1989 225 Yamaha excel Runs great Except at WOT

[Ray Neudecker]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Leaking fuel pumps can cause an overrich mixture on those cylinders. They can also serve as a fuel restriction causing the other problems. If you are actually seeing carbon on those cylinders, you may need a better quality oil. Past experience shows that to be a common problem with Wally World brand and other discount oils.

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Ray,

I replaced the pumps a week or two ago.

I have always used Yamaha oil. It is amazing that the rest of the plugs look so good.

I did go through the carbs again and was sure to clean out the main jets.

I am ready for another run to see what happens..............

The saga continues..

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

This week Cleaned out the Carbs and re-ran.......No Change.........Last night dismantled and used the sonic cleaner. It is amazing what the sonic cleaner can get to.

Will run on Tuesday or Weds.

Complete Fule system change out from hoses to pumps.

I did find that the CARBS are 6G701's with Main jet at 190. The book shows that it should have a 6G702 with a #160 and #156 jets.

I will call the Tech that rebuilt the engine to see if he changed them out due to the over over boring on the engine.

As always any comments appreciated...........

 

[Ray Neudecker]

Re: 1989 225 Yamaha excel Runs great Except at WOT

The jetting stock should be 160 port side of carb and 168 on starboard side. 190's which didn't come from Yamaha since there largest is 180 is too rich. Even with the overbore a maximum would be 168 port and 174 stb an that is on a mildy ported as well as bored 225.

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Correction:

Main Air Jet is 190
Main Fuel Jet is 154

These Carbs are 701's. If I rejet to the Air for 230 and the Fuel Jets as you suggest Ray am I OK being that I have the 701 Carb and Not the 702's?

Even when the thing ran right it had wet plugs...........

Oh I almost forgot............found that the spark coil wires on the Port Side were damaged as if smashed in the engine halves...............I just repaired them today. I have not ran the boat after this repair but am hopeful that the perfromance problem is repaired............

The Saga Continues...All comments appreciated.

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Still no change with the primary coil wires replaced.
I have accounted for the fuel system.

Can the CDI unit reduce the spark to # 2 and 4 cylinders? IT was replaced during the rebuild 3 yeatrs ago.

What about the pulsar coil? To me the pulsar coils is just a switch that allows the electric to go to the coil?

Current status is that I still have a weak spark in cylinders 2 and 4.

Any comments appreciated.

Thanks

Mike

 

[Ray Neudecker]

Re: 1989 225 Yamaha excel Runs great Except at WOT

It seems more like you still have a carb problem which could be needles sticking. Did you replace the bowl gaskets and needles while rebuilding the carbs? Have you checked or replaced the plug caps.

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Did find that the needle valves were sticking.

After running the engine tonight the plugs were not soaked as usual. The engine ran the same. No performance @ WOT.

I did replace the plug wire caps earlier.

Can one of the CDI componets break down at 4100 rpm's?

Appreciate your response Ray.

Thanks,

 

[Ray Neudecker]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Not very likely. I haven't seen or heard of this. The plug caps have a 5K resistor in them which can break down and cause a misfire.

 

[Johnshan1]

Re: 1989 225 Yamaha excel Runs great Except at WOT

I am having the same issues with my 1991 Yamaha 150- it is now to the point where it is surging sometimes at wide open.

I had it going wide open, when suddenly it came right out of it, and ran up to near 5400 rpms. It lasted for a week or 2, now I am back to the same deal.

I am going to play with the engine tommorow, but it is gonna be a crap shoot.

One thing I did notice- my oil tank is not being pumped up anymore- I had to manually add to it today. I wonder if this is related at all? Hard to say, doubt it.

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

It was not the primary wire to the coils.

With the engine not running as well as it did prior to the stand down, I will spend time this week going through the wiring since I seem to be finding damaged wires. I will also check the readings on the CDI, Pulser Coil and Thermo switch. Knock, throttle indicator and crank indicators all checked and working. Timing seems to be on...

