Yamaha 200 Power Loss

[matthewH]

We run a Grady White 222 Center Console with a 200 hp Yamaha Saltwater Series outboard. Both are 2001 models. The engine has been a good performer over the years with some minor technical problems.

During the return leg of a roundtrip from Wareham to Edgartown, the RPMs would mysteriously drop from 4700 RPM to 3400 RPM then go right back up to 4700. She'd run fine for a few minutes then it would happen again. It seemed like the power drop would happen when the boat plowed into a larger wave or wake. The trip out to E-town was FAC, return was mild chop.

Any ideas?

[keithJ]

I don't know if you end up so lucky, but I've had this happen with bad gas. Switching the fuel/water separator frequently seemed to help. Although I have no idea why power would drop when youy hit a wave. (#$119)

[fmw]

Sounds to me like the dreaded ethanol gas problem (high ethanol content in gas causing debris to get into fuel line). I had the EXACT SAME symptoms last year on my '99 200 Yahama. . . would start to lose power going over a big wave or wake. I believe in the end my mechanic -- who was last seen working on Paul Dixon's boat on "Guide House:Montauk" -- changed the fuel filter/separator. Do some searches here and on boating websites and you will find out all about it.

[eastcoast617]

We had a similar problem a few years ago and it turned out that the O2 hadn't been serviced in a while.

[DaleH]

When I had that happening when hitting waves, it was crud intermittantly blocking the fuel pick-up. Also see if that Yam has a VST filter, as that will also cause bogging problems.

[tsheehy]

That engine has the VST filter, and most often when people report surging problems as they go into waves, it is because there is junk in the VST tank that is getting sloshed around and temporarily clogging the VST filter.

The junk is most likely stuff that has been freed up by the Ethanol fuel. I would do the following:

1) Drain the fuel/water seperator and replace the element
2) Replace the fuel filter mounted on the port side of the engine (at least inspect/clean it)
3) Drain the VST tank after depressurizing it - keep in mind that the VST tank contains gas mixed with oil, so don't freak out if it looks a funky green color
4) Remove the VST tank from the port side of the motor and remove the top by removing the 8 or 9 screws around the top - try to loosen as many of these as possible first, before removing the tank from the engine block
5) Inspect the VST filter at the bottom of the pump by twisting it off
6) Clean it with some solvent, it is a very fine mesh and might not appear to be clogged at first
7) Make sure the inside of the VST tank is spotless, clean up any gunk that has accumulated in the tank
8) Re-install the VST filter and tank
9) Prime the fuel filter, VST tank and fuel/water seperator cannister with the bulb

You should plan on replacing the gasket on the VST tank, as it gets really stretched out over time and is nearly impossible to get back in place properly.

-- Tom

[matthewH]

Thanks for the replies. I am leaning towards the ethanol issue as well. I can give you some more info that will probably confirm your suspicions.

This isn't the first time this season we have had a power issue. In early July I could not run the engine over 3700 RPPM. Any higher and the the power would drop right out. Mechanic replaced the plugs and cleared the filters. Engine ran like a top for the next trip.

The next week, my brother borrowed the boat and ran the reserve tank dry. The Grady has two tanks, a 90 gallon main tank and a 57 gallon reserve. He was running of the reserve, but the gauge was showing main. Not knowing what to do, he continued to try to start the engine without gas. He had to be towed in. The mechanic cleaned the filters and primed the engine. It was the next use that the power problem re-asserted itself.

Does this confirm the dirty fuel line issue? I think so. What is the VST?

BTW- I'm not going to do this work myself, but having the information will make it easier to communicate with the mechanics.

[tsheehy]

Matt,

The VST is the Vapor Seperation Tank. It is the big aluminum tank on the port side of the engine under the cowling, you can't miss it. It gets fed fuel by the low pressure fuel pumps. The oil gets injected and mixed within the tank, and then it is fed by a high pressure pump (the pump within the VST) to the fuel injectors.

If you had any junk/residue in your fuel tanks in July, then I could certainly see how running out all the fuel in the tank would allow all that crud to get sucked into the various filters and cause the type of problems you have seen.

The other thing that you definitely want to stay on top of is the Oxygen Density Sensor. If this hasn't been serviced regularly, it can eventually cause some major problems, the first symptoms of which are not being able to run at WOT. If you are brining the engine in to a mechanic, and you haven't serviced the O2 sensor in the last 100 hours, have them remove/inspect it and clean it for you. It will go a long way towards preventing more problems down the road.

