Weird Prob - Motor stalls when accelerating in gear.. help!

[Mnemonic]

Just launched the boat for my first time owning it today, its a 1977 Johnson 70, When i had it on the trailor it would rev just fine in neutral, when i got it in the water today, anything above 5mph would stall the motor, and twice, i just punched the throttle and it jumped and held a fast speed... <br /><br />Why would it stall like this only in gear? I replaced the spark plugs and all that jazz, so I dont know whats going on.

 

[BoatBuoy]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

I'd guess there's trash/water in the carbs. Disassemble them, clean them, and install carb kits. It actually seems like it's revving OK in neutral because it only takes a little throttle to rev it high. When under power, it takes a lot more and any trash in the carbs (float bowl) may be interferring.

 

[DHPMARINE]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

Also do a spark and compression test.These basics will indicate how well the motor can run once the carbs and a tuneup are done.Also look into sync & linc if the testing is ok.<br /><br />DHP

 

[Mnemonic]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

Just went to my local OMC Dealer & got the carb rebuild kits.. gonna go down to the marina and pull the carbs now, hopefully I'll have enough light to take it for a test run after i rebult today.

 

[Mnemonic]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

Hey, Just rebuilt the carbs, could this cause it? <br /><br />The little pin on carb 1 and 2 wasnt moving with the float... they were stuck pretty good in there, replaced them and they move fine now.

 

[Barnacle_Bill]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

If you are talking about the needle was stuck in the seat, yes, that was most likely your problem.

 

[Mnemonic]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

I removed the carbs, found the needles stuck in the seats, rebuilt them, and now they are back on - i also added a new water/fuel seperator.<br /><br />Now it runs WORSE.... in neutral, i can rev all i want. the second i put it in gear now even at idle it stalls... Im at my wits end.<br /><br />I took a video of what is happening. Click here to view it.

 

[cvx35]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

In the front of your carbs on the bowl, there's a bolt with a 7/16 head. Behind that is a highspeed orifice. Did you take those out and clean them?<br /> Other than that, make sure your timing is advancing to the stop when you advance the throttle. Sometimes the timerbase will stick. You'd need to remove the flywheel and timer base. Clean the plasting bearing and and lubricate it with moly lube.

 

[Mnemonic]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

cvx35 - I did take compressed air and blow those out when i had the bowls off, but didnt remove the highspeed oriface. <br /><br />I am not THAT good mechanically, I dont know how to check the timing...

 

[Walker]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

Did you use any carb cleaner to get the gum out?? Compressed air alone is not adequate. Those carbs need to be sparkling clean through and through.

 

[Mnemonic]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

Walker - To my suprise when i opened it up they were sparkling clean, But yes, I did scrub the inside with carb cleaner and a toothbrush...<br /><br />Anything else i can try without pulling the carbs off again? That was a real pain

 

[Walker]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

Every passageway and orifice must be open and sparkling clean too.

 

[Mnemonic]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

OK, So i'll take em off again... So the points I want to attack with carb cleaner is the highspeed oriface in the bottom part of the bowl on the inside, what about that screw on the top of the carb that has another screw inside of it, is that called the idle screw?

 

[Walker]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

You want to remove all screws, plugs, and jets. Clean even the tiniest passageways and make sure air will blow through them. I can't remember for sure, but I think the starting point for your mixture screws is 5/8 of a turn off the seat, for when you put the carbs back together. You might want to double check that though.

 

[Mnemonic]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

I am used to working on mercury motors, where are the mixture screws? On Merc's there were mixture screws with springs on em, but on these johnson carbs I cant seem to find it, even in the diagram pm ishopmarine.com

 

[voodoo]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

have you timed it? Done link?

 

[voodoo]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

It is not running on all cylinders. <br />New plugs yet?

 

[Mnemonic]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

voodoo - How can you tell its not running on all cylinders? - Yes i have replaced the plugs - first thing i did acctually.

 

[Solittle]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

When you get it running pull one plug wire at a time - use rubber gloves as it will bite you. If the engine slows down that indicates that the cylinder is firing. Reconnect & go to the next.

 

[fireman57]

Re: Weird Prob - Motor stalls when accelerating in gear.. help!

Mnemonic, if you replaced the sticking needle valves then maybe your float got out of adjustment. If I remember right it should be set so it is level with the carb when turned upside down. I don't have a manual for your engine (but you should) so I don't know if you have fixed jets or not. Some did not have an adjustment for the high speed. Check for leaks in your gaskets or fittings by getting it running and spray some WD40 around the gaskets. If it picks up you have an air leak. Pull the plugs and tell us what they look like and maybe we can get a clue from there.<br />Did you replace the seats in the carb too? It's not always the needle valve that gets worn.