The carbs on the engine are for a 200 hp. Each carb is jetted with a 154.
I do have the correct jets ordered but am concerned about replacing them with the incorrect carb. 6G701 is on the boat and should be a 6G702. Can anyone tell me is the Voume of the 701 and 702 are the same? Also the 701 has an air jet of 190......book calls for a 220 for the 225.

One last item: Compression checked with a new tester ran out at 105 to 110 psi.

Any comments appreciated.

Mike

 

[Johnshan1]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Hey Mike,

I have been doing research and talking to co-workers with boats and I keep coming up empty handed. I myself went through all my wire connections yesterday, did not find any issues.

I am wondering if the reeds are keeping my engine from going above the 4000 ish mark.

How can an outboard run so well and smooth when there is something so wrong with it that it starves it of 1500 rpms? It just doesnt make sense.

If it were electrical, one would think that you would be loading up the spark plugs with excess fuel. Or you would be having mis-fires (rough running).

If it were a fuel issue, how would it run so smooth and not mis-fire along the way to 4000 rpms?

It is very confusing, but I am 100% sure we are both chasing the same problem.

 

[JUSTINTIME]

Re: 1989 225 Yamaha excel Runs great Except at WOT

u have a high speed and low speed stator that is why
u need a manual and a DVA and voltmeter to test things right

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Human Built and Human Fixed: I think of that everytime I work on this engine.

I have the CLYMER Manual:
Lighting Coil Resistenace: .6 ohms (is this the low speed coil?)
Charge Coil Resistance Brown - Red Leads 1050 ohms, Black/Red and Blue leads 24 ohms

CDI specs:
BL to Brwn 20 ohms, BL to Wh 15 ohms, blk to yellow 22, no continuity with pink
Wht to Brwn 50 ohms, Wht to Black 15 ohms, wht to yellow 60 ohms
Pink to brown 50 ohms, pink to Black 28 ohms, pink to wht 75 ohms, yellow to pink 50 ohms

Are these specs correct? What about the trigger coil? Is there a low and high speed trigger coil? book shows 360 ohms for the trigger coil.

Justintime, do you have any idea on the difference between the carbs on a 200 hp to the 225? Book says that the main fuel is a 154 and the air jet is 190 for the 200hp. (Which some brain surgen has installed in my engine) The 225 should have main fuel jets of 160 and 168 with an air jet of 220. I am about to re-jet the carbs but am concerned about the volume difference if any, and the air jet. Apparently the 6G702 carb for the 225 does not have a air jet that you can replace.?

Thanks for your input.

 

[Johnshan1]

Re: 1989 225 Yamaha excel Runs great Except at WOT

I am not sure I would re-jet right now, it could make hunting for the problem harder. I have got to do more research on the high speed stator thing, sounds like the problem to me?

 

[Johnshan1]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Hey Mike,

Any new news? I have put about 16 hours on mine since friday, cleaned every single connection I could find, still the same.

I am pretty sure its a bad stator. Have you taken any other actions yet? Thanks.

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

This past week.
Disconnected each wire at the CDI and checked all resistance values. Each was consistent and close to the book values. (Cylmer) What I have decieded is that the CDI, which is a capacitor for the coils is draining losing its ability to keep high spark values on Cylinder 2 and 4. With the resistance values on the stator and trgger coils I feel confident that my issue is the CDI.

Timing is correct, compression, Carbs cleaned out multiple times once with a ultra sonic cleaner...................new fuel system..new gas........multiple sets of plugs................

If this dose not work you will be reading about me here in Central Florida!

Now to find a used CDI?

Keep the Faith! One day at a time.......

 

[JUSTINTIME]

Re: 1989 225 Yamaha excel Runs great Except at WOT

throw the ohms scale out and use volt with a dva
u need to check input of cdi and output of cdi

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Justintime would you have the spec sheet on the CDI. My Clymer book dose not show........

Thanks

Mike

 

[Mueller1956]

Re: 1989 225 Yamaha excel Runs great Except at WOT

Changed out the CDI yesterday afternoon. I have not run in the water yet but I was able to tell a difference in the engine.

I belive that I am firing on all 6 now.

More to follow.

Mike