1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

[SparkieBoat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

here are some pics, this should put to rest the mounting height suggestion. also you can see the hull is clean and slick. again, thanks for every suggestion, I really do appreciate it.

 

[Haffiman]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

Are you running with the tabs in the position shown on the pics?

 

[SparkieBoat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

they are smart tabs, they retract at running speeds, but it runs the same with or without the tabs.

I could put a 115 or a 130 on this boat and outrun this 150, I am reasonably sure that my problem is with the engine itself, there is some mechanical/electrical component I am missing, I just do not know what it is.

Thanks too all who have taken time out to help me, I really do appreciate it.

 

[Faztbullet]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

Hey sparkie, Did you set the timing indicator or just go with where it was set? Did you have the rubber coated reed blocks? Pull cowling off and test run it to see if it picks up rpm. Check you spark with a timing light as that motor will run and idle on 4 cylinder just as good as 6. Buzz me on cell if you got any questions....

 

[SparkieBoat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

I did set the timing pointer to top dead center #1 cyl. I did not even look at the reed blocks other than to check to see that the reeds were sealing properly, but I do not think they were rubber coated. It runs the same with or with out the cowl. I have not checked spark at high RPMs, but cranking spark seems strong with a hot blue streak @ 7/16" gap on all plugs. I will check spark while running monday when I go for a test run...

this thing really has me baffled. only thing I could figure is something with the crank case. but I cannot figure out where to check, everything is either new or appears in good shape.
Thanks

 

[Big flop]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

Also check VST float level.
Make sure the main jets are tight
They will back out if they are not seated tight.
You can pull one plug wire off at time
and run WOT and see if you can find
one cylinder not pulling good?

 

[aerobat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

what sounds odd to me is when you write that 2 years ago you had an another 150 with the same power output problem.

when you have the chance- maybe truly dyno this thing to check if it pulls the desired horses before starting screw on it.

you have a bad engine or something is wrong with the boat/ engine combination. a 150 should outperform a 115 easily of course.

 

[SparkieBoat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

thanks flop, I will check the VST float, it appeared to be getting plenty of fuel from a visual inspection of the carbs at WOT, so I never did check the VST chamber, maybe something wrong there, but I will not get my hopes up. the motor drinks fuel like a sailor on shore leave.

I will also try pulling plug wires and running to see if there is a cylinder that is not contributing, although with good compression, good spark and good fuel, I dont see how.

I removed and cleaned and reinstalled all jets recently, made sure they were the correct jets, they are all tight, but I will double check.

This boat/motor combo is very common, I cannot see any way that could be the issue, the motor 2 years ago was on another boat, and I do not believe it had anything to do with the boat motor combo then either, just a weak motor.

It is odd to have 2 motors with the same weird problem. makes me just want to swear off these 60 degree motors. I have a late 80s 150 merc,and have friends who have the same motor, and man do those thing put out some HP, this motor does not hold a candle to them. although the 115 I had on it ran out great. I also have a friend with a 1996 150 60 degree on the back of a 18' bass boat, he tops out at about 60 MPH. his motor runs great, you can really feel the power when you throttle up.

I have had quite a few motors and boats come through my hands, I have never had this problem with any other motor, 90 degree OMC motors run out great so do mercs and yammys. these v-6 60 degree motors have really let me down.

 

[Haffiman]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

You should be able to read the most from your plugs. If running lean, lack of fuel, it should show up on your plugs. Got a pick of them after some hard running?
Tearing into the engine without knowing why, will not give you much. Get the basics verified first like plug conditions and timing. Used to run the 60-150 as standard on my Boston Whaler 17 Outrage, and with correct prop and setting just hit the 50 knots on GPS! However on the earlier ones up to late 90's, had a lot of powerpack and sensor changes. Those problems were however more noticeable at the lower rpm's.

 

[SparkieBoat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

this motor cranks and idles and runs extremely smooth, I have already tore it apart, everything seems to be within spec. I put new crank seals upper and lower. I will be doing a high speed shut down and plug pull monday. I will take some pics.

