Finally got the boat uncovered, same engine problems

[allen456]

Finally took the boat out this year the past two weekends.  Still having issues with the old mosquito killer.  I have replaced the coils, plugs, plug wires, thermostats, checked compression again (110-115 on all cylinders), rebuilt the carbs, but I am still having issues.  The motor starts up good at the ramp, idles great, idle over to the dock, pick up people, launches out of the hole shot, runs great (except I still can't get over 4100-4200 rpms) and gets to the first fishing hole. When it is time to move to another hole, the problems start again.  It is like an act of congress to get it to start and I have to keep the rpms up and hope to be able to quickly move it down and into gear and give it gas to keep it running. not sure what is going on here.  Is the timing way off?  Are the power packs going out? Lost, need help.  Don't understand why it runs great cold and won't start for nothing after it has been run.  I know it is not getting to hot.  Is it possible the powerpacks would cause issues once the are hot and have been run?   Thanks for the help.

[flounderpounder225]

Electronics are all subject to heat problems, when a component is starting to have problems, heat will always exagerate the problem.  What you need to do is troubleshoot for spark and fuel when the engine is acting up, these are the 2 things other than air and compression (which you have checked) that the engine needs to run, so first determining which one is the culprit is your first step.  Have another person along to assist you.  If you can run it around for a while to get it warmed up as you would running to a fishing spot, but bring it back to the dock, where you can work on it, have a can of starting fluid with you.  If you can get it to duplicate the no start problem, remove the engine cowling and carb cover plate, manually open the throttle plates with your hand on the carb throttle linkage, have your assistant start to crank the engine, WHILE CRANKING just mist the carb throats with the starting fluid, if it busts off immediately, shut it down, you have a fuel problem.  If no difference, then you probably have an electrical issue.  If you had a coil pack problem it would probably make the engine run crappy, but not stop the engine from coughing and trying to start, more than likely if it is an electrical issue, I would look at the stator being the culprit, the stator provides spark for running and charges the battery, it is a large coil of wire under the flywheel and is very subject to breaking down when it gets hot.  This is how I would approach the problem to start with... Good luck

Marc

[Capt. Bob]

Sounds like fuel to me.

[allen456]

Thanks for the input.  Concerning the starting, it will cough a little after it is warm.  I forgot to mention that I also rebuilt the fuel pumps and they are working great.  The bulb seems to stay firm showing that there is not a vacum problem with the tank line.  How can I check the stator and see if it is part of the problem?  is there any tale tale signs that I should look for?  If i removed the flywheel at the shop and visually inpected the stator or trigger base, what should I look for?  I will try to take it out this weekend and do the test with the starting fluid.

[flounderpounder225]

As far as visual, sometimes the stator will exhibit some of the potting or black like "goo" oozing out from the coil (stator) if that is happening, replace it.  As far as reading the stator, you need to have a decent Volt/Ohm meter, preferably digital, and understand how to take resistance readings, and Voltage readings.  I would have to find the specs in a manual, or as I just did search the internet, without too much searching I found this site, http://www.boatpartstore.com/page40.asp which had a decent page and specs.  You may want to search further for "stator testing on OMC/Johnson/Evinrude" etc... But before anything, let's find out where your going, Fuel or Spark.  

First, you have to get the engine to fail, when your prepared to troubleshoot.  You say sometimes it coughs and sputters when trying to start, this is after a normal cold start and run for a period of time with no issues, Fuel pump is assumed to be working, primer ball is hard, This sounds like an ignition breakdown after getting hot.  To check for spark, pull the plugs, all of them (makes the engine easy to spin over). Keep the plugs in order so you know which plugs went to each cylinder.  put #1 plug in the boot, and somehow get the plug base to make contact with the cylinder head in a non painted area, or you can create a jumper lead with some heavy alligator clips, you just need a good ground to the engine.  Do not have the other plugs in the boots, too much sparking going on, make sure you don't have any strong fuel vapors or such around the back of the powerhead, have someone crank the engine momentarily while watching the plug gap, you should get a good strong blue "CRACK" if you have nothing, or it is weak, check your other cylinders with their plugs, write down on a note pad what each cylinder did.  If all are weak, it is the power pack or stator, if just a few, you could have some bad coils, swap bad ones in the place of your tested good cylinders and see if the problem recreates in that cylinder... this is all just some basic checks to determine what the basic problem is, but that is where you have to start.  A note of Safety, I am not trying to alarm you, but you should always have a small fire bottle within reach when doing these fuel and spark tests, it is rare, but I have seen accidents occur which were not expected, better to be prepared and safe, just good practice.  Good luck
Marc

[GoneFission]

I think Capt. Bob has it right - fuel feed problem.  Check the hoses and clamps between the motor and the tank.  I think you are sucking air somewhere - the fuel pump will suck air before fuel every time - so look for a loose connection somewhere.

