1995 Yamaha 225TXRT NO combustion #2, surges above 4000 rpm SOLVED FIXED

[ddog]

Edited title since technically I have spark on #2, but no combustion taking place.

1995 Yamaha 225TXRT. First noticed the problem as a surge sensation running at 4000-4200, 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 other wise planes easily (226 GW Seafarer). Replaced spark plugs, ran the same. Ran it for about an 1hour. 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.

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) 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 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??

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

Don't have a winky blinky YB6444, but the manual says it works on mine. Is the winky blinky a reliable test? Would you condemn a pulser based on the Winky blink code if there is one?

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

Thank You,

Derrek

 

[99yam40]

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

You need to be also testing while problem is happening (motor running).
Specs show loaded( motor running) and unloaded( wire disconnected and hooked up to meter only) and different RPMs.
A DVA adapter with regular meter or a peak reading volt meter made for these ignition systems is what I would use. I never used one of what you have and never saw the specs in the manual for it.

An inductive timing light should show if you are getting spark to the plug when running.
If you have compression and spark on #2, then you are left with the wrong fuel/air mix in that cylinder to fire properly. Too much or not enough fuel will keep it from firing

 

[ddog]

Re: 1995 Yamaha 225TXRT NO combustion #2 surges above 4000 rpmSOLVED FIXED

Re: 1995 Yamaha 225TXRT NO combustion #2 surges above 4000 rpmSOLVED FIXED

You need to be also testing while problem is happening (motor running).
Specs show loaded( motor running) and unloaded( wire disconnected and hooked up to meter only) and different RPMs.
A DVA adapter with regular meter or a peak reading volt meter made for these ignition systems is what I would use. I never used one of what you have and never saw the specs in the manual for it.

An inductive timing light should show if you are getting spark to the plug when running.
If you have compression and spark on #2, then you are left with the wrong fuel/air mix in that cylinder to fire properly. Too much or not enough fuel will keep it from firing

Agreed on the testing while running. I've been on the water doing plug checks and checking fueling. If it was not enough fuel, I think it would have done some damage by now. Prior to this problem cropping up, plugs always looked the same. Carb is not flooding, and primer bulb pumps up with no apparent leakage at the fuel pump (Top fuel pump is on #2.) Fuel spray patterns on 2 4 and 6 look the same at 4000 rpm with the air cleaner off. Manual choking with your hand will bog the engine.

Have not done the timing light light trick yet. Forgot about that one. If I get off work in time tommorrow I will give that a go and report back.

With respect to using a DVA adapter or peak volt meter, those specs for running loaded and unloaded aren't published in my 1995 Yamaha Factory Service manual LIT-18616-01-14(See Pics). Since you haven't seen a Kent Moore YU 91022-B CDI Tester (also refered to as the 1Y ignition tester in the FSM), I have added some pics and the published test specs for same. Manufactured by Electro Specialties in Chicago for Yamaha (sold through Kent Moore). Mercury has a similar looking tester, its old school predates peak volt meters and digital VOM but was still the OEM test in 1995. The only other specs are the resistance tests.

I see from boats.net that the pulser for my engine was used through the 2000 model year and the stator through MY2001, so maybe those newer manuals may have the specs you are referring to. If you or someone can pass those along that would be great.

Thanks,

 

[99yam40]

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

very interesting piece of equipment , but I still would think taking a peak voltage reading would be easier.
Sorry but I do not have the specs for a 225 motor, maybe someone that does will chime in

 

[ddog]

Re: 1995 Yamaha 225TXRT NO combustion #2 surges above 4000 rpm

Re: 1995 Yamaha 225TXRT NO combustion #2 surges above 4000 rpm

Well this site kicks you off fast when your trying to post. Didn't copy it just in case, lost it all,so not retyping everything. Anyway its a fuel problem. Timing light confirmed the diagnostic tests. Has spark even at 4000 rpm.

Takes over 6" HG with the mity vac to pull fuel at the engine. This is using the mity vac to pull fuel through all the components in the line, this is not a running measurement with a vacuum guage in the line.

Suspecting anti-siphon valve at the tank but it never sucks the primer bulb flat??

ddog

 

[99yam40]

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

Try hooking up and measuring vacuum at different points to see where the problem (restriction) is.

Still does not explain why only #2 is not firing properly

 

[ddog]

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

I started doing that last night (checking in sections) but it got dark. I have a six gallon tank I can hook up and eliminate the boat fuel system. I'll give that atry as well.

It has always had a somewhat rough idle when you drop in gear and would smooth out around 1200 rpm and run right to 5500 no problem. Never a bog or hesitation until this problem.

If the fuel delivery is limited, Number two is the highest carb so makes sense it would starve first. After running it you can touch the number two spark plug while the rest are hot.

Hmmmm should know more tomorrow.

 

[railroad.builder]

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

good thread cant help

 

[ddog]

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm

OK so running with a six gallon tank and by passing first just the boat fuel tank, second I bypassed the racor (has a new filter but what the heck), then bypassed the primer ball. NO change- still acts the same, surging from 4200 briefly to 4500, #2 plug is colder than the other five.

The only thing I haven't bypassed is the check valve on the engine (the one between the engine fuel strainer and the fuel pumps). Check valve test ok though. I ve seen where some people eliminate or gut it, but I haven't had a problem before now.

The fuel pumps appear to check good using the mity vac test. the pressure tests on the inlet and outlet are good. The vacuum test is a little subjective depending on what they mean by "doesn't fall too quickly". They all fall about the same. Not leaking past the diaphram into the crank case.

Haven't seen one in the manual, Is there any kind of an out put test for the fuel pumps? I can always start the boat without having to pump the primer ball.

Next step is pull #2 carb and see if something got in it but I sure don't know from where. Little or nothing makes it past the Racor into the engine strainer.

Any ideas??

Thanks

ddog

 

[ddog]

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm SOLVED FIXED

Re: 1995 Yamaha 225 TXRT NO spark #2 Tries to fire above 4000 rpm SOLVED FIXED

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.

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 99yam40.

ddog

 

[erniefish]

Re: 1995 Yamaha 225TXRT NO combustion #2, surges above 4000 rpm SOLVED FIXED

overthought/ very thorough, there is a fine line, thanks for the posts, glad you got it right and let us know, this place and its members are the best resource!!!!