3.0 OMC i/o does not idle

[Schico]

I have an 86 OMC 3.0L cobra in my 19' boat.<br />It was running bad and I found out the manifold rusted through getting water in the engine. I got a new manifold and had the engine rebuilt. Now it runs great, but it does not idle well, especially after a hard run. It will run slow, just not at idle and it stalls when going from forward to reverse. Trying to idle around to pick up a skiier is would be very dangerous. It makes docking a very embarassing event as I have no "brake" <br />I tried adjusting/cleaning the carb. Had the marina check it out prior to putting it in this spring. It seems to work OK under no load so they did not find anything. Also I discontcted the shift interupter just to rule that out. <br /><br />Any advice welcome.

 

[fone_man]

Re: 3.0 OMC i/o does not idle

Sounds like it is loading up... this should be a Rochester Carb / 2 bbl.. Look down the throat of carb... see if you see it dripping & let me know.<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[Staffan]

Re: 3.0 OMC i/o does not idle

Schico! I have a OMC Cobra 3.0 1987.<br />Have you cleaned the backfire flame arrestor recently? Mine was very clogged with oil & dirt. I put it in a bath of solvent for a week while off on a business trip, brushed it clean with an old toothbrush when I came back and put it back on the carburettor. The engine went smoother after that - it wasn't getting much air. Also, I had the same problem 'braking' because the lever was in need of lubrication.<br /><br />------------------

 

[Schico]

Re: 3.0 OMC i/o does not idle

I changed the points to the electronic sensor module and it seems to work better. The points were burnt. I have not been able to take it out yet to see if the problem is solved. It idles fine at the dock in neutral, but it was not too bad before when it was in neutral. <br /><br />In warm weather the choke seems to stay wide open. <br /><br />The idle screw is in as far as it will go. Idle speed is relatively high, but backing off on the screw just a little leads to heavy chugging and imminent stalling. I do not have a handheld tach to chek the speed, I may be able to borrow one. <br /><br />I have had significant trouble with the adjustments on the shift spark interupter. It does not always disengauge when the boat gets in gear. That is why it is currently disconected. I tried doing what the manual says, but it does not solve the problem. Any hints on this adjustment would be welcome.

 

[fone_man]

Re: 3.0 OMC i/o does not idle

carb rebuild for starters... when you close down idle mixture screw... it should die!!!!!<br /><br />Flooding... gas dripping in carb!!!!<br /><br />Fuel economy has got to be very POOR!!!!!!!!!!<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[Schico]

Re: 3.0 OMC i/o does not idle

Closing the idle mixture screws does cause it to die, I did not see any gas dripping in the carb. I ment the idle screw on the linkage is in as far as it can go.<br /><br />Thanks for your advice. <br />If it continues to have problems I believe the carb rebuild is next, Any sources for kits?

 

[fone_man]

Re: 3.0 OMC i/o does not idle

How long have you owned this boat???<br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[Schico]

Re: 3.0 OMC i/o does not idle

I have had the boat for 4 years, it was my Dad's before that, He bought it new in 86.<br /><br />Last night I took it out and it seemed to be running fine, but once it got up to 180 on the thermostat it would not idle well again. It will idle all day at the dock.<br /><br />Also now it seems to be starving for fuel at full throttle it goes about 20 seconds and dies, but if I back off on the throtle when this happens it will keep from totaly quitting. I had this problem in an old car and the filter was plugged, but I checked both filters ont the boat, and they were basically clean. <br /><br />I am about ready to throw in the towel and pay someone to do all the things I just did.<br /><br />Steve

 

[fone_man]

Re: 3.0 OMC i/o does not idle

Now for a lesson I learned along time ago... was on an 1971 Chevy Impala Sport Coupe w/ 402 CID Big Block 4 bbl Quad/ Rochester. Still remember that car... my first one!!!<br /><br />Fisrt day washed it, drove around block to dry off... all I heard when I got in driveway was... "pssssssssssssssssssssd"... dove over a "pork chop" bone in road & ruined new tire... heck i was trying to figure out where I was going to come up with $5.00 for gas to put in for the weekend!!!!!!! That was about 10-12 gals at the time... Half a TANK!!!!<br /><br />But back to the point... I determined why I was having fuel starvation on hard acceleration... pick up tube in gas tank had figerglass filter tube on it & it was stopped up... now this went on for years!!! I was pulling tank to replace fuel line hoses & thought I would look!!! BINGO!!!<br /><br />Now I am not saying this is your problem because when I replaced my tank unit 2 years ago there was not a filter on mine but would defintely be a starting point. Could be as simple as a pinched fuel line or weak/collapsed fuel line if it is a fuel starvation problem... they can be wicked problems to diagnose but once you find it... you say "BINGO"!!!!!!!!!!!!!!!<br /><br />Also, Check Fuel pump presuure could have problem on high RPMS... Keep us posted!!!<br /><br />I cannot fix it for you, all I can do is give you my experiences with this type of problem.<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man