Getting to the reeds

[wsmith]

No it isn’t like hitting something. I mean like misfiring when I let off the gas with it in gear. When giving it gas it does not seem to Misfire it just won’t go over like 2500rpm’s. When it’s doing the misfiring thing under load when I shift into neutral it stops and idles smoothly. I wonder if it could be something that tells the motor to shift into the higher rpm’s. It’s like if there is something that tells It to shift into the higher rpm’s it’s not working right. I wish I could explain it better. Is there a way to post a video? I still have not checked the fuel pressure. I’m a single father and my children’s mother, though she wasn’t really involved, passed away last week. It is a difficult time having to tell an 8 yr old and an 11yr old their mother is gone.

[JOE54]

there is no shift mechanism for high rpm, as mentioned above many things can cause problem with engine without a service manual and some test equip it will be hard to diagnose , need to test fuel psi , sorry for your loss sir my thoughts are with you

[EuropeanAM]

Sorry for your loss- take care of your family and we will be glad to help where we can.

[wsmith]

No it’s like after it stops at 2500 rpm and won’t go past when I bring back down to idle but still in gear it’s like it’s misfiring. When I put it back in neutral it idles smooth again. Its odd. I’m lost

[wsmith]

Thank you

[Timbonello]

Stator issue possible on the high side

[wsmith]

I’m trying to upload the videos of the pressure test. At first under idle it was reading 32-34psi I pushed the release just to see if it would climb again and it did and under load about the same thing. Next test it was reading barely anything at idle and under load it crept up slowly to 10-20psi but did get on plane. I never got what seemed to be repeatable readings. Most it went to was about 34psi under any condition. I had my 11 yr old son helping me while I did it so, the test was suspect at best.

[wsmith]

It also was reading virtually nothing at idle and it stayed like that until I have it gas then it climbed to 10psi under load I pushed the release on the gauge and it wouldn’t climb back up, however, the motor is as running. The motor starts fine.

[JOE54]

should maintain 36-39 psi from startup to wide open throttle , recommending you enlist the services of a QUALIFIED MERC TECH how far are you from GREENVILLE SC. , i know of one there

[wsmith]

I’m about 30 mins north of Durham, NC. I have had recommendations to Buckhorn Boat Doc. Anyone heard of them? I’m gonna replace the fuel pump and clean the VST while I’m at it. Figured if I take it apart to clean the screens I might as well change out the pump. What do you think? How fast would the fuel pressure have reached maximum psi? Should it have shot right up or slowly climb? When I connected the pressure gauge, I turned the key on and heard the humming from the vst but no pressure read on my gauge. Problem and confusing part to me is when it reads zero or really low, why does it start so good?

[JOE54]

good idea , quickly , be sure bulb is pumped firm = no fuel = no pressure

[wsmith]

Thank you Joe. So the fuel pressure should jump up almost instantaneously?

[JOE54]

yes

[wsmith]

Cleaned the vst and replaced high pressure fuel pump. When connected to the schrader valve with the key in the run position the pressure rose to 32 psi. The old fuel pump didn’t produce any psi with the switch on. Took the boat out this evening and same issue exists. It will go up to about 1800rpms in gear and won’t go higher. I have to let off the gas put back in neutral and then back in gear and repeating this until the boat finally climbs above the 1800 mark and goes on up on plane and runs like a top. While at 1800-2000rpms when it won’t go over it is misfiring and rough running I’m assuming possibly the cylinders are getting flooded or something. If I put back in neutral the idle is smooth again. Any ideas of what to check next?

[wsmith]

Note, when the key was turned on the fuel pressure took about 4-5 seconds or more to climb to 32psi. It was not instantaneous. Could that be the pressure regulator? Once the fuel pressure reached 32psi and the pump turned off the pressure slowly decreased.

[EuropeanAM]

Had you primed up the primer bulb to completely fill the VST (until firm), and the re-primed the bulb to make sure it was again full (after fuel has made the system's loop and returned through the pressure regulator)? If not, readings may be delayed and aren't reliable.

[wsmith]

Only before starting. I didn’t prime after the fuel made it’s way through the system.

[EuropeanAM]

Might do that and recheck- the VST has a limited volume of fuel and when the system is DRY, you may need to pump the bulb two different times (at least).

[wsmith]

Hey sorry it’s been a while but I have some update information and a problem. Boat has been in the shop for about 2 months. Mechanic states boat is not firing on #6 cylinder. Has tried everything, checked everything, new ecu still won’t fire on 6. That whole side is a little weaker but 6 is the only one not firing. It’s got spark, good compression, changed tps, been in contact with computer manufacturers, and Mercury. In his last statement to me last week he said everything that can be bolted on to the motor has been swapped and tried. He said it defies logic. He did try a ecu that was bad on another motor just to see and when he tried it, it fired on 6 but not on 5. ECU people said it can’t be the computer, he was gonna try a new fuel rail to see if that would do it despite already checking the injectors but that would be the last bolt on component that could be swapped. He has over 20hrs into trying to diagnose this issue. I guess my question is if he can’t figure this out, what should I do? He said the motor is in great shape when I asked is it worth continuing or if I need to think about buying a rebuilt motor. Any ideas/suggestions? What do I do? Am I gonna be on the hook for all his labor if nothing was fixed? Obviously his time is worth something but I don’t know where to go if this can’t be solved. I don’t know if this cylinder not firing is causing the dead spot at about 2500rpms I initially reported the with the boat not wanting to get past those lower rpm’s. If you let off and get back into it you could eventually get it to go past 2500 and when it hit the higher rpm’s I had a top speed of about 60mph gps. I’m stumped.

[JOE54]

had one do exact same thing same side same year models trigger was bad 01 200 efi