Rinda Diacom Diagnostics - bogs at 3000rpm, wont plane

brandonmayberry

Boat is a 2000 rinker 242 with a mercuriser mag MPI 350. Been fighting this issue all summer. Idles fine and puts around fine, but when i go to give it power and plane out it goes to about 2800-3000 rpm(by my tach) and stays. It just bogs real bad and will not plane out. I have replaced fuel pump, pressure regulator, dist. cap, rotor, coil, IAC valve. I cant figure it out.  Below is a screen shot of the live Diacom that maybe someone can spot an issue. Boats not throwing any trouble codes. My only ides left are either oil pressure sensor being bad as ive read else where, havent had the chance to check it since learning on it, or a PCV issue. According to my manual on this boat the PCV valve is on the port side of the engine. Mine is on the starboard and runs to the connector on the back of the throttle body by the IAC valve. The port side is just an open elbow that goes to the flame arrestor. i tried switching the two but the hoses are different sizes so i dont think they are wrong based on that but maybe someone else will know better.
Thanks for the help in advance!

Handymans342

Is the bottom clean and tabs up?

brandonmayberry

yes, bottom is clean and tabs are all the way up.

JC290

Prop size? this boat new to you?

raybo3

Bad gas???? Is the gas from last year? 

MarkB

You need Drew to chime in on this discussion. @212rowboat? @212rowboat? Can you hear me?

brandonmayberry

Props are original. Don't remember pitch. Boat is new to me. It ran decent a few times last year and once this year. Been having problem since. Gas is kinda old. Fuel stabilizer was added for winterization. I topped the tank off in like January when gas went super cheap around me so it's kinda old I guess. 

Handymans342

Have you verified that the when the throttle handle is in the max position that the throttle body is open 100% as well? 

brandonmayberry

Have not verified this no but it hasn't been tampered with so I would assume it's the same as prior. I can rev the engine freely and reach the high rpm range still 

JC290

Do you use your tabs to help to come on plane? Is your drive down all the way. Alpha drive if I remember right 

Handymans342

Maybe an illegal switched props on you 

brandonmayberry

Handymans342 said:

Maybe an illegal switched props on you 

HAHA! i dont think so but who knows.

I do use the tabs to help come on plane sometimes when a heavy load but havent needed to usually. I have been testing with just myself and wife and a light load other than the 3/4 fuel tank so they shouldnt be needed as it usually will pop right out of the water. It is a bravo 3 drive thou and i have checked and do not think the props are slipping.

I want to say its 26 pitch props also but not guaranteeing that.

Also want to say thanks for the help and taking the time to answer guys i really appreciate it!

brandonmayberry

OH also i have checked the fuel water separator. It was replaced before winterization but i went ahead and poured the gas from it into a clear container and it appeared fine.

planesailing

I also have a 2000 242 and am suffering the exact same problem. Bogs down at around 2800 - 3000 RPM. Thought it was a trim tab issue but maybe I'm suffering the same fault as you. I've also carried out a full service, changed plugs, leads, cap and rotar arm plus just filled the tank full of fresh fuel but still struggle to get on plane. Let me know how you get on and I'll do the same.

brandonmayberry

planesailing said:

I also have a 2000 242 and am suffering the exact same problem. Bogs down at around 2800 - 3000 RPM. Thought it was a trim tab issue but maybe I'm suffering the same fault as you. I've also carried out a full service, changed plugs, leads, cap and rotar arm plus just filled the tank full of fresh fuel but still struggle to get on plane. Let me know how you get on and I'll do the same.

Will do!

check your fuel pressure on yours as in my vast amounts of research thats one things i kept running into. See if its proper and also check your fuel pressure regulator at the same time and see if when you unplug the vacuum hose that runs from the manifold to the pressure regulator if your fuel pressure rises. Apparently the pressure regulator is notorious for going bad and causing this issue. Also when you do a fuel pressure test, let me know your results. My pressure kicks to 30 when i turn the key on then runs at 25psi and when i hit WOD it will go to about 32. Specs for my manual state 30psi at 1800RPM.

