86 Suzuki 65hp

[dsinger]

What a mess. This thing starts on the first bump and will run in neutral great. When you put it in gear it will jump out of the hole like crazy and plane out great. It will run for about 40 - 60 seconds then cut out like it is running on two cylinders. You can shut it off and turn it right back on and it will run out great again but cut right back out. Tonight on the lake I touched the throttle position sensor and it shocked me a little is that normal. I also noticed when I was changing it out and putting on a new throttle position sensor it sparked just a tad from the screw to the screw driver. Got to looking and found a ground under the CDI was lose could this be the entire problem. Prior to running today I rebuilt the carbs which were clean, new fuel pump kit, and spark test good. Also it is has a tiller kit on it and all the sensors are removed as well as the oil tank and pump disconnected. I say this because when it cuts out it seems like it is killing a cylinder as if it is going into safe mode. I also checked the plugs after today and all were golden brown and just replaced a few days back. The compression is 120 on all three cylinders. I appreciate any help here.

 

[hopalong]

Re: 86 Suzuki 65hp

Before I answer, a couple of questions.... how long have you had this motor and boat? And are you familar with the rev limit rpms for the Suzuki?

 

[dsinger]

Re: 86 Suzuki 65hp

How about this I think it is the flow sensor it being an 87 it is just a flow and no temp I think. I temp tested all the cylinders after running a little and they all tested good with a laser thermostat. I guess the best test is just to unhook and see if it happens again. I have a cd manual for this motor but it is all scratched up and will not load. I read there is a bench test for the sensor but need to know the OHM read outs. I think I have another one floating around the shop somewhere. Can anyone tell me at what temp the thermostat should open.

 

[dsinger]

Re: 86 Suzuki 65hp

Unplugged the flow sensor and it still does the same thing.

 

[hopalong]

Re: 86 Suzuki 65hp

When you got the boat and motor did the motor run ok? Or is this the first time you have run this motor? Do you have a tach connected to the motor? Reason I ask is if you are turning too many rpms (due to too small of a prop or slipping of the hub causing the prop to turn rpms greater than the rev limit design) the motor has a rev limiter which will drop the rpms down to around 3000 and if you turn the motor off and restart it and jump on the throttle it will do the same thing if over revved. The combo temp and flow sensor may cause the motor to act the same way.
If you run the motor at say 4000 rpms does the same thing happen?
Bottom line is you would need to know what rpms the motor is running at.

 

[dsinger]

Re: 86 Suzuki 65hp

5500 to 5600 RPMS is WOT and it ran fine before the problem. If you disconnect the flow sensor is it bypassed. If you just run at 3000 RPMS it will also cut out after the same amount of time.

 

[hopalong]

Re: 86 Suzuki 65hp

Disconnecting the sensor should not eliminate the built in safety shutdown. Remove the sensor and see if the float arm moves. Then see if it open and closes with an ohm meter. That sensor went bad on my new motor a few months after I had it in 1986. That was the only part that went bad in the 20 years of running that DT115 besides the rtegular changing of water pump and plugs. The indication you should be getting if you have the Suzuki monitor gage would be a red light/beeping with the water temp indictation light on.

 

[dsinger]

Re: 86 Suzuki 65hp

It is a tiller and the light has been removed. I completely disconnected the flow sensor from the CDI shouldn't that bypass the Flow Sensor.

 

[dsinger]

Re: 86 Suzuki 65hp

Oh ya the arm moves freely but have not tested it will a meter just figured if the thing worked properly after it was dissconnected then it was the problem since that is the only sensor left on the motor.

 

[hopalong]

Re: 86 Suzuki 65hp

I assume it will run ok at idle for quite awhile. Are you running it by water hose or in a lake? Could it be the angle of the motor when leaving the hole shot that may cause the needle to hang up or stick. Had that problem before myself were it shuts the flow of fuel to one cyl and caused the motor to run rough and shut off.

 

[dsinger]

Re: 86 Suzuki 65hp

I am running it on the lake. How would you test this. When the rev limiter kicks in does it kill the spark completely to the bottom cylinder or just deliver intermittent spark to the bottom cylinder. The needle sticking thing I need to check. About the same time of good running weather slow or fast.

 

[hopalong]

Re: 86 Suzuki 65hp

I am running it on the lake. How would you test this. When the rev limiter kicks in does it kill the spark completely to the bottom cylinder or just deliver intermittent spark to the bottom cylinder. The needle sticking thing I need to check. About the same time of good running weather slow or fast.

It does not kill the spark were the engine would cut off. It changes the demand to lower the rpms to around 3000. You now could have other things causing the problem. Check the fuel supply, condition of the fuel etc.
Also if you still have the fuel quick connect fitting that attaches the fuel line to the engine check it. This is overlooked many times and can be the culprit. Its an easy fix and or replacement. The coupling can cause intermiitent fuel supply to the motor by sucking air into the coupling, then into the fuel line. The motor may bogg down at WOT or pulsate then die. It has an "O" ring inside that can get damaged,worn, or thin over the years and even the fitting metal surfaces can wear enough to cause a problem. Sometimes the movement of the fuel line from the primer bulb to the coupling when tilting/triming the motor will cause the coupling to shift within ever so slightly and suck air. I eliminated this male/female fitting by removing it and replacing it with a brass brab fitting. But to check and eliminate the coupling just by pass it and connect the fuel line directly to the inlet of the fuel filter line. Worth a try.

 

[dsinger]

Re: 86 Suzuki 65hp

Ya I already removed the pit **** had that happen to me on the last suzuki I had. So how can you test the motor to see if the rev limiter is actually causing the problem and can anyone give me the bench test for the power pack.

