Yamaha Outboard Help 1995 225TXRT Carb V76 Miss, No spark on #2

[RSTDdog]

Well figured I would post this here just to see if we have any out board Techs or folks familiar with this engine. Here's what I have got.

 

1995 Yamaha 225TXRT. Carbureted (6 individual) 76 degree V6 First noticed the problem as a surge sensation running at 4000, would get an intermittent burst for 1-2 secs then drop back. Had a little miss stutter I could detect coming up on plane, but otherwise planes easily (226 GW Seafarer). Replaced spark plugs, ran the same. Ran it for about an 1 hour after that. Checked the plugs and number 2 looks new. Here's what's been done.

 

The engine has spark on all six at idle and I have visually verified spark at the spark plugs on all six at cranking speed (old school test with plug in the boot).

 

Checked the ignition coils resistance primary and secondary windings. All OK per spec.

 

Checked the resistance on the spark plug caps and found #2 way out . Replaced the spark plug cap on # 2. Test ride no change.

 

Swapped complete coil assembly between #2 and #4, Still no change, problem does not follow the coil. Still missing with no coloring of the #2 plug.

 

Resistance of Both Charge Coils and each of the 6 poles of the pulser coil are in spec.

Using the Yamaha (Electro Specialties) CDI Tester (Black box with the dial, light and High/low switch) The Pulser coil (all six poles), the charge coils, and the CDI outputs to the ignition coils (using the specified load coil) all test in range.

 

All of them tested higher than the minimum specified set point. Spec for CDI output to coil is dial at 75 and switch on high. All 6 cdi outputs would continue to light the light up to a dial setting of 82. Cranking speed with all plugs removed.

 

Same for pulser coil output. Spec is 45 and low switch. All 6 poles will light the light with a dial setting up to 55.

 

Repeated the output tests with the Yamaha CDI tester with engine hot. Same result.

 

Ran boat with Air intake removed and confirmed fueling on #2 with same spray pattern as 4 and 6. Fresh fuel, 90 octane No ethanol Recreational marine fuel, New Racor filter, have never had any fuel starvation problems. Still have even compression 125-130 in all cylinders.

 

Can Pulser Coil check good at cranking speed and be bad at higher Speed?? Pulser coil is over $300.00 don't want be wrong on this.

 

Anyway to check if I'm dropping the pulser for #2 under load??

 

Don't have a winky blinky (Yamaha Diagnostic Tool YB 6444), but the manual says it works on mine. Is the winky blinky a reliable test? Would you condemn a pulser based on the Winky blinky code?

 

Have I missed, not checked anything obvious that would effect just #2?

 

Thank You in advance for any help, suggestions,

 

Derrek

[dacheedah]

1) Do you have a fuel / water separator? If so drain it or for cartridge replace the filter. If you don't have one, get one.

2) get a gallon of fresh clean gas from a shell , Phillips in a fresh container and go direct to the motor. Cheap gas causes lots of issues. ( I always run marine stabil and this time of year I double up)

3) If it's DI pull the plugs and mark a line on the ceramic on the opposite side of the ground electrode. I know that this will cause an e-tec to run bad, the electrode needs to face away from the injector.

4) Bad injector , try switching the injector to see if the problem moves / or carb hose . . . I had to replace all my hoses with lined hoses because of ethanol and use oetiker clamps instead of the cheap hose clamps. Make sure your priming bulb is hanging vertically from the motor and not laying horizontal.

[dacheedah]

I use http://forums.iboats.com/forum.php for my boat issues, not real familiar with Yamaha marine but lots of good help there. Good luck

[RSTDdog]

1) Do you have a fuel / water separator? If so drain it or for cartridge replace the filter. If you don't have one, get one.

2) get a gallon of fresh clean gas from a shell , Phillips in a fresh container and go direct to the motor. Cheap gas causes lots of issues. ( I always run marine stabil and this time of year I double up)

3) If it's DI pull the plugs and mark a line on the ceramic on the opposite side of the ground electrode. I know that this will cause an e-tec to run bad, the electrode needs to face away from the injector.

4) Bad injector , try switching the injector to see if the problem moves / or carb hose . . . I had to replace all my hoses with lined hoses because of ethanol and use oetiker clamps instead of the cheap hose clamps. Make sure your priming bulb is hanging vertically from the motor and not laying horizontal.

