My motor will only run in low gear why?

[ryantcobb]

I have a 1973 20hp thunderbolt mercury and the motor use to run in high gear, but oneday it just run in low and stayed like this eversince<br />why is this happened, and is this cheap to fix?<br /> thanks in advance RCobb

 

[JB]

Re: My motor will only run in low gear why?

Howdy, RCobb.<br /><br />Your engine is probably running on one cylinder.<br /><br />Another possibility is that it is starving for fuel when you try to get "in high gear". We call that revving up, or wide open throttle.<br /><br />First, carefully remove the lead from one spark plug and try to start her on the other cylinder only. Then try it with the other plug wire.<br /><br />If it starts on one, but not the other, you probably have lost one cylinder. Most likely culprit is ignition.<br /><br />If she starts on both, but still wont rev up with a load (in the water and in gear) squeeze your primer bulb and see what happens. If she takes off, you have a fuel pressure problem.<br /><br />Either of these problems can be fixed without too much expense by a handy person who has and reads a Service Manual for your engine.<br /><br />You can order a Service Manual from iboats, right at the bottom of this page.<br /><br />Good luck.

 

[ryantcobb]

Re: My motor will only run in low gear why?

Thanks for your reply so soon...<br /><br /> I have heard alot of different things that could be the problem..exne guy said that it could be the rubber hub in the prop that spun out is this a possible answer ? anyway i will try these as soon as i get a lower unit for the motor. Thanks again for the reply ans i will check back for more replys and leave a answer to what was the problem......<br /> thanks again Rcobb

 

[Scoop]

Re: My motor will only run in low gear why?

Rcobb, more information will help. When you give it the gas, does the motor rev up or do the RPMs stay the same? Are there any other symptoms?

 

[rickdb1boat]

Re: My motor will only run in low gear why?

When you run the Motor, what happens when you open up the throttle all the way in Forward? Does it rev up and you don't go very fast or does it stay at the same revs? I'm not really getting the High Gear/Low Gear meaning! Do you mean High Speed/Low Speed? Try to be more specific.

 

[ryantcobb]

Re: My motor will only run in low gear why?

Mr Grandfather gave the motor last year. It hasn't been run since it went to the shop to which it was to be fixed, but instead the man took the foot off this engine, and gave my grandfather a bare foot-my grandfather doesn't know much about the engines so he took it home <br />and now here it is no drive shaft or foot. My grandfather says the motor has a high/low gear but i do think so---he said it would only go half speed(which is low gear) and it would not go no faster. But at one time it did run full speed, but not now...I hope this is enough info----- rcobb also i started it up in yard a while back and it started so it does run....