 

[grid]

Re: 86 Suzuki 65hp

Quickest test for the CDI is 1) if there's no spark, the CDI is bad; 2) if it won't shut off, the CDI is bad. Other than those 2 things, the CDI should be okay. The rev limiter breaks cylinders down indiscriminantly: it won't select just one cylinder. The engine will just about shake you overboard. If you can identify one cylinder as dead, look to the carb. But, before you do that, back off the 2 10mm head bolts holding the fuel pump on. Squeeze the primer. Since you rebuilt it, there shouldn't be any leakage. If there is, though, there's your problem.

 

[dsinger]

Re: 86 Suzuki 65hp

So you are saying loosen the two bolts holding the fuel pump on. What does that tell me if fuel comes out. Ya I think it is the rev limiter it will about shake your arm off.

 

[grid]

Re: 86 Suzuki 65hp

What I'm trying to do is discern what type of cut-out is going on. If the engine drops one cylinder just plain DEAD, then you could look for excessive fuel being blown through the fuel pump diaphragm into #3. The procedure I described will tell you if there's a problem with the pump. If one cylinder drops, and you don't know which, pull one plug wire at a time until you fing the one that doesn't respond when you pull it. I know it's a tiller unit, but maybe have somebody steer while you--with life jacket on--uses plug cap removal pliers (NOT regular pliers!) to remove one cap at a time. If you find one cylinder STONE DEAD, and the engine starts and idles fine, the problem is NOT compression. Many times when the carbs are being rebuilt, the tech flips the carb upside down to remove the bowl. When he does that, whatever it was floating around drops into one of the 2 holes in the body and becomes a non-problem until the carb is righted after reassembly, where whatever it was floating around gets sucked into the main jet under acceleration. Okay, that ought to cover a cylinder that has gone flat dead.

Addressing the rev limiter: on that model you have a water flow sensor on the cylinder head-disconnect the light green wire; you have an oil level sensor-separate that plug coming from the oil tank; you have an oil flow sensor-separate the pink wire. If your problem goes away, reattach one at a time until the problem returns, and you'll know what to direct your attention to. If the problem doesn't go away, you're left with the engine really over-revving, and that can kick in +/- 10% of roughly 5500RPM. I've been servicing Suzukis since 1979, and replaced only one CDI, and that was on a 6hp. Their electronics are really good, so I'm betting the CDI is not at fault. Hope this helps.

 

[dsinger]

Re: 86 Suzuki 65hp

Grid thanks for the info I would run out to the lake right now but it is frozen a little. I dissconected the flow sensor last time I was out but I just dissconnected all the wires do I need to connect them all back but the green one and try it again. I have determined it is the rev limter causeing the problem because when it kicks in and you hook a light up to the wires the spark is all over the place.

 

[hopalong]

Re: 86 Suzuki 65hp

What I'm trying to do is discern what type of cut-out is going on. If the engine drops one cylinder just plain DEAD, then you could look for excessive fuel being blown through the fuel pump diaphragm into #3. The procedure I described will tell you if there's a problem with the pump. If one cylinder drops, and you don't know which, pull one plug wire at a time until you fing the one that doesn't respond when you pull it. I know it's a tiller unit, but maybe have somebody steer while you--with life jacket on--uses plug cap removal pliers (NOT regular pliers!) to remove one cap at a time. If you find one cylinder STONE DEAD, and the engine starts and idles fine, the problem is NOT compression. Many times when the carbs are being rebuilt, the tech flips the carb upside down to remove the bowl. When he does that, whatever it was floating around drops into one of the 2 holes in the body and becomes a non-problem until the carb is righted after reassembly, where whatever it was floating around gets sucked into the main jet under acceleration. Okay, that ought to cover a cylinder that has gone flat dead.

Addressing the rev limiter: on that model you have a water flow sensor on the cylinder head-disconnect the light green wire; you have an oil level sensor-separate that plug coming from the oil tank; you have an oil flow sensor-separate the pink wire. If your problem goes away, reattach one at a time until the problem returns, and you'll know what to direct your attention to. If the problem doesn't go away, you're left with the engine really over-revving, and that can kick in +/- 10% of roughly 5500RPM. I've been servicing Suzukis since 1979, and replaced only one CDI, and that was on a 6hp. Their electronics are really good, so I'm betting the CDI is not at fault. Hope this helps.

Very good explanation to the questions. Some of these post should be sticky IMO

 

[dsinger]

Re: 86 Suzuki 65hp

Found a lose ground to one of the coils. Notice while it was running it on the hose it was arcing and would sputter when it arced. Hope this is it because everything else has checked out ok. Going to run it later this evening.. Thanks to everybody.

 

[dsinger]

Re: 86 Suzuki 65hp

Ok it is still doing the same thing. So far I have
- eliminated the flow sensor
- eliminated the fuel
- disconnected the throttle sensor
- eliminated all other sensors
- thermostat checked good
- new fuel pump and rebuilt carbs

Now the thing that gets me is when I ran it tonight you could see a arc flash on the side of the motor when you would throttle down. It was arcing on the oil injections where it goes into the crank case, which in disconnected. Another question what is the proper way to disconnect the oil injections on these suzukis. This is a 65hp tiller conversion which the tiller pan came off a 55hp. When I wired it up I had to cut alot of wires to get it hooked up. I am guessing the arcing is not normal and might be part of my problem. I will post a video of the motor running tomorrow. It will run great for a few seconds but then just cut out. It does not matter if you gun it or just take off real slow runs about the same amount of time either way. You can shut it off and it will run good again. I even tried pushing the rest button after it cuts out but it did not matter you still have to shut it off to get it to run right again.