2001 OX66 225 VST operation

[Suncoug]

I have been having various problems and I think I got it zero'd in to something in the VST. When I switch the ignition to on position, I can hear some sort of pump going off (not sure if it is the low pressure pump), then unlike the port motor, the starboard one continues to run without stopping, until I move the shifter to forward or reverse position. It sounds almost like toilet running continously because the float mechanism is not working. Also, the fuel pressure is at about 35 psi, though for about a second shortly after I turn on the ignition, I hear some metal needle moving rapidly. And, during that time, the fuel pressure flutuates rapidly as well.

Unfortunately, the motor won't crank on that motor either; I suspect the neutral switch. So, I don't know how the motor is runnng now but it was running poorly before the starter issue.

I would like know what should happen when the ignition key is on and what might cause the VST tank to buzz continously.

 

[rodbolt]

Re: 2001 OX66 225 VST operation

double check all electrical connections, make sure there is no voltage on the brown wire at the starter solinoid with the key on. the system is designed to operate the high pressure pump for about 3 seconds at key on power to pressurize the fuel rail.
at key on start power is diverted from the stater to the ECU to keep the pump running during engine start as well as a few other functions at start. when the key is released the ECU shifts to run mode if pulser coil signals are present.
the pump speed is controled by the large resistor on top of the throttle body at speeds below about 2000 rpm it runs in series with the resistor, above that the ECU controls the ground at a full 12 volts.
as the injectors open either sychronous or asynchronous the pulses cause the fuel pressure in the rail to fluctuate, the function of the fuel pressure regulator is to dampen the oscillations and maintain 35PSI within 4 psi.
the vacum hose on the regulator goes to the intake manifold, its function is to close off the regulator more when the throttles are opened rapidly. on rapid acceleration the system keeps synchronous injection and also adds asynchronous(batch) injection to prevent bogging due to fuel leanout in the intake track.
if the fuel pressure fluctuates more than 4 PSI that motor will do stupid things yall aint never seen.
I dont follow your logic on the float.
all the float does is maintain the level of fuel in the VST coming from the low pressure pumps which are mechanical and wont work at all with the engine not running or at least cranking.
the VST vent goes into the intake at the lower stbd side of the throttle body. if during priming or running the float needle leaks it will run very rich on the lower cylinders as the excess fuel/oil mix is beaing dumped into the intake. I cant remember your specific model but quite a few EFI motors cycle the injectors once before cranking to aid in preventing sticking.
at High pressure pump shutdown or engine off condition the rail pressure should stay close to 35 PSI for several minutes, if it doesnt suspect a faulty regulator or a leaking injector.
for your starting issue trace the brown wire from the keyswitch to the Nuetral stat switch and back to the main harness then at the bullet conector at the start solinoid.
a quick test of the solinoid is simply unplug it and touch the solinoid end of the brown wire to the solinoid positive cable, if it works its ok if not test the continuity of the brown wire to ground.

 

[Suncoug]

Re: 2001 OX66 225 VST operation

Thanks for so much your help on this. I will certainly check on the items you have mentioned, but I am still confused about what condition could cause the high pressure pump to continue to run. In other word, what tell the high pressure pump to stop after 3 seconds?

Also, the rapid needle fluctuation sound may very well be caused by the injectors. However, it doesn't happen with the port motor at all and I think the fuel pressure stays within 4psi, I will double-check.

 

[Suncoug]

Re: 2001 OX66 225 VST operation

Mr. Rodbolt,

Your advice was right on and I found the bad connection on the brown wire as well as black wire. Now, I have no problem cranking the motor and the high pressure pump stops running after 3 sec. or so.

I took the boat on the James River to perform the rest of the tests. Here is what I learned:

1. Started right up
2. Idle speed still fluctuates between 6-800 rpm
3. I can push the rpm to about 4900 under no load however under load (when in gear) it goes only upto 3200. If I push the other motor higher (say to 4300), it will run up to 3800 or so. But, it still seems to bog down with no power.
4. fuel consumption is considerably higher on the problem motor.
5. Fuel pressure while running fluctuates rapidly around 35psi. The range is just about 4 psi.
6. Winky Blinky indicates all is normal. I get code 1 after warm up.
7. I had put in a new o2 sensor, but I only got .05 V. I put another one and I got .56V. The running condition did not change.
8. I ran the motor with o2 sensor disconnected and it ran pretty much the same.
9. I ran with the emergency CDI bypass, but i didn't change anything.

