Quick question for 1989 OMC 3.0L with trouble running

[offshore79]

Again, 1989 OMC 3.0 in a 20 ft Baja open bow, fresh rebuild that I had running finally for a short time.
Ive replaced coil, points, condenser, wires, plugs, rebuilt carb, good fuel supply and pressure, adjusted valve lash, I'm trying to time it to 1* BTDC but having trouble because of the running problem.
I can start it with throttle which spikes to 2000-3000 RPM before I can try to bring her back down, I get it down to around 800 and she runs for a bit and then about the time I get back to the timing light, it dies. I've been trying to figure this out for hours.
I just read a thread in the merc area that sound almost like what I'm seeing and they mentioned a bad coil. The recomendation was to connect a jumper between + coil and + battery. I tried this and happened to notice that my coil was extremely hot.
***So my question is, is this an indicator that the coil is bad (did I cook my new coil) or that something is shorting making it hot and the coil is still good***.
By the way, I never finished the test because I ran the battery down trying to get it to start. Needs a charge.
Thank you
Offshore 79

 

[bruceb58]

Re: Quick question for 1989 OMC 3.0L with touble running

Re: Quick question for 1989 OMC 3.0L with touble running

How did you set your dwell? Use a dwell meter?

What is the compression?

Connecting straight from the battery is a good test but you can't run it that way forever. It gets too hot from too much current which you noticed. That is why you have a ballast resistor...to limit the current.

 

[offshore79]

Re: Quick question for 1989 OMC 3.0L with touble running

Re: Quick question for 1989 OMC 3.0L with touble running

Unfortunately I dont have any way to test the compression but they were all just bored and honed to 4.030 - 4.031 with new pistons (4.0275) and rings with .020 gap +/-.001. My guess is that I have excellent compression, I just dont know what it is.

I dont have any way to test the dwell either, I just put in new points and set the points to .019.

 

[fishrdan]

Re: Quick question for 1989 OMC 3.0L with touble running

Re: Quick question for 1989 OMC 3.0L with touble running

^ Yup

You said this is a fresh rebuild. Have you broken in the cam yet, 15-20 minutes at 1500-2000RPM? If you haven't broken in the cam, stop monkeying around with the idle quality and get the RPM's up,,, or you could wipe out the cam.

Also, since the carb is rebuilt, it will need to be adjusted, idle speed and idle mixture. This along with timing or dwell set wrong could make the engine die at idle. You have to play with them, get one set correctly then move to the next, go back to the first as it could have been disturbed, etc, etc... Once you set dwell, that won't change, do it first.

 

[bruceb58]

Re: Quick question for 1989 OMC 3.0L with touble running

Re: Quick question for 1989 OMC 3.0L with touble running

I dont have any way to test the dwell either, I just put in new points and set the points to .019.

Easy to fix that...buy a dwell meter.

 

[offshore79]

Re: Quick question for 1989 OMC 3.0L with touble running

Re: Quick question for 1989 OMC 3.0L with touble running

Bruceb58

"Connecting straight from the battery is a good test but you can't run it that way forever."

I was only able to do this long enough to hook up the jumper, get to the ignition key, turn it over for a few seconds, and I was out of battery juice. I think the heat was from before I put the jumper on and when I had enough juice to get it to fire for a bit....I think.

As for the dwell meter, I've been stuffing so much money into the boat that there isnt much left for a meter. I'll see if I can find one an auto parts store. They usualy let you loan things like these with a deposite.

 

[offshore79]

Re: Quick question for 1989 OMC 3.0L with touble running

Re: Quick question for 1989 OMC 3.0L with touble running

Fishrdan
When I first got the engine back together I was able to run it on the muffs for about 15 minutes at 1500. I think I should be fine there but it was after that when the latest problem presented itself. It just stumbled a bit and died off. I then had to put it to about half throttle to get her going and then try to back it off quickly to idle. Then it dies. Very frustrating!

 

[Autowizzard]

Re: Quick question for 1989 OMC 3.0L with touble running

Re: Quick question for 1989 OMC 3.0L with touble running

I feel your pain ive been fighting with a similar prob same engine. Make sure your grounds are good and there are micro switches on the shifter bracket that must must be not pushed on

 

[Howard Sterndrive]

Re: Quick question for 1989 OMC 3.0L with touble running

Re: Quick question for 1989 OMC 3.0L with touble running

I've never needed an engine running to set timing in the ballpark, the light will flash cranking on the starter just fine.

When I was 16 years old, I bought a kit that had a timing light, compression tester and dwell meter- it also came with a momentary switch tool to operate the starter. sounds like you need a kit like that.

 

[offshore79]

Re: Quick question for 1989 OMC 3.0L with touble running

Re: Quick question for 1989 OMC 3.0L with touble running

Well folks, I tested the coil with an ohm meter and I thought the numbers were off. I found 2.5 ohms across + and -. I couldnt find what it was supposed to be in the book so I went to another book. Chiltons. It said I should see around 4.0
I went back to the store and the guy at the counter said that the coil I have 1st) looks like it was cooked 2nd) was a cold spark to begin with.
He recomended a slightly hotter coil. (Another $30 shot in the ***).
Anyway, got home and installed the new coil (2nd time) and she fired right up. I timed it and checked the idle. I let it run on the muffs for about 2 minutes on idle and then about 5 minutes on about 1300 rpm. The coil was cool as can be.
Now I think it's finally time to take it down to the lake and give it some dock time. Thanks to all for offering up the guidence and I'll keep you posted.
(I may have finally scared away the gremlins)