150 2.0l Help (timing and carb)

[dolphinhunter]

Hey guys I have a lovely 150hp frankenmerc that the only thing i know for sure about it has an 86 mariner 150 power head. I was told this thing was an 93 and has the tilt trim and cowling of one. To the point now. I'm trying to solve the bad load up i have on this motor at idle. I run premix and 89 or better octane. The carbs are squeaky clean as of 2 months ago. The motor stays rich untill about 2-2200 rpm than it finally starts to clear out. (just a tiny bit fast for the trolling i do) i know these motors don't like to go slow but i can also smell the fuel in the exhaust when it idles. my goal is smooth running at 15-1800 range. When i sea foam out the motor she leaves behind a nice black oil slick through the exhaust. As soon as i can get my hands on a timing light i'm going to check it. i have cynced the carbs already. Also should i time it to 86 spec or go with the 89 and up manual i have now? what's a good ethanol bump 2* or so? do i need to change idle jets possibly? Or should the timing clean this up? Also which ngk non surface gap plugs can i use. That should also help a bit right? If not i'd like to know anyway cause i don't really like surface gap plugs.
Thanks

 

[sschefer]

Re: 150 2.0l Help (timing and carb)

In many cases your condition is caused by a couple of regular tuneup things. Clean the carbs and adjust the floats properly. Test the bleeder check valves. Do a "by the book" link and sync.

If your engine has the advance module on it, you can remove it as well as the idle stabilizer. Once removed, WOT timing should be set to 23-25 degrees.

If your carbs have idle needles, set them to 1.5 turns out from a lightly seated position.

Perform the oil pump test to check output at idle. If the pump has been removed, make sure your mix is correct at 50:1.

Use only fresh fuel. 89 is fine above 3500 feet below that you should run 90 or 91.

If you're running ethanol (E-10) fuel, make sure you have a fuel/water separating filter system installed. Depending upon the carbs you may need to change the floats to a E-10 rated plastic style. Make sure new floats are available before you discard the old ones.

Change all your fuel related hoses. All hoses sold today are E-10 rated.

 

[dolphinhunter]

Re: 150 2.0l Help (timing and carb)

Thanks for the input. I have done the link and sync and did the timing. I also removed the idle stabilizer. She's still a little rough on idle. I'm going to pull the carbs again and look to reset the floats. That's the only thing i can really think of giving me the rough and rich idle condition. I am also concerned about the temp she runs at idle. The pump and t-stats are new and the pisser is putting out good water. On the hose it gets kinda hot on idle too when it revs a bit it cools off just fine. I don't know what to make of it. when the water temps get up around 90 again i don't want to worry that much about it. I am just trying really hard not to blow this thing up. Maybe i am just too nervous about it since the last motor i had developed really bad piston slap from a crap aftermarket fuel connector. I guess i should just stop nukeing this but i don't want to throw any more money away on things that can be prevented.

 

[sschefer]

Re: 150 2.0l Help (timing and carb)

Thanks for the input. I have done the link and sync and did the timing. I also removed the idle stabilizer. She's still a little rough on idle. I'm going to pull the carbs again and look to reset the floats. That's the only thing i can really think of giving me the rough and rich idle condition. I am also concerned about the temp she runs at idle. The pump and t-stats are new and the pisser is putting out good water. On the hose it gets kinda hot on idle too when it revs a bit it cools off just fine. I don't know what to make of it. when the water temps get up around 90 again i don't want to worry that much about it. I am just trying really hard not to blow this thing up. Maybe i am just too nervous about it since the last motor i had developed really bad piston slap from a crap aftermarket fuel connector. I guess i should just stop nukeing this but i don't want to throw any more money away on things that can be prevented.

That rough idle can and typically is caused by 1 or more failed bleeder circuits. If the check valves are gone they're failry easy to change and the hoses are just 7/64 tubing that you can buy locally. Proper bleeder hose routing should be checked also. The Merc Manual has the correct routing. You should get one of those if you don't already have one. You might also consider decarbing it with SeaFoam and then run Merc QuickClean in it regularly.

As for temp, mine runs around 175 in 55 degree water when idling around for a while. It drops to 130-135 at speed.

 

[Chris1956]

Re: 150 2.0l Help (timing and carb)

The rich condition at idle and the oil slick in the water can be caused by a leaking fuel pump diaghram. The one on my '93 V6 leaked so badly, it locked up the crankcase with fuel.

 

[dolphinhunter]

Re: 150 2.0l Help (timing and carb)

That rough idle can and typically is caused by 1 or more failed bleeder circuits. If the check valves are gone they're failry easy to change and the hoses are just 7/64 tubing that you can buy locally. Proper bleeder hose routing should be checked also. The Merc Manual has the correct routing. You should get one of those if you don't already have one. You might also consider decarbing it with SeaFoam and then run Merc QuickClean in it regularly.

As for temp, mine runs around 175 in 55 degree water when idling around for a while. It drops to 130-135 at speed.

I do have a service manual and it's come in handy so far.

The bleeder circuit, i have had one hose that has come off and i repaired it. Is there supposed to be a significant amount of fuel running through them or is that the check valve failing that you're eluding to.


Also the fuel pump. i'll take a look into it i have one that's damn near brand new off of the other motor that i have been keeping around. if i see any problems i'll swap them.

 

[j_martin]

Re: 150 2.0l Help (timing and carb)

Coupla items.

Bleeder hoses and routing are critical, as are the check valves. It's all easy to check and replace. One thing to keep in mind, being it's a frankenmerc. Any one bleeder hose goes from a cylinder's reeds to the opposite (in timing) cylinder. 1 goes to 4, 2 to 5, etc. Which side of the reed plate it comes from depends on if it's horizontal or vertical reeds. With vertical reeds a carb bore and reed valve serve the cylinder behind it. With horizontal reeds, they serve the cylinder on the other side.

If it's rich at idle, try setting the floats slightly on the low side. Also, that little gasket in the middle of the bowl is critical. If it leaks, it'll flood a little all the time. Do a "firm squeeze on the primer bulb" test to be sure all the needle valves are seating. The bulb should not collapse even slowly once the bowls are full. If it does, look down the throats of the carbs to see which one is leaking. Firm does not mean white knuckle. Over 7 lbs fuel pressure can overpower a good needle valve and float.

If it idles good, but balks at high idle under load, try opening up the gap on the idle pickup cam a bit.

Again keying on frankenmerc, look up the jetting for the carburetors that are on it, not the original jetting. Jet sizing goes with the carb, modified only slightly by the engine type and size. You might be small on the idle jets. Smaller is richer. If the link-n-sync original idle timing is way too slow, this could be the problem.

Pop the pulse hose off the fuel pump. If it's dripping fuel, you have a problem with the pump.

hope it helps
John