91 40 horse johnson will only idle after running out of gas

[rjrobin2002]

My brother used my boat and ran it out of gas. The boat had just had the carbs rebuilt with new plugs, and 2 new gas tanks installed and had been running great. It has a new pre-mix fuel pump and the oil injection has been removed. He put gas in it after running out and it would only idle. It has a smooth idle but will start running bad as soon as you gave it any gas. He limped back to the launch and brought it home. I launched it in my bayou and it cranked great and ran perfectfine for the 5 minutes I drove it. I went to the river last night and it cranked fine and was running great for a few miles, then started sputtering and would only idle again. Does this sound like carb to ya'll? I have a in line fuel filter that is clean and does not seem to have trash in it. I replaced both plugs and it still will only idle. I also put new fuel in the other tank and tried running off of it to see if it was bad gas.

 

[rjrobin2002]

Re: 91 40 horse johnson will only idle after running out of gas

Anything, please. Tashadaddy, save me again please, LOL.

 

[schematic]

Re: 91 40 horse johnson will only idle after running out of gas

sounds like some debris has made it through to the carbs. If firming up the primer ball has no positive affect, reclean the carbs....

 

[jtexas]

Re: 91 40 horse johnson will only idle after running out of gas

Running out of gas really does nothing to the motor except make it stop.

Does switching tanks have any effect?

sounds to me kinda like the fuel tank vent is closed (or blocked, if those are built-in tanks).

Does the fuel line hold pressure? What happens if you squeeze the primer bulb while it's acting up? What do the spark plugs look like afterward?

 

[rjrobin2002]

Re: 91 40 horse johnson will only idle after running out of gas

It runs no different when I switch tanks or if I pump the bulb while I give it the gas. The vents were open, I checked. The plugs looked good and it ran fine the next day after it initially started running bad on my brother. I would think if it was trash in the carb, that when it ran good for that 5 minutes the next day that the trash would of passed through. Both plugs are firing also.

 

[SparkieBoat]

Re: 91 40 horse johnson will only idle after running out of gas

when it is running out of gas it is running leaner (more air and less gas) this makes it run a little hotter and will eventually burn out your piston..you need to clean/rebuild your carbs and check the idle air screws if your carbs even has them. check timing and check compression and check spark with a spark gap tester. 7/16 gap..also new correct champion plugs.

 

[jtexas]

Re: 91 40 horse johnson will only idle after running out of gas

... I would think if it was trash in the carb, that when it ran good for that 5 minutes the next day that the trash would of passed through. Both plugs are firing also. ...

If any little bits of debris from the dregs of the tank that ran dry were small enough to get through your filter and, after 5 minutes of good running, get lodged in the carbs -- I bet it'd still be in there.

got compression? got spark (spark test described by sparkie)? time to rebuild the carbs.

 

[rjrobin2002]

Re: 91 40 horse johnson will only idle after running out of gas

Well I guess I will go through the carbs for the fourth time. The last time they were done by a boat shop and they stole 300 dollars from me. New plugs are in and still running bad.

 

[AlTn]

Re: 91 40 horse johnson will only idle after running out of gas

welllll...look at the proficency you're getting a carb rebuilding...might wanna make that brother help you...good luck

 

[Rudi2]

Re: 91 40 horse johnson will only idle after running out of gas

I have a in line fuel filter that is clean and does not seem to have trash in it.

I'd replace that filter before doing anything, I'm guessing the same filter was used when you switched tanks. Sure sounds like a plugged or partially blocked filter. Sometimes looks can be decieving.

 

[waynehol]

Re: 91 40 horse johnson will only idle after running out of gas

I concur. If it were me I would

1st Replace the fuel filter or cartridge

2nd rebuild/clean the carbs

Running the tank dry could have pulled up some gunk from the bottom of the tank

Good luck and report back!

 

[N Wolf]

Re: 91 40 horse johnson will only idle after running out of gas

The last post has it right. If it runs fine for a while then there is nothing wrong with your timing, carb settings or anything else. If any of these were messed up they would be messed up all the time. Timing doesnt change itself while you're running then change itself back when you stop. If you ran out of gass you sucked something up. There is almost allways some debris in the botom of the tank. And no mater how long you run it, it will never pass. Clean it out because you are running lean when it slows and you will burn it up.

 

[rjrobin2002]

Re: 91 40 horse johnson will only idle after running out of gas

I will replace the filter element and try again. I unhooked the fuel line from the engine and was able to pump the bulb and freely squirt gas through the line which made me feel that the filter was free flowing. It looked good through the clear plastic also. I will check back Monday when I can work on it.

 

[SparkieBoat]

Re: 91 40 horse johnson will only idle after running out of gas

also check your float level...