-- Tom

[matthewH]

Tom,

Thanks. A google search of Yamaha VST lead me to Virtual Studio Technology. I guess Yamaha also makes digital instruments.

I will add the O2 sensor to the list of things for the mechanic to check. I'll let you know what he finds. I just want everthing to be working before the albie/bonito/bft action gets hot.

Thanks,

Matt

[tsheehy]

Here is a diagram:

http://i42.photobucket.com/albums/e317/BandDad/fuelinjectionpump.gif

You can find one specific to your engine here:

http://www.boats.net/yamaha/partsystem/browse-model-parts.pl

-- Tom

[matthewH]

Well the local mechanic can't figure it out. Got to take it to the yamaha specialist. :confused:

[tsheehy]

What did the local mechanic do to try and diagnose the problem?

-- Tom

[RPratt]

I had a similar problem in June with a Yamaha 200 hpdi 2002. I was coming back from Jeffrey's the motor would run about 3400 then cut to 2400. I got back to the dock with the assumption that it was ethanol. I changed the 10 micron filter and tested the motor again. At this point it would run up to about 3500 to 4000 rpm for a very short period of time then cut back to 2400. I checked the other filter attached to the engine block, no water. Drained the 10 micron, there was a minimal amount of water. The dealer found a loose ground in the engine. No problems since. One symptom that I did not notice at the time was that my Garmin would shut off whenever I started the motor.

[matthewH]

The mechanics report was rather brief- Said he checked/cleaned the filters and checked for a loose connection. Did a water test and the boat checked out fine. I'm not even sure if he checked the VST!! :confused: Anyway- the prblem still persists and thats why i am taking it to the Yamaha guys. They should be able to figure it out fairly quickly.

[matthewH]

The mechanic now admits that the boat "burped" during the sea test and is at a loss- He thinks it may be electrical in nature. Never did check the 02 sensor.

If it is a bad ground- is there something obvious that i could look for?

[tsheehy]

I'd take it to a mechanic that is more familiar with the fuel-injected Yamahas. It doesn't sound like he even did the basic stuff that was outlined above.

A clogged VST filter or a carboned up Oxygen Density Sensor are very common on these engines, and are the first things that should be checked given the symtoms you described. Other basic stuff like checking the TPS voltage and fuel rail pressure also go a long way in figuring out what is happening. If he didn't know enough to check these first, I wouldn't let him start replacing random electrical parts at your expense trying to fix the problem.

The original problem you described above (surging when hitting waves) is a classic symptom of a clogged VST filter - which could have come about as a combination of E-10 gas and running the tank dry, sucking up all the debris at the bottom of the tank.

-- Tom

[matthewH]

Tom,

I agree- I've had it with this crew. I'll get the guys at the Yamaha dealer to look at it on Monday. I'll post the results.

Thanks for all your help.

Matt

[Slamdance]

Excuse my ignorance, but I don't believe this is a Fuel injected motor. The Yamaha SWS motors I'm familiar with are all carbed. The HPDI and OX66 motors are both Fuel Injected, with the HPDI being a DFI. If so, I don't think there is a VST tank. Am I wrong on this Matt?

Either way, I'd first look at the battery terminals to make sure all connections are secure. Even if they look nice and tight, I'd probably remove all wires, use a wire brush on the connections and battery posts. I'd also make sure you are using Nylok nuts, rather than wing nuts. Also check the ppower leads under the cowling for corrosion and tightness. Chances are high that when you hit a wave you are getting a short somewhere.

If that didn't do it, I'd check the pick-up tube in the main tank. If the problems manifested themselves after your brother ran the reserve tank dry, I'm assuming you've been running off the main tank since then? If so, try filling the reserve tank and running off that for a while. If it runs fine on the reserve, you've narrowed it down to a fuel delivery issue with the main tank.

[matthewH]

Steve,

Thanks for the suggestions. My dad ran the boat on the aux fuel tank today and had the same issues so it's not that. I'll check the electrical components that you suggest. How do i identify the power leads?

BTW- Fished with your friend Gordon on Wednesday. Seems like a good guy. He really slayed the banded rudder fish.

[flyfshr1]

Matt,

Check your pm

[tsheehy]

I don't believe this is a Fuel injected motor. The Yamaha SWS motors I'm familiar with are all carbed. The HPDI and OX66 motors are both Fuel Injected, with the HPDI being a DFI. If so, I don't think there is a VST tank. Am I wrong on this Matt?

