fouled plugs on 92 Pro V 200

[StevoH2O]

Does anyone know of service bulletins on the issue of fouled plugs on a 1992 Yamaha Pro-V 200. My issues include:

• wet oily plugs after 2 uses
• an occasional "heat buzzer" that has happened 3 time in the past 2 years (2 under load, one at idle)

My mechanic hopes that a service bulletin may be out there to inform him of jet issues or running a hotter plug. He does not want to experiment. He has been unable to duplicate the heat buzzer issue, but I am wondering if items are related? Water always coming out the return when it occurs. New water pump 3 seasons ago. I am swapping out plugs like crazy. Thank for insights!

[boats.net]

No there isn't any bulletins on that, we have had issues with ruptured fuel pump diaphram causing it to run rich.

[StevoH2O]

Thank you - will try to look into that!

[StevoH2O]

Fouled plugs from Electrical???

Mechanic had another notion. Could the fouled plugs be from insufficient electrical pulses? He is not convinced that the diaphram issue is totally at fault or else performance issues would be likely at WOT. I can go 50+ MPH with clean plugs and holeshot is great. However, if voltage/amperage is insufficient from the charging mechanism the spark would suffer and eventually foul the plugs evenly which is what I am seeing. It may also explain the errant hot signals that i seem to be having as he says a waivering powersource can throw off all sorts of odd issues. I did add a radio a few years ago and an extra interior light.
Another case - my digital speedo was show my speed at 6 mph despite me holding the boat at the pier. It was the first start-up of the season. I switched between tack, hours, time, and it still showed the errant speed?

Any thoughts on this direction? Anyone else experience anything like this from an electrical perspective.

[Tucker]

Following your dilema Stevo. Did you mention that you changed the stats?

[jb123]

run motor on hose, pump ball, see if it makes it bog down..

i would also seek another tech if they jump from jets to electronics

[StevoH2O]

Ok, heading North for a week's use. I bought a laser digital thermometer to assess thermo issues. I believe that will be more reliable than putting my hand on the engine. What is the desired operating temp? I should be able to test the temp of the output water too.

I will try squeezing the primer bulb while in operation. Am I trying to assess if the diaphrams in the fuel pump are ruptured? I will log in at library to report back.

Thanks to you all for your expertise. I need to get this resolved...

[jb123]

buzzer 3x in 2 years, personally i wouldnt have any concern, your motor needs full flow over intake and any interruption will cause an overheat

[StevoH2O]

Ran good with clean plugs y-day. Took temp readings. 145 on the heads and 150 on side block. this was after a hard run. then idled for 10 minutes and 126 on the heads. Is this normal?

[StevoH2O]

OK put in the next hotter plugs and tech is monitoring them for coloration and oil residue. So far so good today with the plugs.

However, the heat light went off while I was wakeboarting at 23 MPH. I grabbed the laser heat thermometer, and the heads were showing 181 to 184 degrees - so the past heat issues may have been real. Let it cool down and used it the rest of the day with out issues (ran 150 degrees after cooling). Thermos? sensor? waterpump(replaced by Yamaha tech 3 yrs ago)?

THanks for feedback.

[pappastratos]

Not uncommon to replace waterpump every year. Do you run a jackplate ? water intake too high ? When wakeboarding, motor runs 2000-2500 RPM ? May not be enough RPM for pump to flow enough water. Before I do anything drastic, I would install another water pump & pump housing/sleeve.

[99yam40]

I would replace the thermostats and water pump, pull and clean the PRV to start out with.
If still having overheat the it may take a manual descaling of water passages
then test compression and spark and look at the fuel system if still having problems

[StevoH2O]

good suggestions! Mechanic had me remove thermostats y-day. and no heat issue. However, we did not spend much time on H2O as it was very windy.

When wakeboarding, I trim the engine to "3" to create a bigger wake for jumping. this has never created an issue in the past. water stream seemed somewhat faster with stats removed. I took a head temp reading at they ranged from 150 to 153. Mechanic counld not understand why it was hot on both banks when I had my heat issue. Perhaps somethings up with that pump.

plugs are still turning black. that appears to be a seperate issue to work on. they are all universally black and oily.

[jb123]

have you checked your oil linkage setting/pump output ?

your waterpump is 3 years old, i do mine every year,alng with stats and PRV, CHEAP ins, lil over the maint schedule but i prefer to be safe than stuck.

[dilb1229]

I echo the boats.net reply on the fuel pumps. I have a 1991 ProV200 and was always having fouled plugs. (At one point, I had 5 or 6 sets of plugs, including a higher heat range set.) Believe I was running on only 1 of 2 fuel pumps for a year or so and could never figure out why the plugs were fouling and it was not running as it used to. Second pump gave out and was pretty much dead in the water. Replaced the fuel pumps (they are cheap and easy to replace) and along with rebuilding the carbs (always a good place to start), motor has been running great. I did not have any overheating issues, so I can't say whether this will help with that, but I wouldn't be surprised.