1989 Johnson 70 doesn't always start easily after running and idles rough

[sumocomputers]

First, I don't know if the two problems of hard starting and rough idle are related. And sorry for the long post, just wanted to make sure I provide as much info as possible.

When first starting with muffs or just at the dock, the engine usually starts fairly easily, after now understanding from the Secret Files the correct procedure with pushing the key in for a few seconds as well as lifting the high idle lever a bit if needed. The cranking itself seems healthy. We put Stabil Marine in every tank, and have a 6.5 gallon portable gas tank. We also have been running SeaFoam in the gas for about 5 tanks, with no real change.

The problem is that after we are in the water running for awhile, turn the engine off to fish, and then try to restart after sitting for 15-20 minutes or more, it is hard to start, and requires lifting the fast idle lever for about 30 seconds, otherwise it will die when taking off. But, if we restart in less time than that (say 5 or 10 minutes), it starts first or second time, no need for fast idle, we can just go. In all scenarios, the engine runs rough at idle, but runs well at anything above that.

We have good compression on all 3 cylinders (all 120-125), spark plugs & wires are less than 6 months old and properly gapped at .03", and don't look oily or burned.

Fuel filter was replaced recently and new snap clamps were used for everything.

Engine temps are now normal after replacing the thermostat recently. It never goes above about 160F. I have a new temp gauge, and have checked it repeatedly with an IR gun at various places on the block while in the water.

I have removed the primer solenoid, and performed both the electrical and fuel tests according the service manual, and it checks out perfect. It is in the correct position of being parallel with the primer body.

I have checked voltage at the battery. It is 12.6V at rest, and 11.6V when cranking.

I removed the fuel/bulb line completely, cut off both ends, checked for suction, and the bulb check valve seems OK. Reconnected with new hose clamps, and made sure it was in the right direction. Bulb does get somewhat firm after pumping, but not totally hard. Every time we go out in the morning, it does get soft again. Read a few things about this, and I am still not sure how it this should behave.

I have checked spark, and couldn't get any of the 3 to show a spark at 7/16", had to reduce it to 3/8", and they all had spark. The spark was very thin, not sure if that is the type of tester I have, or if that means the spark is weak. And not sure if I really need 7/16" or not.

One last thing. We notice a very little bit of green/blue spray at the bottom of the motor case (under the carbs), so I am thinking we have a very small leak somewhere around the carbs. Our gas is greenish-blue because of the Stabil-Marine and Premix Oil. If there is a leak, I suppose extra air could be getting sucked in at the leak point.

I have been reading around as well as looking at the service manual, and I have a list of things I want to try, going from cheap/easy to expensive/harder, and just wanted to see if I am on the right track.

FREE
Increase the idle speed a little with the adjustment screw? No idea if this is needed.
Check Primer lines for blockages
Check Fuel lines from pump to carb for blockage/leakage (the one with all the little Ts and zip ties)
Clean Carb in place (are there high and low jets?). Going to follow the Secret Files.
Check Timing. The manual makes this sound very complicated, and I don't have a timing light.

$10
Replace Airbox to Carb gasket (already have a new gasket)

$15
Replace Spark Plugs for good measure

$60
Rebuild Carbs (never done this before, looks kinda scary). Also I need to check if there are any OMC service bulletins on replacing the jets; I read this somewhere, but can't find it now.

$60
Replace Fuel/Bulb Assembly with OMC branded (the current one is a Walmart special)

$120-$360
Replace Power Pack(s). I have no idea if this is even relevant here, but have seen a few references to this, and if I need 3 of them, that is damn expensive.

Thanks,

Chris

 

[racerone]

The system should easily jump a gap of 7/16" on it !!!!!!------Take the starter apart for inspection / new brushes.

 

[racerone]

The system should easily jump a gap of 7/16" on it !!!!!!------Take the starter apart for inspection / new brushes.----Fact ,your motor has just 1 powerpack.---Many powerpacks are replaced needlessly by folks who are desperate in finding a solution...----Good trouble shooting will beat guessing every time.

 

[sumocomputers]

The system should easily jump a gap of 7/16" on it !!!!!!------Take the starter apart for inspection / new brushes.----Fact ,your motor has just 1 powerpack.---Many powerpacks are replaced needlessly by folks who are desperate in finding a solution...----Good trouble shooting will beat guessing every time.

OK, I will do. I have the service manual which is pretty straightforward on servicing them (except the part about turning it on a lathe!).

Silly question. Let's say I get the weak spark fixed one way or another. It seems it might address the starting issue, but what about the rough idle? Would it have anything to do with that?

 

[racerone]

????---I have repaired lots of those starters !----Usually install new brush kit that I get for $4.50 at a starter alternator place.---Have never needed a lathe or other fancy tools.---Do an ohm test from commutator to the shaft.--The late production 89 motor had adjustable low speed jets.---------------------Does the tell tale hose come off the side of the block or off the top of the block ??------Is you compression test done recently ?

