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BoxMN

1997 Merc 150efi issue

6 posts in this topic

1997 Merc 150 efi that has been totally reliable seems to be acting up. A few times this year so far it has just sort of killed for no reason. Always at idle or slow speed. We put on a new bulb as it seemed like it would start and run fine after squeezing bulb. Gas is good and fresh and usually non-oxy.

But it has done it once since as well. We did not change the fuel line.

A coupe other odd symptoms:
Our locator has been popping up the low voltage indicator when we start the motor. I think we had it set at 11.5v. I tested the starting battery and it is showing a good battery, and it was just bought last year. Tried to check water, but it is closed battery.

The engine smokes more than usual upon starting the first time in a day. It has never done this, but it REALLY smokes a white smoke when you start it.

Any advice is appreciated! Thanks!

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A buddy had a 175 (same motor) and he had a fuel pressure regulator go out. I am not sure where or how hard that i to fix, but on cars it is easy (at least chev 3.1...)

Not sure how to trouble shoot it on outboard. Hopefully something simple. I dumped the fuel filter just to see if any water in it (no alarms going off) and we are changing plugs as we didn't last year, or maybe not even the prior. Usually we do every other year. It gets lots of hours, and lots of hours trolling as well.

Also, we have used it for several trips so far this year, in some big wind and lots of WOT running and quite a bit of trolling and when it is running it is just like new. Just a few tiles at idle or coming off throttle to idle it acts up.

Edited by BoxMN

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The unusual smoke at startup is probably some kind of clue.  Not sure what it means though

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"White" smoke can indicate water in a cylinder. When you pulled the plugs did you notice and thing unusual? Droplets of water? Water will bead up on plugs, gas won't. 

 

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So I dumped the fuel out of the filter - no water in fuel -  and put on same filter. We put in new plugs, but at the advice of a guy behind the counter at NAPA (who seemed to have quite a bit of experience with motors) we tried a very slightly hotter plug. Other than the gap it was the identical plug. 

When we pulled the plugs, I didn't notice droplets, but two of them were much less clean than the others. My brother said the smoke was more blueish than white prior to the plug swap.

He used it last weekend and said that it was like a new motor. No smoke, no stalling, even ran and idled smoother, and said just sounded like it should. Maybe we had a fowled plug or two. This had never happened before though, so maybe I just didn't put it together, as when other motors would get fouled out they really really ran poorly.

Thanks for your advice, I will post again if the plugs didn't do it.

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