1982 Johnson 70hp (J70ELCNB) stalling after acceleration... sometimes...

[cal1319]

Hey guys, just got the boat out on the water and I am having an interesting issue. I just changed all the plugs, wires and fuel lines. Boat starts right up and idles great, put the boat in gear no issues... start to give it gas all good till around 2K rpm then stalls out unless I throttle down. If I slowly increased the throttle after some time idling around the engine will take off and she runs no problem at WOT. If is slow down and start putting around at idle and accelerate again no problems. If I turn the boat off and sit for a bit I will have the same issue were I really need to slowly increase the throttle till it seems ready to go. I am thinking it may be a failing fuel pump? Anyone else have any possible ideas?

 

[racerone]

As a test have an assistant operate the manual pump.

 

[cal1319]

You mean the primer bulb? I did that it did not seem to make too much of a difference... boat still stalled on acceleration....

 

[racerone]

Then your motor fuel pump is NOT failing.------Do some more trouble shooting

 

[cal1319]

Any suggestions on were to start. Its odd to me that its intermittent. Once I can slowly get the boat up to speed it works great no issues, I can slow back down and accelerate again no problem.

 

[F_R]

Possible sticky timer base. Disconnect the throttle cable at motor, then put your fingers on the stud where the cable was attached. Slowly push it aft-ward while watching the upper end of the lever assy. It should move toward full spark advance without lagging. As it does, the carb throttles should open just a bit, until full spark advance is reached. Then, at full advance the carbs will continue to open to WOT. If they open before full spark advance, motor will stumble and maybe conk out.

 

[thatone123]

If this hepls at all, I just totally cleaned the carbs on an 82 75 hp and it still has a cough at idle. Seems the carbs are not adjustable> I noticed that the throttle assembly was sticky and put some WD-40 gel up on the throttle stator plates ( at least what is visible under the flywheel) and it helped. Seems these run up to full throttle with a lot of room left on the cam?? Don't know the story on that?

 

[cal1319]

I’ll give those a try and see what goes! I’m going to put a kit on the fuel pump even though it may not be an issue... I talked to the original owner and he never replaced it so either way it’s time!

 

[cal1319]

I was taking closer look at the engine this last week and it turned out that the cam roller follower we off a bit. It was opening the carbs before the timing advance was at full. Adjusted the follower and now she runs no issues! Thanks for the help everyone!

 

[cal1319]

So I thought I found the issue, but the last two times out I started to get the same issue. Engine starts right up. Will idle great, will go in gear forward and reverse no problem, idiling around 800rpm... can advance throttle till RPMs get to around 2500rpm then boat starts to bog down. If I keep the thortle there long enough the engine eventually will take off and then runs fine throw the RPM range (Sometime it takes a minute or two, sometimes it takes ten minutes). Last time I was out I put it in neutral and lifted the fast idle until RPMs hit 4K for a few seconds, boat ran fine after that. Any ideas on why I get this hestation at first? Its frustrating me a lot haha. Thanks for any help guys!

 

[racerone]

Report the actual compression numbers.-----And letting a motor like that run at 4000 RPM in neutral is not a good idea !!

 

[cal1319]

Report the actual compression numbers.-----And letting a motor like that run at 4000 RPM in neutral is not a good idea !!

Totally agree not a good idea! I was just trying to see if it would go to higher RPMs in neutral, which it did without a problem. Will have to wait till this weekend to get those numbers.

Another thought, I put on a Five Oceans primer bulb. Iv read numerous places that aftermarket bulbs can cause issues. When I prime the bulb it gets firmer, but never to the point to wear its compeltly firm, I checked for fuel line leaks and that is not the case (I replaced all the fuel lines). I can also hear what sounds like air getting pumped into the fuel tank when priming the bulb. Could this be a culprit to the problem? Thinking of replacing that primer bulb with OEM.

 

[racerone]

Many folks overthink the primer bulb.----Once you operate it and fill the carburetors it's job is done.----Once motor is running it does not need to be hard.-----Perhaps check the fuel pump diaphragm for a pin hole.

 

[cal1319]

Many folks overthink the primer bulb.----Once you operate it and fill the carburetors it's job is done.----Once motor is running it does not need to be hard.-----Perhaps check the fuel pump diaphragm for a pin hole.

Yes, I know the bulb wont stay hard once the engine is running. Im not very experienced with outboards, so I dont know how firm the bulb is suppose to get. I do feel it getting harder but I can always squeeze it even once its hard.

 

[dfrants]

Make sure you don't have the primer bulb on backwards. ...I've seen people do that before.

 

[cal1319]

Make sure you don't have the primer bulb on backwards. ...I've seen people do that before.

I did check to make sure the arrow is pointed in the right direction...

 

[cal1319]

Going to try a carb kit. Thinking I may have a stuck float that is causing the engine to flood out. The RPMs rise until timer base is at full advance... as soon as the carbs start to open the engine bogs down and dies. While in gear if it push the key in for the primer it will kill the engine as well (not sure if that will happen with a normal running engine). Hope the carb kit fixes the issue!

 

[racerone]

You would need 3 carburetor kits for that motor.

 

[cal1319]

You would need 3 carburetor kits for that motor.

Thanks Racerone,
Yes, I know I need a kit per carb

Hope it helps fix this issue, its been frustrating!

 

[cal1319]

Long overdo update (kinda). Finally getting around to doing all three carburetor cleaning and install new kits. Ill update if it fixes the issue!