Handymans342

You def need to verify the prop size and pitch. Very important. I have seen a lot of props get ripped off. 

brandonmayberry

Handymans342 said:

You def need to verify the prop size and pitch. Very important. I have seen a lot of props get ripped off. 

I know both props are still there and they are original which the boat has run perfect on befor. I will look next time im at the lake and verify the pitch and let you know but i know its the same props as the boat had on it since i purchased it and have run it without issue

planesailing

I'll be back on the boat on Sunday so will check the fuel pressure then. How do I go about checking it? 

brandonmayberry

planesailing said:

I'll be back on the boat on Sunday so will check the fuel pressure then. How do I go about checking it? 

You can get a fuel pressure gauge at the local parts store (i got mine at oreilly's for 40 bucks). On the front port side of the fuel rail is a valve that looks like a tire valve. It should have a cover over it that twists off and under it will be a schrader valve that looks just like your car tires. youll hook the gauge up to it. Its really simple. Turn the key and see what it goes to and write that down, run the engine and see where it is and write it down and lastly check when under WOT conditions. make sure when you go WOT that the pressure doesnt decrease as that will indicate an issue.

From what i have been reading on my issue, its usually a fuel pressure issue but i think i may have drawn a short straw and run into something more complex or possibly more simple that im looking over but i recommend checking the fuel pressure just to get a starting point to eliminate an entire issue. Someone else here who knows more may chime in and have another idea but thats where i started at.

planesailing

I'll make that my first job on Sunday and will let you know the results. Many thanks.

Weber

Your pulse width is close, but your flow rate seems low under load.

The pulse width is decided by the ecm depending on the rpm, map, and tps.  If your fuel supply is low or has water in it it will not allow the rpm you need and may max out.  This will not set a code or an audible alarm.

Check you fuel pressure with the just the key on, check at the start and then watch it for 5 mins without starting.  Then start it and observe at idle, and over a few minutes.  Then check it under load.

If the pressure does not seem to be an issue, I would then run the motor from a portable tank of fresh gas from a gas station not on the water.  See if the performance improves.

brandonmayberry

Key on the fuel pressure is 30psi and it holds there. running it goes to 25psi and at WOT it will go to about 30-32PSI. It does not set or trip any alarms

Weber

Check you regulator for a color mark, there should be either a blue or pink mark.

There are two different fuel pressure ratings on this motor, and I'm not sure what yours should be.  The mark will tell you if what pressure the regulator is designed to regulate at.

Pink is the 30psi regulator and the blue is 43psi.

brandonmayberry

my mark when i pulled the old one off and replaced with a new was pink so it is the 30psi

Handymans342

What is it supposed to be?

brandonmayberry

I have not verified anything on timing or firing order. I did change plugs and wires last season but boat ran fire after the change then and also once this year. the problem just appeared out of nowhere it wasnt after any change.

brandonmayberry

Ok. That will be my next thing to check. It'll be a few days likely Befor I can get back out to the water. 

brandonmayberry

I have not done a balance test. Not sure how. I'll have to look up how to

brandonmayberry

Ok, ill check that when i get a chance to get back on the boat. It may be a week or two, ill update when i get it checked out.

brandonmayberry

Ok, finally got a chance to get back on the boat. i checked compression and compression is good. between 145-160 on each cylinder. I also unplugged the injectors one at a time and it didnt do anything. However the boat was running super rough at this point and ended up dieing during this test. I pulled it out of the slip and put it on the trailer to bring home to do the compression test and it was way way underpowered when trying to trailer and was trying to die, backfire and sputter.
I have siphoned all the gas out of the tank and am going to replace it with fresh gas and hope maybe the gas has just been bad this whole time.

brandonmayberry

Ok, new discovery. Im awaiting my new spark plugs and doing some research. Came across a video that shows a guy replacing the exhaust flappers. Well i replaced my shift cable a while back and had what i now know to be the old exhaust flappers come out of the lower unit. So apparently my old ones are broken. Is this something that would cause my issue and do i need to replace these anyways?