Suzuki dt40 only 7 mph

[johnnyjack1]

Hi guys I have heard good things about this site and I need some help. I have a 1982 Suzuki outboard on a pretty cool bass boat. 40 hp. Bought it used last month and we have a big problem. The motor will not go faster than 7 mph. Here is what happens:

in neutral, if I use the hand throttle, all the way up, the boat will idle at about 1500 rpm, then it will slowly increase the rpms at about 200 per second until after about 15 seconds it is very high.
in the water, when I engage and give it full throttle, the rpm stays at about 1500 rpm and we can only do 7 mph.
today I tried spraying starter fluid into the carbuerator at our top speed of 7 mph on the river, and the rpms never went up, even after spraying the starter fluid.

I have no idea what it could be. Any help would be greatly appreciated.

Thanks in advance,
May your fish be big and your women like to cook.

 

[steelespike]

Re: Suzuki dt40 only 7 mph

I have a feeling you have one cylinder not firing.Get a spark tester.Spark should jump about 3/8" snappy blue spark.
You could pull the plugs see if one is wet and or fouled.
You may find one that is exceptionally clean.

 

[Silvertip]

Re: Suzuki dt40 only 7 mph

Reving the engine in neutral will eventually have you looking for a new engine. Stop doing that. You need to ensure the engine is actually running on both cylinders. If not, figure out why not! The problem will be lack of fuel, lack of spark, a cylinder with low/no compression, or someone has been mucking with the link&sync and has it all screwed up.

 

[steddy]

Re: Suzuki dt40 only 7 mph

First of all, welcome to the Forum!
Less of a high-tech test - after the engine has run for a while, shut it down and feel the plug wire caps. See if one is colder than the other. The colder one is the dead/dying one.

 

[waffles1]

Re: Suzuki dt40 only 7 mph

Johnnyjack. it's not a good idea to spray starting fluid or any other cleaners in your engine while it is running. you are asking to blow a hole in your piston. Only spray mixed gas in there while it is running. Has there been any changes to the motor? New prop, carb work engine work....? have you checked your throttle cable and linkages to make sure everything looks like it is moving as it should? Does closing the choke help or hurt? Does pumping the fuel bulb help? try these if you haven't already and let us know the results. Good luck!

 

[johnnyjack1]

Re: Suzuki dt40 only 7 mph

Thanks for all the help and info.

I think the #2 coil is not working under a load.
I will replace it and get back to you.


Thanks again

 

[rapture36]

That actually sounds alot like what my motor was doing and I had a sheered piston. The tell tale sign was that I wasnt getting compression in one of my cylinders. It costed me $1003 dollars and that was at a discount. Only positive was that now my motor runs at about a fifty horse instead of a fourty after the boring and over sized cylinders were put in.

 

[rapture36]

That actually sounds alot like what my motor was doing and I had a sheered piston. The tell tale sign was that I wasnt getting compression in one of my cylinders. It costed me $1003 dollars and that was at a discount. Only positive was that now my motor runs at about a fifty horse instead of a fourty after the boring and over sized cylinders were put in.