Seeing all this has started after I messed with idle speed screw, which makes no sense, I am wonder some critical wiring has been disconnected. I will go back and check everything over. I don't have test harnesses for CDI peak votage, as well as Pulser coil. I will check them.

I really appreciate your help on this. I feel like I am very close but I am at a loss to what other things to check. I would appreciate your help on this.

Thanks!

 

[Suncoug]

Re: 2001 OX66 225 VST operation

FYI, I have done the following:

1. Checked VST filter
2. Replaced all three low pressure pumps
3. Synched Throttle plates
4. Checked TPS (was slightly off but adjusted to spec.)
5. Replaced spark plugs
6. Replaced spark plug caps
7. Swapped ignition coils with other motor
8. Replaced thermostats
9. Replaced fuel/water seperator and fuel filter on the motor

Bad fuel/water in the fuel is a possibility but the other motor which shares the same tank runs great.

I would really appreciate your help on this. I will order wiring harness for additional test for ignition related items including CDI and pulser coil this week.

 

[rodbolt]

Re: 2001 OX66 225 VST operation

if you quit splatter gunning it, it works a lot easier and cheaper.
if you replace enough parts eventually you have no choice but to hit it.
however that method is a tad expensive.
do you have a multi meter that either is a peak readig or has a DVA adapter ?
RMS wont work.
test compression, test spark at 7/16ths gap. if both passs the pulsers and the ign coils are capeable of making spark.
then at the running speed test the CDI Peak voltage to the ign coils.
remember that depending on the prefix to the model the system may shut certain cylinders off at certain RPM.s above about 1800 all 6 will spark.
if they dont above 1800 you have a possible ign failure.
why would ya ever ever touch the idle speed screw on an EFI motor ?
it either idles its entire life at what the factory set it at or its BROKE.
remember, the sequence is suck,squeeze, bang and blow. everything else helps make it go.
correct intake of the correct fuel to air ratio, compression that is within 10 PSI on all six, spark at the correct crankshaft orientation and exhaust and it has no choice but to follow the laws of physics.
you have lost one or more of the 4 basic functions, however if you keep playing,especially no load RPM's at 4900 you may get to start with fresh mechanicals before solving this issue.
if all you wish is RPM leave the prop at the dock and go play.
if you suspect an injector, simply remove the airbox, run the boat until the problem RPM and spray 50/1 premix down the air throats, if on picks up then look at why that cylinder is not getting fuel to the piston crown side of the cyl.
did you ever verify correct output voltage from the O2 sensor at operating speeds as per the 3 or so tech bullitens ?.
have you tested the fuel pressure regulator as well as inspected its filter? have you popped the injectors out and had a look at the inlet filters?
if your nervous about running with the hood off and listening to it scream beside you then make up an octupus for CDI output testing. use 6 wires and carefully tinn the tips, insert the tinned tips under the bullet connector sleeve and insure a good metal to metal contact, bring the other 6 ends outside the hood. all you need is 1 known good ground and the + lead can be touched one at a time on the 6 CDI output leads. if you have the correct CDI output voltage on all 6 go chase the fuel issue, if not chase the ign producing or ign controlling systems.
have you checked ign timing at the problem RPM? certain failures, most will be detected by the winky blinky, can lock ign timing at 7* BTDC but that normally results in a to fast idle.
I see your boating on the james, what part of VA are you in?
I may know a tech near you in the suffolk area.
I am 80 miles from norfolk.
look in the 05 or 06 tech guide for a copy of the engine condition sheet, if you fill in each and every blank by the time you get to the end you will have it nailed.

 

[Suncoug]

Re: 2001 OX66 225 VST operation

Mr. Rodbolt,

Unfortunately and sadly, it is tough to find a good mechanic. In Richmond, there is only one good Yamaha dealer (Cooper's), and my boat is too big for me to bring there, as they are in the middle of the city. Having been ripped off so many times by auto and marine dealers recently, I refuse to take my boat to a mediocre mechanic pay $1,000 to $2,000 with no guarantee to address all underlying issues. I have asked you where your shop was a while back, so I could drop it off on the way to OBX where I fish, if you are interested in taking a look at it. I don’t mind paying for good quality service…

I changed the engine idling speed as per manual. My mistake was to do it while the motor wasn't running. I have changed idling speed on cars, so I figured it won't hurt it to increase the idle speed up a little, since the motor was running at 4-500 rpm and died sometimes when bumping in and out of the gear. Looking back with the motor's propensity for rough idle and smoke at idle, they may all been related. Still, simply changing the idle speed should not have caused all these issues.