 

1. Yes, a Racor with the clear bowl,Has always had one, No water in it, Replaced it anyway.

 

2. Running Non ethanol 90 Octane marine fuel, always run Blue Stabil. Just bought 77 gallons and changed Racor at the same time. Running with the air cleaner off, Its fueling (would have melted the piston by now otherwise)

 

3. NA_ As indicated in post its carbureted not DI.

 

4. Same as #3, No injectors, Carbureted.

 

I use http://forums.iboats.com/forum.php for my boat issues, not real familiar with Yamaha marine but lots of good help there. Good luck .

 

I have it posted there as well. Figured I would try here too. We have a lot of members with a lot of experience.

 

Thanks for the reply.

 

Derrek

[RSTDdog]

Well its not spark related, have continuous spark (per timimg light even when it surges). No significant combustion taking place though. #2 is colder than the other five. Surges and tries to make combustion around 4-4200 rpm jumps to 4500 when it does hit.

 

Ran using a 6 gallon tank and eliminated the boat fuel system, still does the same thing. Boat starts right up every time, hot or cold, never need to prime it.

 

Fuel pumps seem to test ok per the manual.

 

Next step is have a look inside #2 carb I guess.

 

Getting enough fuel to keep from melting pistons but not enough for combustion ( or that's my theory since there's spark and compression)

 

With all the Yamaha motorcycle folks here I figured we have at least some Yamaha outboard techs in this bunch.

 

This one has got me stumped.

 

rstddog

[dacheedah]

Two questions, is that a two stroke and have you checked compression on the cyls?

[E-Fishin-C]

Replace all Spark Plugs??

[RSTDdog]

Yes its a two stroke. I checked compression 125-130 psi in all cylinders.

 

I replaced the spark plugs twice. When it first did it, that's what I thought it was and my friend brought me out some BR9HS-10 because thats what he had (one heat range off). Still had the problem. DUring diagnostics I replaced them again with BR8HS-10 which it calls for.

 

It sparks on all 6 while cranking (visual spark check at plugs), Stator and pulser check good, sparks on all six with the timing light running at idle and under load at 4000.

 

I went through the carbs (all six of them) in December. Other than slightly rough idle in gear (which it has always had), starts easy, idles good, and ran fine until this problem started.

 

Since the last carb overhaul I have only bought non ethanol fuel from the marina.

 

GOing to work on it some more today.

 

Thanks for the replys,

 

rstddog

[E-Fishin-C]

Did you read the comments on iboat http://forums.iboats.com/showthread.php?t=519111

[RSTDdog]

Did you read the comments on iboat http://forums.iboats.com/showthread.php?t=519111

 

Yes, that's my thread. ddog is me. I tried for ddog here but somebody had it already, thus rstddog. I tried for rstddog personalized plate in FL and that was already taken too.

 

Any way I figured it out today.

 

Found a piece of trash in the #2 carburetor main jet. A sliver of something, my best guess some varnish residue broke loose from inside a fuel line. Carburetor still spotless otherwise.

Diagnostic errors I made.

 

1. Over thinking it.

 

2. If you have spark and compression move on to fuel.

 

3. Misread spark plug (will update with pics) closer examiantion revealed there was spark taking place. Lean misfire.

 

4. On Yamaha V76 carbureted motors, the carburetor is on the opposite side of the cylinder. i.e Carbs 1,3,5 are on the port side, Spark plug and coils for 1,3,5 are on the starboard side and vice versa for 2,4,6. So I first examined the #1 Carb (thinking it was #2) for a problem with the #2 cylinder. Realized it today looking up parts, went and pulled the real #2 carb and fond the problem. Running on the main tank again with anti-syphon valve still in place.

 

Thanks for the input.

 

rstddog

[Ozlander]

Good on you.

 

I was going to suggest you revisit #2 carb.

[RSTDdog]

Good on you.

 

I was going to suggest you revisit #2 carb.

 

Actually it was the FIRST visit to the "correct" #2 carb:doh:

 

Not sure what part of the TPS being there didn't clue me in that the first visit was #1 carb. Just not thinking......

 

Having Six individual carbs is kind of a PIA except for when you only want to have a look at one of them.

 

Runs good on 5, but runs much better on 6!!