1984 Mercury V6 150 Outboard Problems - I am stuck

[something2do]

I want to thank everyone on the forums as I have read many, many of the helpful posts and have learned a lot in the past few months about outboard engine operation and repair.

Quick Primer: I am pretty technically experienced, but my new experiences with Outboard motors is testing my skills and patience lately. Thanks to many of you on the forums, I was able to tune up, repair, and setup a 1989 110 Evinrude for my 30ft pontoon boat and am very pleased with the motor now.

My new problem is a 1984 Mercury V6 150 Outboard that I got in another boat transaction. I located a 1996 Procraft 180DC bass boat and put them together. Prior to mounting the engine on the boat, I thought it was running pretty good, but my first water test has me stumped now.

Engine Background/Setup:

• Mercury 150 V6 1984 - Serial Number: 6480926
• unknown hours
• on a 1996 ProCraft 18' dual console bass boat
• no jack plate or set back
• Cavitation plate even with the bottom of the hull
• 21 pitch aluminum prop (had a 19P, but prop guy told me to start with this one for testing)
• No oil injection - mixing 50:1
• Carbs are all 3: WH27-1
  
  • stock jets I think: .054 and .064 sized
  
  
• Spark Plugs are BU8H NGK
• added dual steering bracket (works good)
• single piston trim style (re-built pump, works good)

Work Done so far:

• New water pump
• New thermostats
• New poppet valve/kit
• Rebuilt fuel pump
• cleaned all 3 carbs and put in new kits
  
  • did not change floats, has plastic ones
  • did float test, floats are not holding water
  • Kit included all gaskets and needle/seat
  • set floats to be even with float bowel body when held upside down
  • Blew into fuel line to test needle seal when upside down, passed test
  
  
• New Spark Plugs (BU8H NGK)
• New Coil wires (checked firing order to wiring diagram - ok)
• New Stator
• New Rectifier
• New Trigger
• New Starter and wires
• All new fuel lines, priming bulb, and water lines
• Added a spin-on water separating filter between tank and motor
• New cranking battery showing 12.90-13.4 volts (kept charged frequently)

Problem:
Unloaded (just me) on the water in forward gear, I put down the throttle and the engine only gets up to 1800-2000 rpm's and boggs down like the boat weighs too much. It will not get on plane or produce any power. I have tried working up the throttle slowly, but that does not work either.

Here is everything I have tried:

• Compression test - from 1-6 - 90, 90, 100, 100, 100, 95
  
  • tested with rental compression tester - put on my air compressor and readings were showing 10psi too low compared to compressor
  • so, my thinking is that the readings really should be: from 1-6 - 100, 100, 110, 110, 100, 105
  
  
• Spark air gap test - all 6 cylinders get a 1" gap spark, bright blue and nice "snap"
• I also put a timing light on all wires while cranking, light is steady and consistent
• Set timing according to book:
  
  • using timing light, all plugs 2-6 out and grounded, air gap tester on cylinder 1
  • throttle at WOT, full advance to stop, cranking speed set to 18 BTDC
  • throttle at rest, cranking speed set to 11 ATDC
  • Carb linkage roller spins freely, not touching cam at rest
  • all carb butterfly's closing completely at rest, opening/moving in sync
  
  
• Ohms on new stator are within spec (used CDI troubleshooting guide

The engine starts up and runs great on the hose and on the water. I can rev it up to 5,000-6,000 RPM with no hesitation. When the engine boggs down, I have tried pumping the primer bulb (nothing changes), but when I hit the enricher/primer by pushing in the key the engine dies. The engines smokes considerably as well. I do have a little fuel sitting in the front of the carbs (pictures below), but I don't know if that is leaking there when trimmed up for trailering or from running the motor on the water.

I could really use some help to point me in the right direction. I have a feeling I just need to adjust my throttle pickup a little more to get everything in sync. I have read the timing setup/link and sync at least a dozen times and I still don't think I have a fundamental grasp of what pickup timing is or what the goal is for it. I have read that the butterflys on the carbs should not begin to open until the timing is fully advanced? Not sure if that is true.

