Trouble before, and now different trouble after carb rebuild, any thoughts?

[RI_Bred]

Hi Folks,

2005 Johnson J90GLSOB, carb'd 2 stroke.

I have a qualified marine mechanic assisting me "on the side" with my latest outboard issue, but I wanted to bounce the circumstances off of you good people for some additional ideas...

Original symptom was bogging under load over about 3K rpms, and would not get above 4k rpms. Started to happen about a month ago and was getting progressively worse.

Prior to any repair, we had the boat out on the water for diagnostics...we tested the spark under load and all four cylinders were getting spark (removed plug wires one at a time to test for dropping cylinders). My guy then tested the carbs while underway by using carb cleaner to spray a bit into each intake, and tested by holding his hand briefly in front of each intake to note changes, etc.

Determined that the starboard side two carbs were not getting fuel at higher rpms.

All four carbs were rebuilt this past Friday, including new float bowls. The old ones all showed signs of warping around the rim. Reinstalled and went to put the boat back in the water Saturday afternoon. Started it in the water but on the trailer...started right up but did not want to stay running for more than 30-60 secs and that was at fast idle. Called my guy and he came down after work. Took the boat back out on the water with it running rough in gear but low speed. Now, throttle up and accelerates wonderfully...top rpms back up to 5300 or so, running perfectly smooth top end.

Fools around with the plug wires and carbs some more...determines it's now the port side carbs that are cutting out at lower rpms. So, opposite carbs, opposite problem.

I'm guessing that although the carbs were sprayed with cleaner upon rebuild, there's something stuck/gunked in the port side carbs. They were not mechanically cleaned, just sprayed. Overall the carbs were very clean inside however.

I run the boat a lot during our season up here in New England, and I treat all my fuel with marine Sta-Bil and Seafoam religiously, just as an FYI.

Any thoughts or suggestions are appreciated. My mechanic is good, and I know he will eventually figure it out. He is on vacation through this weekend however, so I am sitting here with my mind racing and dwelling on it!

Thanks!
Dave

[omcforever]

Hi Folks,

2005 Johnson J90GLSOB, carb'd 2 stroke.

I have a qualified marine mechanic assisting me "on the side"

Prior to any repair, we had the boat out on the water for diagnostics...we tested the spark under load and all four cylinders were getting spark (removed plug wires one at a time to test for dropping cylinders). My guy then tested the carbs while underway by using carb cleaner to spray a bit into each intake, and tested by holding his hand briefly in front of each intake to note changes, etc.

Fools around with the plug wires and carbs some more...determines it's now the port side carbs that are cutting out at lower rpms. So, opposite carbs, opposite problem.

I'm guessing that although the carbs were sprayed with cleaner upon rebuild, there's something stuck/gunked in the port side carbs. They were not mechanically cleaned, just sprayed. Overall the carbs were very clean inside however.

Need to find a "new qualified marine mechanic". NEVER use carb spray especially under load as you are washing all lubricant away inside the motor. Checking spark and fuel while under way is a no no as well. Just spraying the carbs down is not correct either. Did he use new parts and gaskets on the carbs? Anyway, the REAL qualified guys will be along shortly to assist. They are great on these motors..

[RI_Bred]

Hi omcforever, thanks for the feedback. My guy has worked for a well-respected outfit here for several years, can't imagine he would be short-cutting me for any reason...

I can understand where you're coming from with the carb spray...although I have heard plenty of times people checking the spark and fuel while underway/under load. Spark and compression were good on the trailer in my driveway too I should mention.

Yes, all new parts and gaskets on the carb rebuilds. OEM OMC kits...

Glad to have your feedback and others!

[omcforever]

Fred and the gang will be along later,,they are top notch on diagnosing these motors. They will help yah get back under way.

[ChampioNman]

It is very simple to check fuel delivery to each side of the throttle bodies, the fuel is split at the fuel bracket and sent to both the port and starboard so it is basically "T'd" coming out of the pump, the only way you wouldn't get fuel to either side carbs would be due to, 1 a clogged hose to the throttle body or 2 clogged fuel manifolds on each throttle body. Seeing the fuel comes into the fuel bracket and is filtered prior to entry into the motor and then goes from the vapor tank to the VRO pump it is unlikely this is the case. You can verify fuel flow to the manifolds by removing the hoses from each one and squeezing the primer bulb.

[RI_Bred]

Thanks ChampioNman! I should also mention that my VRO has been disconnected for the entire time I've owned the motor (11 years) and is set up to pre-mix...

It seems strange that prior to the carb rebuild, the fuel delivery issue on the top end was with the starboard side carbs only, and now it's seemingly with the port carbs only, and on the low end. If we check the fuel delivery as you mention above, and it checks out, would you be then considering an issue within the problem port carbs themselves? We've changed nothing else but the carbs...?

