Suzuki DT60-Loses Power/bogs down/no rpms

hugr20

Cadet
Joined
Oct 28, 2003
Messages
16
I am trying to diagnose a motor for someone. He just bought the boat/motor. The motor is a Suzuki Dt60 about a 1984. It is oil injected, 2 cylinder,2 carburetors. It is a very low hour motor, very clean under the cover. We took it out when he bought it a week ago and it ran great. We had it out approximately 45 minutes and idled and cruised/accelerated without a flaw. It pumped water great. Compression on the motor reads about 140 on both cylinders. Fuel filter was checked(clean), tank is clean, newer hose and primer.

He took it out again and this is what it did. It started at the dock and idled out of the harbor fine. There is a long no wake zone so you have to idle for aways, it ran fine the whole length there. Upon acceleration it it took off fine and ran fine top end for maybe ten minutes then the rpms began dropping down on its own without moving the throttle- nearly down to a fast idle. He limped back with it and I took it out today and verified the problem. I got down the channel to the end of the no wake zone without a problem running at a fast idle (slow speed). I put the throttle down and the rpms increased normally and the the boat got up to speed. I ran for a minute like this, and then pulled back on the throttle down towards a fast idle. Upon trying to reaccelerate, the motor just bogs and will not accelerate. It makes a slight popping noise out of the exhaust when doing this. I limped back to the dock and pulled the spark plugs, and to my surprise they seemed realatively wet. I checked for spark and it seemed to have it on both cylinders. I put in a dry set of plugs and tried it again. I was able to accelerate normally again, but after about 5-10 seconds of running wide open, the rpms began dropping again. Again I limped back and pulled the plugs. They seemed pretty wet again. Also while I was running it and it would not increase rpms, I tried squeezing the primer bulb-I was told if the fuel pump is weak, this would make the motor increase rpms, but it didn't seem to help. I also blipped the choke while it was doing this and it seemed to briefly increase the rpms alittle.

Does this sound like a fuel problem or an electrical problem? It seemed like the oil injection was working because the oil level has gone down some, and the plugs don't look the the motor was running hot, although is there a limiter that will decrease the rpms on this motor if it is not getting proper oil amount?
I figured if it was the fuel pump, the plugs wouldn't seem so wet. I would say maybe the carbs have gunk in them, but then why does it run good initially? Would a bad stator or coil. etc. act like this??

Your help would be greatly appreciated. The nearest Suzuki dealer won't work on it, they only work on the 4 strokes. If I can get a consensus from a few of you, maybe we can get this going strong again with few parts.
 

hugr20

Cadet
Joined
Oct 28, 2003
Messages
16
Re: Suzuki DT60-Loses Power/bogs down/no rpms

Shouldn't the primer bulb have been soft if it was the fuel pump diaphram or not necessarily? It seemed fairly firm.The plugs seemed pretty wet like it was getting fuel. Just want to make sure before I start replacing parts....
 

manitoba1

Petty Officer 2nd Class
Joined
Jan 8, 2002
Messages
121
Re: Suzuki DT60-Loses Power/bogs down/no rpms

I used to have a 1985 DT55 that had the intermittent power loss you describe. Drove me nuts as the boat would run great at time and other times like when I hit larger waves the engine rpm would drop. If I throttled back to idle and then re-accelerated the thing would run fine. Turned out to be a water flow switch in the power head which was faulty and would engage the rev limiter. The switch is a float switch which is there to protect the engine against overheating in conditions where in-adequate water is circulating through the powerhead like when the impeller goes bad allowing the engine to limp at low speed back to port.
 

sportsman

Cadet
Joined
Jun 23, 2006
Messages
10
Re: Suzuki DT60-Loses Power/bogs down/no rpms

I have been having these same problems on my 1987 DT75, it will run great for 15 minutes or so and the motor just bogs down and appears to be running on two cylinders instead of all three. I had it to the dealer twice and they have exhausted any fuel problems. I am bringing it back in tonight and they are going to check for an electrical problem. I did some resistance tests and everything passed except for the Pulser (Trigger) Coil so they are going to check into it. I will try to repost to let you know the results.

The last time I took it out the motor actually wouldn't stay running at all and I had to use my trolling motor to get home so I am assuming that the problem is getting worse. Is this possibly a coil breaking down? I don't know for sure but hopefully I find out soon. It's been bugging me for awhile now.
 
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