sick 1978 mariner 140hp

joshgar8

Seaman
Joined
Aug 6, 2012
Messages
65
Re: sick 1978 mariner 140hp

I am running alittle more oil than 50:1. I run one bottle that says mix with 6 gallons to achieve 50:1 with about 5 1/2-5 3/4 gallons just for safety. The oil I use is quick silver, not the synthetic just the regular two stroke oil.

As far as the trigger goes, when I took it to him I had a cdi replacement trigger in the engine. He said that when he brought the non missing engine up to high rpms and the back to idle the cdi picked up a miss. That being said he pulled my cdi out and replaced it with a old oem type. I took it to the lake with that after he "fixed" it the first time and it would run ok just cut out like the switch was turned off. It would always start right back though. I took it back to him and explained the issues and he R&r'ed the trigger with yet another used oem one. It doesnt cut out and is te one currently on the engine

As far as the carbs go, he took my clogged up set that I took to him off and replaced them with another oem used set. Here again, I take the boat for a test run after he "fixed"it and she won't plane at all. She won't even build no more than 1500 rpm with the fast idle on the trailer out of the water. I take it back to the mechanic and he says he looked at my carbs that came off and thought they needed a cleaning and also he found out somebody "tuned" the engine with the old clogged up carbs so he rebuilt them and put them on it. He also mentioned they have 80-81 jets instead of the 70sometging the engine came with. He mention that it has the same jets as a factory 150 has. All that being said he put the "tuned" carbs on and got it back to me. That's is when she ran, and she ran awesome until I had a gut feeling to verify timing and idle mixture. That's when I found the settings I referred to in the first post. All out of whack to say the least. Sorry about the general area on the jet sizes, I not sure the numbers I just know he told me they are the same as came in a 150 hp
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,319
Re: sick 1978 mariner 140hp

Josh, That is one strange story. Your mechanic has too many parts of unknown quality, for my tastes. You probably should check the main jets to see what he has put in there. I never saw soot on my Merc 1500, and I had it for decades.
 

joshgar8

Seaman
Joined
Aug 6, 2012
Messages
65
Re: sick 1978 mariner 140hp

It's not excessive, but is for sure there. If I could post picture I would do so. It looks kind of like a pickup truck with a deisel engine looks right outside of the tailpipe in the bumper area ect. Just a darker discoloration that will wipe right off. It's not caked on or anything. Im wondering if it could have been from the rich condition I had when I first put it in the water and it fell on its face. I had to lean the mixture out to get it to plane. After getting it to plane, I didn't attemp to go any leaner, it still could be on the rich side cause it was slow to come out of the hole. Just a guess I would say I am close to 1 3/8 turns out on all screws, if I went any fatter, it won't plane. I was at 11/2 on all screws when it stumbled and wouldn't plane.
 

joshgar8

Seaman
Joined
Aug 6, 2012
Messages
65
Re: sick 1978 mariner 140hp

I have not been able to look at any of the plugs since the last test, I will try to do so in the morning. What are the characteristics on a rich condition on the idle screws, and if I use a temp gun to get all 3 sets of plugs the equal temp, what is a ballpark temp I would be shooting for?

As far as the main jets go, how do I identify what is in them, is it a easy visual inspection? All that being said from the description of the work provided, who is to say for example the 80 jet is actually a 80 size hole in the jet?
 

joshgar8

Seaman
Joined
Aug 6, 2012
Messages
65
Re: sick 1978 mariner 140hp

Chris, I think I have everything dialed in. I ran it a couple hours today. All was good except one little hiccup for a matter of mins, it acted as if it had a minor miss but then cleared up. My guess was maybe a fouled plug from all the tuning they have been through. After than it ran great for an hour and a half or so.

It's still alittle slow out of the hole but I'm beginning to think its just the nature of the beast with a heavier boat and all.

Thanks allot for your help
 
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