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six new injectors would cost me about $ 1,800. I can't see me ordering them just in case I have an injector problem. If that's the level of spares I would need to run this motor, it would be better to just bite the bullet and throw the thing overboard now and find something reliable. It would cut my costs in the long run. But what is really bugging me right now is that we have gone weeks without a working boat now.
I have to believe that the longest I would ever be down with a 'conventional' motor would be a week or so while troubleshooting and then waiting for the part.
I am pretty sure my next motor will be a carbed two stroke, once again.
Squeezing and holding the fuel bulb pressurizes everything between it and the boost pumps. That is soft, gray, low pressure yamaha fuel line there. Any leak would be very apparant. We don't see any, and the bulb holds firm. If there were a leak between the bulb and the boost pumps, I would expect the bulb to slowly go flat and have to be squeezed again. That is not happening. The bulb stays firm. We cannot find any fuel leaks in those lines. The bulb is right past the Racor in the bilge. The Racor has all new lines on it. But, thinking about it, if there were a fuel or air leak BEFORE the bulb, this test would not find it. I will take a look at that.
Drop is sudden. Motor starts and idles well. It's about a mile or so out to open water up this canal we have been launching in, so the motor has plenty of time to warm up, stabilize, etc. It seems to be running well. When I get to open water, and slowly advance the throttle ( If I hammer it, the Contender swamps the engine with water) it accelerates fine up to, usually, around 5,000 RPM, which it holds for maybe ten seconds or so. Then it starts running ragged, and the RPM drops to around 3,000. It is erratic at 3,000, bouncing around, say 2800-3400, but this number varies. The throttle is still at WOT at this point.
Then I bring the throttle back until the engine smooths out at something less than the 3,000, where it seems to run okay although a little ragged still.
If I advance the throttle full again, it will not run back up over whatever max it declined to. It will not, for example, go back up to 5000 RPM a second time.
Until the next time I take it out.
Sorry if we are going around in circles -- I assume you've tried pumping the primer bulb while the motor is running WOT and that makes no difference. I think a fuel restriction would cause a gradual decline in RPM not a sudden drop.
Sudden drop in RPM suggests electrical. Could be spark or given that this is a fuel injected motor, electrical could mean one or two injectors deciding to quit after they've heated up. In this motor, aren't the injectors essentially valves operated by a solenoid? If the solenoid stops actuating, the valves don't open and close and fuel stops getting injected. Fuel stops getting injected instantly, motor RPMs will drop suddenly.
Seems to me you need to perform some kind of a cylinder drop test to see if you can isolate the problem to a particular cylinder or cylinders. Again, suggest you run the boat with one sparkplug cap pulled. The boat isn't going to run to 5000 RPM in this condition but you should still be able to see whether the RPM drops from whatever you can get with 5/6 cylinders in operation. Do it for all of the six cylinders and if you don't get an RPM drop on one (or two or three) of the six tests, then you've potentially isolated the problem to the disabled cylinder.
Rather than run the boat with the cowling off is there any where you can run the boat in gear tied to a dock or on the trailer. You wmay not be able to get to 5,000 RPM but it may help spot a problem while under load.
Or if the rope fails you mau have created the solution above.
Don't think the whole concept of insurance scam hasn't crossed my mind.
But nah, I really ain't wired that way. It's fun to think about, but basically I think I am just too damned honest. Oh, I know I could plan something well enough to get away with it.....but I would never feel right about it. And I HATE that feeling.
Is the engine able to get back to 5000rpm if you idle around for a while and try it again or is it a one off 5000 rpm hit then back down for the rest of the day? Do you have any warning lights go off as or before this happens?
"Rather than run the boat with the cowling off is there any where you can run the boat in gear tied to a dock or on the trailer. You wmay not be able to get to 5,000 RPM but it may help spot a problem while under load"
Maybe this is your answer to your offshore run. Tie the stern to a good set of pilings, or dock and see if you can't do your testing from there?
__________________
"Lickety Split" 31 Fountain with 250 efi's
"Rather than run the boat with the cowling off is there any where you can run the boat in gear tied to a dock or on the trailer. You wmay not be able to get to 5,000 RPM but it may help spot a problem while under load"
Maybe this is your answer to your offshore run. Tie the stern to a good set of pilings, or dock and see if you can't do your testing from there?
YEAH This would work then he would sink the stern and therefore sink the motor and file a real claim.