[something2do]

One thing I forgot to mention was the bleed lines. I have not touched them since I started working on the motor. I am going to replace them all today and see what happens. Any chance that those lines could be causing or contributing to the bogging issue?

I have also not touched or inspected the reeds. Thoughts there as well related to bogging?

Thanks everyone.

[Stig]

I could be way off here but from my engine experience I've noticed when things run fine under no load, but die under load it was a carb issue.

[something2do]

Thanks Stig, I already rebuilt the carbs very carefully and put in new kits, but I am going to set the floats a bit higher to see if that makes a difference. I originally set them so that they were dead level with the float bowl wen turned upside down, but I read several places here on the forum that you should set the far side (away from the hinge) so that it hangs down just a bit further than flat level.

I also purchased all new bleed lines. I will replace those today and check all the bleed check valves as well.

Any other ideas are appreciated.

[XstreamVking]

You are still getting too much fuel. Go thru the carbs again.

[something2do]

Thanks everyone. Anything I should look for when looking through the carbs again? I am going to set the floats a bit higher for sure. Does anyone think that an improper link and sync could be putting too much fuel into the engine faster than it can compensate with timing?

[transomstand]

NEVER, EVER rev that motor to 5000-6000 rpm on the hose Bad things can happen.

Does this thing still have the advance/retarded(intentionally misspelled) modules still installed?

[something2do]

NEVER, EVER rev that motor to 5000-6000 rpm on the hose Bad things can happen.

Does this thing still have the advance/retarded(intentionally misspelled) modules still installed?

By "bad" you mean other than making my neighbors really irritated right? Duly noted won't do that again.

yes you make a good point I forgot to mention I removed the idol stabilizer before I did anything. And left it disconnected on the advice I found on this forum.

[transomstand]

Might be fighting a losing battle here, compression is pretty weak. I'd go back to the 19" prop and bump the max timing to 21° and see how it acts.

[something2do]

Got the carbs off and all the bleed lines replaced. Checked each line I took off by blowing in one end, covering the other end, all under water. All the lines tested ok (no bubbles). I also tested all the check valves and they all tested good except for one. The one is on the air box. I am not 100% this is a check valve, but if it is, it is not working as I can blow air throw it both ways by mouth.

Here it is, is this supposed to be a check valve or a pass thru fitting? (the one to the right of the fuel line)



Took a look at the Reeds while I had the carbs off. They all looked good to me. No nicks or scratches and all seemed to be seated nice against the block.They all looked like this:


As for the carbs, I have always heard to set the floats so that they are even with the float bowel body. This is how they were when I took them off. You can see that they are actually just a bit below the body.


I adjusted them a bit to be even so that they can't be seen from a direct side view.


Anyone know which method is correct? I would like some advice before I put them all back on the motor.

[Fred Reed]

Thanks Stig, I already rebuilt the carbs very carefully and put in new kits, but I am going to set the floats a bit higher to see if that makes a difference. I originally set them so that they were dead level with the float bowl wen turned upside down, but I read several places here on the forum that you should set the far side (away from the hinge) so that it hangs down just a bit further than flat level.

I also purchased all new bleed lines. I will replace those today and check all the bleed check valves as well.

Any other ideas are appreciated.

Loss of power under a load,equates to misfiring. Suspect one of your switch modules,check fire to each cylinder.

[transomstand]

Carb floats should hang out 1/16", first pic looks pretty close.

[Glastron1987]

If you're using an infloor fuel tank maybe I'm wrong but trying an external fuel tank will eliminate any restriction issue.

[rock]

I think Pete hit the nail on the head with his compression comment. Try that smaller prop and see what happens.

Rock

[XstreamVking]

On the carb pics, look at all the fuel sitting around the bowl vents. It sure looks like it is puking fuel from flooded bowls. jm1/2 cent.