Steve,

The 0x66 motors are labeled "Saltwater Series" as well, but good question.. I believe Yamaha made both carbed and EFI versions in 2001.

Matt,

Does your engine say "Electronic Fuel Injected 0x66" on the side? Or do you have the exact model number? ie SX200TX for EFI and S200TX for carbed?

-- Tom

[Slamdance]

Matt: Just look for the large guage red and black wires going from the main harness to the fuel pump, starter, etc. Make sure the terminals are corrosion-free and connections are tight. While you're in there, spray them down with Boeshield T9 or something similar. If the issue still persists after all of this, consider getting the batteries themselves checked out. I have had battery posts and plates get dislodged inside the battery casing and cause all sorts of mystery power issues in the past. Knowing the way you run a boat, it wouldn't surprise me if your batteries were falling apart from the inside out! And yes, G-Man is the trashfish King!

[JGH]

Sounds suspiciously like a problem I had with an older Grady 204 and a brand new Yamaha 150 Saltwater Series. At first it was bad gas/dirty tank. After having the filters replaced I eventually had the tank replaced. The next season the problem recurred and Ethanol was to blame. Had the fuel pump replaced. Twice. Worked for a short time, then the problem happened yet again. The servicer -- a reputable Grady/Yamaha dealer -- never did get it completely right. (In their defense, the hull was quite old, and I think the dirty fuel got the new engine off to a terrible start.) After a few additional unrelated problems having to do with the age of the boat, I sold it. --124-3

I'm not suggesting your problem is not fixable, but I am suggesting that it can take even reputable dealers with the right expertise a long time to get to the bottom of this kind of problem. Hope it's under warranty.

Good luck.

[matthewH]

Unfortunatley, it's out of warranty. I have a ton of confidence in the Yamaha dealer- they always serviced the engine in the past.

[JoeyM]

wow, i have almost the same exact motors and had the same exact problems. (dunno if you have ox66's, but i do, and they says SWS on them too)

check it out:

http://www.thehulltruth.com/forums/thread-view.asp?tid=114372&posts=5&highlight=ri%20edge&highlightmode=1#M1141642


i just spent the morning fixing it. i tried to get a mechanic, but everybody is booked and my boat isnt trailerable so i ended up working on it myself.

here's what i did:

cleaned o2 sensor, new plugs, cleaned vst screen, replaced racor, replaced fuel filter on powerhead

results: motor runs great.

i think it was really the vst screen, everywhere i looked i found red sand type material clogging the filters. the vst screen was especially dirty.

from what i have researched, it was most likely due to the ethanol gas cleaning the gunk off of my fuel tanks.

the posts on this thread about the vst cleaning are right on. and i agree 100%, get the VST O ring before you try to clean the filter, trying to get that damn o ring back is almost impossible as it gets all stretched out.

it's not that hard to do. if you order a yamaha repair manual its pretty easy.

good luck!

--127-3-

[Frequent Fly-er]

JoeyM

If you put the VST o-ring in the refrigerator for a couple of minutes it will shrink the o-ring and make it easier to reinstall.

[JoeyM]

JoeyM

If you put the VST o-ring in the refrigerator for a couple of minutes it will shrink the o-ring and make it easier to reinstall.

yeah, that's pretty much what we did. although we were at the dock...so it was a cup of ice water. doesnt give you much time, but it helps a little bit. was in the mid 80's when we were doing it, and it would get hot and stretched out again fast.

next time, i'll just get a new o ring.

[matthewH]

VST! Just got the call this morning from the Yamaha dealer. VST filter was all fouled up- likely cause is the ethanol. He also reported that the F/W serparator was not a 10 micron. Replaced that too with Yamaha recomended parts. He suggested that we change the F/W after 20hours.



Thanks again for the input.

Matt

[tsheehy]

Matt,

Sweet.. Glad the problem got fixed!

-- Tom

[FireFly]

Tom really knows his VST stuff and helped me out this spring.

Glad to hear you are back on the water.

[Whisky Dick]

interesting reading this thread because misery loves company. i having similar problems, here's my yahama story trying to make it short so we can work problem.