I have rechecked all wiring harness and connections and they look good. I will check the remaining items per your advice. A few questions for you:

-At operating speed, the fuel pressure fluctuates about 4psi going from 33 to 37 psi. Is this normal? I should have tried the same on the good motor.

-How do I check the timing?

-How often do you see CDI failure?

-Where I can find the Yamaha bulletins.


Again, I really appreciate your help on this. Please let me know how I can contact you. I am sick of missing out on the tuna season at OI.

 

[rodbolt]

Re: 2001 OX66 225 VST operation

the yamaha shop I work out of is Joe's Marine in whanchese NC. I dont know if I can help but I do know how frustreating this type issue can be. to correctly set the idle speed on the OX66 motor requires the motor to be running. you first set the TPS output voltage with the throttle shutters fully closed,not just on the idle stop. then turn the idle speed screw in about 2 turns after it contacts the throttle arm. then start the engine and adjust as per tech/tune up guide after it enters normal run mode. the HPDI sets somewhat different.
most automotive EFI units have an IAC or ISC, yamaha 2 stroke EFI motors dont,yet.
the throttle shutters have idle air bypass holes and correctly setting up the linkage is imperative.
timing can be checked with a standard timing light.
I have seen 1 CDI failure on a V6 in about 7 years.
the V76 motors occasionally lose a charge coil.
I did have a Vmax 225 HPDI a few weeks back with a pulser coil failure after 13 min of run time above 5000 RPM.
but the ECU did not catch the failure my multimeter did, it was way over voltage.
I dont think your messing with the idle speed screw alone created any issues, I think they were happening already.
I cant guess at the time to repair only that when I am done it will power up correctly.

 

[Suncoug]

Re: 2001 OX66 225 VST operation

Update:

I couldn't get hold of a peak voltage tester. So, I continued on with the fuel side of troubleshooting. First, swapped out the vst tank and fuel injectors with the other motor. It made no difference. VST filter and injector filters were in good shape.

Then, I swapped out the CDI. Again, no difference. But, I hooked up the winky-blinky again and this time it displayed code 18, which means that it was receiving incorrect input from the TPS sensor. Hooked up the TPS sensor tester harness, and it was way off.

I took the TPS sensor off and discovered that one of the wires (I forget the color) was damaged. I am not when it got pinched but I am sure it happned when I swapped out the low pressure pumps. But, I have taken them off a few times so I am not sure exactly when I did it.

Took it out to water and it was definately better. But, still it was sucking gas big time and it won't push more than 4k rpm. I suspect that O2 sensor got messed up from getting too much gas from wrong TPS voltage input. The range of voltage was normal but something wasn't right.

This weekend I will replace the O2 sensor and the gasket and I am hoping that everything will be back to normal.

BTW, I did the compression check and they were OK, ranging between 115-122 with 115 on the lower two cylinders.

I will report back again after this weekend. It has been at times frustrating but I got to learn a lot thanks to Rodbolt, manuals, and generally tinkering and thinking about the OX66 motors.

Again thanks Mr. Rodbolt!

 

[JUSTINTIME]

Re: 2001 OX66 225 VST operation

you can get a dva at esitest.com for under $40

 

[Suncoug]

Re: 2001 OX66 225 VST operation

I would like to give a belated report. It took a while to take the boat out in the ocean to give it a full run. I took her out and ran all day last weekend and everything went well and caught a couple of nice stripers to boot. Looking back, I may have had several issues including mixing E10 gas with non-E10, defective low pressure pumps, carbon bulidup, damaged TPS, dirty O2 sensor, etc. All issues have been addressed and both motors run good now - no more smoking, stalling, bogging, etc.

I appreciate help from others particularly Mr. RodBolt. I have learned a ton about these motors and now I have most of the tools neccessary to maintain them properly and to troubleshoot them. Thank you!