 

[sumocomputers]

????---I have repaired lots of those starters !----Usually install new brush kit that I get for $4.50 at a starter alternator place.---Have never needed a lathe or other fancy tools.---Do an ohm test from commutator to the shaft.--The late production 89 motor had adjustable low speed jets.---------------------Does the tell tale hose come off the side of the block or off the top of the block ??------Is you compression test done recently ?

Looking at the service manual, seems I can just take the bottom off to replace the brushes/springs. Will do an ohm test also.

Telltale comes off the bottom side, though I have rerouted the hose over the top of the block (have not relocated the outlet to the top yet). Assuming this means I have an early production 89?

Compression test was done about 2-3 months ago, we have been having the problem from day 1. I will check again to be safe.

If I do dive into rebuilding the carbs, is there any need for the $40 OMC carb jet tool, or can I use something else cheaper?

 

[racerone]

There was a service bulletin that came out in 1994 to drill the top of the block for the tell tale,-.-------To me this means that the motor has not had " proper service " attention for many years !!!!--------You can modify a 3/16" diameter screw driver to make the tool.

 

[sumocomputers]

There was a service bulletin that came out in 1994 to drill the top of the block for the tell tale,-.-------To me this means that the motor has not had " proper service " attention for many years !!!!--------You can modify a 3/16" diameter screw driver to make the tool.

The tell tale relocation is on my list! But since it doesn't seem to be causing a problem at the moment, I am trying to address some other issues first.

Agree with you that this thing probably hasn't had official dealer-level service for quite awhile, that is why I am trying to work through everything in order of priority!

But this starter brush suggestion may save me a lot of dough, so thank you for this; I certainly wasn't on my list.

 

[racerone]

??????------They do not publish these service bulletins as a joke.------Relocating that tell tale is in fact a priority !!

 

[sumocomputers]

??????------They do not publish these service bulletins as a joke.------Relocating that tell tale is in fact a priority !!

Understood, will make plans to get it done ASAP.

On the ohm test between commutator and the shaft, what am I looking for roughly?

 

[racerone]

???--Roughly-----You are looking for infinity.--Any continuity and the starter is bad.

 

[fireman57]

When you stop to fish do you put the engine up on tilt? IF you do then the fuel drains out of your carbs and that is the green/blue spot you see. Just try refilling the carbs by pumping your primer bulb and starting it up. If your engine cranks over fine your starter is good. Cleaning the carbs is simple just buy a rebuild kit and take your time. You can file a small screwdriver to fit instead of buying theirs.

 

[sumocomputers]

When you stop to fish do you put the engine up on tilt? IF you do then the fuel drains out of your carbs and that is the green/blue spot you see. Just try refilling the carbs by pumping your primer bulb and starting it up. If your engine cranks over fine your starter is good. Cleaning the carbs is simple just buy a rebuild kit and take your time. You can file a small screwdriver to fit instead of buying theirs.

We don't have power tilt, so no. But we do tilt up when trailering to put the transom saver on, so maybe that is the problem. I suspect one of the carb gaskets or the fuel supply line with all the T's and zip ties might just have a small leak, but I will know once I get in there.

I am buying the carb rebuild kits today. After reading around, looks pretty simple. Everything I read recommends soaking the carbs (nothing plastic or rubber of course), but the manual specifically says not to. So not sure what to make of that. I know user F_R sells the carb jet tools himself, but if I can't get one this week, I will buy a cheap grinder, and try to make one myself.

Regarding the starter, I think racerone was suggesting that since my spark shows less than 7/16", replacing the starter motor brushes is a cheaper first step to see if that improves it, rather than go with a $120 power pack right away. I am ordering the brush kit today also.

 

[fireman57]

Your starter brushes have nothing to do with spark unless it's not turning the engine over fast enough. I usually use a small wire and go through each jet and spray well with carb spray. Make sure that you do take the core plugs out and that the small holes under them are clear. Carbs are pretty simple once you do one.

 

[racerone]

Most folks do not understand the concept of a slow cranking motor not producing enuff spark.------When brushes are worn way down the springs exert less pressure and less current is tranferrred.-----This is all simple stuff to me but obviously a mystery to some !!!

 

[sumocomputers]

Your starter brushes have nothing to do with spark unless it's not turning the engine over fast enough. I usually use a small wire and go through each jet and spray well with carb spray. Make sure that you do take the core plugs out and that the small holes under them are clear. Carbs are pretty simple once you do one.

fireman57, looks like replacement core plugs come in the rebuild kit, so will definitely be doing that too.

 

[sumocomputers]

So I did the following, and I won't know if the hard starting is fixed until tomorrow, and although the idling is a little better, it still seems rough to me. It seems to be pulsating a bit.

