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88 bayliner cabin cruiser bogs down under full throttle

T

Todd Alexander

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"My sweetie is a 88 bayliner w

"My sweetie is a 88 bayliner w/ a 3.0L OMC / Cobra Outdrive. I have had a $5k new engine installed from Jasper Engines and a good mechanic who seems to have ran out of ideas on what is still wrong. Initially I had a busted block which lead to the new engine. It runs like a beauty on the dyno maxing out at 4800rmps. When in the water, it fires right up, idles perfectly, and is perfect at no wake. Once the boat gets to about 3/4ths throttle, the engine bogs down and boat wont go over 3000rmps. We have had the timing set dead perfect, and had the dist function tested. What else could it be??? I'm wondering if I should try a new fuel pump? Could something that simple cause the problem? Mechanic says carb is in good shape. Hope you can help!!"
 
Are you running the same prop

Are you running the same prop as before? Sounds as if you're trying to swing too much prop. Try one with less pitch.
Check your flame arrestor for good air flow. What is the condition of the plugs and wires?
 
"When replacing the exhaust be

"When replacing the exhaust bellows and having the riser off what other than rust, grime and etc.would be included in a visual inspection?"
 
"Hey Ron, Why don't you ad

"Hey Ron, Why don't you add this question to your original thread? It will move back to the top.
proud.gif
Also to avoid confussion, you should refer to these as "exhaust hoses" There is actually something called an "exhaust bellows" but that is not what you are dealing with."
 
"Thanks Maranda1. The boat ha

"Thanks Maranda1. The boat has done this since we bought it (bogging down at 3/4ths throttle). We were hoping the new engine would take of it. When we bought the boat the prev owner had installed a new prop. My mechanic says that the prop seems to be okay on the pitch. Any other thoughts? Thanks for you help. Right now, I'm replacing the fuel pump just to see if that helps.

Todd"
 
"Todd,
What size boat is it?

"Todd,
What size boat is it? Do you know what it weighs? What size prop have you got? Should be stamped on it.
Describe what you mean by bogging down. Is it just never getting past 3000 rpms? What happens at full throttle?"
 
"21ft length...not sure of wei

"21ft length...not sure of weight, sorry, but I think I remember former owner saying 3500-4000lbs...but not sure.

Prop is a 14 x 13. By bogging down, I mean all goes well until about 3/4th throttle @ 3000-3300rpms; then from 3/4th throttle to WOT nothing happens....rpms stay at 3000-3300 range and the engine seems to go under stress (bogs down). The valves also start to rattle at 3/4th throttle.

I've been doing some reading today about prop pitch and marine engine's sight has been very helpful. My OMC manual says engines rpms s/b 4200-4600 and mph s/b 25-32. Based on what I've learned today I decided to check the prop pitch myself to see if pitch was too high maybe. But its only a 14 x 13 prop, and based on what I've read that doesn's sound like too much pitch.... and if pitch was too low, I would see too high of rpms if i've understood everything I've read. So I'm back at square one. Any more suggestions would be appreciated.

Thanks!"
 
You said in your first post th

You said in your first post that engine is a 3.0L. Did you mean 5.0L by any chance? I would think that boat would be grossly underpowered with a 3.0.
 
"Thanks Maranda1. No, unfortu

"Thanks Maranda1. No, unfortunately, I did mean a 3.0L. However, this is what the boat originally came with in 1988. I just cannot believe that they were ever able to sale a boat that would not go over 10mph/3000rpms. I know after we first got the boat, we did have a short spurt one day where the boat ran 25mph, although it only lasted for a few minutes; so I feel like it is capable I just can't figure out what it is that is hendering it. Any of you advanced members out there have any other ideas??...Hy Stat, Bondo, Bob Hill, or Morten Ringvold?? I'm getting desperate hear and my pocket is already $5k lighter. Thanks guys. This is a great site full of info."
 
Hopefully one of those guys wi

Hopefully one of those guys will chime in soon but this has really got me curious so I'm still think'in. Hystat had asked if the dyno was done in the boat. Did you come up with the answer?
Couple of ideas:
Have you checked if the throttle is opening fully?
Have you checked the choke and is it opening fully?
You said "distributor function was checked". Is the advance mechanism working freely?

Still think'in.........
 
When you said $5k on engine I

When you said $5k on engine I assumed long block? If not was the head reworked? Have you done a compression test?
 
"thank you, thank you, thank y

"thank you, thank you, thank you! I'm calling my mechanic 1st thing tomorrow to load these questions onto him since I dunno how to do a lot of this stuff! I'll keep you posted on the answers and results. Your think'in cap is definately sharper than mine so I appreciate any thoughts you have that help me to smell a little smarter when talking to the mechanic. Hopefully those advanced guys will chime in soon too.

I'm really curious about hystat's question too. That got me thinking maybe he was leaning toward fuel related issues if the dyno wasn't done in the boat. That's why I went ahead and ordered a new fuel pump. That may have been a stupid thing to do...but pump is 20yrs old...and $80 bucks was nothing considering what I have put into this thing already.

