OMC ESA and overstroke switches

[floattest]

After rebuilding my carb because of what I thought was an idle circuit problem. And also after going through other fixes and general tuning of my engine I am convinced my problems are not in the Carb. I am also convinced that my problems are not fuel related.

I could go through all that but you could read my other posts if you would like to relive it.

Here it was it did last time.

Consistently the last several trips I can launch and run at idle or at speed for a good 30-60 minutes. When the boat is slowed down to idle it dies. It can be restarted and will idle in neutral but when put in gear it dies. I have tried adjusting the 2 idle screws but the engine always seems to favor the approximate starting point. 3 turns out. When it is first started it runs fine. Very smooth. Timing is set at 8 degrees and dwell is nailed on 30 degrees. I was told by a reputable mechanic that 8 degrees is better than 10 degrees because of our ethanol gas. I don't know how or why that is, but I took his advice anyway. At those settings the boat ran very smooth and steady at 4000 rpm and about 32 mph. Temps were steady as well.

When we slowed down and the engine died I let it sit for a good 15 minutes and then tried to restart it. Get's going rather easily in nuetral and then when the shifter is moved forward it dies. It is very consistent. Dies without a cough or sputter, just dead.

I tried to adjust the idle a little higher just to get it going and back to the dock.

Finally I was able to get it putting along in reverse and we managed back to the dock and trailered the boat.

After reading the factory procedure on the ESA and overstroke I will be going through that test and adjustment today.

I believe this may be my only problem.

My main question is; Has this happened to others and do any of you know if it's adjustments or a bad ESA module? Any other advice you'd like to give is also appreciated.

Thanks,
floattest

 

[Kainon]

Re: OMC ESA and overstroke switches

The ESA Should only assist when shifting OUT of gear, not Into gear, and should NOT Kill the engine, its supposed to only Intermittenly Interupt Spark enough to take some torque off the prop and gears to ease the shift to Neutral.

You may have a lower shift cable issue or binding, as you didn't mention the year and type of drive, I've got no idea exactly what you have.

no ideas on the overstroke switches, I haven't seen any connected and havent' looked into what their function is.

 

[floattest]

Re: OMC ESA and overstroke switches

It is a 1979 OMC 800 drive, hydro mechanical shifting I believe, and it's a 350 GM motor.

I believe the ESA works both going into gear and out of gear and the overstroke switch is there to prevent the ESA module circuit from "stumbling" the motor when already in gear or when in neutral. At least that's what I have gathered.

 

[floattest]

Re: OMC ESA and overstroke switches

I'm posting my results here from the last 5 weeks.

These results also answer some of my posts about idling problems.

SUCCESS! Engine Fixed!

Sorry for the Long delay. It has been an adventure.

It wasn't a fuel issue afterall. 2 rebuilt carbs, I've pumped the tank twice now, All filters have been replaced more than once, many iterations of idle screw adjustment, also cleared the tank vent (more on that later) and blew out the antisiphon valve with carb cleaner, it's in good working condition too. Anyway, Who cares now, it's fixed. Just a lot of time lost, but the good news is a lot of new knowledge that I can share.

After replacing the fuel the last time and no success I was convinced I may have an iginition and/or ESA problem. I tested the two switches on the shift converter and made a slight adjustment to the overstroke switch. I found some corrosion and questionable condition on the old ESA so I put a new one on it. Also replaced the coil and wires. The plug wires were pretty old so I figured no reason not to eliminate them as the cause.

Same thing. It would run great for about 30 minutes in the driveway at 1K or on the water at 3K. didn't matter. The idle quality loss and stalling when going into gear was repeatable every time.

Finally dug into the distributor and completely dissasemble it. (lesson learned, should have looked at distributor long ago, after first carb rebuild) Well, one of the weights had lost it's advance plate guide pin. Was rattling around inside the dizzy. Not the pivot pin but the other one that goes in the slot in the advance plate. The shaft bearings were good except for too much end play. Was going to replace the weights but decided to make the plunge and upgrade to breakerless. Total cost about $410 including the CDI ESA.

I bought the Mallory breakerless, coil and wires kit. This coil requires the ballast resistor, part 700. Then you run a 12V wire from ignition switch to the ballast resistor/coil. The new ESA is the CDI unit and does not require a diode fix. I like the plug wires from mallory a little better than the sierra wires. They both seem like good quality but the boots and the terminals seem like better quality on the mallory wires and the mallory wires are trimmed to different lengths. They fit better. Who knows, they are both better than way old wires!

Mallory kit to replace the old YM624JV: M9-26000 SS
It includes YLM624AV and coil 9-29716 and wires set, then add ballast resistor Mallort part 700.
The ESA is CDI 123-9898P.
Also needed 25 feet of 16 gage wire and a few connectors.

Idle is steady now, shifting is perfect. It will stumble slightly as it is designed to it seems both into and out of gear. When at idle around the docks shifting from fwd to revers it is smooth and easy, idle drops down to as low as 500-600 and no stalling! In nuetral I have the idle at about 700. Maybe a bit high.

The one weird thing left to figure is that My cheapo direct hook up timing light doesn't work right. Can't figure this out. It fires at about 30 degrees btdc of #1. Been all through this finding tdc 1 and setting the dizzy multiple times. Had to time it by ear and then test run it to eliminate ping. Not happy about this but it has proved successful as we were pulling hard on her yesterday through some tough wind chop on Puget Sound and going 27 mph. Daughter thought we caught air a couple times, but it was just the big 5 feet deep holes between the chop, fun ride, dry too, this hull is a tough girl.

So my plan is to find a better timing light, inductive, to perhaps weed out this strange problem. I really want to be able to get the timing perfect by the light, but I probably have near perfect the way it is.

So the last thing as I mentioned earlier is the tank vent. I noticed while doing some wiring that it has a loop. Kinda like you do with a dishwasher hose. I'm sure that the idea is to keep water from getting into the tank from the vent, and maybe it works becasue the last time I filled it with gas it was spitting water/air OUT of the tank vent while filling indicating that there was water in the bottom of the loop. Anybody have this loop in the tank vent hose? My concern is that if the lower portion of the loop get's water or gas in it that the vent won't pull air and it will stall. The last two cruises kinda disprove that though. I'm thinking that if on a long cruise in rough water a lot of water could get pulled into the tank through the vent and the loop.

Anyway, all minor stuff now.

Took my buddy crabbing on Thursday. Took 5 dungeness. On Friday Wife, Daughter and captain went for a long cruise by Hat Island and Whidbey. Great Fun! Run most of the time around 1.5K and about 7-8 mph on the gps. I like that speed best for low stress cruising.

Thanks again for all the help and happy cruising to all.