1990 dt115 suzuki with full throttle issues

[vhard2]

I have a 1990 Dt115 that was recently overhauled with a new powerhead, water pump and serviced lower unit. The motor starts right up and idles ok, steady stream out of the water pump..when i go to throttle up the motor sounds good and revs right up and planes out...as i approach full throttle and trim there seems to be a certain point in the throttle where the motor cuts out and slows but if i drop back the throttle and then go in a gain it picks right back up and will run out for a while until it hits that point again......also when idleing it does do the occasional sneeze and cut....the motor is a fresh rebuild with about 2 hrs on it...any and all info would help as i just bought the boat and am new to baoting...

 

[deejaycee_2000]

Re: 1990 dt115 suzuki with full throttle issues

mine does it aswell ...... water flow switch ..... don't trim it out to much ..... check that your engine height is properly setup on your boat, the anti cavitation plate should be in line with the bottom of your hull ......

 

[vhard2]

Re: 1990 dt115 suzuki with full throttle issues

would the water flow switch also account for the rough idleing and stalling? I was thinking maybe a idle screw adjustment or air fuel mix adjustment for both cases....the hieght adjustment might also explain my ride at certain throttle bieng left bow heavy until trimming out past it.....your info and quick response inice to have around rather than taking it to a mechanic and having him tell me the same thing for 100 bucks an hour

 

[vhard2]

Re: 1990 dt115 suzuki with full throttle issues

any ideas?

 

[hopalong]

Re: 1990 dt115 suzuki with full throttle issues

Could be a lot of things. Before it was overhauled did it act up as you described? If not I would make sure the service tech set the timing and related adjustments correctly.Were the carbs overhauled/rebuilt?
I would suggest you could check the following yourself. (Be careful of the dangers of gasoline especially around a warm engine) The fuel line quick connect fitting that connects at the lower cowl area sometimes may suck air. The engine may crack back thru the exhaust, run rough, and or stall. There is a small O ring inside of the quick connect, check it. Also check the fuel hose connections from the tank to the squeeze bulb for pin hole leaks. Check the fuel filter. If any of the carbs floats/needle vavle & seats get hung up at times they would cause similar problems. Connect a small rubber tube or alike to each carb drain fitting and open the brass screw to drain the fuel into a cup. See if there is any water or bad gas. Note sometimes if the gas in the carbs are left there for a long time, residue may form on the needle/seat and cause intermitent problems. Last but not least check the fuel pump diaphram and associated fuel lines in the engine to carb area.
Remember as you trim up or go up on plane the fuel line outside of the motor that connects to the qiuck connect may bind just enough to move the quick connect fitting and suck air at the fitting. These fitting are know to cause intermittent problems. How one could troubleshoot the problem is to eliminate the fitting temporarily by disconnecting the fuel line from each side of the quick connect fittings (off the fuel hose from the bulb of the male fitting and the hose from the fuel filter off the fitting inside the cowl area) and connect the two ends of the hose together with a barb fitting and clamps. Test run the motor and see if eliminates the problem. If so replace the quick connects. They do wear out in time.

 

[grid]

Re: 1990 dt115 suzuki with full throttle issues

Whoa. Did you pay for a service NOT RECEIVED??? Does that sound logical? Does it make MORE SENSE to have the guy who rebuilt the engine TWO RUNNING HOURS ago STAND BEHIND HIS WORK???? Hold his head underwater until he can spell "ETHICS."

 

[deejaycee_2000]

Re: 1990 dt115 suzuki with full throttle issues

would the water flow switch also account for the rough idleing and stalling? I was thinking maybe a idle screw adjustment or air fuel mix adjustment for both cases....the hieght adjustment might also explain my ride at certain throttle bieng left bow heavy until trimming out past it.....your info and quick response inice to have around rather than taking it to a mechanic and having him tell me the same thing for 100 bucks an hour

yes ..... it can cause the rough idling, when the motor heats up too much this happens .... but first things first how is your motor setup on your boat maybe take a pic and let me have a look, if your motor is mounted too heigh up on the transom it might not get enough water and explain the symptoms ........

 

[deejaycee_2000]

Re: 1990 dt115 suzuki with full throttle issues

grid .... what the hell are you on about again ......

 

[vhard2]

Re: 1990 dt115 suzuki with full throttle issues

i checked everything hopalong was talking about and everything is tight and snug....the fuel lines are directly fit over male fitting with stainless clamps on each port, the fuel ball is new and not craking and the water seperator is clean as well as the in line filter right off the tank......as fo deejaycee....the motor when at full down tilt places the anticavitation plate about 1-2 inches above the bottom of the hull leaving a solid 8-12 inches of lower unit below the keel....it does not look like the transom mounts have ever been moved.....also the idle screw was on slow so i turned it up one click to see if that made a differance.....the motor runs strong no smoke with a great stream from the pee hole.....where is the water flow switch located on the outboard? and how much would it cost to replace? Thanks in advance!!

