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OMC COBRA 30 liter 9 MPH

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wmdmedic

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"I have a 1989 Bayliner Ciera

"I have a 1989 Bayliner Ciera with a rebuilt 3.0 liter GM block. The engine starts easily and idles very well. when I run it up in neural, it does just fine. The prop 13.75 x 15 is listed as one of the correct sizes for this engine. My problem is that I cannot get over 3000 RPM and 9 MPH while cruising. I have tried to trim the boat well while under power and have checked to make sure the throttle is wide open at the carberator. I cannot find the problem. Can anyone help?"
 
I had a similar situation once

I had a similar situation once. I was only able to pull 2200 rpms and maybe 15-20 mph tops. In neutral I could pull the full range of rpms. Turns out I had lost compression in a few cylinders which was due basically to lack of use. I had to redo my engine.
 
Put new fuel and "press&#3

Put new fuel and "press" the engine. Just drive it I think it "opens" for you. Maybe moisture in the carb or...
 
"Thanks for the reply. The bo

"Thanks for the reply. The boat is a 22 footer. No water in the hull and it floats and trims well. I thought, perhaps, it was a clogged exhaust causing backpressure but I checked that before taking it out. No change. I will retune and check compression/vacuum. What I dont understand is that the engine sounds ok and the first half of the throttle takes it to 3000 RPM it is the second half that brings no change."
 
You of course confirmed the sp

You of course confirmed the speed with a gps?

22 footer with a 3.0 Maybe 25-30 mph tops.

You could try disconnecting the esa if equipped.

This the first time out on the water with the new motor? Who set up the valves?

Do the compression and the vacuum test via the link i gave you and then post we will go from there.

What size prop That prop might have to mush pitch.

Lets get the motor running right. Then the prop business latter i have 2 11 pitch props that will fit.Might just be the ticket for you. you have to be running between 4200-4600- rpm regardless the speed. Capice?
 
Hi and thanks for the assistan

Hi and thanks for the assistance. I have boated most my life and this one stumps me. I did confirm the speed with my GPS. I made it up to 10 mph today with a following sea. I sold my classic 17 foot glaspar when we moved to the great lakes this winter and bought this from a "trustworthy" :) individual who still swears it ran out good when he put it awy for the winter. It is my first time out with this boat. It is a new -remanufactured- motor. I do not know who set the valves. Sorry ESA? The prop is 13 3/4 x 15. The references say that it goes with this engine set up but at this point I am not sure. I am going to reset the points and plug gap and timing. Then I will check compression and vacuum. I am stumped as to why it runs up to 3000 rpm with no problem on the first half of the throttle and then the second half makes no difference. I will check as suggested and post. I do work 24 hour shifts so It may be Tuesday before I post again. I am not getting anywhere near 42-4600 rps out of her.
 
"I had the same problem with m

"I had the same problem with my 175 br with 2,3L engine for a couple years ago. The previous owner had it winterized and he told me in ran good before that. I couldn`t get it up on plane and it backfired thru the carb once in awhile. When in neutral it reved up to 6000 rpm. I rebuilded the carb. and made a full tune up to the ignition. It didn`t help. I put new gas in it and had a friend in the bow and we just ran the boat up`n down the river (2miles) and it got better and better every time. After riding it about 1.5 hrs. it was quite normal a top speed of 35 mph. I don`t know what the real problem was but the running helped. The winter after, I was about to change the oil and it was milky (leaking exhaust). I had the whole cylinder head rebuilt because of bad valves and seats. And a new exhaust. I hope you don`t have the same problem with yours."
 
"I had a very similar problem.

"I had a very similar problem. But i had a 120 hp motor in a very heavy 19 footer. Had a 15 pitch prop, would get to 4000 rpm with just me on the boat.

So i tore up the floor looking for water. Found a little wet foam in the cuddy.

But no more rpms went to just barely 25 mph gps confirmed with the speedo on my boat.

With 2 people with a 15p prop ,just barely over 22 mph.

Long story short i had to go to a 11p prop, to get to 4200 rpm and with 2 adults and 2 kids made just barely 25 mph. I did 20 mph all the time anyway.

Now to your problem, i don't really care what anyone says, a 22 foot boat with a 3.0L motor is way under powered.

And if you do look at the manual it lists 11p props to 21p props.

Each boat needs a different prop.

You have to turn between 4200-4600 max rpm regardless of speed.

SPEED IS SECONDARY, RPM'S ARE THE MOST IMPORTANT."
 
"I had a similar problem with

"I had a similar problem with my 20 footer with Buick V6. 4 guys in the boat, and I couldn't get OVER 2000 rpm. First thought it was fuel problem under load, but engine revved right up to top rpm in neutral. Changed ALL fuel filters, NO effect. Took the boat home,did a " compression and leak-down test"...compression ok.NO leak-down.Then realized I had the Spark Plug wires on in the WRONG order. Check yours...MAYBE you got them on in the wrong order. I re-tested the boat after correcting, and it goes like stink now! Funny thing is.... the Cap has the wire numbers RIGHT ON IT.... forgot my GLASSES !!!!"
 
"I am going to check the compr

"I am going to check the compression and vacuum in the morning. Question, does anyone know if the incorrect spark plug would cause it not to reach its full rpm? Would it miss and run rough or just not reach its full potential (RPM?) Have to get it up and running my wife is to the point where she just glares and taps her foot when I talk about the boat. :)"
 
"DO the Leak-Down Test. If you

"DO the Leak-Down Test. If you don't know what that is... I'll tell you. When I did a leak down, I connected the Pressure indicator gauge to the number 1 cylinder(AFTER removing ALL the plugs).
I then cranked the engine a few seconds, and read the pressure indicated. Then leaving it connected, WATCH the dial for a drop in pressure over a given period (I went for about 2 to 3 minutes) There should be NO drop. IF there is, it could indicate a bad valve (burnt)
My ancient engine read 105 psi on number one, with a high reading of 140 psi on the rest.I know it's not withing tolerance, but I didn't see any oil fouling on the plug (good color, as well), and the engine runs strong.I think it's got a sticking piston ring, maybe. Not bad readings for a 43 year old engine. I think I got this right....
If I'm wrong, someone can correct me.
Remember, I'm 6 years older than my Boat, and subject to spells of confusion...lol.