Could you look at this short video, and tell me if you think it is idling rough?
https://dl.dropboxusercontent.com/u/...ugh-idle-1.mov

What I did so far
-Stripped, Cleaned, and Rebuilt all 3 carbs (replacing all 6 gaskets from carbs out to air silencer). Many gaskets had bad tears.
-Inspected the fuel "T" line that feeds the carb, and re-ziptied all and a new Snap clamp for the fuel pump side. I think my mystery fuel residue problem is gone.
-Installed new brushes and cleaned commutator on starter motor. Starter motor was and still is strong and fast.
-Tested and found I had one bad coil, replaced that.
-Installed 3 new spark plugs gapped at .03" just for good measure. Old ones were kinda oily, but I am running premix 50:1.
-Checked compression again cold and warm, and all are still 120-125

What I am looking at next
Check spark again, as soon as I have a 2nd person and dark conditions. If I still can't get 7/16" spark, then...
Check Power Pack (looks like I need a DVA adapter and resistor cable, which are about $100)
Check and Adjust timing/synchronization (manual makes this look like a pretty scary and complicated process, but I'm down)
New Fuel/Bulb assembly as a hail mary, though I think mine is fine. Bulb still doesn't get completely firm.
Fuel Pump? Have no idea if this is relevant to the problem

Thanks,

Chris

 

[sumocomputers]

So here is an update:

Still idles rough in neutral or just in gear (750-1100 RPM), but runs smooth once accelerating (say 1200 RPM and above).

Spark is giving me 7/16" on all 3 leads when cold. Haven't been able to check when hot yet.

At the dock, had a hell of a time starting it. Finally got it started, and needed to adjust the idle speed. It is now at about 750 RPM when in gear and about 1000-1100 RPM when in neutral. I believe it had been changed to compensate for bad gaskets.

When we would stop for 10-20 minutes, it would usually start right up with no choke needed, but unless we used the high idle lever for 30-60 seconds (usually around 1200-1500 rpm), if we put it in gear right away, it would die.

Right now I am looking at things to test or replace that relatively cheap/simple, and are things I want to do anyway.

-Replace Cheesy Moeller Fuel/Bulb assembly with an OMC one.
-Test Compression when hot
-Test Spark when hot. If weak...
...Test Stator when hot. If it passes...
...Replace Power pack (don't have a DVA to test the Power pack correctly)

-New Fuel pump is damn expensive at $450, so may look at rebuilding it if you think this might be a problem.

-The timing/sync process requires a test tank and prop, as well as some other things I just don't have, so this procedure might need to go to the mechanic.

 

[fireman57]

The fuel pump cost you are quoting has to be with the VRO pump still hooked up. A regular fuel pump mixing your own should come nowhere near this price. If it is still dieing when you put it in gear you missed something in the carbs. Did you take the core plugs out and make sure the small holes under them are clear?

 

[sumocomputers]

The fuel pump cost you are quoting has to be with the VRO pump still hooked up. A regular fuel pump mixing your own should come nowhere near this price. If it is still dieing when you put it in gear you missed something in the carbs. Did you take the core plugs out and make sure the small holes under them are clear?

I am now seeing that others just use a straight fuel pump, which seems to be closer to $100, so that is something I can put on the list. Is there a good resource to find out which OMC or Sierra pump would work correctly? I have seen where the wrong pump can cause burn up of the engine.

Before the rebuild, I had the dying issue and rough idle. Basically I still have both. Starting issue is better, and there is no more fuel spray inside the engine compartment.

As for the carbs, if there is one thing I feel 100% confident about, its the rebuild I did. I went to great lengths to soak/scrub/resoak these bad boys, inspect every little orifice, and use alcohol with a syringe to make sure every passageway and orifice was clear. Removed both jets, soaked them as well, and use a jet cleaning tool to make sure.

And yes, I removed both core plugs, and the holes underneath were very clean to begin with, but gave them a scrub anyway. Finished everything with a generous blast of spray carb cleaner through everything followed by compressed air at fairly low pressure. I also adjusted all floats according to the manual, and when reassembled I tested several times and they open and close as they should. The entire carb was actually very clean to begin with; I suspect it had a rebuild in the last 2 or 3 years, and maybe the SeaFoam we have been running in every tank helped a bit.

I am actually getting a DVA this week and going through all the electrical tests (stator, sensor coil, power pack, etc.).

Also want to do a basic sanity test to make sure all 3 cylinders are actually firing when running, since I am really wondering if it is only running on 2 cylinders some or most of the time.

I also have a new OMC fuel/bulb assembly coming for good measure.

The one thing that scares me is the timing/sync procedure if I need to go that far. Anyone have any experience doing this? Is it as hard as it sounds?