Just got a 2000, 30 hp Yamaha. Very shaky/jumpy, at low speed in gear. Runs perfectly smooth in neutral and high speed, just rough at “no wake” idle in gear.
Also have to keep pumping bulb every 20-30 seconds or it dies down. Not sure whether to dive into the carbs (3 of them) or replace fuel line and bulb first?
Any suggestions?
sounds like a fuel pump
first compression test
then drop cylinder test
compression test comes out to 132, 135, 132 top to bottom.
Not sure what you are talking about with the drop cyclinder test. Leak down?
Crank it up.
While running, use an insulated tool to remove one spark plug wire. (Spark plug wires in good shape won’t shock you. Some will and it is a pretty good jolt.)
If the motor does not run worse, that cylinder is NOT making power.
If the motor does run worse, that cylinder IS making power.
If a cylinder does not appear to be making power, you have either a fuel or spark problem on that cylinder.
17’ Henry O Hornet
26’ Palmer Scott
10-4, thanks
Alright replaced the fuel pump diaphragms this afternoon, seems to have fixed the pumping the bulb issue.
Tried the drop cylinder test, didn’t get far…
FYI #1. Channel locks are not well insulated enough to pull this off…
FYI #2. Thick leather gloves and channel locks are still NOT insulated enough to pull this off…
FYI #3. The tingling in your hand lasts for awhile… 
Will try again tomorrow after buying some THICK rubber gloves.
haha^^^ have been unfortunate enough working on cars to know that #3 first hand. A chevy 350 will kill ya by the time u get all 8 tested lol
I had a good laugh while I was standing in running water pulling the wires. It had been a while since I got hit good by a motor.
At least there was no picture of you for us to enjoy!
John
Pathfinder 23 HPS
I 4 dollar plastic spark plugboot removal tool from your local auto parts store works well for preventing that
I use my timing light, lot easier than pulling wires.Just clamp on wire pull trigger, if it flashes you got fire. Look at plug if dry no fuel.
River rat, sorry. Didn’t mean to get you lit up. Hope the tingling is gone.
17’ Henry O Hornet
26’ Palmer Scott
haha, no a problem PalmerScott, I have gotten a good laugh out of it. The fuel pump seems to have solved most of the issues, ran it hard the other afternoon and seems to be idling alot better in the low range as well. I am thinking it may have been a little piece of trash in the low speed jet that finally worked its way through.
First time running the motor and I am usually a litte over aware of every little bump and shake.
River rat, sorry. Didn’t mean to get you lit up. Hope the tingling is gone.
17’ Henry O Hornet
26’ Palmer Scott
ronfishn
timing light will show spark, but it wont show which cylinder isn’t making power from a lack of fuel
true, I know you are a pro, but just seems there should be a better way than pullin wires with that much voltage. Is this pretty much the accepted way to troubleshoot? Really not tryin to be a smart mouth,just tryin to learn,I know some power packs will fail with an ungrounded plug wire
i would try some evenrude engine tuner… its a foaming/cleaning spray… spray directly into carbs and down the jets… it will break up carbon and will usually get a good bit of dirt/debris out of jets/carbs… run it on the ears after u do… get motor warm(let it run for few minutes) repeat process… and let sit.(when you start a ton of smoke will come out dont be alarmed…
depending on model and price i would replace the coil packs… my mercury started to show signs of weak spark. i ended up gettign a deal on new old stock the whole coilpack/wires for like 100bux… it made a huge difference.
other options would be to check your idle speed/rpms… over time i have had older 2 strokes loosen the throttle tension it would almost chase in low idle but once it got 200 more rpm it would clear up… not farmiliar with your motor but you may have an idle screw with a spring… you can turn it in or out and the spring apply’s load to keep it seated… i recommend doing this at the landing bump in gear on trailer the load will act like low speed… i have never gotten them dialed in on the ears in driveway… always took a ramp/trailer…
you may also have voltage regulators… mine were 2 boxes under the coilpacks/wires… sometimes they go bad or get weak… u would need a ohm/voltage reader to check this… along with a manual.
I have put 50 miles (gps) on her so far this weekend. The fuel issues are gone for the time being. Still has a little shutter at about 1/4 throttle but less pronounced than before.
Picked up a set of boot pullers the other day, just been on the water too much lately to get after it. Will get to it tomorrow as I am not getting back on the water after the Charlie foxtrot that Sunday was with everyone and their brother on the water.
ron
yes, its called a drop cylinder test
they make special pliers to do it so you don’t get shocked
Well, been running great, and catching plenty of fish… Till today, started second pull, ran great first 7-8 miles, then bogged and died…
Finally got it recranked and headed back to ramp, died again, just bogged down and died. Pulled and pulled to no avail. SeaTow saved the day, best $ ever spent. Now I have to start trouble shooting over again.