Scott"
 
"You may also want to check an

"You may also want to check and make sure the throttle cable is set correctly and opening the throttle fully.

My father-in-law has a 21' cuddy Bluefin similar to a Bayliner, and it does 32-35mph at 4200rpm with a 19p I think, could be a 17p but definately not a 15p and it's a OMC 400 (83)."
 
Compression and vacuum test ap

Compression and vacuum test appeared rather normal. I have autolite platinums in the engine. Throttle opens all the way. Get higher RPM's on the trailer but only 3000 in the water. Still reach 3000 with first half of throttle and nothing more for the second half. Would putting it on a dyno help? Wife still glaring :)
 
140psi on the compression test

140psi on the compression test ? Hows the fuel look? Whats the timing at ? is it getting 30 degrees at 3000rpms? Sounds like the power valve on the carb is stuck or there's some junk in there. When was the carb last rebuilt?
 
Do you have a esa module?? If

Do you have a esa module?? If yes please disconnect it and run it on the water again. Don't ask me how i know that the module will limit revs if bad.
 
"I know your pain. My wife als

"I know your pain. My wife also use to glare and tap her foot when I was spending time with the boat. I had the same problem with a 87 bayliner with a 2.3 liter engine. It sounded great on muffs in the driveway but when in the water all I could get was about 3200 rpm's. I did all of the same tests (compression, vacum guage, etc.) and all was good. I pulled the carb off and rebuilt it and when I reinstalled it I also found that the timing was set to 4degrees after tdc. Between the carb rebuild and getting the timing set correctly the boats performes like a new boat. hope this helps nothing is as bad as the wife glareing."
 
"hey if shes giving you the si

"hey if shes giving you the silent treatment be grateful. that means she ain't flapping her gums at you.

they think they are punishing us by not talking to us.

hey you can be like me i pulled my bowrider out of the backyard, it hasn't been run for 4+ years.

during a lull in the winter i put in a new impeller and ran it very briefly, couldn't believe it started on the second touch of the key. But Squirrels ate my seats. they were new when i put the boat away.

1977 arrowglass couger 70hp 1976 evinrude. never kissed saltwater. if it has a 100 hours on it i would be surprised.

My wife has been giving me the fish eye cause now i have 2 boats in the driveway side by side in front of both garage doors."
 
Thanks for all the info. I am

Thanks for all the info. I am going to check the timing and perhaps rebuild the carb. If that doesn't work perhaps I will volunteer it to become the next artificial reef in Lake Erie. How do I chaeck to see if it has an ESA module?
 
If you look at the earlier pos

If you look at the earlier post there is titled 1990 king cobra no reverse the date on the post is 2-22-09 under that thread there is a picture from Mr. bob hill that shows the shift bracket and the interupter switch and the overstroke switch. with the engine running press on the interupt switch as long as the overstroke switch is not pressed the engine shhould start to stumble and miss but should not die. there is a two wire plug near the back of the bracket comeing from the ESA module if you unplug it that will disabe the esa. The esa module is norally bolted on the back of the shift bracket. your boat should have an ESA unless soeone has removed it. hope this helps
 
"14.5 MPH!! I will look into

"14.5 MPH!! I will look into a pitch change on the prop and see if I cannot get a couple more MPH out of it. I think if I want anymore than that, I will have to go for a winter project and change out the engine to a few more cylinders."
 
"I have a 1988 FourWinns with

"I have a 1988 FourWinns with the 3.0 liter Cobra. While vacationing last week at Lake Cumberland my boat was doing the same thing, running at 3500rpms and only doing about 15-18mph. I found 2 spark plug wires where the coating was cracked or dry rotted so I changed the wires with some used ones I had on board and it seemed to help very little. The next day I went to a marine parts/service dealer and bought the OEM type parts for tuneup (plugs,plug wires, distributor cap, condenser, rotor, & points), the boat is runnning like a champ now 4500rpms 30-35mph). I did a tuneup 2 years ago with parts bought online that were made be Sierra (points, distributor cap, condenser, rotor) but for these parts to start breaking down after 2 years seems premature for me. I will not purchase the cheaper parts online anymore, just like the saying "you get what you pay for" probably some Chinese crap. Good Luck!!"
 
"Changed the plugs and wires,

"Changed the plugs and wires, rechecked the point and plug gap, played with the timing and the more I ran it, the better it became. Hit 18mph this weekend. I will try a different prop to see if I cannot squeeze a little more out of it."
 
"Hi Mike, you mentioned the Co

"Hi Mike, you mentioned the Compression test
"appeared rather normal" what were the numbers ?"
 
"Ok, next test would be to eit

"Ok, next test would be to either spray some carb cleaner in the carb while under power or first close the choke plate to see if the power comes up, if it does the carb is lean. maybe only running on one jet.

Have you checked your timing at 3000rpm ? should have 30 degrees of advance, if you dont, problem with your mechanical in the distributor."
 
"I will check these two issues

"I will check these two issues out today. If i had to guess, I would tend to lean towards the carb as being the problem. I am also going to try less of a pitch on the prop. I have a 13 3/4 x 15 right now. I was going down to an 11 would you suggest I try this?"
 
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