90 Sport Jet Question (Thundercraft Typhoon)

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JW-JetBoat

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Hello everyone,

I just got into boating and I had at first a 95' Northstar Blast with the Merc 90 Sport Jet and wanted a slightly bigger boat and got a great deal on a 95 Thundercraft Typhoon. I think they are only a Canadian boat. I'll post a picture of it if anyone want's to see :)

Anyways, on to my question. I've been reading EVERYONE's problems with these engines and all of KEND's help. I took the boat out first time and it basically worked in low speed and died when I gave it gas. I had the carbs cleaned, checked the fuel pump, checked for spark and now it runs. (It was sitting for a season when I got it).

Two questions:

When it's been sitting over night or a few days it has a hell of a hard time starting the first time, and after that it starts no problem. My old boat was like that, does anyone else have this problem? Any suggestions?

The boat seems to be making a beep from the engine when I hit a big wave and the intake comes out of the water. I thought it was the overheating beep, but it only happens when no water is going to the engine. Is this normal with these boats? Does everyone else have this issue? It never did this on my Northstar, but that boat was slightly different. It wasn't oil injected and didn't have the "muffler" over the carbs, which is a god send!

Thanks for the help!
 

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kend301

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

Nice ride ! very clean :)
The starting issue you have is somewhat common to early sport jets . They will let most of the fuel evaporate out of the carbs so you have to crank it to refill the bowls before the engine sees enough fuel to fire. Some people have worked out a way to prime the carbs via electric pumps or primer bulbs BUT remember running a primer bulb inside a closed engine compartment is against the USCG regulations in the US .
Your second issue has me a little baffled , How long does the alarm continue to stay on ? Also when you do get the back out of the water is the engine hitting the rev limiter ?
 

JW-JetBoat

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

Thanks for getting back to me.

This boat has a priming bulb (maybe because it's Canadian) and I'm pretty sure it's from the factory, it doesn't appear to be an add on, but I could be wrong. I prime it until it's full and still get that problem with the start. I think priming it until it the pressure on the bulb is full actually floods the engine. I'll have to figure it out as I go.

For the beep... It only happens for a short second as I jump out of the water. This boat, and I don't know why, does not have a tach. Most times I am at full throttle hense the jumping out of the water but even at 3/4 throttle I was experiencing it while hitting waves. Just a quick beep the intake comes out of the water.

Any thoughts?
 

kend301

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

I know you had the carbs cleaned but recheck the vent tubes on the side of the carbs , You should have brass fittings coming out of the carbs and plastic tubing taking them to the carb air intake/muffler . If these get clogged in anyway you will indeed pump fuel into the engine due to the floats closing slowly . Also were the carbs rebuilt or at least had the float level set and needle and seat checked ?

As for the buzzer if it is for only 3/4 second I think it may be an over rev alert . I just do not see a boat triggering an overheat in 1-2 seconds time that only lasts 3/4 of a second . The other thing to check is the engine harness for a rub through , perhaps the impact of jumping a wave is causing a wire to short .

One last possibility is the oil tank does have a low oil alert , if the oil gets slushed around and off the oil sensor it could also trigger a short alarm until the oil settles down .
 

dmball

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

My regal rush (sport jet90) has also had a alarm go off when comming out of the water. I also have no tach. My only other guess would be the oil level alarm. My tank was about half full when it happend to me this weekend.
 

JW-JetBoat

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

Ahh, I did not know there were any other beeps beyond the over heat. The oil might make sense, I was at half full for the oil. I'll try that first and go from there. If it's a short, oh help me! That will take ages to track down.

Those vent lines do have a little bit of gunk in them, they weren't cleaned. I took the carbs to a powersports shop, I'm not sure how he cleaned them but he did and they looked brand new. They have a good reputation so I'm assuming he did everything correct there.

I won't get to take it out for another week and a half so I will post back then my findings. :)
 

kend301

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

If the lines had gunk in them , pull the brass fittings out of the side of the carb, they are a loose press fit should come out with pliers . Most of the build up will be in the "elbow " portion . use a very small drill bit rotated by hand to clean them until they flow completely unobstructed .
 

JW-JetBoat

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

Just an update here in case anyone else has this question down the line.

I topped up the oil tank and no more beep. It must have been too low and sloshing around at 50% full. :) Thanks for the help.

The boat still takes a great deal to start.. Once it's started once I can fire it up no problem though. However, after a 40min run, I docked it, put the trailer into the water, and went to turn it on, and it wouldn't start. Took me a few mins of trying, the bulb was primed it just wouldn't go.. It eventually did and then after that it started up no problem as I tried it 3-4 more times. It's strange.. I don't think the lines are gunked up as mentioned above. I was able to blow in them, I haven't taken them off to inspect, but they seemed to be fine.
 

kend301

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

Glad you got the buzzer alarm off , Mine has the same starting problem , if it sits for a few days it could take 6 tries to get it to fire and run but once it does it fires 1st try for the rest of the day . Double check your idle air adjustment , that is what helped mine. the screws are on the left side of the carbs just above the mounting bolt , Pull them out . be sure they are clean , run them all the way in then out 1 1/2 turns and see if that helps
 

JW-JetBoat

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

Thanks, I will take a look. It gets me nervous if I want to stop out on the water and go swimming that it may not turn back on.

On a side note, I saw on another post that you were mentioning the side rails for the jet are a good investment. Do you know anywhere I can buy them? I found a place that doesn't have them but will make them for $200 plus shipping. Do you have any connections for some before I buy those?

Thanks.
 

kend301

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

Nauticus Smart tabs , call 1-800-233-0194 and ask for Greg he will hook you up with the proper part number for your boat . They can be ordered from the parts store on this forum , they are around 130.00 to 150.00 for the kit and are self adjusting .
 

kend301

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

That is a steering response system that works great, Gets any Jet drive to turn on a dime , Not sure if the nozzle angle is changed to help the boat plane. I do not think it will not help you plane quicker . I need to call Jeff and ask him . If you want to get the boat on plane quicker and have more stable handling Smart tabs are the way to go .
 

JW-JetBoat

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

The plane is not to bad on the boat actually.. I think I'll try out the steering that's what I'm looking for right now.

Thanks!
 

kend301

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

Just got off the phone with Jeff , you need to make it very clear what you are looking for in the performance aspect of things to him so he can do the right thing for you . I really respect his products and if my over the winter mods work on my boat I will need more steering and he is the one I will call .
 

wildlifeguy

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Re: 90 Sport Jet Question (Thundercraft Typhoon)

so since these threads have been posted, how has your typhoon run? any updates? My typhoon with the force 90 sportjet beeps as well out of water, and has a hell of a time starting at times. Im not much a mechanice but a quick learner and understand mechanics. Do you have a pic of the primer bulb ( Im in Canada) and is an automatic prime or manual? Any pics of the lines which can be removed from the carb for cleaning as well.
I'll post pics myself to anyone else who needs assistance with maintenance on these motors, as Im sure I will be doing alot of the work myself.
Thanks guys
 
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