175 sportjet failure "again"

[browning]

I have a 18' alicraft with a 175 sport jet, about 150 hours on it. It runs like a top all summer and when I take to the muskwa, it dies on me. Last year took it north to the muskwa, ran good all the way up to kluchesi creek, camped for a week and when we packed up to come home it ran fine for about an hour and then would die when I took my foot off the throttle. It would run wide open or only at an idle. not the greatest feeling for someone up there for the first time, but made it back to the launch without a scratch thankfully. Took it home and had it looked at and changed the stator and module. Was suposed to have solved the problem. This year. Yesterday to be exact, launched at kleedo launch to try it again and made it an hour up before I had a repeat of the same problem, as soon as I took my foot off to back off on the throttle,it died, WOT or nothing . To say I wasn't impressed was putting it politely. Has anybody else had this problem with their sportjet? We made it back to the launch safely with a watchful eye from some fellow boaters passing by, and home again. Not the place where I want to have a boat not running in tip top condition. Now I need to fix the problem, but not sure what to look for seeing I thought the problem was solved last year. Any help would be great. Thanks in advance.

[gitnadoix]

Did you use ethanol blended fuel on your trips up north, but not elsewhere.........

I have heard that ethanol blended fuel can carry water through a filter but not help it burn like methyle hydrate will......175's do have a history of stator trouble but usually have heard that they out right shut down....dead,

[longstonec]

I have no experience with those powerheads but it sorta sounds like more of a fuel problem and less electrical are the carbed or injected?

[Jagermeister]

If you Google 175 sportjet problems, you will get a lot of hits. two thing seem to stand out, the one that gitnadoix writes of and the other is the switch boxes, there are two of them. Of course the stator is mentioned also. on the fuel water seperator, one suggested that using a 10 micron filter instead of a 50 micron would solve the water in fuel problem hard to determine if it is a fuel problem or an electical one.

[Singleshotneeded]

Try Chevron gas, if you're using ethanol blended...you can also buy a fuel filter if it's that finicky...

[mountainman]

I would try running some Seafoam through it and see if it helps it at all. It almost sounds like a reed problem and elevation changes as it keeps happening in the same spots. Doesn't sound like it would be very fun at all. Glad mine is a 240 which is EFI!

[tuchodi]

There are 5 of us that have the 175 Sportjet's and we have had a few problems like this. The first couple of times we were stumped and after about 3 or 4 hours of checking everything out and found nothing they ran fine again. We had it happen again and a very experienced Merc mechanic happened to come by and told us they were just freezing up the carbs. We could not see any indication of freezing on the outside but when we took the carbs apart he was right. I talked to Guy Scott who ran the river more than anyone with his Sportjet and he also had that problem a few times. All the mechanic could tell me why it happened was it was a combination of air temp, water temp, humidity, RPM, weight your packing in the boat so you may have to run a little higher RPM to keep going the speed you want. Since then we have made sure we don't pack to much and keep our RPM down and never had another problem. Hope that's all that has happened to you.

[wos]

I would check to se that the throtle linkage is working corectly sport jets timing is advanced and ******ed mechanicly by the throtle linkage. Only running at full throttle I would think fuel or timing.

[browning]

Thanks for the help. I have been running the same setup all year,same fuel,amsoil hp injector oil, only difference is the boat is loaded heavier with gear and running about 4200- 4600 rpm upstream from leaving the launch. Runs good at those rpms but when you back off the throttle, it wants to die. If you let it sit for awhile, half an hour, I can get the mid range back to get back up on step, but by the time I got back to the launch it was doing the same again. Going to do some more looking, found some info on oily residue in the carb vent holes, giong to give it a check on outlaw forum. Thanks again..

[Rock Doctor]

Used to happen to us sometimes. EXACTLY like you describe, and the fix is simple.
Pull the front cover off the carbs
In the front of the carbs there are some Brass Jets
In cool, moist weather these jets can accumulate an emulsion of oil/water/gook, partially choking them off
Get a can of Gunk carb cleaner, with the little straw
Give each Jet a little shot and you're good as new

Pipe Cleaners work too, just poke them in and twist

I would also recommend that you jet the mains down 2 sizes, and replace the SS Reeds with Composate Reeds


RD

[tuchodi]

Used to happen to us sometimes. EXACTLY like you describe, and the fix is simple.
Pull the front cover off the carbs
In the front of the carbs there are some Brass Jets
In cool, moist weather these jets can accumulate an emulsion of oil/water/gook, partially choking them off
Get a can of Gunk carb cleaner, with the little straw
Give each Jet a little shot and you're good as new

Pipe Cleaners work too, just poke them in and twist

I would also recommend that you jet the mains down 2 sizes, and replace the SS Reeds with Composate Reeds


RD"RD" is correct about the front of the carbs. I know that is where some of the ice congregates but I always clean that area each year before I leave so I don't have any dirt particles or excess oil in that area. I found it takes about 3 to 4 hours before the motor runs right again after freezing and I don't know why. We have made lots of trips up there and never had problems so I don't know what combination of humidity, cool weather and RPM cause the freezing but it happens.

