Omc 5.8 RPM questions

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daddybx

Seaman Apprentice
Joined
Jun 4, 2011
Messages
37
Hi all,

Got my boat in water
had mechanic set timing she purrs :)

took it out for run boat will not go above 2000 RPM ??? Seems like fuel

I have Brand new Holley 4160 in seems like secondary's aren't opening? Same carb that was on boat but new.

In neutral boat will rev up np under load nada?? What could it be?

Spark plug gap ?
Fuel filter?

Any ideas appreciated.

Also point gap is at .18
Dwell .30

plugs are .40

Thanks
 
airdvr1227

airdvr1227

Lieutenant Commander
Joined
Jul 15, 2009
Messages
1,666
Re: Omc 5.8 RPM questions

daddybx said:
Hi all,

Got my boat in water
had mechanic set timing she purrs :)

took it out for run boat will not go above 2000 RPM ??? Seems like fuel

I have Brand new Holley 4160 in seems like secondary's aren't opening? Same carb that was on boat but new.

In neutral boat will rev up np under load nada?? What could it be?

Spark plug gap ?
Fuel filter?

Any ideas appreciated.

Also point gap is at .18
Dwell .30

plugs are .40

Thanks
Click to expand...

I'd think the carb would be the first place to look. Haven't had much luck with rebuilt carbs. My next one will be new in the box.
 
airdvr1227

airdvr1227

Lieutenant Commander
Joined
Jul 15, 2009
Messages
1,666
Re: Omc 5.8 RPM questions

Brand new or a reman from a place in Florida? I missed that you said it was new. Possible to be bad right out of the box.
 
D

daddybx

Seaman Apprentice
Joined
Jun 4, 2011
Messages
37
Re: Omc 5.8 RPM questions

Gonna put new fuel filter in and check gap on plugs I know there set at .40 and looking further they should be at .30 could that cause issue?

Thanks
 
S

snake77

Cadet
Joined
Jul 26, 2011
Messages
27
Re: Omc 5.8 RPM questions

Just another thing to check but this same thing happened to my first omc now on my second. But it was the fuel tank vent tube kinked and would not alow venting at at 2500 rpms actually started to suction the fuel back out of the carb.
this tip that I'm saying was mentioned once here on Iboats and thats where I got it. After repair just rerouted vent line ran great.
 
R

roger302

Cadet
Joined
Jul 22, 2011
Messages
8
Re: Omc 5.8 RPM questions

I had same problem on 89 5 liter, ran great with ear muffs put it in water and as soon as I placed in gear and got above 1500rpm she would stall run rough and die, put it back in nuetral and it would start right up. Ended up being points and condenser, $17 plus 10 minutes of my time. Guys at shop said anti siphon valve on your fuel line or coil when it heats and fails, soon as it cools down it works again, just some options to rule out a couple more things, good luck.
 
D

daddybx

Seaman Apprentice
Joined
Jun 4, 2011
Messages
37
Re: Omc 5.8 RPM questions

ok found the issue it is the part below the points the "bracket" that holds the mechanical advance together its cracked

hoping I can find this part


Thanks all for the help
 
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