Indmar Vortec rebuild low RPM

[skibus]

Have a rebuilt 350 Vortec engine long block installed in my Mastercraft.
It is producing only 3200 RPM. Previous 350 Vortec was producuing 42-4400 rpm.
All work done by reputable(?) engine rebuilder and marine mechanics...they are stumped!!
Any suggestions would be appreciated.
Going to chat with the engine rebuilder tomorrow.
Thanks

 

[Howard Sterndrive]

Re: Indmar Vortec rebuild low RPM

start with a compression test

 

[Don S]

Re: Indmar Vortec rebuild low RPM

List of possible causes of low WOT (Wide Open Throttle) rpm.

In no particular order

Engine Won't Reach Operating RPM. Check

1. Fuel condition. Type and Octane possibly old fuel
2. Propeller pitch or diameter, damaged blades
3. Restricted fuel pickup tube or anti siphon valve Fuel System Test
4. Crankcase oil volume, high oil level can cause aerated oil and lifter collapse
5. Marine growth on hull and outdrive
6. Wrong gear ratio in outdrive
7. Restricted carburetor air intake (clogged flame arrestor)
8. Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive
9. Poor cylinder compression Compression Test
10. Carburetor defective, or wrong type.
11. Fuel pump pressure and vacuum
12. Boat overloaded, improperly loaded, or improperly trimmed.
13. Engine Overheating
14. Engine timing and ignition system operation
15. Remote control cables and linkage for proper travel to open throttle plates fully.

 

[salty87]

Re: Indmar Vortec rebuild low RPM

Previous 350 Vortec was producuing 42-4400 rpm.

isn't that a little low for wot, too?

 

[skibus]

Re: Indmar Vortec rebuild low RPM

Thanks Gents for your input...
The engine rebuilder offered no information at all, and simply stated it was a remanufactured Vortec 350 engine with all marine specs and that he does over 500 engines a year.

Compression test was good, and some kind of a new black magic "Sensor" was installed.

The marina took it out a few more times and it began to achieve higher RPMs (whether it was a sensor or not, I am not sure. ) I think they were a little stumped as well. They began thinking it was the old ECM. (1995 boat was one of the first with the Electonic Fuel Injection!)

I now have the boat back and it seems to be running well. I am slowly breaking the engine in with varying power and such. I've had the boat since new, and the top speed in the owners manual states "43 mph" I have almost always been able to achieve this (clean hull, new plugs, wires etc...) with max RPMs about 42-4400 with stock prop. Manual also states that WOT max rpm is 5000.

Its been a great boat over the years, but this is sadly the 3rd engine. (1150 hours) I use it basically only for barefoot water skiing, so I wonder if we are stressing it a bit much (hard pull out of the hole and 38 MPH constantly)

I guess I am rambling on a bit, but the bottom line....personally I think it took an hour or so of running for the new engine to seat and ECM to sort itself out???

Thanks again for your help.

 

[Tail_Gunner]

Re: Indmar Vortec rebuild low RPM

Looks like a mefi 4

replacing the ECM module only a jumper wire P/N 88963118 is available to convert a MEFI 4 module to a MEFI 3 wire harness to retain your open loop system. The computer has a "green mode" that controls the RPM's for the brake in period. From start up to the end of first hour is 4000 RPM, second hour is 4500 RPM and third hour is 5500 RPM.


http://sdparts.com/details/gm-performance-parts/12499116-0

 

[hottoddie]

Re: Indmar Vortec rebuild low RPM

5-600 hrs for a Vortec engine is not very good. Only getting 42-4400 rpm indicates an over propped condition. Dropping 2-3 inches of pitch will reduce the stress on the engine and may also improve fuel economy, etc.

 

[skibus]

Re: Indmar Vortec rebuild low RPM

5-600 hrs for a Vortec engine is not very good. Only getting 42-4400 rpm indicates an over propped condition. Dropping 2-3 inches of pitch will reduce the stress on the engine and may also improve fuel economy, etc.

Thanks for the input...
This is all stock 1995 Mastercraft 205 Prostar boat with original propeller and "hurth" transmission. These same parameters since new. (I bought it new from the Mastercraft dealer at the time.)
Interesting idea though. Going to chat with Mastercraft about this.
Thanks again.
Skibus

 

[Tail_Gunner]

Re: Indmar Vortec rebuild low RPM

Opps i missed something here. Did they not replace the orignal ecm with a new one??? Or are you using the old ecm on the new motor? if so that is the problem. A 95 350 is vastly differnt than a 2000 plus. Heads..cam type etc I assumed you were using a new mefi 4 which does have a green mode and had it reprogrammed or tuned for your engine

Here is a list of mefi controller's assuming its a mefi that is there should be a part number on yuour ecu does it match any of the part number's below


GM Part No.

MEFI Type



16159919

MEFI-1



16189069

MEFI-1



16220371

MEFI-1



16234539

MEFI-1*



16210729

MEFI-2



16237009

MEFI-3



16237019

CEFI-3



16236999

MEFI-3*



12489488

MEFI-3



12489493

MEFI-3



12569494

MEFI-4



12575479

MEFI-4a



88962717

MEFI-4a



88962718

MEFI-4a



12584052

MEFI-4b



12597744

MEFI-5



12607802

MEFI-5a

 

[Rossterman]

Re: Indmar Vortec rebuild low RPM

If you replaced the engine with a tbi 350 in kind with the old one, the stock mefi should be fine. They (the mefi) are engine specific and can cause problems if you run a stroked motor or larger cam but sounds like this one is down on power for some other reason. Also new mefis must be programmed for the specific engine by you M/C dealer or indmar directly so you cant just buy one and bolt it in.

If you havent changed the prop, it should behave the same as the old one and not need a re-prop to perform and should reach at least same rpm and mph. Almost sounds like they put a 5.0 liter instead of 5.7 by accident. May want to check casting numbers to be sure.

If it isnt performing correctly, could be timing or something else. Either way, the shop doing the work should be on the hook to figure it out (and should be working with rebuilder to straighten it out).

Finally, curious as to the black sensor they referenced as there arent any sensors to boost power and such. Can you get more info as to what they are referring to?

In response to some other suggestions posted:

Biggest difference between 1995 and 1998 is the Vortec heads and intake. Easy to tell which you have as the vortech heads use a different bolt pattern than non vortec requiring a different intake. If the original intake was used, that as a potential difference causing the need for mefi remap can be ruled out

Also mefi 4 engines are all open loop (i have the same engine in. A 2001 mastercraft) as is mefi 3.

If you are getting runaround from installer you may want to consider taking to a M/C dealer as they will likely sort it out.