1992 Mercury EFI Smoking (white smoke) really bad

[Chad628]

I am having an issue my motor. Its a 1992 Mercury XRI EFI 175. Last weekend I carried it out to the lake and upon starting it, it had a awful smoking. It was white smoke. Thought that it was water in the gas, but pulled the fuel filter off and poured it into a jar and there was no seperation. I should also say that it ran for about 10 minutes idling before it quit running. So then I saw a white looking substance coming from the exhaust relief port. Looks like oil mixing with water. I did a compression test and all the compressions were fine. All were between 120-125 psi. So, to me that ruled out a head gasket leak. Motor finally started firing again. Checked the spark plugs and the all looked normal. Could this be that the fuel oil mixture is to lean or does it sound like that one of the injectors be stuck open. At one point, I just fired the engine up just to start it for a second, and it blew fire out of the prop area. To me, that means the motor is getting too much gas and it is not using all of it up in the cylinders. Any thoughts would be greatly appreciated. Please try and help me. At my wits end.

 

[achris]

Re: 1992 Mercury EFI

Re: 1992 Mercury EFI

Hi there,

Too much fuel would produce black smoke, too much oil would produce blue smoke. White smoke is usually, as you suspected, water. So, where's it getting in? you pulled the plugs and said they looked 'normal'. Did they look clean? Because the first sign of water in the cylinders is really clean spark plugs. The water steam cleans them. They should have a small amount of oily residue on them. If the head gaskets and exhaust cover gasket have never been changed I would suggest they need doing. These gaskets get heated and cooled and eventually get brittle and start to leak small amounts of water. They usually should be changed every 5 to 7 years.... That's the first place I'd start...

Chris..........

 

[Chad628]

Re: 1992 Mercury EFI

Re: 1992 Mercury EFI

Chris, the power head had to be rebuilt 2 1/2 years ago thanks to the oil injection finally going bad. The oil injection has now been bypassed. So the gaskets have been replaced in the last 3 years. I was told that it would blow white smoke if it running to lean. Whats your thoughts on this.

 

[achris]

Re: 1992 Mercury EFI

Re: 1992 Mercury EFI

Can't see white smoke from running lean. The plugs would show also if it was lean. They would look as the engine was running hot, any oily residue would be burnt and look like carbon. Tell me the read on the plugs again, in as much detail as you can, or better, post pictures.

 

[Chad628]

Re: 1992 Mercury EFI Smoking (white smoke) really bad

I will check the plugs again tomorrow. But all 6 plugs looked normal to me. They all had a little oil on them as they have in the past when I have changed them. The best way to check this out, I guess, would be to hook an external gas tank up to it and mix the oil and gas in there and see what it does when doing this while running it. If it still smokes, then I have another issue going on. Maybe a injector stuck open or something in the fuel pump. I have only owned the boat for 4 years, so not sure what was done prior to me owning the boat. It has always ran well, except for the powerhead incident and now this. I am not mechanically inclined, but can figure out how to do most of the little things. I will post about the plugs again tomorrow. Thanks for your help and ideas.

 

[tashasdaddy]

Re: 1992 Mercury EFI Smoking (white smoke) really bad

white smoke = water somewhere.

 

[Doug57]

Re: 1992 Mercury EFI Smoking (white smoke) really bad

After the power head rebuild have the head and exhaust cover bolts ever been re-torqued? If not go back and start with doing that. I have a carb'ed 150 and had a bad needle in one of the carb's that caused fuel to leak into the engine. The gas would evaporate leaving the oil. When I would start it up the first time of the day it would cover the lake with smoke. Early in the AM in dim light it would look white. Are you sure smoke is white?

 

[Chad628]

Re: 1992 Mercury EFI Smoking (white smoke) really bad

Ok, rechecked the spark plugs again today, and they all look good. I went ahead and changed the fuel filter/water seperator and changed out the lower unit gear oil. The gear oil had a little water in it. I drained it in to a 16 ounce water bottle so that I could see what it look like. It looked and smelt a little burnt and had about 1/8 of an inch of water around the top of the gear oil. After putting the filter on and changing the gear oil, I did a compression test again and got good readings all the way across the board. So I put the plugs back in and started the engine again, and it started up as normal and idled as normal. It also had a normal amount of smoke. Another thing that I noticed when draining the lower unit was oil that was draining out of the exhaust around the prop. Is this normal or does this mean that I might actually have a problem in the lower unit with some of the seals and gaskets down there. Also, would the fuel filter cause that much smoke? Gonna take it to the ramp this weekend and let her idle and if she runs a little better, I might putt around a little bit and see how she does. Also talked to a mechanic today, and he told me that he thought that it could be the throttle position sensor and that the timing could be off a little bit. Any thoughts on any of this?

 

[sschefer]

Re: 1992 Mercury EFI Smoking (white smoke) really bad

You've already been told what it is. It's water intrusion and it's one of three things. Cracked block, head gasket, exhaust divider plate. Not sure why you think it's anywhere in the lower unit. If it's getting hot enough to burn oil down there, under water or on the hose, you've got some really serious problems.

A diesel engine will blow white or black smoke depending upon fuel mixture but not a gas engine and definitely not a two stroke.

Unless, you got diesel fuel at the pump last time by accident. It might be possible for a two stroke to run on it but it would be running really bad unless it's a multi-fuel design. They did make two stroke (EPA banned now) diesels.

Just thought I'd throw that in..

 

[Chad628]

Re: 1992 Mercury EFI Smoking (white smoke) really bad

Figured out why the lower unit had a little water in it. Checked the prop nut and it had come a little loose apparently had lost the pressure on the seal into the lower unit gears. Tightened the prop up and the oil stopped leaking. Then went to start the boat and run it at the ramp. It started to turn over, but then abruptly stopped. Thought the starter had gone out so I left. When I got back to my cabin, I plugged the batteries up and thought I would just try to crank the motor one more time, and she fired right up. Not sure, could this be the beginning of the starter going bad, or the solenoid going bad. By the way, I ran the boat and pretty much all of the smoke has gone away. Thinking that it could have been the fuel system treatment that I had put in it. I know that on my truck, when I put certain brands of fuel treatment in it, it smokes really bad for a while. I am going to take it and get the lower unit looked at since I did find a little water in it, to make sure that nothing is going to wrong on it. Thanks.

 

[Doug57]

Re: 1992 Mercury EFI Smoking (white smoke) really bad

I'm confused! Was the engine smoking or the operator? Think I'll go check my prop nut.