Motor has no top end....

[suzuki40]

Went out and ran my recently purchased 50 h.p. Mariner outboard model# 6139149 I soaked and cleaned the carbs, did not replace the plugs, but I did clean them, they are very differant looking they dont have a ground electrode? anyway I used decarb and let set over night. timing is right on. starts right away and idols great. choke works fine. will not handle a hard start. will run good up untill half throttle with easy throttle progression. after that it misses badly, no backfire but seems to want to go.<br /><br />sorry so long,<br />thanks,<br />Suzuki40

 

[mellowyellow]

Re: Motor has no top end....

have you tried to squeeze the primer bulb when<br />it happens? does it stay firm or go soft on you?<br />(fuel starvation)<br />good luck,<br />M.Y.

 

[suzuki40]

Re: Motor has no top end....

Primer Bulb stays firm...<br /><br />Suzuki40

 

[suzuki40]

Re: Motor has no top end....

^

 

[suzuki40]

Re: Motor has no top end....

^

 

[mellowyellow]

Re: Motor has no top end....

perhaps flooding? stuck float? see any gas coming<br />out of carbs???<br />bad/torn pump diaphram? cracked fuel hose etc.<br />sucking air instead of gas when u punch it...

 

[gomalley51]

Re: Motor has no top end....

I am by no means an expert but I had a similar problem with a 2001 50hp Merc. I have since purchased a new boat but I asked my new dealer about the issue (my engine would sometimes but not all the time run roughly and lose power in the higher rpm range but never stalled). He said that certain newer Mercurys have a fuel pump that is a bit too strong and it puts too much pressure on the fuel line coming from the tank. He told me to knock the fuel bulb on a hard surface a few times to knock open a valve in the bulb that may have partially shut due to some back pressure. I have not had this problem with my new engine.

 

[suzuki40]

Re: Motor has no top end....

Thanks for all the imput...I'll give those suggestions a try. I'll let you know what I find out.<br /><br />Thanks again,<br />Suzuki40

 

[foxjohnc03]

Re: Motor has no top end....

I would check timing. Sounds like it might not be advancing correctly.

 

[suzuki40]

Re: Motor has no top end....

Ok, I took the carbs off today opened them up and cleaned them again just in case. everything is set. checked timing, installed new plugs,new fuel lines from tank to pump and new bulb.new fuel pump.Im at my wits end. I put it in the lake and she fired right up, idles well. ease on the throttle and she pulles on out up to about half throttle. after that she starts surging, missing, but wanting to go....You can go wot and she will stay running, just dose what I just explained above?<br /><br />Any other ideas?<br /><br />Suzuki40

 

[speedwrench]

Re: Motor has no top end....

Reeds??????? Broken reed(s) will cause this!!

 

[suzuki40]

Re: Motor has no top end....

Speedwrench, thanks I never thought about that....I'll check it out.<br /><br />Thanks,<br />Suzuki40

 

[suzuki40]

Re: Motor has no top end....

Ok, last night I took the boat out, it started fine and pulled out ok while idling out of the marina. went to wot and the same thing happend. missing and surging. wanting to go. So I had a buddy of mine pump the bulb. as soon as he did, the motor took off! ran like a champ as long as he was pumping the bulb. as soon as he quit...so did the motor? what do ya think of that one? (fuel pump)?<br /><br />Suzuki40

 

[suzuki40]

Re: Motor has no top end....

^

 

[Bear]

Re: Motor has no top end....

mellowyellow said:<br />"perhaps flooding? stuck float? see any gas coming<br />out of carbs???<br /> bad/torn pump diaphram? cracked fuel hose etc.<br />sucking air instead of gas when u punch it..."<br /><br />Yes. Get a fuel pump kit for it. You probably have a small hole in the diaphragm. What year is that Suzuki40? 1982 Mariner?

 

[mellowyellow]

Re: Motor has no top end....

nothing worse than a hole in the diaphram! <br />ain't good on outboards either...concur with the<br />swedish Admiral, fuel delivery problem.<br />good luck,<br />M.Y.

 

[Bear]

Re: Motor has no top end....

 

[suzuki40]

Re: Motor has no top end....

Ok, Last time and I quit.<br />Tonight I changed all the fuel lines from the gas tank to both carbs. I installed new clamps on all connections. I got ride of all zip tie clamps and installed new screw type clamps.(the ones you tighten with a screwdriver.) new fuel filter, The only Part I couldnt replace because part store was closed, was the connector that fits to the tank. it used to snap on when you pushed it on but it dont snap when pushed on anymore if that makes sense? I pump the bulb up before I take off(the bulb is new too)Sorry I forgot, New fuel pump diaphrams installed tonight too. it starts fine and runs fine at half throttle bulb stays firm. When I hammer down it takes off like a scalded dog for about 10 seconds then it falls on its face,(but dosent die, just surges)The bulb looses pump. squeeze the bulb couple of times and your off to the races again for anther 10 seconds? I dont know what else to check? Like I said before the only thing left that I know to do is change the connector to the tank? am I forgetting anything else? Im sorry to take up so much space but I have to let you know everthing I have done.I used two differant tanks tonight too to rule out a bad one.<br /><br />Thanks for any more imput,<br /><br />Suzuki40

 

[The Marine Doctor]

Re: Motor has no top end....

Did you change the check valves in the fuel pump...and if you did...did you reinstall the new ones correctly?<br /><br />Here is the fix if you cannot get the Fuel pump to work...ELECTRIC FUEL PUMP...its possible that you are not creating adequate crankcase pressure to operate the fuel pump.<br /><br />TMD

 

[Bear]

Re: Motor has no top end....

"the connector that fits to the tank. it used to snap on when you pushed it on but it dont snap when pushed on anymore"<br /><br />I think you got an air leak there. At higher revs the fuel pump suck air. <br /><br />You are almost there