OMC 3.0 hard starting in water

[OMCERIK]

SORRY FOR THE LENGTH OF THIS! I have a 1991 3.0 OMC COBRA motor, when I am getting ready to go out I usually fire it up in the driveway, now i hook up the flusher and garden hose, and it starts right up no problem, now i tow it 15min. down the road, put it in the water and it's 5 embarassing min. of turning it over to finally get it running, I do prime it, and it is not flooded. Now once it is running it runs great, until i turn it off. even if i let it sit 5 min. it will eventually start but it is difficult, no matter how long it sits as long as it is in water. now i bring it home hook it up to the hose no problem, also the boat does not take on water.<br />ON the same note could a bad shifter or ignition switch have anything todo with this? The reason i ask is when you start it in neutral it will turn over now when you engage the throttle (NO PROP)it sometimes will turn over some timesi turn the key and get nothing until i put it back in neutral. Could these be related? Thanks in advance for your thoughts!!

 

[PropNut]

Re: OMC 3.0 hard starting in water

i have a 1985 3.0 ltr that does the same exact thing. i even changed the points to electronic ignition and that doesn't help either-except for starting like a champ in the driveway. i have heard that this is the "nature of the beast"-talking about the omc 3.0 ltr. sorry i don't have an answer for you, but maybe we will get some insight from someone else.

 

[dhammann]

Re: OMC 3.0 hard starting in water

It has alot do do with the fact that the exhaust is under water. Some engine designs or valve timing designs do not allow the engine to breathe until you overcome the restriction in the exhaust.<br />Remember the old "potato in the tail pipe prank"

 

[dhammann]

Re: OMC 3.0 hard starting in water

Next time you launch your boat, try this. Get in the boat and let someone back into the water just enough so the outdrive is submerged up to the cavitation plate,crank the engine and then back up enough to drive off the trailer.

 

[sea wolf]

Re: OMC 3.0 hard starting in water

i hope i'm reading your post right, but i think u said u have to put it back in neutral to start it after it stalls? it has to be in neutral or it won't start. that's what the neutral safety switch is for. also, u shouldn't have to prime it to start it. have u checked fuel pump & carb?

 

[OMCERIK]

Re: OMC 3.0 hard starting in water

I tried starting it on the trailer backed into the water with just 1/2 the outdrive under water, no change, but thanks for the suggestion.<br />I think something is wrong with my neutral safety switch, because when i go to start it, the throttle is in the upright position (neutral) an it will turn over no troubles, however every now and then, when I put it in the water and there is trouble starting, I will push the button on the bottom of the control handle and move control handle forward, (not putting into gear) still in neutral and the motor will turn over, then after a while of not starting i'll put it back in the same position and it will not turn over? If i am still confusing you, i'll try to explain it a little differently, when your on the water and for some reason you want to rev the motor but not engage the prop, you push that little button on the bottom of the control handle and move the control handle forward to rev the motor but not move the prop. this is what i mean, so in my owners manual and i have been told if the boat is on in the water and i want top give it some fuel while starting i just push that button move the throttle forward and my motor should be able to turn over, now sometimes this works and sometimes it does not, I also think there is another problem fuel related, which i agree with the other gentleman who wrote in. for starters i am going to replace the fuel filter, then check the carb, if for some reason this doesn't work i'll look at the fuel pump. Thank you for your responses, I look forward to some more!

 

[dhammann]

Re: OMC 3.0 hard starting in water

If it starts easy on a hose and muffs it seems that would rule out any other problem. The throttle control lever does not control the ignition, just the starter solenoid. The key switch controls ignition. If the motor is turning over and the key is in the on position it should start. Just to be methodical, what is the only difference between your driveway and the water? I wold still suspect the exhaust restriction. Part of the exhaust flows out the prop and the port or ports at the gimble ring, maybe these ports were still under water when you tried the launch thing. One other ttick you might try...but with extreme caution; back into water far enough to submerge lower unit ( this will temporarily wet your impeller) then pull unit completely out of water and try to start it...If it starts shut it down emedietely to protect the water pump. Another thing, exhaust blockage ( and that is what you have until exhaust pressure overcomes the water pressure)is cleared by pumping air through the intake and out the exhaust while cranking the engine. Now, if you are cranking in the neutral position that means that your carb butterfly is closed, hence no air in- no-air out. The valve overlap (that all engines have) allows the dead air that is trapped in the exhaust riser to be sucked back into the combustion chamber (cylindres) this air is loaded with either carbon monoxide or unburned fuel. This situation will either smother combustion or make it to rich to burn. Also when your boat sits awhile the auto choke butterfly will close causing the same problem. You should always crank at open throttle and then throttle back.<br />4 cyl are worse than v6's or v8's simply because of air volume and less valve interval per revolution. In a 4 cyl, the interval is longer waiting for one valve to open and another to close allowing more time to suck back dead air.<br />Another thing, this hard starting is fairly common, I have it too. Don,t operate the throttle more than once or twice while cranking..this will just aggravate the condition causing more unburned fuel to accumulate in th riser. Hope this helps..keep me posted.

 

[PropNut]

Re: OMC 3.0 hard starting in water

it is somewhat tricky on my set up since i cannot advance the throttle without engaging the prop, and when the prop is engaged, you cannot turn over the engine. after trying and trying, it will finally start and run at low rpms (300-400) at rough idle for about a minute and then everything is fine. now if i try to shift into forward during this period, it will die. i have just taken it in to the marine shop to have the carb adjusted and still no change.