I'll get 'em all answered tomorrow and let you know. Please pass any other thoughts you may have.....if you are ever in GA, I owe you dinner or at least a case of your drinking choice! I appreciate the time you've given me."
 
"First:
When You said 4800 on

"First:
When You said 4800 on dyno, did the dyno read out specified HP/torque for the engine all the way?
Conditions of the spark plugs should give an indication. If lack of fuel is the reason they should be white. If so, try to hook up a separate loose fuel tank (outboard tank) directly to the engine. Remember to use a 3/8 hose.
Give it a run, take a pick of the plugs and post.
Double check Your tach to see that it gives correct info.
Are all the valves rattling or just one. It might be a faulty lifter, and again this should be noticed on the spark plugs."
 
"Hey Marada, I just saw your o

"Hey Marada, I just saw your other question from 8:49...yes it was a long block.

Also, I should mention that when I put boat in reverse, the power is extremely strong...so much that i couldn't even hardly steer the boat. Hope we can get that kind of power going in the other direction!....that may mean my fuel pump hope won't work..but it seemed to be worth a try anyway.

any thoughts about the outdrive....like maybe the gearing...could that cause this sort of problem???"
 
Hey Mortan. Thanks! I'll

Hey Mortan. Thanks! I'll pull the plugs tomorrow and check b/c I have tank that i can use to test your theory if plugs are white.

FYI: mechanic put new plugs on when I bought the long block replacement; so I'm hoping to see white...so that it will point to a solution finally!

Thanks!
 
I checked the plugs but they a

I checked the plugs but they are all clean still. I'm wondering if the white would show yet? I've only taken it out twice since the new engine was installed and only stayed out for about 30min before getting frustrated and coming back into dock.

Haven't talked to the mechanic yet as he doesn't come in until late afternoon. Will post more after discussing the other ideas that you guys have thrown out.

Thanks for all!
Todd
 
"just wondering, I have a 2.3

"just wondering, I have a 2.3 L that the outdrive went bad, bought a 3.0 outdrive. Wrong gearing would only do 10 mph at 3000 rpm. Do you have the right outdrive on it? I would think that a new motor would have solved the speed problem."
 
"Hey guys. I've learned a

"Hey guys. I've learned a little more today thay I hope will help matters a great deal.

Few things first:

* dyno was done IN my boat; it maxed out at 4600rpms; mechanic says my tach was off a little from the dyno's...my tach showed 400rpms less than the dyno did; but he's not making issue of that right now....I'll explain later.

*the plugs were NOT white...although, I could see just a little smidge of white that looked like it might be the start of something??; I'm proceeding w/ putting a new fuel pump on anyway.

* "advance mechanism" in my distributor function is working freely...no problems there

* All the valves are rattling at 3/4th throttle so he (mechanic) doesn't think its a lifter problem.

* fuel filters have been changed and look good

* Boat is a 1988 Ciera Sunbridge (Model 2150) ("Cabin Cruiser") w/ a 14x13prop and a 3.0L OMC long block. These specs look right to me (based on what I've read, and assuming I understand it).

In talking to the mechanic today about the fact that turning the pins on the carb last time I took her out didn't really do much to the function of the engine problem at 3/4th throttle.... he mentioned the fact that my carb cover was painted black and suspected that the problem may be that there is a mercruiser carb on the omc engine since we know nothing really about the boat's history...he says that this would mean that maybe a wrong carb is hendering the gas flow so that the boat cant get over 3000-3300rmps at wot (or at 3/4th throttle either, for that matter)........any thoughts out there to his theory????

In the meantime, I'm running with ordering a proper omc carb to fit the engine; installing a new fuel pump; and 'takin her for another spin...

thanks again for all your input guys. I'll let you know how it turns out.

Todd"
 
"How familiar are you with thi

"How familiar are you with this mechanic? The mixture screws on the carb only affect idle, they have nothing to do with 3/4 throttle.
Is this a new engine or rebuilt? If rebuilt, by who?
Also, have you run it on the remote tank yet?"
 
"I'm getting a bit suspici

"I'm getting a bit suspicious of the mech.
Did he run a torque/power curve noting at different rpm's or just let it up to 4800 and adjusted the dyno to get a reading at that rpm? My guess is that Your tach might be better than his as the nominal max HP would be around 42-4400 rpm. Unless there is a high-rev cam put into Your engine which might explain a lot.
Mercruiser or OMC carb has nothing to do in Your case, unless it is a 2,5 carb, which I doubt.
Would be nice with a pick of the plugs. Change in color is normally immediately at the first run. Normally the Champion gets light brownish if OK, the NGK gets a bit yellowish. Turning white might lead to disaster, black to oily running rich.
Next question might be at what rpm does Your boat plane out? 3000 is normally not a planning speed for that combination, and I have the feeling that might be the problem. If You get it planning, it will probably gain quite some rpm. Try distributing weight in the boat or take out everything at the back including floor boards. Be sure trim is all the way in at start and minimum fuel.
My believe is that new carb and fuel pump will be a waste of money."
 
