30HP Suzuki no power under load

[crappienick]

does anyone have any suggestions on what the problem might be. It's a 1993 model with oil injection. Cranks beautifully, idles fine, revs fine, but in gear will not push the boat. Boat is very light and same boat motor has been on. The carbs have been cleaned and inspected 4 times, tank, bulb and fuel line replaced, spark plugs changed, cylinders compression tested. I'm thinking power pack? coils? oil injection sensor? Any suggestions appreciated.

 

[boatster]

Re: 30HP Suzuki no power under load

spun propshaft bearing?

 

[iwhitevt]

Re: 30HP Suzuki no power under load

If you find out what was wrong let me know. I'm having the same trouble w/ my 90 yamaha. Does your's lose power after running a little or atart that way?

 

[phatmanmike]

Re: 30HP Suzuki no power under load

when you say"under load" are you talking on the boat, in the water driving around or in a barrel in your driveway. 2 diffrent scenes.<br /><br />usualy this is a case of one of 2 things:<br />1. dirty high speed jets. you say you cleened the carb 4 times, how throroughly? did you blow out with compressed air, maybe something is stuck in there.<br /><br />2. motor is dropping a cylinder. i had a evinrude 50 that did this till it puked a rod. check your ign coils, check your plugs(how do they look), check your compression(whats the numbers)<br /><br />how much weight is in the boat, is the foam waterlogged, hows the prop?

 

[crappienick]

Re: 30HP Suzuki no power under load

to boatster: prop has been replaced since the summer and due to the below reason, i've ruled that out<br /><br />to iwhitevt: when it first started, it would start out bad and then all at once "kick in" and take off normally. That gradually got worse and is now bad all the time<br /><br />to phatmanmike: i'm talking about in the water driving around. hooked to a set of "ears" on land there is no noticeable problem. Yes carbs have been removed 4 times, each time taken completely apart and jets cleaned, all holes probed and blown out with compressed air. weight is not a problem, no foam - the boat is a fiberglass/wood "High Tide" (built in S.C.)primarily used for Duck Hunting here.<br /><br />Thank you all for responding and if you have anything else based on the above information please respond back.

 

[boatster]

Re: 30HP Suzuki no power under load

You should be able to check the resistance on the powerpacks. the primary winding should have .1-.4 ohms resistance. The secondary winding should have 1.9-2.7 ohms resistance. The tester should be set to the 1000 scale. Primary coil is test the orange/blue/grey to one probe and the other probe to the black wire. The Secondary coil is test the orange/blue/grey to one probe and the other probe to the spark plug cap I believe, if I'm reading my manual correctly. Hopefully this will rule out/in the coils.<br /><br />Have you performed a leakdown test? Is the throttle position sensor working. It sits on the #2 carb. If you open the carb #2 to WOT the voltage should be 2.5-3.1 volts. At full closed the voltage should be .50 volts. Not sure if this is anywhere near your problems but it might at least help you rule those things out. <br /><br />Are you sure its not the carbs being improperly adjusted i.e. not enough fuel? Can you explain how it doesn't get up to speed? Does it bog? What symptoms can you describe about this lack of power? Does the motor almost stall? I'm no expert but I do have a DT30 that I've been tinkering around with alot. I'm beginning to know this motor really well.

 

[crappienick]

Re: 30HP Suzuki no power under load

boatster: I have not performed the leakdown test or tested the coils. Essentially, what it does is: when i give it throttle, it acts as if the power is "cut back". It does seem "bogged", but there is no fluctuation in the way the motor runs. In other words, it goes from idle to "bog" with nothing in between, no surging, sputtering, shuttering, shaking or anything like that. It's a smooth transition from idle to WOT, except WOT doesn't push it but about 8MPH and won't get up on plane when normally it would top out at about 35MHP. One thing regarding stalling, it will stall sometimes after I stop if it's a sudden stop. A slow stop will normally not stall it. Thanks and let me know if this provides any other clues!

 

[crappienick]

Re: 30HP Suzuki no power under load

boatster: I have not performed the leakdown test or tested the coils. Essentially, what it does is: when i give it throttle, it acts as if the power is "cut back". It does seem "bogged", but there is no fluctuation in the way the motor runs. In other words, it goes from idle to "bog" with nothing in between, no surging, sputtering, shuttering, shaking or anything like that. It's a smooth transition from idle to WOT, except WOT doesn't push it but about 8MPH and won't get up on plane when normally it would top out at about 35MHP. One thing regarding stalling, it will stall sometimes after I stop if it's a sudden stop. A slow stop will normally not stall it. Thanks and let me know if this provides any other clues!

 

[boatster]

Re: 30HP Suzuki no power under load

Are you getting fuel to the motor? Maybe while your bogging at WOT you can have the motor cover off and the carb intakes exposed and shoot some carb starter down the throats and see if that increases the power. Did you rebuild your fuel pump? Are your needle valves stuck? Or your floats improperly adjusted? It certainly would seem like a fuel delivery problem. Get a fuel pump replacement kit. Maybe your diaphragm has an air leak. Again I'm no expert and if you read my posts most people think my motors dead even though I think otherwise. Keep the faith. These Suzukis are one of the nicest engines I've seen. It'd be a shame to give up on em.

 

[jafa]

Re: 30HP Suzuki no power under load

It sounds to me like a classic jamming needle valve , the bowl empties as you power up and leans out , a squirt of premix in the throat wil confirm. If your out on the water get it to bog down and give the carb a sharp tap. If it suddenly surges forward and throws you off the back you know where the problem is.

 

[crappienick]

Re: 30HP Suzuki no power under load

I'll be testing the coils, power packs and TPS today. I'll let you guys know if I come up with anything. Thanks. Oh, by the way, thanks for the advice rockhopper, I'll be sure to wear my life vest when I try that.

 

[boatster]

Re: 30HP Suzuki no power under load

TPS is just a timing advancer. You could probably pass that one. I would say check your fuel delivery.

 

[wildfire]

Re: 30HP Suzuki no power under load

What did your problem end up being? I have a 1988 DT 30 Suzuki that is currently acting similar to your problem.

 

[crappienick]

Re: 30HP Suzuki no power under load

i guess i could have posted it, but believe it or not, it was a bad or corroded connection where the #3 coil connects with the wire coming from the power pack. i discovered it by accident. a GOOD friend of mine who has the exact same model engine was going to let me start taking parts off of his and putting them on mine in order to troubleshoot my problem. by luck i decided to start with the coil since it was the easiest to remove and install. after checking #1 and #2 which ran fine, i swapped out #3 and it ran like a champ. i bought a can of 6-56 and sprayed and cleaned all of my electrical connections and haven't had a problem since. Since then i purchased a 1996 40 Yamaha and replaced the Suzuki which is now sitting there waiting on the Yamaha to break down. Hope this helps...

 

[wildfire]

Re: 30HP Suzuki no power under load

Thanks for the reply. The water is hard here now, but when things melt I'm going to check things out. That is, if I don't just go by a different motor.

 

[jleus]

Re: 30HP Suzuki no power under load

I cleaned up most of my connections and then put a dab of di-electric grease (bulb grease) as I reassembled the connector when satisfied with my cleaning. Think twice about giving up on a DT25c or DT30c. Strong and dependable motors.