Dave

[ChampioNman]

Need to check the ports on the throttle bodies and make sure they are free and clear. Fuel is delivered to both sides at the same rate. Fuel comes in tfinehe back side of the carbs by way of the throttle body.

[RI_Bred]

OK will do. Will report back, probably not til next week though...many thanks!

[316jughead]

[QUOTE=RI_Bred;9620136]Hi omcforever, thanks for the feedback. My guy has worked for a well-respected outfit here for several years, can't imagine he would be short-cutting me for any reason...

Why would you not think he would be short cutting you, he is short cutting his employer of several years.

[RI_Bred]

[QUOTE=316jughead;9620671]

Hi omcforever, thanks for the feedback. My guy has worked for a well-respected outfit here for several years, can't imagine he would be short-cutting me for any reason...

Why would you not think he would be short cutting you, he is short cutting his employer of several years.

No, there is more to the story than I have mentioned. One major thing is his employer no longer services OMC motors in-house. He's a good guy, and I'll leave it at that. Not looking for an Internet argument, thanks!

I was just in Wichita for work, I'm a Coleman lantern enthusiast and I visited the outlet/museum, and a couple of the local taps while I was there. Cool town.

[316jughead]

OK, now I see why he's working on your motor. I'm not wanting to argue either. One of the reasons that I try to help is that some folks don't have any one to work on their motors. I agree with what omcforever posted, about the carb spray, good luck.

[RI_Bred]

Appreciate it. I'm no newbie, just a bit above my pay grade on this one with diagnosis...I try to do as much DIY maintenance in life (including older outboard maintenance) as possible...I have this motor, and a much simpler 25hp 1985 Johnson on a runabout...wish they were all that easy!

The carb spray is not ideal, I agree. But I will say it was very slightly "spritzed" into the intakes, not heavily sprayed at all...so hopefully no harm no foul...we'll see I guess!

I've had this motor a long time and when it runs well it is great, but has suffered many gremlins over the years...always something...

Thanks,
Dave

[RI_Bred]

Quick couple questions: I've noticed a slight weeping of fuel out of the top of the primer solenoid at the gasket under the cover. I've ordered the rebuild kit which includes the new gasket, cover and red manual lever.

Could a leak at the primer solenoid cause my rough idle / not wanting to stay running at idle issue?

Another symptom I've noticed: when I push the key in with motor running in neutral, it "chokes" the motor (drops RPMs) as it should. When I then release the key, after a couple of seconds the RPMs pick up to about 1200, runs like that for 15 seconds or so, and then idles back down before eventually stalling out again. Any thoughts on that?

Going to do some more work on the motor after work today...thanks!

Dave

[316jughead]

OK, Check the idle orifices for the correct number of turns out.

[RI_Bred]

316 - you got it! Just got back from the boat - my guy did exactly that - idle orifices...turned out they had a case yesterday at work with the same symptoms as mine, and they cured it in that way. Couldn't run the boat tonight due to thunderstorms, but I will take it out as soon as possible. Feeling pretty good about it, sounds real smooth on the idle and into gear now. I will report back with results...thanks!

Dave

[RI_Bred]

An update, and not a positive one...

After taking the boat out the next day after the fix, and having a great run for over an hour at all speeds, she sat for about a week at the dock. Went to take her out again...she starts fine, but anything over just knocking her into gear and she dies out.

I mean I cannot move the throttle AT ALL above just knocking her into gear...both forward and reverse.

I'm baffled, since she ran so well after the initial fix.

Any ideas? I have to think it's more carb adjustment...?

Thanks!

[316jughead]

I don't quite understand what you are saying. It will start and idle? It will shift into gear and idle? It will idle but not take any throttle? It will shift into gear and die right then?

[RI_Bred]

I don't quite understand what you are saying. It will start and idle? It will shift into gear and idle? It will idle but not take any throttle? It will shift into gear and die right then?

It will idle fine and shift into gear and keep running - I can inch along in gear at a snail's pace.

If I give it any throttle at all when shifted into gear, it dies.

Again, it ran great after the carb adjustment, then this new problem occurred the next time I went to use the boat, about a week later.

Thanks,
Dave

[316jughead]

I would look at the timing and throttle linkage, is the timing advancing and the carbs opening when you give it throttle, and at the same time. Does pushing in on the key to activate the primer make any changes.

[RI_Bred]

I would look at the timing and throttle linkage, is the timing advancing and the carbs opening when you give it throttle, and at the same time. Does pushing in on the key to activate the primer make any changes.

Ok thanks for the advice...will be working on it tomorrow morning...will report back...

Dave