I recently bought a bassboat witha 70 hp yamaha on it. It is a 1984 model I think. The motor starts and seems to run good. With the flushers on it, it runs fine, idling and in gear... but when I put it in the water sometimes it tries to die when I put it in gear, and when it goes, it will only put out about 2000 rpms... almost just idles across the water. I don't have a clue what the problem is... it seems to be getting fuel, no stopped up lines, or filters... where do I start looking for the problem... ( btw.. it had set up for a couple years before I bought it)
I had the same problem with a 40hp Yamaha and it was an 87. I rebuilt the carbs and put new floats in all three, went to launch it and no plane. To make a long story short, I ended up readind out all three coils with a meter and found that to were out of the spec range so I changed the two and boy did she run then! Get a book and try that. It helped me! Good Luck!
Thanks seamule... I was hoping it would be something really simple. Did you have to replace the coils, or just adjust them... How big of a procedure is what you did?
No, the coils weren't adjustable, and yes I had to replace them. They were only held on by a couple of bolts so the replacing them wasn't the hard part. Reading them out takes the knowledge of using a multimeter and checking for resistance and continuity. If you don't know how to do that, the book explains everything except the use of the multimeter. If you don't know how to use one, get one of your buddies who is knowledgeable in electricity to do it for you.
kwitcher,It sounds as if you are not running on all three cylinders. Get yourself a spark checker and start by seeing if all three plugs are firing. If so, it's time then to look for fuel related issues. Any engine that has set up for a couple of years will proabaly have clogged jets at least.I cannot explain it, but Yamahas and Suzukis seem to be more sensative to this.
I just put new plugs in the motor, because someone else told me the same thing... could it be further back than the plugs? if so where? where can I get a spark checker?
If the motor has set up for a while you can just about bet the high speed jets are clogged up. I have a Yamaha too and it's very easy to get the high speed jets plugged. I've tried running the fuel out before storage with no luck too. What I do now is put the muffs on it and run it for a while if it's out of the water for more than three months. So far this has worked for me.I'd clean the carbs and give it another try.Good luck
This might be a stupid question, but I am still kinda new to working on outboards... I have tinkered with carbs before, but I was just wondering what the best way to go about cleaning them is? Can it be done effectively without taking them off? If not, should I just break them down and clean every part?
I'd pull the carbs since this motor is older. They are fairly easy to remove. There should be a screw (brass usually) on the carb housing (screwed up flush to the carb housing without any spring). Remove this screw. The high speed jet will be located behind it. The jet will have a small orifice in the center of it. A small piece of soft wire works well to clean it out. After you get the wire through the orifice, flush it out with WD 40 or the like. Blowing it out with compressed air after flushing helps too. Just be sure to hang onto the jet real good if you remove it.
You can try in place but you will get better results if you pull the carbs off and disassemble them. If the jets are adjustable make sure you know where they were set.
if the high speed jets are the only problem, can i get by without disassembling the entire carbeurator? Ps... just fr the sake of narrowing the problem... even if the high speed jets are plugged, would the motor still throttle up good in gear out of the water?
I'm not sure on your motor if you can pull the jets without pulling the carbs. I've been able to pull and clean the jets on mine without pulling the carbs but they were hard to get at. You can try it if you want to. If it were me I'd pull the carbs and give them a good cleaning. Yup, the motor will throttle up pretty good without a load on it.Good luck
Thanks a heap DS and everyone else too... i'm really glad i found somewhere that I can get answers without paying out the wazoo! I appreciate all the help...
Howdy, Kwitcher.You will do yourself a favor if you find out what is wrong before you start buying and replacing every part someone suggests might be bad, or tearing into your carbs without even a manual to guide you.Take DJohns' advice. Find out if you have spark to all three cylinders. Pull the plugs. ground two and hold the third against the block. Turn the engine over and watch for spark. Now do the other two.If you have good spark, crank the engine and spray a bit of fuel mix into each carb, one at a time. If the engine suddenly speeds up a bit, that carb is gummed. This test is best done with the engine under load (on the water).Then you will know what is wrong. Get a manual and fix it. You will have saved at least enough to pay for the manual, probably more.Good luck and let us know what you find.
Kwitcher,You can USUALLY just lean them against the block. Sometimes you can use a garbage bag twist tie to hold them in place. Place it around the ceramic part though and the other end to something not grounded. A plastic piece or something. You want the electrode (curved piece at bottom of plug touching the head or block. I just mentioned a spark tester because I didn't want you to get "bit".JB gives good advice. His idea of using premix is a good one. It will help you nail down which carb. is giving you trouble. Buy a manual. Carb. rebuilds are actually quite simple.Another thing, DO NOT use carb. cleaner to spray into the carbs while running. It has NO lubricity and will potentially score your cylinders.
Just a short reminder. A spark doesn't mean that it is a good spark. The book points out to read each coil out with a multimeter which is much better than a spark checker. A bad coil will spark enough to give you a great running motor in the barrel or hooked up to the flusher. But until you put a load on it it the water, then and only then will you be able to tell if that spark is hot enough to burn all that extra fuel being dumped into the pistons without flooding them out. I did it the hard way. Take the advice given here by all and get a book, about 25 bucks and a multimeter about 25 bucks, then you will have an excellent way to troubleshoot any electrical or fuel problem that comes up now and in the future.
Hey, Kwitcher.You also need to keep all of your questions together in one thread.Your other thread on the carbs belongs here, so we know what you know. Otherwise you will be getting wrong and conflicting advice.
Just a thought did the motor run fine until after you changed the spark plugs. Have seen new sparkplugs cause wierd problems. If so try the old ones or other new ones
70 HP YAMAHA dead in the water, EMERGENCY
Linear Mode
