60 HP 1996 Yamaha bogs down under load

[Awrey]

Hi, hoping someone on here can steer me in the right direction cause I'm out of ideas. History:
2 stroke, oil injection, mdl P60TLHU.
I've owned this engine for @8 years now and the only problem I have had was the neutral position switch failed open and I thought it was the ignition (**** poor troubleshooting on my behalf on the water that day)
On the way back to the boat ramp a few days ago at WOT. All is good then all of a sudden it bogs down like I had hit a large patch of millfoil. Shut down, in reverse to clear prop, back in business right? Not this time. At WOT it wont get anymore than @1100 rpm. When I used to get 2700 rpm and 35mph. Nothing overheating, no buzzers (I have had the over temp buzzer go off when setting decoys once and the RPM's were limited until it reset/cooled off) But strange enough if I trim it all the way into the water I can get up to 1400 RPM's. Idles rough as well. The RPM's actually go up and down with the motor trimming up and down. Without touching the throttle.
Changed out plugs, no change. Runs fine up to max RPMs with muffs in the driveway. But put it in the water and it bopgs out. Good fuel. Checked fuel filter, it was clean.
Any help would be great.

 

[SalmonSlayerr]

Re: 60 HP 1996 Yamaha bogs down under load

I just had similar problems with my 85 70hp yamaha. I replaced the fuel pump and rebuilt the carbs and it fixed it. test your fuel pump. check fuel filter. check fuel lines to make sure your not sucking air. if that all checks out rebuild your carbs. good luck hope this helps.

 

[Awrey]

Re: 60 HP 1996 Yamaha bogs down under load

I just had similar problems with my 85 70hp yamaha. I replaced the fuel pump and rebuilt the carbs and it fixed it. test your fuel pump. check fuel filter. check fuel lines to make sure your not sucking air. if that all checks out rebuild your carbs. good luck hope this helps.

Thank you for the tips. I took ther fuel pump apart to see if the diaphram (sp/) had a hole in it or something. Looked a little "streched" out. Like wrinkles in it. No longer taught (for that matter if it ever was). So, not seeing the obvious, put it back together and same problem when back in the water. Sure is getting old hauling it down to the lake to try out the various "fixes". Guess I'll just have to put around when there and get in some Bassin. Did your bogging down happen all of a sudden like mine? Going WOT, then with no warning bog down like your running out of gas??

 

[Awrey]

Re: 60 HP 1996 Yamaha bogs down under load

More info from today. Brought the Ignition coils to work to OHM out the secodary side since we have a nice analog meter here and my cheap digital one at home couldnt do this job. Found (on the 1K OHM setting)
Coil #1 needle barely moved from the infinite symbol. A lot of resistance there
Coil #2 1K OHMS
Coil #3 4.25K OHMS


Which one(s) are bad??? And could that be my problem under load? Next is to see if they are firing the plugs at all.

 

[SalmonSlayerr]

Re: 60 HP 1996 Yamaha bogs down under load

Yeah. I left the dock and opened her up to WOT and we got about 150 yrds from the dock then she just bogged down almost to a complete stop. Yes it was like i was running out of gas. when i cleaned my carbs the low speed jets were gummed up in 2 out of the 3 carbs. i would rebuild your carbs and buy a new fuel pump or rebuild it. I just got a new 1 for $35.99 from boats.net and the carbs kit for all 3 carbs was around $95.00... but they were all genuine yamaha replacement parts. I am almost sure its the carbs. when you clean your carbs twist strands of speaker wire together to fit throught the hole and ports, thoroughly clean it. let me know when you get it fixed.

 

[SalmonSlayerr]

Re: 60 HP 1996 Yamaha bogs down under load

More info from today. Brought the Ignition coils to work to OHM out the secodary side since we have a nice analog meter here and my cheap digital one at home couldnt do this job. Found (on the 1K OHM setting)
Coil #1 needle barely moved from the infinite symbol. A lot of resistance there
Coil #2 1K OHMS
Coil #3 4.25K OHMS


Which one(s) are bad??? And could that be my problem under load? Next is to see if they are firing the plugs at all.

My book say the resistance ohms should be between 0.20-0.24 & the secondary ohms should be between 3840-5760 ohms.. i dont know if that will help you.. i havent read this section yet.

 

[99yam40]

Re: 60 HP 1996 Yamaha bogs down under load

A manual and the proper test equipment should tell you what the problem is.
Fuel pressure/vacuum is easy to test, as is the inputs and outputs of the ignition system.
Sounds like a fuel restriction , but you need to test to be sure.

If it is a problem that causes a lean condition on one or more cylinder, you will hurt the motor if you keep running it without fixing

 

[SalmonSlayerr]

Re: 60 HP 1996 Yamaha bogs down under load

Yeah. I left the dock and opened her up to WOT and we got about 150 yrds from the dock then she just bogged down almost to a complete stop. Yes it was like i was running out of gas. when i cleaned my carbs the low speed jets were gummed up in 2 out of the 3 carbs. i would rebuild your carbs and buy a new fuel pump or rebuild it. I just got a new 1 for $35.99 from boats.net and the carbs kit for all 3 carbs was around $95.00... but they were all genuine yamaha replacement parts. I am almost sure its the carbs. when you clean your carbs twist strands of speaker wire together to fit throught the hole and ports, thoroughly clean it. let me know when you get it fixed.

