Engine Won't Run When Warm

[twoelvis]

I am new to outboards. I have a lot of mechanical experience, just not with outboards. I just bought a pontoon boat with a 2005 90hp Johnson 2 stroke outboard. The engine runs great for the first 30-60 minutes of the day. After 30-60 minutes, it will either not idle, or barely idle. When it is barely idling, it stalls if I try to open the throttle in gear. If I open the throttle in neutral, there is a 50% chance it will stall, and a 50% chance it will rev up. If I keep it revved up, it runs just fine. But, then if I close the throttle to the idle position, it wants to stall again. It got me stuck on the river yesterday. So, I splashed some gas in to the intake and started it with the throttle in the idle position. It idled on the splashed gas for long enough that I could rev it up, and get back to the dock. Any help would be appreciated...

 

[saltchuckmatt]

Sounds like you sucked up some crap in the fuel system. Any fuel filters? How old was the fuel?

 

[flyingscott]

compression and spark test need to be done.

 

[Crosbyman]

one filter on the small lift pump one filter on the inj. distribution

 

[flyingscott]

Isnt that a carb motor?

 

[twoelvis]

The model is

• J90PLSOA

It has 4 carburetors. Tank had next to nothing in it when I bought it (not enough that the ball became hard when I pumped it) I put 20 gallons in off the bat. Then took it on the water the day that I bought the boat. That was the first time that the problem occurred. I put a fuel/water separator in it the next day, and then took it out again. The same exact thing happened both times like clockwork. It ran perfect for the first 30-60 minutes, then would barely idle. The motor only has 180 hours on it. So, I dont think that it would be an internal engine issue. I have a stack of paperwork that came with the boat with meticulous service records. After it warmed up and quit running, I tried pumping the ball again, and the ball was not real hard. It took 1 or 2 pumps until the ball got hard again. But, pumping the ball also did not help the problem.

I am not sure if this is related. But, I believe the rectifier/regulator is bad. The tachometer works intermittently. I replaced the tachometer with a known good tachometer, and it does not work on this boat either.

 

[saltchuckmatt]

one filter on the small lift pump one filter on the inj. distribution

I believe this is a standard carbureted vro system....no injectors or lift pump, correct?

 

[saltchuckmatt]

The model is

• J90PLSOA

It has 4 carburetors. Tank had next to nothing in it when I bought it (not enough that the ball became hard when I pumped it) I put 20 gallons in off the bat. Then took it on the water the day that I bought the boat. That was the first time that the problem occurred. I put a fuel/water separator in it the next day, and then took it out again. The same exact thing happened both times like clockwork. It ran perfect for the first 30-60 minutes, then would barely idle. The motor only has 180 hours on it. So, I dont think that it would be an internal engine issue. I have a stack of paperwork that came with the boat with meticulous service records. After it warmed up and quit running, I tried pumping the ball again, and the ball was not real hard. It took 1 or 2 pumps until the ball got hard again. But, pumping the ball also did not help the problem.

I am not sure if this is related. But, I believe the rectifier/regulator is bad. The tachometer works intermittently. I replaced the tachometer with a known good tachometer, and it does not work on this boat either.

Your tach could be having issues because of the screwed up rectifier.....try some 50 to 1 fuel in a spray bottle and see if that keeps it going.

When you remove the plugs what story does the engine tell you?

 

[twoelvis]

I believe this is a standard carbureted vro system....no injectors or lift pump, correct?

I do not know alot about this engine. I just bought it. Outbaords in general are new to me.

 

[twoelvis]

Your tach could be having issues because of the screwed up rectifier.....try some 50 to 1 fuel in a spray bottle and see if that keeps it going.

When you remove the plugs what story does the engine tell you?

I am pretty sure that the rectifier is what is causing the tach. issue. I plugged in a replacement rectifier momentarily to see if the tach worked, and it seemed to have solved the problem with the tach. I can not say for sure, because the tach. worked intermittently with the original rectifier. I do not have the gasket yet for the rectifier yet. So, I was not able to permanantly replace it. I wrongly assumed that the new rectifier would come with a gasket. On a side note, is it OK to use silicone sealant as a gasket for the rectifier, or should I wait for the OEM gasket to be delivered? Is there any chance that the potential rectifier problem would be causing the idling problem?

 

[twoelvis]

I am pretty sure that the rectifier is what is causing the tach. issue. I plugged in a replacement rectifier momentarily to see if the tach worked, and it seemed to have solved the problem with the tach. I can not say for sure, because the tach. worked intermittently with the original rectifier. I do not have the gasket yet for the rectifier yet. So, I was not able to permanantly replace it. I wrongly assumed that the new rectifier would come with a gasket. On a side note, is it OK to use silicone sealant as a gasket for the rectifier, or should I wait for the OEM gasket to be delivered? Is there any chance that the potential rectifier problem would be causing the idling problem?

I am pretty sure that spraying gas/oil mix in the intake would keep it going. I am basing this on my experience just splashing gas in the intake to get it started.

I have to pull the plugs to see.

 

[flyingscott]

Check compression and spark when that happens

 

[Crosbyman]

I believe this is a standard carbureted vro system....no injectors or lift pump, correct?

yeb carb version in the list... helps having the mdl#

 

[twoelvis]

Check compression and spark when that happens

I shoul

Check compression and spark when that happens

Hopefully I can get the motor to act like that when running on the trailer. So far, it has only done it on the water. I really dont want to have to do a compression check on the river.

 

[saltchuckmatt]

Not aware of a rectifier gasket....if there is one it's there to keep it cooler I'm guessing. Use anything really.

Still sounds fuel related. Run motor...let it die and check the plugs.

 

[Chris1956]

My 1998 Johnny 150HPV6 (6 carbs) does that whenever you run it for a while and turn it off. It idles rough for a few minutes but will idle. I usually let it run for a few minutes at high idle and then she will clear out and run fine.

I think it is a slight overheat issue. You might check/change your thermostats and rebuild your waterpump, if it has not been done recently.

 

[racerone]

The rectifier sits on top of the block.---It is water cooled.----Therefor it has a gasket.-----Are you pushing the key in and holding it in while cranking it over for cold starts??

 

[saltchuckmatt]

Didn't see any water nipples on the rectifier....maybe I'm wrong.

 

[racerone]

You mis-understand how these motors are put together.----The rectifier mounts directly over the water jacket.----There for it uses a gasket , 0350357 is the part #.

 

[saltchuckmatt]

Or, since water doesn't go through it, the gasket insulates it from the hotter aluminum.

Two ways to look at it.