1983 15 hp chrysler slows down at full speed?

[rlw6774]

This is my first boat motor so ya'll bare with me, I'm learnin slowly but surely! I recently bought a 1983 15 hp Chrysler or montgomery ward made by Chrysler. I learned from a reply to a recent post of mine from the other day how to fix & adjust the float in the carb, which was most appreciated cause I don't really have the funds to take it to a mechanic... anyhow here is my problem now, took the boat out today to do a little fishing. Which was an awesome feeling i'm here to tell ya! lol I've lived near & around water all my life & at 46 I've finally got me a boat with a motor! no more paddling "I hope" lol anyhow, got to the creek motor started fine, runs & idles great but when I try to get up to max speed it slows down? when u first take off it sounds good but then at full throttle slows down? I said that twice I think my fishing bud that went with me also has a 15 hp Chrysler & he swears by his so i'm kinda hoping to get mine to where I can swear by it too! my friend says it may be the plugs? he said something about one plug is set different from the other? one is set for low end & one for high? is this correct? & if so does anyone here know what the gap setting is for each & which one goes where? and if that could be the problem? also, what is the adjustment screw on the carb for? & how do I set it? screw it all the way in & then how many turns out? I'm really hopeful that it could be just the plugs & carb adjustment. Please if ya'll could help me with some info i'd really appreciate it! My wife loves to fish too & shes been fighting brain cancer since 2004 & i'm hoping to get her out & in the water asap so she can enjoy life a little better, kinda rough right now for her being on chemo, but if I could get this motor to be a little more dependable
I can get her out & boost her morale maybe? Any input would help! Thanks, Rob

 

[foodfisher]

Re: 1983 15 hp chrysler slows down at full speed?

The engine dogs down or the engine revs. and the speed across the water slows?

 

[rlw6774]

Re: 1983 15 hp chrysler slows down at full speed?

yes & yes taking off it sounds good but then at full throttle it bogs down & speed slows, & it acts like it trys to rev up but bogs back down. up/down, up/down at full throttle. I can slow down at idle speed & hit it, starting out, it sounds really good but then the same thing every time ? Rob

 

[Jtom7]

Re: 1983 15 hp chrysler slows down at full speed?

I'm no guru at this but I had a similar situation a couple years back. Have u checked your fuel filters to be sure there's nothing clogging them? Mine ran fine at idle speeds and slow speeds but when I accelerated it bogged down and even died cuz it was starving for fuel. I had to out a couple of in line fuel filters and replace them due to sediment in the gas tank. Also, the fuel line/stem that drops into the fuel tank (forgive me idk the name for it) has a screen at the end of it and was plugged up a bit from crap in the tank. Idk if this helps but I'd check to be sure it isn't something as simple as engine starving for fuel before jumping to carb adjustments. Fuel flow is so much greater at wot or even acceleration that it really can big u down tremendously if anything blocks its flow. Good luck and let me know if that helps at all??

 

[foodfisher]

Re: 1983 15 hp chrysler slows down at full speed?

Yes, sounds like fuel starvation. If the bulb collapses check the pickup tube and vent line for blockages.

 

[rlw6774]

Re: 1983 15 hp chrysler slows down at full speed?

Well, I got the old motor running good today! Checked the fuel pump filter & it was full of trash, gas tank & hose was fine "new". It did start out the same way as before but the hose bulb was losing prime so I pumped the bulb while I was giving it more throttle & that helped a little, made a small adjustment on the carb & it cleared right up! Runnin good & fast! Now the only thing I can see that worries me just a little is oily looking water coming out of the top pee hole on the lower unit, & it only comes out when the motor isn't running? any ideas? Thanks for all the help everybody hopefully it'll be dependable for a while! Rob

 

[Jtom7]

Re: 1983 15 hp chrysler slows down at full speed?

Glad to hear it was something simple and that I actually helped give some decent advice on here. As far as this oily water out of a "pee hole" well I guess one of the more seasoned people will have to weigh in or perhaps u could be more descriptive of what it is or maybe a picture of where this "pee hole" is located so I have a better understanding.
Good luck and I hope u stay running strong on the water.

 

[Jtom7]

Re: 1983 15 hp chrysler slows down at full speed?

Maybe u need to check your lower end gear oil to be certain u have no water in it? It's possible water is getting in the lower end and that's why u see it after being in the water?? There are YouTube videos on checking and changing lower end oil and it describes what to look for. If u see any whitish looking or milky oil then u have water in lower end. Did u happen to change the lower end gear oil when u first got this motor? If not u should.

 

[rlw6774]

Re: 1983 15 hp chrysler slows down at full speed?

Yep already did the gear oil change, didn't see any water in it. Only thing was it was the same color as the oil I mixed in the gas? Don't know if gear oil is supposed to be that color? What I put in was totally different. I put in Penz 80-90w marine gear oil & thank god for youtube I'll get a pic of the lower unit up here this evening so ya'll can see what i'm talking about! Hope everybody has a good Memorial Day! Rob