My mistake.... I meant pilot jets... not low speed like a chainsaw. I bet they are just gummed up and restricting fuel flow.

 

[Awrey]

Re: 60 HP 1996 Yamaha bogs down under load

OK Gentlemen. The latest. Replaced the coils (terribly high resistance and barely making a spark Strong blue spark now) and fuel pump. Well, put it in the water this morning and still bogs. Played with the throttle up and down up and down several times. It got better (picked up speed to 1300 RPM's at max throttle) but by no means on plane and full speed. Couldnt get anywhere near my old 2700 RPM's. When I got back to the dock took advantage that it was a slow day at the lake. No one trying to fish from the dock or launch a boat. Tied to the dock, put it in gear and floored it. Oh, and need to mention that it will hardly idle too. Upon start up it idles GREAT for @ 20 seconds. Then wants to die. Anyway, peddal to the metal, and noticed that the middle carb (cover off now)
the "JET" that sticks up in the throat just before the butterfly's is spitting gas at BEST. Then other two have a pretty steady flow coming out of them. Place my hand over the throat opening of the middle carb, and I'm glad the boat was tied up real well as it TOOK OFF!!! I mean like it just got a shot of Nitrus or something. WOW!! Did the same for the other two and the motor just about died when I barly covered up the opening. But the middle carb needed the air to be cut back. Sorry to ramble on. But just want to get all of what happened out there since you guys know more of this than I do. So, if I need to pull the carbs and give em an overhaul, so be it. Just real hard to believe that one (or all of them) would go bad all at once.
Thank you for your help!!

 

[99yam40]

Re: 60 HP 1996 Yamaha bogs down under load

sounds like the middle carb has something plugging the main jet pull and clean all of them just to be sure and it would not hurt to clean the lines and pump as anything in there will end up in the carbs once they have been cleaned.
And do not forget to do the link and sync once you reinstall the carbs


I thought you had missed typed the WOT RPM in the 1st post, but you posted that again.
The motor should turn a lot more than 2700 RPM at WOT. You must have that thing way overproped or it has been sick for a long time

 

[Awrey]

Re: 60 HP 1996 Yamaha bogs down under load

99yam40,

I'm ordering a carb kit for it Tuesday. As for the 2700 RPM's. I purchased it (the boat) from a good friend (still is) I will ask him if that was the prop the motor came with. Like I said, with just me in the boat I can get it to 35 mph per the GPS at those RPM's. I has alwas had a great hole shot. No hesitation, and if the trim is set correctly to start with, it will be up on plane in seconds. For the heck of it, had it on the muffs in the driveway this evening. And running crappy as ever after it idles for @20 seconds. And disconnected the yellow leads on the ignition module (CDI unit) the ones you disconnect in case the engine starts acting weird (hey, that sounds familiar) and the engine would then idle. Not the smoothest, but didnt die. Dont know what that would do for WOT performance. But an immediate improvement at idle. Does that make any sense to you? Any recomendation on carb soak cleaner??

 

[99yam40]

Re: 60 HP 1996 Yamaha bogs down under load

Maybe the tack if not set properly and reading wrong if it ran good but did not show proper RPMs.

My 16 ft Xpress semi-v will do 34 at 5500 with a 40hp.
You may need to check this site to see what you should get out of your 60
http://www.yamaha-motor.com/outboard/products/perfbull.aspx

As with all problems with a motor check compression, spark, and timing to see what is going on.
But if you cover the throat of middle carb and it runs better then it is running lean and you have plugged carb passages/jets

 

[Awrey]

Re: 60 HP 1996 Yamaha bogs down under load

99yam40,

Well, broke down and pulled the carbs. They all have a white (when it dries) turns to powder looking stuff packed around the pilot jets. And guess what, the middle carb was the worse one. It not only has this junk ON the pilot jet but IN it TOO. And in one corner of the bowl, the corner that would be at the lowest point when stored, this stuff is caked to the bowl. Easy to scrape off. Dont know if from water or what. It has NEVER acted like it had water in the gas. Well, a good soak and replace the jets cause they are so plugged I cant clean em out with a cutting torch tip cleaning tool. For the few bucks they are not worth trying to salvage in my mind. I've come this far might as well go the distance.
Thank you for all of the tips. I will be sure to post the results from the lake when I get her back together in a few days.

 

[Kendragon]

Re: 60 HP 1996 Yamaha bogs down under load

Awrey. I was looking into your thread from back in June. Can you let me know if it helped? I am having simlar problems with my 90 2 stroke.

 

[Awrey]

Re: 60 HP 1996 Yamaha bogs down under load

Kendragon,

Well pulling and COMPLETLY cleaning the carbs, I mean EVERY crack, crevace, channel, orifice, and hole. There was ethanol residue in many places. Obviously doesnt take much to effect performance. What a difference the hole shot is now. WOW!!! I would strongly urge you to get a manual for YOUR SPECIFIC motor. You wont regret it. It will pay for itself X10 in what you will save by taking it to the shop. I used regular Sta Bil before with all gas. Now I use Marine Grade Stabil. The difference in its ability to suspend the moisture more effectively.

Good luck. Rebuild em and your problems are over (if carb related of course)