Check my theory...Too much oil in fuel at startup?

[Conn]

150 V-6 Merc XR2 OB221010 Model # 1150766<br /><br />I've only had this rig for a month or so, and I'm still trying to work out the bugs...<br /><br />It's always smoked quite a bit at startup (OK, a LOT), but the last two times I've put it in the water, it took FOREVER to get it to start and when it did, the smoke was THICK, thicker than ever before. <br /><br />I had to crank and choke the dog crap out of it to get it to start these past two times, even after priming the bulb. It wants to chuff and backfire through the exhaust at startup and it's a bit "cold natured" as told to me by the previous operator (my uncle).<br /><br />The oil res. in the boat is holding pressure. I took it to the lake on Sunday, loaded it up at about 1pm and yesterday morning, it still had a LOT of pressure. <br /><br />I'm replacing the check valve in the engine. Hoping this will cure the smoke and hard start problem. <br /><br />My theory:<br /><br />I'm hoping that the excessive pressure when it sits is forcing oil through the metering valve and into the carb bowls making the oil and gas mixture too rich in oil for it to start correctly, therefore causing lots of SMOKE!<br /><br />Once started and warm, it still smokes quite a bit at startup, but it starts easy, and will quit smoking after a few minutes.<br /><br />Does this sound like a logical explanation? Can the oil mixture get too rich in the carbs and cause a running problem at startup such as this?<br /><br />The engine does not like to troll at idle, even when it's hot. Could the check valve be at fault for this as well? It's acting like it's loading up from idle-2000 rpms. On the water, I can pump the bulb and it boggs down, almost dying. The engine shakes around and misses off and on up until about 2000 RPMS. I've cleaned the carbs, replaced the fuel pump and filter, changed the plugs, and checked the spark on the muffs.<br /><br />I have heard switchboxes are a common problem on these engines with intermittent spark problems, but don't want to cough up the $100+ for each one and it not be the problem. (motor takes two if i'm correct) <br /><br />Any suggestions?<br /><br />Thanks. <br /><br />Conn

 

[KCLOST]

Re: Check my theory...Too much oil in fuel at startup?

You have a mechanical oil pump on the motor.. It's on the port side of the engine. Oil should not flow unless the engine is running/turning over.... <br /><br />You are not running pre-mix by chance?<br /><br />You can also disable the oil pump and run on pre-mix to see if the smoke problem improves or remains the same...<br />But the pressurized tank should not cause a problem...<br /><br />I'm guessing your motor is late eighties in age based on your serial number. You might consider removing the oil injection and running pre-mix..<br />Some may disagree with me, but the plastic drive gear in the crank that drives the oil pump will not last forever...

 

[Conn]

Re: Check my theory...Too much oil in fuel at startup?

no not running pre-mix. the oil injection system is still hooked up. <br /><br />well shoot. I had searched on here somewhere (and may be wrong) with the idea that prolonged pressure in the oil tanks would cause some sort of problem relating to too much oil? causing smoke? i might be wrong though. <br /><br />could the oil not be forced through the mechanical oil pump with air pressure?<br /><br />i'd rather not remove the oil injection system if at all possible. metering gas and oil in jugs is a pain.

 

[AndyL]

Re: Check my theory...Too much oil in fuel at startup?

Have you thought about checking the spark strength and timing. If you are choking and the like it will be trying to start in a very rich condition, added to which there would be an excess of oil left around the system after the fuel has evaporated since the last time it was started. I have run mine on premix 50:1 plus the oil injection after having some work done on it where I was concerned the auto oil may be in question and the smoke wasn't really that bad. <br />My guess would be to check basic engine status ie Compression, sparking and timing to eliminate a fault caused by age rather than going straight for the oil system directly.

 

[timmathis]

Re: Check my theory...Too much oil in fuel at startup?

Have you done a decarb lately? Could help!

 

[Conn]

Re: Check my theory...Too much oil in fuel at startup?

Yes. I cleaned the carbs once real good, ran the boat 2-3 times..it was still not idling right, so I took them back off, cleaned them again to doublecheck and checked the float levels. <br /><br />i've tested the spark on all six cylinders and all emit a nice blue spark across the gap. haven't checked the timing. it runs like a raped ape after 2000 RPMS. I pulled the recently installed plugs to check for any fouling. all were a bit oily, but none to the point of fouling.

 

[gss036]

Re: Check my theory...Too much oil in fuel at startup?

You migh start unscrewing the cap on the supply tank (when you come in)to relieve the pressure so the oil is not being pushed into the system. That may help you in your troubleshooting.<br />Changing the check valve is a good idea.<br />What kind of oil are you running?

 

[Conn]

Re: Check my theory...Too much oil in fuel at startup?

Merc. Premium plus 2 cycle oil.I had thought I heard someone else having the same problem with the constant air pressure in the oil tank causing a smoking problem, but can't find the thread anymore. I just kind of figured too much oil might make it run like crap.