[gran398]

Fuel...Electrical...


Side-bets?


The plot thickens....


 

Bottom line.....we'll get her right.

[flounderpounder225]

Should be interesting... without being there hands-on, it hard, but it don't take much to make those old OMC's run, there pretty simple.  If it's a fuel feed problem, the starting fluid test should bring it out pretty quickly.

[Mike453]

I've seen the same symptoms on lots of equipment, sounds like water. A very small amount of water in fuel will get mixed or dispersed at start-up/ choke on, run fairly well, then after warm and shut down. water condenses in carb bowl. and restart.is very difficult. In the northeast we see this every day with this great gas we have!  

[Capt. Bob]

Mike,
My guess that fuel is the culprit here is just as you stated.  I don't know if Allen is running a water separator/filter and how long has E-10 been running through the tank and such.  My 96 Rude exhibited these same systems. I began changing filters out twice/three times during the summer season. I rebuilt the carbs with kits that I purchased long ago (still made by OMC) only to see the gaskets disintegrate over the summer.

I would be looking for water and dissolved tank varnish as crap in the fuel system. Follow that with connection checks for air.

I love corn but it should be left on the cob, not in the tank.  

I'm just saying.

[allen456]

I agree with the corn, its only good on the cob.  I always treat the gas with Stabil and just picked a bottle of the stabil ethanol marine treatment this past weekend.  As anyone used it yet?  I do not have a water separater, thought of adding in, just never went that far.  I just rebuilt the carbs this past weekend, and I have to say, I was impressed, there was very little sign of any varnish in the bowls, on the floats, or anywhere.  I will go and pick up a new fuel line/primer in the morning and see if that helps with the equation. I hate doing all of these changes at once before running again, but every little part upgrade is nice. Keep the suggestions coming, I am liking them all and trying to make use of them.  Thanks again, Allen

[RickK]

I've gone through about a half bottle of the Marine version of Stabil - seems to work ok. Ain't cheap though.

[Mike453]

If you need to test for water in tank, I use a product called colorcut . originally used to test for water in diesel tanks or home heating fuel. It's a paste apply it to a long rod , dip in tank,(I go through sending unit opening) If it comes out red you have water. Can be purchased at most heating supply places. (Not Lowes or HD) Mike

[Mike453]

Allen456, Up in the north east(R.I.) I treat even my small engine fuel when I fill my cans. It helps but not 100%,And Rick is right, I buy at dealer and it's still expensive.

[allen456]

Well, took the boat back out last week and fired right up, ran great, until we were ready to go to the third fishing hole, same starting issues.  Finally got it started and headed back to the ramp.  Played with the timing as directed in the original OMC service manuel with no luck.  Took it back and pulled it in the shop and decided to take a look under the fly wheel and see if there was anything busted or not properly connected.  everything looked ok but the  magnets on the fly wheel and on the stator showed signs of rust.  decided to scotch brite the rust and cleaned it up and headed back to the lake.  Started right up, best hole shot I have ever had and looked down at the speedo.  Top speed i have ever been able to acheive was 33-34 (confirmed by gps) and i was running 41 (confirmed with gps) but the rpms were still around the same 4400-4500.  Running good and then heard a bam and the engine died.  ( OOH @#$%)  tryed to start and nothing but a CLANK, great the engine blew!  Pulled the cover, checked to see if it was locked up but the flywheel had normal pressure and could feel the compression.  Hit the key, started right up. I then retarded the timing back down past base setting, ran half throttle back to the ramp and let it sit.  Decided to try running again, ran awesome, then took it back and let it sit for 20-30 mins, repeated, and it ran great.  Did it four more times with no problems.  Confused......  What was the bang and why did the motor stop?  did it blow, but still run ok? Checked the compression when i got back and all cylinders were 115-121?  Any thoughts?  Thanks