 

[deejaycee_2000]

Re: 1990 dt115 suzuki with full throttle issues

http://store.brownspoint.com/dt115/fig001-1158601.asp

 

[vhard2]

Re: 1990 dt115 suzuki with full throttle issues

so with the stream strong out of the water pump this would just be a faulty switch and not something i should worry about as far as a cooling issue of the motor correct?.....I don't want to run it this afternoon if the switch may control or inhibit cooling in the rebuild.....

 

[hopalong]

Re: 1990 dt115 suzuki with full throttle issues

Do you have tach on board? If so at what rpm is this happening?

 

[vhard2]

Re: 1990 dt115 suzuki with full throttle issues

i have one but it is not working currently, it seems to be right around 3500 to 4000 by the sound feel and throttle posistion....

 

[hopalong]

Re: 1990 dt115 suzuki with full throttle issues

So we assume the carbs have never been cleaned and or had a kit?

 

[vhard2]

Re: 1990 dt115 suzuki with full throttle issues

carbs were from the powerrhead that was clean bored and rebuilt, they were gone through and cleaned.....the boat runs too good at all speeds (beside WOT) for a carb issue...when starting from a dead stop you can go full throttle and it doesn't cut out right up on plane nice and strong.....however while on plane and slightly trimmed the motor will cut out when you go further down past a certain point, the exact same point everytime....it cuts it out like a light switch if you back the throttle out as soon as this happens and then immediately jump back on it the motor goes right back to where it was right before it cut out....you can do this before it even comes off plane thats how quick it jumps back up......im leaning towards the motor height being to high on the transom causing the water flow switch to cut it out when going for WOT.....i will drop the motor about 3/4 to one inch and check....does this seem logical?

 

[vhard2]

Re: 1990 dt115 suzuki with full throttle issues

motor is only aquater inch off the transom and the same thing is still happening....sounds like i should replace the sensor.....any other ideas? the boat was run today for 30 miles and runs great until you try to get past the point on the rpms and it cuts out like a light switch...what exactly does the water flow sensor do? does it regulate the water flow or does it only sense that the motor has water....also is it tied to t he ecu inthe spark and fuel managment system?

 

[deejaycee_2000]

Re: 1990 dt115 suzuki with full throttle issues

yes it does, it all points to water flow switch ......

 

[mvitiello]

Re: 1990 dt115 suzuki with full throttle issues

wow. You may have solved a problem in this thread that I asked about regarding a yamaha F200 4 stroke at this post: http://forums.iboats.com/showthread.php?t=215339
The boat i am talking about is a triton 2690 cc and the engines mount on a bit of a false transom (ie extends down about 2 or so inches short of the rest of the hull) which I guess may keep the water flow a bit lower relative to the motors - especially at WOT. I also noticed in my test run that even with the engines trimmed full down, the wakes right behind the motors looked like the wakes coming from nicely trimmed outboards (perfect) and not at all like the wake you would get from an outboard that is digging a bit deep and needs to trim up a bit. (PS the boat has trim tabs which keep the bow down nicely). The description in the start of this thread about cutting off "like a light switch" is certainly accurate for me too. I could not play with the issue as much however because I don't own the boat although I think I will go for it and purchase it. Also, it was also difficult to determine exactly what the one motor was doing because the second motor, of course, was still going like gangbusters. Do you think a water switch, if it's even malfunctioning, would be covered under the last year or two of the extended warrantee?

 

[rdmmdr]

Re: 1990 dt115 suzuki with full throttle issues

are you getting the buzzer/ and do you have a monitor installed. It sounds like a rev limiter kicking in. the suzuki limiter kicks in at anything over3200 rpm if either the temp, oil level, oil flow, is in alarm condition for more then 10 secs.find the temp sensor it is the black plug in the head with wires coming out of it one will be black and one green/yellow. disconnect the green/yellow one from the harness and ground the harness side. this will bypass the temp switch. Then take for a test run
rick

 

[vhard2]

Re: 1990 dt115 suzuki with full throttle issues

UPDATE!!!! Check that your electric choke has the retention spring in place, mine did not and when at higher RPM and throttle position the negative pressure was pulling teh throttle plates up to full choke and cutting the motor out.......after $300 and alot of hair it came down to a 20 cent part....