off but with the liner and foot off I cant see anything inside the jet housing. There is nothing in the exit of the jet either but i really noticed the change after the weather cooled off and water temp has dropped. I'm real mechanically inclined but this thing has a 5 year warranty that covers everything except liners and impellar so I dont want to go real deep into it so will more then likely end up in the shop but i want to learn all i can about it and more then the basic of how it works. Any and all input is appreciated and i hope the pros will chime in. Jets are rare in my area and I've herd of a few guys having them but have never seen another one on the river or lake.

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If your on Facebook I suggest go to semo jet boat enthusiast page and join. Unbelievable amount of knowledge on there. I would ask your question and you will get several relies. Several dealers, mechanics, fabricators are members and always chime in and are very helpful. I live in south central Missouri and just about everyone owns a jet. I have a 1852 blazer ss with merc 4 stroke tiller. Love it. I am NOT mechanically inclined so sorry, I can’t help you. I take mine to a guy once a year and have him sharpen impeller and check liner clearance and all that. So many rivers here that we have to use jets.


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I'm one of the few in this good world that doesn't have Facebook. Dont have time for it. I went to the lake yesterday and fished a while. Same thing still going on. Running about 53 or 5400prm so I just stayed back out of the throttle. I read on outboard jets that a impeller with blunted blades will cause high rpms. I've had the foot and liner out again a few days ago and found nothing other then some gouging on the liner and the little damage on the impellar. I'm going to call the shop tomorrow because I seen how backed up with lake life boats and see how long the wait is. I work alot and rarely ever get more then a few hours of fishing at a time. I would still like to hear about others experiences. Usually if you read on the problems people have they hardly ever come back on post on forums what the solution was. I swear guys that I will. Lol

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Wear on the impeller and liner will affect rpms. I've also heard as these new 4 strokes break in somewhere around the 40 hr mark they produce a few hundred more rpms.

Definitely get it checked out to be sure, anything other than the liner, impeller, or shoe should be covered under warranty if there is an issue.

Welcome to the jet world.
 
Went to the shop yesterday but they are really behind winterizing the idiot boats. I talked to one of the mechanics I know there and he said the want nothing to shimming and sharpening the impellar so I grew a set and deciding I'd do it myself. Pulled the foot and liner out, folded the ears on the keeper back, and broke the nut loose. Shims came off and impellar slid right off too. I took a flat file and counted my stokes on each blade of the impeller and just cleaned the burrs from rocks off. Took a piece of fine sand paper and hit the liner a few times around. Put 2 shims on top of impeller and checked fitment but was rubbing the liner so I pulled 1 off the top and put it back on the bottom and everything seems to be alright. Gonna try to test it out in a few days. 2 days of trick or treating with the kids and 2.5in of rain coming this week so maybe I'll get out the weekend. Will update you guys then.

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Crankbait said:
Went to the shop yesterday but they are really behind winterizing the idiot boats. I talked to one of the mechanics I know there and he said the want nothing to shimming and sharpening the impellar so I grew a set and deciding I'd do it myself. Pulled the foot and liner out, folded the ears on the keeper back, and broke the nut loose. Shims came off and impellar slid right off too. I took a flat file and counted my stokes on each blade of the impeller and just cleaned the burrs from rocks off. Took a piece of fine sand paper and hit the liner a few times around. Put 2 shims on top of impeller and checked fitment but was rubbing the liner so I pulled 1 off the top and put it back on the bottom and everything seems to be alright. Gonna try to test it out in a few days. 2 days of trick or treating with the kids and 2.5in of rain coming this week so maybe I'll get out the weekend. Will update you guys then.

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That should help it, knowing how to remove, sharpen, and shim your own impeller is imperative if your going to continue owning/running an obj. If you search on here there are a couple of older threads that have pictures and descriptions of how to sharpen. lil blue rude prefers to sharpen what would be the top of the leading edges of the impeller vs the bottom as obj recommends on their site. I prefer this method as well the leading edges the ones that are picking up water so the ones on the bottom when the impeller is installed sharpen the the top of them.
 
Agree, just knowing the basic ins and outs of the impeller, the liner, and the shimming process, is a big plus to a jet owner, pretty simple to do on your own.
 

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