Idle/RPMs too low - boat won't idle

nateo

Petty Officer 1st Class
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Apr 13, 2014
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352
finished up the timing today and got er back running smooth. Thanks everyone for your help.
 

skippy2235

Petty Officer 2nd Class
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Aug 24, 2009
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138
Glad you found your issue and solved it, I think I would find a Rev limiter so this wont happen again, for any reason. Spun prop, coupler, broken drive, throttle being miss adjusted. you get the idea.
 

NHGuy

Captain
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May 21, 2009
Messages
3,631
nateo, good for you. Once you trust it just run it. What you just went through is rare. It's so unlikely to happen again that you can drive it whatever way you want!
 

achris

More fish than mountain goat
Joined
May 19, 2004
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27,468
nateo, good for you. Once you trust it just run it. What you just went through is rare. It's so unlikely to happen again that you can drive it whatever way you want!

Drive it like you stole it! :D
 

nateo

Petty Officer 1st Class
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Apr 13, 2014
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352
Took to lake tonight. Running like crap out of hole. 3000 rpm max. Rpm jumps to 900 in neutral. Forward gear idle got it at 650-700. Timing at 8 btdc but timing mark jumps. Its got a bad tick but not sure if thats exhaust flappers or engine. I think im giving up on this boat. Is the engine toast? I.e. time for a rebuild?
 

skippy2235

Petty Officer 2nd Class
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Aug 24, 2009
Messages
138
I am thinking vacuum leak?
Since you know the basics of this engine.
Start with easy stuff.
If you have good compression.
Look at timing, chain alignment.
Then fuel.
 

flipbro

Master Chief Petty Officer
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Feb 8, 2013
Messages
830
Do a compression test if it passes. Get yourself a vacuum gauge and plumb it in to the vacuum port on manifold behind the carb. You can set timming and set carb off vacuum on these older engines. It will indicate bad valves bad rings ect.. a healthy motor will hold a steady18 to 21 inchs of mercury.
 

nateo

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Apr 13, 2014
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352
Well I took valve cover off and adjusted rockers properly. It sounds like it has a bad tick to it, even when running at idle. It sounds like is coming from the area near the head that I worked on. Anyone know if there is a good chance that something else is bent such as camshaft or piston connecting rod?
 

flipbro

Master Chief Petty Officer
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Feb 8, 2013
Messages
830
Cam shaft no.. Connecting rod possible. Is it up high on the engine or lower. Did you check the push rods for straitness? How about collapsed lifter? Its never just an easy fix when a motor is over reved to the point it looses a keeper and the piston hits a valve.
 

nateo

Petty Officer 1st Class
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Apr 13, 2014
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352
Got rid of the tic. Figured out that I didn't adjust the valves properly. Got those adjusted properly now. It sounds pretty good now but still having problem with sluggish out of hole and top rpm 3600. got timing set at 8 btdc but rpms are erratic. Sometimes idle rpm 8 or 900 sometimes it drops down to 500. In forward gear in water lowest I could get it to run was about 700 rpm whereas last year I had it humming at 650. Seems like I've done it all on this boat. Not sure what could be left, unless that connecting rod is bent. Unless anyone has any other ideas, I'm going to try to a compression test tomorrow.
 

achris

More fish than mountain goat
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May 19, 2004
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27,468
What it sounds like it crappy fuel, or water in it...
 

nateo

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Apr 13, 2014
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352
hum...will look into that. discovered this morning that I forgot to connect carb sight tube. Anyone know if that can cause any problems?
 

nateo

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Apr 13, 2014
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I started thinking about this. I know there is some water/condensation in oil because I had a vacuum leak (that I have sense fixed). There was some drops of liquid dripping out of carb yesterday. I thought maybe I was burning some of the water out of oil but now wondering if this was water?
 

nateo

Petty Officer 1st Class
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Apr 13, 2014
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352
I have one more symptom to run by you all before I give up and take it. Seems to be ignition realted. When i turn the distributor I can never seem to get it to land on 8 btdc. Will always go like 9 or 5. When at 5 it wants to die. If i tweak idle set screw i can get it to land on 8 but then my rpms never seem to be correct. Always over or under at idle. Could it have anything to do with that sensor under cap? Maybe wiring wrong or something? I replaced it recently with new "type". Im at a loss now
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Is the distributor body grounded properly? And 'through the block' is not properly.... It needs to have a black wire connected to the distributor body itself and run directly to the engine ground. Also, is the amplifier module (I think yours is mounted on the inside of the port elbow) also grounded properly? It should have its own black wire running to one of the mounting bolts, and another from the mounting bolt to the harness. Basically, check all your grounds. And not just a 'look see', pull them off and make sure they are clean and tight...

Chris.....
 
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nateo

Petty Officer 1st Class
Joined
Apr 13, 2014
Messages
352
No Title

Is the distributor body grounded properly? And 'through the block' is not properly.... It needs to have a black wire connected to the distributor body itself and run directly to the engine ground. Also, is the amplifier module (I think yours is mounted on the inside of the port elbow) also grounded properly? It should have its own black wire running to one of the mounting bolts, and another from the mounting bolt to the harness. Basically, check all your grounds. And not just a 'look see', pull them off and make sure they are clean and tight...

Chris.....

Hum...The sensor and amplifier ground wires are currently connected to one of the amplifier mounting bolts you mentioned. However here's something that's really got me thinking now. Previously there was a ground wire that connected to the distributor (and or old sensor, can't remember which) from underneath. However the new sensor had a it's own ground wire and I did not hook the underneath ground wire back up. do I need to? I'm attaching pictures I found googling that show both the old style and new style sensor that I have now. Just looking at that picture it looks like maybe one of the mounting screws on the new sensor will likely ground the distributor body?

Tonight I discovered that I had added too much engine oil at some pointed. doh. I went ahead and drained it completely tonight and going to fill back up with some mercury oil tomorrow. Could this particular problem be something as easy as overfilled oil? Hauling boat up to lake burns a lot of fuel in truck and I don't know if I could be that lucky. It feels like something electrical to me. With the new style sensor I had to join some wires together, could a bad connection on one of the other wires cause this?

It was all connected to amplifier mounting bolt previously but if you think it will help I'll run all new ground wires as you mentioned.
 

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