johnson 150 hp dies in idle

[crawfordml05]

I have a 1990 johnson gt a50 hp v-6. when ever i start the engine, i have to emediately put the lever in neutral and throttle it up, and then when i am ready to take off i have to center the throttle control and emediatly put it in gear. otherwise the engine will die. Sometimes this takes a couple of tries before i get it. once i have it going, it will run fine until i shut the engine down. i can run the boat all i want, and then when i come back to the no wake zone, i can give as little or as much gas as i want and it will run fine, until i shut it off and try to start it again. my brother-in-law has been working on it. he said that the timing during idle was off. it is at 6 btc when it should be at 28 btc. Would this kill the engine like it is. Also i have new gas, gas filter is fine. new spark plugs, rebuilt carbs and vro pump.any suggestions or should i just take it to a pro to fix it.

 

[tashasdaddy]

Re: johnson 150 hp dies in idle

low speed timing will take care of itself with this procedure. http://forums.iboats.com/showthread.php?t=228183.

i would say that you really need a link n sinc. your idle speed is too low.

 

[emdsapmgr]

Re: johnson 150 hp dies in idle

The 28 degree timing is for max spark advance-for max throttle-set at 5000 rpm. The idle timing can be initially set around the 5-6 degree mark. Both are normal specs for that engine. The final engine idle will be set by changing the idle timing. Don't worry about whether it is 5 or 6 degrees, concentrate on getting the idle at the proper rpm. That engine should idle at 650-750 rpm-set when in gear while the boat is floating at normal level in the water.

 

[crawfordml05]

Re: johnson 150 hp dies in idle

well i will see what we can do. it may be a week or two before i can. but if i have any more troubles. ill post it. at least it ran great for me today when i had to outrun a severe thunderstor. that was fun. thanks, Crawford

 

[crawfordml05]

Re: johnson 150 hp dies in idle

well i took it back out tonight and the tachonmeter was showing 850 rpm at idol. and is still killing out occasionaly, any suggestions?

 

[115johnson78]

Re: johnson 150 hp dies in idle

you might want to check the plugs if it has been awhile since they have been changed. Just for good measure do a compression check.

 

[jonesg]

Re: johnson 150 hp dies in idle

First place poor compression shows up is in the idle,
so...ditto on the compression check.

 

[emdsapmgr]

Re: johnson 150 hp dies in idle

Your engine should idle fine the way you currently have it set. Possible you have a carb issue. Mine would idle fine for 3-4 minutes, then just shut off. It is not unusual for dried fuel to clog one or more of the 6 carb idle circuits on this engine. Once that happens it is difficult to keep it running at idle. Pull the carbs apart, including removing all the jets in the carb bodies. Spray an aerosol carb cleaner through all the passages, esp the idle circuits. Reassemble.

 

[crawfordml05]

Re: johnson 150 hp dies in idle

all right, well we did rebuild the carbs all ready, i do not know about the jets. and i do have new spark plugs

 

[115johnson78]

Re: johnson 150 hp dies in idle

I have had two boat motors that wouldnt idle would stall out and have little or no power.both had 1 or 2 cyl. low in compression. so the first thing i would do is compression check. it will save time and money.