"I'm with Morten. A very

"I'm with Morten. A very good question was asked earlier, " Is the boat waterlogged?" Not unusual at all for a boat that age. In fact, very likely. This boat is underpowered at best. Add a hundred pounds (or more) of saturated foam and the 3.0 might not plane it off."
 
"Mechanic was recommended by a

"Mechanic was recommended by a few others that I know in the commercial boating industry. He seems good so far; in fact, he hasn't charged me for any man hours since the engine installation; I've been able to just buy the parts and furnish them, so I really feel like he is a fair guy and seems to be doing all he can to figure out the problem.

I think my wording in prior post was misleading (due to my ignorance); mech didn't tell me that turning the carb pins was a "sign" of anything; it just sparked him to remember thinking it was odd that the carb cover was black b/c the omc carb covers s/h/b blue; it was my stupidness that thought turning the carb pins not effecting engine performance was a sign that we were on the right track.

Aside from my ovious stupid comment about turning the carb pins, is it true that if the carb doesn't meet the specs of the engine that it could cause such a problem as mine?

I bought a new long block from Jasper Engines and my mech rebuilt the engine. I really drilled him today about the dyno test today just to make sure we weren't dealing with any engine issues....but he reiterated that it maxed out on the dyno IN my boat with a man up front pushing the throttle. All was A+ except for that 400rpm differential mentioned earlier.

I've already ordered and paid for the new fuel pump and carb so I'm going to let mech install these and see what happens.

If I don't have any luck with this, my next step will be to run it on a remote tank to see if we can narrow down the problem.

I'm really hoping I'll hear from you or some of these other guys (Hy Stat; Ringvold; Bondo,etc..)that a wrong carb on the engine could cause these kind of problems.

Thanks for all....this is a great site.
Todd"
 
"well, I'm feeling like xx

"well, I'm feeling like xxxx over all this. The fuel pump and carb is already in motion so I'm gonna go ahead and replace those old parts, although your recent comments have my hopes of any of it working at slim to none at this point.

The mech is a certified omc mech; but I really don't have much else to go on other than word of mouth. He has just expressed the he really feels uneasy about the carb b/c it is obvious to him that its not the orignal one. My next post may be to see if you know of any good mechs in my area!

Ringvold-
* I'm not sure if mech ran a curve on the dyno..I'll check.
*how can I tell if it is a 2,5 carb? I checked the #'s on the carb. I see #17086064 and under that D6 2TG1. Rochester / GM is marked on the carb.
*the boat actually planes out at about 2000rpms and continues to gain rpms until I reach 3/4th throttle then all the crap starts; it never goes above 3000rpms at wot (approx 10mph.
*I will definately reduce load weight when I take it out next (after carb and fuel pump i/s on Thurs)
*I'm also gonna be ready with a remote tank for testing on the water.

Maranda1-
Stupid question: Is being waterlogged a potential problem for me if it stays on a trailer in my yard all year?; I don't have it marooned anywhere.

Good stuff ; thanks again guys."
 
"GM/Rochester sounds to me lik

"GM/Rochester sounds to me like an OMC carb, don't think Mercruiser used them, but who knows.
Plans at 2000RPM? With that gear ratio and propeller it is around 5-6 knots! Must be a new invention that I have never come across before, or? It might let the water off the transom, it might not raise the bow, but planning at that speed -NO! My guess is that You are pushing a lot of water, perhaps with the boat leveled, but not planning. Then comes a lot of questions. Is the boat perhaps so light in the stern and heavy in bow that it just nose-dives and works like a snow-plow shuffling water? Planning below 15-18 knots is out of the question for that boat size unless it is a hoover-craft.
Could You please post a pic of this boat? Is it a 21 Trophy?"
 
"Thanks Ringvold. I'll ge

"Thanks Ringvold. I'll get you a picture uploaded tomorrow...she's sitting in my driveway! It's a Cierra Sunbridge 2150.

Hey...I'm really thinking about the order of things when the problem starts and doing a lot of reading/research trying to learn all this stuff. You are way better at calc probabilies than I re: rpms...planing...gear ratios...all that stuff. But one thing I know for sure, I never feel or notice a problem until those 4 valves start rattling at 3/4ths throttle. Valves should not rattle, period,...correct? At this point I'm just thinking of telling the mech to focus on the rattling problem and get it rectified first before we do anymore guess work by replacing parts because there old or don't look original. I think I'll get him to ride with me on the next run. If he's a good mech he should be able to open the engine compartment when rattling starts and figure out what is causing the problem, right?...or is that too much to ask? What else would make all 4 valves rattle??other than a fuel intake related problem? but then I remember your advise about white showing on the wires....hell, I just don't know.

I'll get a picture uploaded tomorrow, and will wait on anymore frustrations to be faced after I see what the new fuel pump and carb does since I've already purchased them to be installed.

Thanks for all-"
 
I did pickup the new fuel pump

I did pickup the new fuel pump but it wasn't a match; so I'm just going to wait and see what the new carb does and go from there.
 
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