 

[wilde1j]

Re: Check my theory...Too much oil in fuel at startup?

The remote tank pressure should be relieved by the engine mtd check valve within a few minutes of shutdown. Very easy to verify. Open the fill cap and if you hear a hiss 15 to 20 minutes after shutdown, the pressure in the tank is forcing oil into the carbs, which is the source of the heavy smoking at startup. It eventually goes away after a few minutes of running, when the oil mix gets right.<br /><br />Change the check valve!

 

[timmathis]

Re: Check my theory...Too much oil in fuel at startup?

My question was have you done a decarb? Not clean carbs. Tim

 

[Conn]

Re: Check my theory...Too much oil in fuel at startup?

Define decarb. I'm not sure what that means. It had a heavy treatment of seafoam. <br /><br />I changed the check valve yesterday afternoon and fired her up on the muffs. It started easy. Not sure why. I did relieve the pressure Tuesday morning. I checked this morning to see if there was any pressure and there wasn't. I'll fire it up again after work today and check the tank pressure 10-15 minutes after. <br /><br />So I'm probably assuming wrong by thinking the more potent mixture of oil in the gas due to excessive remote tank pressure might be causing a low RPM running issue? <br /><br />Thanks for all the help.

 

[studlymandingo]

Re: Check my theory...Too much oil in fuel at startup?

The "heavy treatment of seafoam" is what Tim was referring to by saying decarb. <br /><br />I did a 1 gallon to 1 can seafoam treatment recently, and a few days later I was changing spark plugs and decided to spray deep creep liberally into each cylinder. More crap than the original decarb came out of the exhaust.

 

[Conn]

Re: Check my theory...Too much oil in fuel at startup?

hmmm. I had considered three cans of seafoam in a 20 gallon tank to be "heavy". WOW. I'll try the one gallon of fuel to the one can of seafoam. I guess the Seafoam effects more than just the carbs?

 

[gss036]

Re: Check my theory...Too much oil in fuel at startup?

Conn, check the FAQ's, there is a forluma there. If you are satisfied the carbs are clean, then do the deep creep spray into the spark plugs holes and let it sit a couple of hours, then fire it up. Make sure you have water to the water pump, "do not run it dry".

 

[Conn]

Re: Check my theory...Too much oil in fuel at startup?

i'm in the process of a "heavy" decarb as we speak. 1 gallon of gas, 1 can of seafoam, and I've got some decarb stuff in a can Merc Power Tune I think. It's smoking like mad (from what I understand it's supposed to. I'm goign to pull the plugs and shoot a little mojo into there and let her sit for a while.

 

[Conn]

Re: Check my theory...Too much oil in fuel at startup?

fired it up again after letting the combustion chambers soak for 15 minutes. some nasty stuff on the inside of the prop where the exhaust exits. gummy, oily, chunky stuff. I pulled the plugs again and sprayed the Power Tune stuff in there. In the meantime, I'm goign to get something to eat while they're soaking. I'll get back with you all in the morning or Saturday after the lake to let you know the results. Hopefully this is going to take care of my rough idle-2000 RPM problem.

 

[KCLOST]

Re: Check my theory...Too much oil in fuel at startup?

LoL, it will smoke up the neighborhood!!!!

 

[Conn]

Re: Check my theory...Too much oil in fuel at startup?

fired her up this morning on the tank in the boat and seems to be doing a lot better. idle is still a little rough. i think once i blow the snot out of it tomorrow, it should be fine. I'll post up tomorrow afternoon and let ya'll know how it worked out. <br /><br />yeah, it smoked a LOT when it fired it up this morning. I think the soak of the power tune overnight did that. <br /><br />LOTS of nasty crap coming out of the exhaust. I parked my white truck 10-12' behind the boat (boat is facing engine outward on a 4' tall loading dock) and at some point it shot black crap all over the hood of my truck. <br /><br />i'll get a better report tomorrow. thanks for the help.

 

[Motor Boater Bill]

Re: Check my theory...Too much oil in fuel at startup?

Hey Conn--I'm in Berea. I'll keep my eyes open for the white truck with black crap all over the hood!

 

[Conn]

Re: Check my theory...Too much oil in fuel at startup?

UPDATE!

I finally got to get the boat back on the water this past weekend, and the symptoms are much the same, except it starts easier, and doesn't smoke nearly as much since replacing the check valve. Above 2000 RPMs it does fine, a steady throttle on the lever at 1800-2500 will cause the engine to "hunt" for an RPM..even on the muffs.

When below 2500 or so, and the engine is hunting, I'll whack the choke real quick to help denote whether the engine is running too lean, but the engine speed lowers, and the motor shakes around...so I assume it's probably getting TOO much fuel?

I'm suspecting leaky seals on needle valves? I have taken the carbs apart twice to clean and check float levels, and pulled the needles out, but didn't replace anything...

Sound like a culprit?

Thanks.

Conn