-started jumping rpms...found bad ground...fine for most of summer
-started bogging at 2500's rpm...changed filters (water seprator 10 micron and in engine fuel tube), plugs etc...fixed for a bit
-now started bogging between 2800-3200 more regualrly...cleaned vst screen was all mucked up. still boggin.

we are going to work our way through some more filters but i have a feeling its my fuel pump. maybe run with fuel pressure gauge this week. I need some other suggestions, are we missing anyhthing simple (ie like a ground)first before i go to fuel pump. Im working with a yahama certfied tech and friend so nothing suggested is beyond my capabilties. need some frackin help here before i go insane.

[tsheehy]

Rich,

When you say the engine is bogging between 2800-3200 RPM, do the symptoms clear up after you get above that range, or the engine is limiting you to 3200 RPM?

What other maintenance has been done recently? Have you tested the Oxygen Density and Throttle Position sensors? These should be checked every 100 hours. A fouled O2 sensor may limit your upper RPM range, but if you can't get above 3200 RPM then I'm guessing something else is wrong.

There aren't any other symptoms outside of the bogging? Excess smoke, fouled plugs, etc?

Have the low pressure fuel pumps been replaced yet on that engine? They are relatively in-expensive and should be replaced as preventative maint. at least every 3 years. If the low-pressure pumps haven't been replaced yet, that is the first thing I would do.

You can quickly check to see if the low and medium fuel pumps are operating correctly by installing a fuel pressure gauge to the schrader valve on top of the VST. You should run the boat with the fuel pressure gauge attached and see if it drops when the engine bogs.

If the fuel pressure is below normal at the VST tank, you will have to do some more troubleshooting to determine whether the problem is within the VST system itself or towards the low-pressure fuel pumps and possibly the fuel lines back to the tank.

To troubleshoot the low-pressure part of the system, you will have to use a vacuum gauge to monitor the vacuum between the low pressure fuel pumps and the VST tank. If the vacuum looks ok here, then your issue is within the VST system - either the VST pump, the fuel pressure regulator or the VST filter.

If the vacuum is low at the output of the low-pressure pumps, you will need to slowly work your way back towards the fuel tank to determine where there is an obstruction/restriction that is limiting the flow of fuel to the low-pressure pumps and VST.

If the fuel pressure at the VST tank is normal, then the problem lies on the high-pressure side. There is another inline filter between the VST and the high-pressure system called the medium-pressure fuel filter. If your VST filter was gunked up before, it might be worth replacing the medium-pressure filter if everything else checks out.

After that you are into the high-pressure system, which can only be monitored/diagnosed with the Yamaha Diagnostic System (YDIS), so you will need a laptop with the YDIS software and whatever interface is required.

-- Tom

[Whisky Dick]

Tom,

Runs very well once i get beyond the bogging range, had the o2 sensor cleaned recenlty too because of YDIS hook up. Have not done throttle position sensor. This was when problem ultimately turned out to be ground. they checked a bunch of other stuff too and it all seemed fine.

Like the idea of the low pressure pumps and other pumps and by your description sounds like its time. no other signs except that its worse with clients on board. more weight to get out of the whole seems to really struggle then all of sudden it catches and runs great in the 4000/5000. Im at 390 hours on the engine about 100 this year.it seems like its definately time to run with pressure gauge or should i just change the low pressure pumps. either way im passing this along to my guy he's very methodical and tends to work his way through the engine and problem. thanks.

[tsheehy]

Rich,

If you are going to have someone work on it regardless, I'd replace the low speed pumps.. its only ~$30-35 each x 2. I don't know how much the medium-pressure fuel filter is, but you might want to change it if it isn't too bad, based on your previous problems with clogged VST filter.

If you can run fine above that RPM range, its not likely to be the low pressure pumps or VST.

Sounds like you have someone you are confident in to replace them at a reasonable cost (although its very easy to change yourself) and troubleshoot further.

-- Tom

[Whisky Dick]

thanks tom, ill keep you posted on the problem and hopeful resoultion, appreciate your knowledge.

[RoseMan806]

Usually when the low pressure pumps go they leak fuel into the crankcase and flood the cylinder they run off of-which means the engine is wasting tons of fuel which can be seen the water, etc. Pumping the fuel bulb while the problem is occuring helps diagnose wether the problem is fuel/fuel pump related.


When tsheehy mentioned the TPS, it got me thinking. Since the engine runs fine all around, other than at 300RPM.

If the pump in the VST is clogged or failing, I wouldn't think the engine would rev up to full throttle without dying out.

