75 now dies when throttled up.

[jwr_20]

OK, so I have decided to start a new thread to make things easier for folks. In my last thread I had the problem of not being able to start the engine unless I sprayed gas into the carb throats. Thank to the folks who helped me out on this board, I managed to get it to start normally. I readjusted the idle mixture screw, and that seems to have fixed it. I ran the motor later that day and it worked great. After leaving it for 2 days, I started it up again with muffs, and it idled just fine, so I decide to take it out for a run on the water. At the water, it started up ok, idled nice, and went into gear smoothly, but it was a bit hesitant while in the slow speed range, but it seemed ok. The problem came when I tried to open it up, then it just dies, as if it wasn't getting any gas. It started back up ok, and idled again like it should, and when I tried to open it up, it died again. I know this probably has to do with my carbs, because it throttled properly before I made the carb adjustments. I have never seemed to have very good luck with carburetors on any machine anyway! What I would like to know is what is happening with my carbs, are they not getting enough gas. Should I try to readjust my idle mix screw again, or is it something to do with the highspeed adjustment? I am trying to explore as many options as I can without having to actually rebuild the carbs, although that may be the case as the motor was sitting in my friend's shed for the last 5 years before I got it. My Seloc manual has the info for carb adjustments, but it doesn't really help me in troubleshooting. <br /><br />Any ideas are greatly appreciated.<br />Thanks

 

[shipoffools]

Re: 75 now dies when throttled up.

If you haven't already replace the fuel pump diaphrams (<$15 and about 15 mins) Had similar symptoms with my 70 and that fixed things right up

 

[jwr_20]

Re: 75 now dies when throttled up.

I already rebuilt the fuel pump. In case anyone is wondering, this is the subject line of my last thread, there may be additional info there too. Look for "Problem starting 75HP", dated Nov 3. <br /><br />Thanks for the reply.

 

[Al Kungel]

Re: 75 now dies when throttled up.

I also had the same problems with my 15hp Evinrude. I replaced the fuel pump diaphram and that fixed it.

 

[jimalsk]

Re: 75 now dies when throttled up.

It now starts up fine. After you made the adjustments did you take the boat out and did it go to full throttle then that day? Then you say it sat for two days started fine and then it would not go to full throttle. How many turns out are the idle/mix. screws? Did you mess with any of the stops on the port side of the engine ie: idle stop,full throttle stop,any of those?

 

[jwr_20]

Re: 75 now dies when throttled up.

The day I made the adjustments, I took it out and I could open it up and it would accelerate fine, and plane out ok. I took it out and let it sit for a day or so, then took it back out. After I got it started, it idles fine, and i can adjust the idle speed with the warmup lever ok. The screws are aprox 1 1/2 turns out, and I didn't adjust the stop screws.<br /><br />Since posting the first message in this thread, I took it out and tried again. I was still having the same problems as earlier, but I did manage to get it to open up. After shifting into gear, it will run pretty good at idle speed, but I have to very easily throttle it up. Once I get to a certain point on the throttle, it dies. I tried again, and I very easily kept giving it a bit more throttle, and I could tell when it finally hit the high speed range, then I could drive it like normal, even stop and go into reverse, and back into forward. <br /><br />That's pretty much all I can think of to tell you right now.<br /><br />Thanks again for the help!

 

[jimalsk]

Re: 75 now dies when throttled up.

Open the screws another 1/4 turn. After sitting for five years did you clean the carbs at all or put any additives in the fuel tank? Just a thought is the vent on the fuel tank is open and venting.

 

[jwr_20]

Re: 75 now dies when throttled up.

Hello again alaska.<br /><br />I'll try opening the screws another 1/4. The only thing I did after it had been sitting for 5 years was to change the spark plugs and flush out the fuel tank and lines, aside from the recent fuel pump overhaul. I did check the vent on the fuel tank, and checked my fuel line for kinks. When I was adjustng the screws, it was hard to detect any change in the rpm with small adjustments, only after turning the screws either one or more turns did it seem to have any effect.<br /><br />Thanks

 

[jimalsk]

Re: 75 now dies when throttled up.

It doesn't make sense that it would run one day take two days off and it poops the bed. I beleave you mentioned you were going to rebuild the carbs this winter. That may be the ticket. If you can disassemble each one and soak them in a good carb degunker. It's a good chance some thing floating around in the carb bowls for five years finally tried to make an exit and has clogged a port. The screw adjustment you mention makes sense,but run one day and not the other doesn't. Keep me posted

 

[jwr_20]

Re: 75 now dies when throttled up.

Yeah, I think that'll be my next step, is to rebuild. I am curious to see how the idle mix needle looks, whether the guy who owned it before me maybe over tightened it or whatever. I still have a tank and a half of gas left to burn so I'll give it another shot at getting it running, and once the gas is done, then I will put it away until spring. Besides, its getting too cold to play in the boat now!<br /><br />I'll be sure to post any updates I have should I figure it out.<br /><br />Thanks again for all your help!