 

[dhammann]

Re: OMC 3.0 hard starting in water

Get your throttle control to work as it should and I bet your problem will be solved. It will still be a little slow to start, but that is the nature of the beast. A good stong battery also helps purge the exhaust and makes starting easier.<br />Got to go to work now..check with ya later.

 

[MStokes]

Re: OMC 3.0 hard starting in water

Not sure if this will help, but heres my .02 worth. I have the same engine (vintage '88) I put a battery out of a big diesel truck with 950 CCA (cold cranking amps). It ALWAYS starts instantly, in or out of the water. Ive joked that if the motor ever refused to start we could put it in gear and plane with just the starter! (well...maybe thats a weee stretch!)

 

[nrladeere]

Re: OMC 3.0 hard starting in water

I had a similar problem but not as bad. The engine had gotten hot due to a bad impeller, this melted part of the gasket on the riser elbow allowing water (especially on hose, due to higher supply pressure) to enter the exhaust engine side. Is your engine emitting white steam when on the muffs? Is is idleing roughly? If so you may have the same problem. I sealed mine with high temp RTV which is good to 700F and it solved the problem.

 

[dhammann]

Re: OMC 3.0 hard starting in water

OMCERIK< LET US KNOW WHAT YOU FOUND!!! We're waiting!

 

[rogerwa]

Re: OMC 3.0 hard starting in water

It may your starting routine. I have a 3l Merc<br /><br />My routine on cold start is this:<br />-Turn blowers on (obviously)<br />-Crank engine for a few seconds<br />-pump the throttle in nuetral twice or three times<br />-Set throttle in nuetral at about 1/3 open<br />-Crank engine again. It pops right off.<br /><br />The first crank allows the fuel pump to get fuel back to the carb (or re-primes)<br /><br />The Pump actions squirts some fuel down the throat, which helps give the engine something to fire.<br /><br />It works for me..

 

[PropNut]

Re: OMC 3.0 hard starting in water

rogerwa, i do what you do except putting the throttle in neutral and advanced. i cannot advance my throttle without engaging the prop. i think that is why i have some starting problems in the water. the only i know to try is getting a high crank amp battery so it will have enough power to blow the water out of the exhaust.

 

[DJ]

Re: OMC 3.0 hard starting in water

OMCErik,<br /><br />Why can't you advance your throttle in nuetral? You should have a button in the middle of the throttle handle base that allows you to do this. <br /><br />If the advance function is broken, I think I would be looking for a new throttle quadrant.

 

[nightride]

Re: OMC 3.0 hard starting in water

I HAD THE SAME TROUBLE WITH MY V6 OMC UNTIL I RAN THE EXHAUST STRAIGHT OUT THE BACK OF THE TRAMSOM NOW THERES NO BACK PRESSURE AND STARTS RIGHT AWAY GOOD LUCK

 

[OMCERIK]

Re: OMC 3.0 hard starting in water

Sorry, i was on vacation. Now back to the subject, to answer a few question, 1. I have started boats before and am pretty confident in my starting procedure. as i never had a problem until recent. 2. I was playing with it in the driveway and it gave me the same problem as when i'm on the water, so i'm pretty sure it is not the exhaust. 3. I have a dual battery set up and both batteries are new, and i have plenty of cranking power, i can pick one battery or the other or both and while having problems starting i select both. 4. yes, i have a button i can push to advance the throttle, and i do this and when i go to start, then i turn the key and sometimes it turns over and sometime it doesn't,<br />when it does turn over it starts instantly, when it doesn't work which is most of the time i have to put the throttle back in the vertical position, just to get it to turn over. IS THIS BE A BAD NEUTRAL SAFETY SWITCH???? CAN THESE BE ADJUSTED, OR JUST REPLACED, I'M PRETTY SURE MINE IS MOUNTED ON THE SIDE OF THE MOTOR. AGAIN ANY ADDITIONAL INFO WOULD BE GREATLY APPRECIATED!!!!!

 

[dhammann]

Re: OMC 3.0 hard starting in water

Now we are getting somewhere, read my previous post and replace your throttle control lever unit (about $130) and your problem is solved. It is hard to start a cold motor in idle, let alone having to clear out the exhaust.

 

[DJ]

Re: OMC 3.0 hard starting in water

Erik,<br /><br />The plot thickens. You didn't tell us it won't TURN OVER.<br /><br />That's a switch issue. Either the controller or nuetral safety, which I believe is in the controller.

 

[OMCERIK]

Re: OMC 3.0 hard starting in water

Thank you gentleman, and i'm sorry for not being more clear on my description, and to recap, in the driveway most of the time it starts, usually until i tow it and things start bouncing around. i get it in the water, i go to start it, and it just turns over as if starved for gas, and eventually starts (in about 5-10 very embarassing min.) now i'll take off run for about 30min.-1hour<br />anchor and turn it off and when i goto start it same thing, the one thing in common is when i want to advance the throttle in neutral, to start, i get nothing as if the batteries were dead, although every now and then like in the driveway, it will allow me to advance the throttle still being in neutral, and the motor will turn over, and fire up almost immediatly.<br />thanks for the advice, i'm going to look into getting a new control handle which i hope contains the neutral safety switch, and i'll keep you posted. thank again