johnson 175 dies after engine heats up.

[1985mariner20]

Took out my new, old boat today. 1988 Johnson 175 on the back. Cruised around for an hour or so before I started having an issue. When ever i slow down to an idle then try to throttle up, the boat dies. I was able to get a higher engine rpm by using the cold start lever a little, then I was able to get cruising again. At the ramp trying to load up, same issue, whenever I tried to give it throttle to get up on the trailer, kept dying. Thinking ive gone a lean issue. Not sure though. only happens after boat has warmed up to operating temp. Any help would be much appreciated!

 

[boobie]

Re: johnson 175 dies after engine heats up.

Did you try hitting the choke when it wanted to die ??

 

[1985mariner20]

Re: johnson 175 dies after engine heats up.

I can try to "two hand" it next time and hit the choke as I throttle forward. It doesn't bog and sputter like its running out of gas, It dies like someone turned the key off. Happens quick as soon as I throttle forward when warmed up. I should have it out tomorrow morning and will play with the choke and troubleshoot a little more.

 

[boobie]

Re: johnson 175 dies after engine heats up.

Let us know what you find.

 

[1985mariner20]

Re: johnson 175 dies after engine heats up.

So I had the boat out yesterday and had the same issue. Tried choking before throttling up. sometimes I would hear the engine rev up as I choked then I could throttle up no problem. Other times, when I tried to choke before throttling up, it killed the motor right away. No consistency. I couldn't go from a stop to full throttle once warmed up, but if I played with it enough, I could cruise at around 7mph for a while then tweak the cold start lever and the choke sometimes until i heard it rev up then I could go WOT. Anyone know what the knob on top of the housing with the throttle control is for? I didn't see anything about it in the manual but I haven't read all 403 pages yet. lol

 

[1985mariner20]

Re: johnson 175 dies after engine heats up.

Had the boat out on the fourth and inadvertently fixed the problem. Before I fixed it I noticed if I throttled to right before it wanted to die then tap the choke a time or two until it reved up, then I could go it to WOT no problem. Then,, Had a prop spin off in the middle of lake livingston in 45 ft of water and had to replace the prop in the water with the first thing available at the shop. New prop was a different pitch and gave me a lot more lower end. I can jump that big center console out of the throttle and hit full speed in a couple seconds, only down side is i lost about 5-6 MPH on the top end (based off GPS reading). Boat runs great and hasn't stalled a single time since the new prop was installed. Didn't realize prop could have that much of an effect on the engine performance. Anyways. All fixed now! Any input on why it impacted performance on a lean situation so much would be great!

 

[1985mariner20]

Re: johnson 175 dies after engine heats up.

So I haven't had any issues since the 4th until labor day weekend two days ago. boat kept stalling out and wouldn't let me drive up on the trailer. We had been cruising no problem for a couple hours. no the boat is hard to start after it sits over an hour and will die when throttling up after it heats up. Any ideas what could be causing this??? Any help much appreciated!!

 

[emdsapmgr]

Re: johnson 175 dies after engine heats up.

Couple of things to look at. A low idle will affect slow speed running. A change of prop to a lower pitch may compensate somewhat for a low idle. Make sure the engine idles at 700 rpm's when the boat is floating in the lake and is in forward gear. You can't set it on the trailer. Check for spark on all 6 plugs when the engine starts to act up. Weak ignition components tend to fail once the engine heats up to "normal" operating temps. May run just fine when cold, then cause problems when run for a while...

 

[1985mariner20]

Re: johnson 175 dies after engine heats up.

Ok so after giving it a good tune up, new plugs, new filters, new fuel pumps, I have realized what's happening. It started doing it for just a minute on a cold engine after I had to prime the new fuel filters. It's cutting out as I give it more throttle bc its flooding out. Usually happens after an hour or so of running it though. On my last trip out, It stalled out when trying to load on the trailer. I was able to start it back up, play with the throttle until it was running smooth, then drive it up on the trailer.

So now to find out why it is flooding out! Thanks for everyone's help and ideas so far!

 

[emdsapmgr]

Re: johnson 175 dies after engine heats up.

Any excess fuel that leaks from the carbs will accumulate in the bottom of the airbox. There is a drain hose which will vaccum that oil/fuel back into the bottom cylinder for combustion. If more than just a little fuel/oil gets down into that tube, it will flood the bottom cyl, making the engine smoke and run poorly. Usually this lasts for 30 seconds or so till that fuel/oil is consumed by the engine. Usually this happens when first cold starting each day, or if the engine was tilted up for a while, such as when fishing with a trolling motor.