Being on Rich's boat and experiencing the problem first hand, the engine sounds like its surging at 3000. Periodicly it would also quickly cut-out and higher speeds, which was (fixed?) by cleaning the VST filter.

Hope this help helps.

-Todd
:cool:

[RoseMan806]

After further troubleshooting the problem has still not been repaired. We ran today with a fuel pressure gauge which read consistently above 50psi. I'm wondering if either a malfunctioning tps sensor or a simple sync-n-link of the throttle plates is the issue. Also in adition to the mid-range problem, during cold starts the engine runs rough and has a hard time keeping an idle.

Thats all for now.

:confused:
-Todd

[tsheehy]

Could be a TPS problem I guess - if its gone bad it could give wacky outputs at the problem RPM, and cause the engine to run poorly at idle. I also believe that the idle RPM is actually set based on the TPS voltage for the HPDIs with the engine off (and not the actual engine RPM).

The TPS is one of the easiest things to check on that engine - check for the correct 'reference' voltage 5V +/- .25V first. Then check the 'output' voltage with the throttle valves fully closed.. it should be .5 +/- .02V.

'Reference Voltage' is across the orange and red.
'Output Voltage' is across the pink and orange.

Once you disconnect the throttle links to fully close the throttle valves, you should be able to move the throttle plate by hand and watch the output voltage go from .5V at idle through 5.25V at WOT. If the TPS is out of whack, maybe you will see the output voltage dip at some point which corresponds to the 2800-3200RPM range?

Since the TPS is just a big potentiometer, you should be able to check the full range of output voltages without the engine actually running.

Eliminating any potential TPS issue for now, the fuel pressure at the VST looks good, so the problem is either in the medium-pressure fuel filter or the high-pressure system which needs the YDIS. I don't have any experience with this stuff.

Good luck, keep us updated!

-- Tom

[RoseMan806]

To all who wondering, it was the fuel injectors that caused the problem. Send them to be cleaned and BAM! Engine runs great again.

:-%

[Billfish222]

I have twin 200HP saltwater series motors on a 23 Regulator. Both motors run perfect at idle, boat comes on plane great for 1st 20 seconds. Then Starport motor begins surging between 2000 and 3800 RPM. 3 seconds at 3800, then 3 seconds at 2000, 3s at 3800, 3s at 2000... on and on.... Ran 20miles this way back in.
I have pulled the VST and O2 sensor, they were both dirty, but now both clean and operating properly. VST Fuel pressure to the injector fuel rail is at 40 pounds and stays constant even when RPM is surging. I have also switched the O2 sensor from other motor.
NONE of this has made a difference !! Driving me crazy !!! HELP !

Any more ideas out there ?? - I saw some references to grounds - I am starting to feel like this may be an electrical issue, rather than fuel ??

What was final result of others SWS issues ?

Thanks for your help, Bill

[tsheehy]

Bill,

I'm no mechanic, but it sounds like you need to determine whether the problem is on the fuel delivery side, or the electrical/computer side. Either the computer thinks its delivering enough fuel and it isn't actually getting there, or there is an electrical problem that is preventing the computer from delivering enough fuel to support higher RPMs.

If you have constant fuel pressure even during the surging, it sounds like the problem is not with the low pressure fuel pumps or the VST pump being able to supply fuel to the injectors. It could either be a problem with the fuel injectors or the fuel injector filters being clogged. Thats really all there is left to troubleshoot on the fuel delivery side.

Have you checked the TPS on the starboard motor as I detailed above? That is another common problem area, where the TPS gets out of adjustment and/or starts sending out screwy voltages at a certain throttle range. That would be my next step on troubleshooting the electrical side, as its the easiest to troubleshoot. After that you are looking at the CDI and ignition system.

What is odd is that the two RPMs that you are alternating between (2000 and 3800) are significant. 2000RPM is what the computer will limit the engine too if it thinks there is a problem (oil delivery system, temperature, etc). 3800RPM is right around the point where people start to have problems related to the problems you already addressed, like the 02 density sensor, low pressure fuel pumps and VST filter/pump.

-- Tom

[browndog]

Starport ? Is that on the center line ?

[Slamdance]

Sounds like a bad fuel injector, maybe multiple bad injectors

[Tripple B]

I have a 2004 Yamaha 300 HPDI. It has always run great. This morning we launched the boat. It started on first crank and idle's great. Put it in gear and it stalls. It will start back up but won't run under a load. I changed out both fuel filters and checked the CVT. Any ideas?