__________________
David Kuhlmann
2007 Lowe FM 185
2007 Mercury Verado 150 HP
Mercury Tempest 19"
Wireless MotorGuide 60" 24 Volt
Lowrance 111C HD
Lowrance LMS 520C
If you think you can or you think you can't Your Right!
Just a thought. My 250 HPDI was acting very similar. I thought it had to be electrical the way it would just drop RPMs, almost like the key was turned off but if I dropped it back down it would idle fine. So I looked at the VST filter for the first time, I didn't see a spec of dust on it. So I reinstalled and still had the same problem. I then looked at the vst filter again, this time armed with carb cleaner. I used the spray on the filer from the out put side so that it woudl shoot anything out of the filter and I realized what I had missed before. The mesh in there is really fine and I was expecting a dark filter. Only the particles that get caught on the filter are white just like the filter material. Once I shot it with the carb cleaner I noticed the difference. After that it ran fine. I also have a 3 micron racor filter before the engine and my VST still clogs every once and a while.
Well, thanks for the idea about securing the boat someplace where I could run it up without running it out. I knew just the place: the rough cut ramp where we have been launching.
I was so excited about the idea that we hopped right up and did it this morning.
Backed the boat down until we had just enough water covering the intakes, etc and plenty prop clearance.
I figured that little prop would no way move that boat, trailer, and a Land Rover up an incline. I was wrong. We did a dry run to 2500 RPM and it was definitely moving stuff. So I ran a couple good lines astern ashore and secured one to a piece of rebar ( in the foreground of the above photo) and the other to a small but sturdy tree on the other side. That worked.
Running it up to around 3000, it got ragged. While I kept an eye on the tach, throttle ( in case I needed to shut down quick or something started to give) my youngest son ( baby of the family) directed propane into each of the air intakes. #1, 2, 4, and 5, no effect. In fact, spraying a lot into #1 actually made it run a little worse.
Ah, but cylinder's # 3 and # 4....with the propane going into either one the RPMs picked up around 200-300 and the motor smoothed out. Then he held the propane between the two so that each cylinder got some, and the revs went from 3,000 to 3400.
We did this several times. We made lots of noise, and a whole lot of propwash:
So, I think that 3 and 4 are the two cylinders that shut down when the control lever is in neutral, right? Is this something that might be the path to follow?
It would be pretty strange for those two adjacent cylinders to develop a water, or dirty fuel, caused problem. it was the two lower cylinders, 5 and 6, that had the water fouled plugs. Not the middle ones.
And they are all getting their fuel from the same two fuel rails...so this is telling me that the pumps are fine, the filters are fine, and something else is going on. Injectors? maybe. But strange.
ECM? Neutral switch or whatever tells the motor that the control is in neutral and to shut down the middle cylinders?
and by the way, son and I are in agreement, there is NO way we would have been able to do this offshore. We would have been bouncing, splashing, and doing about 40 mph. Nope. But this worked.
You can clean the injectors with some injector cleaner, a 12V battery, push-button switch and wiring, some hose, and an air compressor. Make you a simple rig to wire up the inectors, push some hose over the injector, fill the hose with cleaner, and put the compressor on the end of the hose, 50psi. Pump the button a few times to force the cleaner through the injector, It should mist. Do it forwards and backwards if you can.
If I just switched, say, injector 3 with injector 5, I would only have to disassemble one fuel rail instead of both. If the problem moved from intake 3 to five, then I would know it's injectors.
checked coils yesterday. All in spec. See previous page for the specifics.
Injectors are running at 1000 psi, and need 200 volts to fire. I don't see an easy way to handle that here. Either the pressure OR the voltage.
If it works down to injectors, I will Fed Ex them to those guys in Florida, or the new guys up in NJ and let them do that for me.
But I am asking why these particular two? What else do these two have in common?
Pull the damn binnacle apart and make sure some spider or mud dauber hasn't made a nest in a switch before you go shipping parts around the world. After 21 pages, 12000 views, and 300 guys responding to this, honestly, it prolly would be that simple.
Also, be careful with the propane, as a motor fuel it's about 120 octane with NO lubrication properties. And those backfires tend to pretty powerful.
If it was me, I would check the muffler bearing. I'm just sayin.
__________________ Andy Munao Our new parts site: www.simyamaha.com Yamaha Outboard Sales, Parts and Service 1-800-213-3323 parts@shipyardisland.com Click the logo to see our THT Vendor Forum
