1989 5.8 omc wont go past 2500 rpm

[talies13]

1989 5.8 omc with hei dist from AAAmarine with E3 spark plugs will only go 2500 rpm, but I am able to go 30 to 35mph and I come out of the hole great. Engine never stumbles and at 2500 rpm it runs strong but won't go any farther I know I should be able to go 45 to 50 and be ataround 400 rpm. I'm wondering what could cause this.

 

[bruceb58]

Re: 1989 5.8 omc wont go past 2500 rpm

First thing I would do is dump the stupid E3 spark plugs.

Have you ever had this boat running at a higher speed and proper RPM?

You never answered my question from the other thread. What is the timing set to and how do you set it for that distributor? How did it run with the old distributor and what else has changed between the old distributor and this one?

Are you sure your tach is accurate? Check with a shop tach.

 

[airdvr1227]

Re: 1989 5.8 omc wont go past 2500 rpm

Have you been changing props?

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

I plan on dumping the e3s Monday. This is the first Time I have had the boat running in the water. First thing I did was replace the points with the hei distributor . Got it running on muffs and did small adjustments by turning distributor. I have not used the timing light but will bring one with me mon to lake . I know I have it 10 degrees bellow 0 on the timing marks, I think.

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

Have you been changing props?

What prop do you use on your 5.8 ?

 

[bruceb58]

Re: 1989 5.8 omc wont go past 2500 rpm

I plan on dumping the e3s Monday. This is the first Time I have had the boat running in the water. First thing I did was replace the points with the hei distributor . Got it running on muffs and did small adjustments by turning distributor. I have not used the timing light but will bring one with me mon to lake . I know I have it 10 degrees bellow 0 on the timing marks, I think.

How do you know what you have for timing if you never used a timing light? Does your new distributor require you to set it in a base timing mode to set the timing?

Setting timing the way you did without a timing light is a sure way of ruining your engine.

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

First off. I bought digital timming light. Rpms on digital light read 4100 wot and 650 at idle. I changed spark plugs tfrom e3s to champion and have thm gaspeto 60 like distributer recommends. Now at wide open throttle I am starting to get backfire and some claret? At idle I am at 10 degrees on timing light, at 4500 rpm I am at 30. Am I off. Never had backfire with e3s could that be problem or is timing off.

 

[bruceb58]

Re: 1989 5.8 omc wont go past 2500 rpm

Your timing is perfect. Many people have issues with Champion plugs.

What RPM does your tach say when you are at 4500 out of curiosity. Did you increase your WOT RPM?

 

[Howard Sterndrive]

Re: 1989 5.8 omc wont go past 2500 rpm

will only go 2500 rpm

Are you sure your tach is accurate? Check with a shop tach.

+1

Rpms on digital light read 4100 wot
At idle I am at 10 degrees on timing light, at 4500 rpm I am at 30. Am I off. Never had backfire with e3s could that be problem or is timing off.

that all sounds fine to me... what happened to 2500 max? How did we get to 4500?

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

Boat tach shows 2800 rpm when digital tach on timing light shows 3800 to 4100.

 

[Howard Sterndrive]

Re: 1989 5.8 omc wont go past 2500 rpm

Just ignore the tach on the dash then. Might have to switch the pulse setting on the back of the tach to get it to read ballpark.

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

I'm assuming tach on boat is bad. I'm using tach on timing light .

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

I'll try some different plugs mon. Any recommendations ? Do you think gap is to much. Is that what could be causing back fire at wot?

 

[bruceb58]

Re: 1989 5.8 omc wont go past 2500 rpm

What gap did you use? All the other ignition stuff good?

Typically, if you have an ignition miss, you will get it all RPMs. The fact that you only get it at WOT suggests a lean condition.

edit: i see you have them at 0.060. Not sure if that's good or not. Seems pretty wide. If you are using the stock specified spark plug and you gap them wide like that, you may have a problem but not sure.

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

aaamarine hei distributer recommended .60 gap.

 

[bruceb58]

Re: 1989 5.8 omc wont go past 2500 rpm

aaamarine hei distributer recommended .60 gap.

But its very possible the plugs themselves aren't designed to be gapped that big. What does the side electrode look like after you gapped them that big? Is it sticking out at an angle?

How did you come up with the Champion spark plug number that you bought?

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

But its very possible the plugs themselves aren't designed to be gapped that big. What does the side electrode look like after you gapped them that big? Is it sticking out at an angle?

How did you come up with the Champion spark plug number that you bought?

They looked fine. I got them from pep boys after they looked up 1989 5.8 l.

 

[bruceb58]

Re: 1989 5.8 omc wont go past 2500 rpm

They looked fine. I got them from pep boys after they looked up 1989 5.8 l.

A 1989 5.8 Ford engine in a truck may be a completely different plug than what is in a boat. Heat ranges and gaps are completely different. The correct plug is probably already on a sticker on your engine or in the owners manual.

Edit: Motorcraft ARF-32M

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

Owners Manuel calls for AC MR43t with a .30 gap. I think I will tryy tha.t

 

[talies13]

Re: 1989 5.8 omc wont go past 2500 rpm

Sorry for the typos. My phone don't work good with thi site