2.5 or 3 liter...Also Barely Moves Boat

[Fidgetcranker]

1999 Merc 200 EFI
Wondering if this motor is a 2.5 or 3...thanks!
# 0G900371

Has good compression, runs & revs fine in neutral...Has been checked and cleaned by certified merc guys.
They said it was ready to go...everything looked great. I couldn't wait to try it.
Then...put it in gear and it makes low, deep rumble sound and barely moves boat. Even full throttle is same as 1/4 or 1/2 throttle.
I mean, Barely Moves! The thing even idles faster, then when it's in gear.

It's back in for service. Hoping someone can give me a starting point to tell them to check first.
I'm getting low on funding this motor.
Thanks ahead!

[grybrd]

Motor under no load will not be an accurate test of anything.
Does your mechanic have access to a dynomometer? (replaces the prop with a hydraulic pump mounted to the prop shaft. allows the motor to be loaded up while not in the water.)

Has the gear case lubricant been checked for evidence of internal damage?

Is the hub spun on the prop allowing the motor to turn but the prop to slip?

[JOE54]

^^^^^^^ hub first then gearcase/ its 2.5

[leonreno]

When you say barely moves and same as 1/4 or 1/2 throttle when full throttle, do the rpms increase? Or does it not rev much when throttle is advanced? Possibly a bad TPS sensor?

[Fidgetcranker]

Thanks or replies. Rpm's do not increase. It does not rev much when advanced. That's why I didn't think it's a spun hub.
Lower unit oil was checked/changed and is fine...no metal shavings /pieces. Impeller is new too.
No on the dynomometer, but he's close to a lake...weather permitting.

A buddy said...throttle position sensor?
Also, could a collapsed hose do that? If so, why will it rev in good neutral then? Don't think hose has been changed out.

Thank you

[JOE54]

would do a complete check on fuel system start at tank then voltage check when problem is occurring to isolate fuel or voltage problem/ hose could do that / check for linning deteration

[Fidgetcranker]

Thank you. Wouldn't linning deterioration clog fuel flow when revving in nuetral, tho? Revs fine in nuetral.
All he could check today is that...
" All cylinders are firing"

[JOE54]

would need more fuel under load/trying to plane out/ try not to rev in N not good

[OldTimer57]

This reving up the motor in neutral reminds me of another bit of bad behavior. Many years ago I had written a computer software package to completely automate a doctor's office. Talking 1980 or so. Used a distributed computer system (barely heard of at the time) where each "terminal" was actually a computer. We kept having data corruption problems. Could not find it. Went one day to watch, and what was happening was when a patient record was accessed at one workstation, other workstations would "hang" if they tried to access the same record, until the first competed its modification. These that were hung would cause their operators to hit the reset button on the front, which blew up lots of things. AHA! says me. I went in to these clinics one night and disabled EVERY reset button. Problem solved? Nope. When the reset fail they would just unplug the thing. AHA! says I. I found some little gadgets that locked a plug into the receptacle using the screw that holds the face plate on. Problem solved? Nope. Damned circuit breakers. Thought about fixing that but decided they would then hit the main breaker and break everything.

Bottom line, if there is a way, someone is going to find it. The idle-up lever and the throttle-only button make sense on carbed motors. NOT on computer-controlled DFI motors. There are lots of things that are bad. big rpm in neutral. Running motor in gear on muffs (you can hear the drive train complain). But basically there is no way to prevent humans from doing things they should not do, if they have an option.

[Fidgetcranker]

would need more fuel under load/trying to plane out/ try not to rev in N not good

I had to rev it a little to keep from stalling on first initial start up. Then when I put in gear it wouldn't pick up speed at all. No matter how far I advanced the throttle, it would stay the same, but sounded different...low and deep rumbling sound. So I put it in neutral and revved it to see if it was getting gas. That was it for revving. It's not like I sat there and continually revved on it. Just wanted you to know. So that's how I know it was getting gas.
Also, I see what you mean about more fuel under load.

[JOE54]

may not have enough fuel press for injectors to use/or electrical problem causing no timming advance hope this helps JOE

[EuropeanAM]

Please see the Sticky Post at the top of the Forum.

It will help you to receive faster, and more accurate responses if you will post your questions in the appropriate forum:

Mercury - 2.0/ 2.4/ 2.5 Liter High Performance
For discussions related to 2.0/ 2.4/ 2.5L motors (Carb, EFI, Optimax or Racing).

(Your engine is indeed a 2.5L engine).

Always start with the BASICS:

-Visual Inspection
-Compression Test
-Spark Test
-Fuel Quality, Delivery, and Pressure/Leakdown Tests

[Fidgetcranker]

Thank you! Sorry, I thought I was in the right forum.
I thought High Performance meant that they were no longer stock motors, but worked on to be made faster.
That is why I went to "Stock Motors".
Just wanted to explain. Thanks

[EuropeanAM]