OMC 5.0 stuttering

C

cajunaire

Recruit
Joined
Jun 20, 2004
Messages
5
I have '89 OMC 5.0 that stutters at full throttle. The boat runs smooth up until about 3,000 rpm and 3/4 throttle. When the throttle is opened up, the motor begins to miss and sputter. I have changed points, rotor, cap, wires, and am certain of dwell, timing, and vacuum at low rpm. I rebuilt carb, and the performance is better, but still will only occasionally run above 3,000 rpm.
 
M

motox6

Petty Officer 3rd Class
Joined
Apr 4, 2004
Messages
85
Re: OMC 5.0 stuttering

When you rebuilt the carb, did you set the float?
 
H

hoot

Chief Petty Officer
Joined
Sep 8, 2002
Messages
434
Re: OMC 5.0 stuttering

ignition coil could be breaking down.
 
C

cajunaire

Recruit
Joined
Jun 20, 2004
Messages
5
Re: OMC 5.0 stuttering

I did set the float as per carb kit standards. I have also replaced the ignition coil.
 
J

jka

Seaman
Joined
Jun 13, 2004
Messages
64
Re: OMC 5.0 stuttering

I have a similar prob with my omc 5.0 1994....can only get to 3000rpm WOT. I haven't changed anything yet...it's going into shop Monday. It's EFI....and hasn't had a tuneup in at least 4 years. I'll post shop response next week.
 
R

rattana

Chief Petty Officer
Joined
Jun 12, 2003
Messages
413
Re: OMC 5.0 stuttering

You can buy a cheap vacuum gauge/ fuel pressure gauge from any autozone, etc. Connect it to your discharge fuel line and read the pressure when cranking.
 
J

jka

Seaman
Joined
Jun 13, 2004
Messages
64
Re: OMC 5.0 stuttering

the omc 5.0 is back from the shop. It needed a new alternator. It was failing. Here's the tech's words on the work order:<br />"the problem with the tilt and trim and low rpm's was the result of the alternator not producing enough voltage to run the computer and electrical system. when trim was applied it would drain the system and create a loss of power"<br /><br />He said the boat did not need a tuneup and everything else was perfect. I haven't had it on the water yet but I'm assuming everything is in working order now. If there's another issue on this engine or reoccuring problem I'll post an update but otherwise consider this issue closed.<br />thanks for all your help guys. nice to know people are willing to share their knowledge.<br />jk
 
H

hoot

Chief Petty Officer
Joined
Sep 8, 2002
Messages
434
Re: OMC 5.0 stuttering

jkarch, thanks for your fixed repair post. it's good to see what was done to fix a boat when symptoms are given. it helps us all. usually it is something fundamental and easy to fix, but in your case, it wasn't. hey cajun, yours running yet?
 
L

lindb40530

Seaman Apprentice
Joined
Jun 25, 2004
Messages
40
Re: OMC 5.0 stuttering

I could not get mine over 2200 but I just found out I installed the points wrong. Have a prestolite distributor and the tension bracket comes on the outside but needs to be installed on the inside. The lack of tension caused the engine to run rough over 2200. I am sure I am the only one stupid enough to put them in wrong but I'll throw it out there anyway.
 
C

cajunaire

Recruit
Joined
Jun 20, 2004
Messages
5
Re: OMC 5.0 stuttering

Thanks Lindy 34 and jkarch. I have cahnged the points. Is the tension lead the solid lead on the points? Changing it to the inside of the points remedied the problem? <br /><br />I have the same problem with the trim causing a miss. I have noticed that the alternator seems to be on the low side unless I am at high throttle.
 
J

jka

Seaman
Joined
Jun 13, 2004
Messages
64
Re: OMC 5.0 stuttering

cajun,<br />if the trim is causing a miss...checking the wiring harness for it. it's supposed to have a clamp holding the two leads. if it doesn't...get a clamp on and it'll solve that issue for you. it solved mine. 4winns shipped the boat without the clamp.<br />john
 
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