 

[aerobat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

ok... when it starts, idles and runs smooth i still do not believe you have an engine problem. following idea: are you sure your rpm gauge is right ? 4 vs 6 cylinder setting... i have also a 150hp V6 ( but a direct injected) and it drives a 14 1/4 X 20 prop on a far bigger boat , not sure what gear ratio you have but running a 15 or 17 pitch seems strange on your small boat and a 150hp- maybe the tach is wrong and your engine simply runs at the rev limit turning a too small prop ?

another silly thing... are your sure the throttle opens fully at the engine when you give full juice at the remote?

further... do you have installed a water separator/filter on your boat ? if yes- sure it can handle the higher fuel flow a 150 needs ( compared to your 115)?

i strongly recommend you to check these additional things since in my opinion you start to screw on an engine without issues and so ask for new problems .

cheers

 

[SparkieBoat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

I bypassed the water fuel separator, no change, yes linkage is opening completely and is in sync. the tach setting on the v-4 and the v-6 is the same, tach seems to be working fine no reason to suspect it is not. the RPM range matches the GPS speed so tach is working properly. yes this motor should spin a 19 pitch prop easily. I have a good deal of experience with outboards and have covered and recovered every obvious problem. this motor is just plain weak, I know how a 150 should feel and run, I have had a number of boats/motors come through my hand. the problem is definatly with the motor, I am going to check the vst and the carb bowls and do a high speed shut down and pull the plugs.

 

[bob johnson]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

doesnt 92 psi seem to tell the story?

for the life of me i cant figure how 6 holes pushing 92 psi can hold a candle to 6 holes pushing 130 psi....

I know that it is always stated that even compression is important....maybe for running smoothly...but compression is what makes power!@!

this is a motor you recently rebuilt ?

if so how far did you tear it down?

bob

 

[SparkieBoat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

90-95 PSI is a common mark on these V-6 OMC motors. you will get higher compression numbers with some motors, like the 175 and the GL/GT models that had 175 heads, they run around 115-120 psi. yes it is recently rebuilt, I tore it all the way down.

the motor I had 2 years ago that had the same problem had 120 PSI on all 6 and was the 150 GL model, (supposed to produce %10 more HP). But it had the exact same weak symptom.

 

[Faztbullet]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

Dont was your time checking the VST float as it has nothing to do with fuel delivery...it only lets vapor out.

 

[SparkieBoat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

roger that faz...thanks

 

[Big flop]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

If the VST needle and seat is
varnished or restricted you can
run out of gas high speed.
It would probably surge but
just looking at all bases.
If you end up in there make
sure you check the level
and drop
Mike

 

[Faztbullet]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

If the VST needle and seat is
varnished or restricted you can
run out of gas high speed.

Has nothing to do with fuel in/out of vapor seperator......see below.

Ok here is run down on how fuel bracket works on 60 degree...(simple version)
When you pump up bulb, fuel is drawn from tank to the inlet filter that is on front side of bracket.(pic 1) As you pump you fill the fuel chamber till it is pressurized by bulb(pic2).Fuel then travels from chamber down rear of bracket and fed into bottom of VRO/OMS pump(pic3)and pump sends it out thru passage in fuel chamber to carb manifolds(pic2) Fuel does not go thru needle and float like a Mercury VST but float opens and closes passage to vapor pump,(pic4) so when you start engine and chamber is full, vapor pump does nothing as float & needle has inlet sealed. As fuel is used and float level falls, vapor pump draws excess vapor from chamber to help prevent a vapor lock condition. If diaphram goes bad or needle/float sticks it can cause bogging problems due to vapors boiling under vacuum (low fuel delivery). The check valves are arranged in vapor pump to prevent vapor separator from venting to atomosphere (vacuum loss)(pic5) Any airleaks in the separator will cause VRO/OMS pumping problems but most will show up buy a fuel leak in the affected area as you can pressurize the separator with primer bulb. I have only seen one cover cracked on these models and it was due to improper reassembly. Click below to see exploded view and pic's
http://forums.iboats.com/showthread.php?t=365244

 

[SparkieBoat]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

that is a very cool and informative post Faz. you said, If diaphram goes bad or needle/float sticks it can cause bogging problems due to vapors boiling under vacuum (low fuel delivery). is this something I need to test/check?

 

[Faztbullet]

Re: 1994 60 degree 150 HP, only getting about 100-110 HP. cannot find the problem.

Thats low end ..will not effect top end performance. If the needle/seat is bad and floods it will dump raw fuel back into airbox causing a overrich condition. Easy check ..just pull line to airbox and see if fuel is dripping from it when bulb is compressed..I think you have a fuel supply issue from the boat to engine as a 115 would need less fuel than a 150. Try running it on a test tank with a 3/8 supply line.