[Barracuda]

is there some way of preheating the intake air like on a car?

[Rock Doctor]

Some of the guys up here have little Diesel heaters under their engine covers. They say it takes care of the ice problem. Don't remember the brand name though.

RD

[Northern Boater]

It is not always icing, high humidity can cause the plugging that is snot like and will not cure it self until the humidity lowers and still may take a lot of hours of running to clear up, have faught this on the Muskwa many times, as Rock Doctor says blow out the jets although sometimes the carbs may have to be removed to blow out the ports on the base gasket, canned air for computers works good. STP also makes an additive for water in fuel in a yellow container that helps considerably, can't recall the exact name of it as its been a few years since I ran 175. I installed handle bar heaters in between the carbs and they worked well except in extreme humidity. Espar builds the disel heater mentioned.

[browning]

I bought some gunk carb cleaner as RD mentioned and I am going to clean and blow the carbs out tomorrow, Load the booat back up with gear and take it out locally on the Nechako to see if it will do it again. Hopefully not, hope its the easy fix as mentioned. If not I guess i`ll have to start replacing electrical,coils etc. Thanks for all the input. Maybe I can gain some faith in the 175 sj again..

[cwm]

same thing on my 175 ,had de- ice kit installed been up 2 times and ran perfect guy scott helped me too.

[browning]

Well, leaving here shortly to try and salvage the rest of my holidays on a short hunting trip locally, and see if I can rectify the boat issues. Thanks for everyones input..Let you know how it goes in a few days..

[browning]

Well, just got back from a local outting with my boat. Still the same problem as before. I pulled the air cover off before I left, cleaned and washed the air box so it was spottless, hooked the engine on the hose and ran it while I sprayed all the jets and openings out with GUNK carb cleaner. Launched the boat with the same load as before and ran it for about an hour before we stopped where we setup our camp. Boat seemed to run fine up and down through the throttle range and I was running it hard to make it really work. Took it out the next day and it ran fine again, no bogging at all. Next day took it out and ran at 4000 rpm steady for an hour and it did it again. Bogs out at 2500-3500 rpm, idles fine and runs fine at above 4200 rpm, I could feel it wanting to fall off at about 4000rpm. Ran it on all 3 tanks and does the same thing. Last day back to the boat launch did the same thing and only took about 15 mins to act up. Bought a spark checker at princess auto that you plug in between the spark plug and the cap. It has spark at all 6 cylinders at an idle and revved up to 3000 rpm and holding it there while it bogs, still has spark at all 6 plugs. Not sure where to go with it now. Any other suggestions? I did some more searching and found some info saying that if a stator has recently been replaced that there might have been damage to the switchboxes..might this be related? Just wondering thanks for the input.

[leather]

I think you may have water and or dirt in your fuel. I recomend a inline fuel filter/water separator to solve your problem, kind of a must if you fill up with gas cans on the river. I have a racor inline fuel filter with valve, which allows me to drain out the water and dirt the filter picks up. I had the exact same symptoms as above. I dont have that problem anymore.

This is my first post.

[ThinAir]

The same thing happened to my 175. It was the stator.... it would idle, then crap out through the mid-ranges and pick up again at higher RPM. Changed the stator... ran perfectly

[REMINGTON JIM]

Well, just got back from a local outting with my boat. Still the same problem as before. I pulled the air cover off before I left, cleaned and washed the air box so it was spottless, hooked the engine on the hose and ran it while I sprayed all the jets and openings out with GUNK carb cleaner. Launched the boat with the same load as before and ran it for about an hour before we stopped where we setup our camp. Boat seemed to run fine up and down through the throttle range and I was running it hard to make it really work. Took it out the next day and it ran fine again, no bogging at all. Next day took it out and ran at 4000 rpm steady for an hour and it did it again. Bogs out at 2500-3500 rpm, idles fine and runs fine at above 4200 rpm, I could feel it wanting to fall off at about 4000rpm. Ran it on all 3 tanks and does the same thing. Last day back to the boat launch did the same thing and only took about 15 mins to act up. Bought a spark checker at princess auto that you plug in between the spark plug and the cap. It has spark at all 6 cylinders at an idle and revved up to 3000 rpm and holding it there while it bogs, still has spark at all 6 plugs. Not sure where to go with it now. Any other suggestions? I did some more searching and found some info saying that if a stator has recently been replaced that there might have been damage to the switchboxes..might this be related? Just wondering thanks for the input.


Did you ever get the problem solved ?? I am looking into buying a jb with a 175 sportjet - thks jim