not getting up to full speed

[bigd5977]

i have a 1979 Johnson stinger 75hp outboard, it starts fine & using the 50:1 mix ration, my problem is it takes forever to warm up & get moving down the water decently. it will take off & troll with no problem, but will not go too much faster then a high troll at 3/4 throttle. it doesn't seem to have a skip to it or run rough & you can tell it wants to get moving but it seems to have a restriction in it. If i put it in Neutral & raise up & down on the throttle lever it does fine, but as soon as you put it in gear/load it sounds like it bogs down & has to work/struggle to get up to any speed & high troll is maybe 5-10 mph & that is at 3/4 & full throttle. yes I have gone thru the 3 carbs & they are all clear & clean & so is fuel filter & new plugs. Please somebody help me with this problem,, getting frustrated here

 

[fireman57]

Re: not getting up to full speed

check your spark when it does this. Sounds like a bad coil. You are running on only one or two cylinders.

 

[bigd5977]

Re: not getting up to full speed

ok,, i had to shut it off,, to take plugs out & got good blue spark on all 3 plugs

 

[fireman57]

Re: not getting up to full speed

With the engine NOT running take any covers off so you can see the carbs. Put it in gear and go to full throttle and watch the butterflies in your carbs. They should all open the same amount as you "give it gas". At wot they should be level. If they are not then you need to do a link and sync so they open at the proper time. If they are okay then you are getting too much air or not enough fuel. Is your tank vent open? Make sure that it gets air in there or you will have the same problem. You can also pump your primer bulb when it does this. If it picks up and goes then you have a weak fuel pump.

 

[bigd5977]

Re: not getting up to full speed

ok,, will take a look at this,, but just so you know, it's a plastic tank with a fill hole & the connector for the fuel linemm that's it

 

[fireman57]

Re: not getting up to full speed

I understand. Just make sure that the vent in the cap is cleared. If you have to take the vent screw out and blow through it to make sure it is venting.

 

[bigd5977]

Re: not getting up to full speed

ok,, the butterflies they are working right as far as i can see,, for the tank vent, there is NO screw, but you put the cap on till it clicks & then the top sits a little bit loose, as far as the fuel pump goes, it does pump cuz it runs but how much it pumps,, i dont know. & where can i get an AIR FILTER for it,, & it's a 1977 not 79, but the is NO TAG for Model # or Serial # on it anyplace,, but i think i might also have a small amount of water in the gas, because i did notice bubbles in the gas, & how can i regulate the amount of AIR getting in, alsdo is the primer pump supposed to be firm while its running to get top speed or not ???

 

[fireman57]

Re: not getting up to full speed

Okay, good on the butterflies. I know what you mean about the cap being loose, that is good, leave it loose for now. bubbles in the gas is probably air. Did you pump your primer bulb when it does this. You need to do this as it will override the fuel pump if it picks up and runs right when you pump it then your fuel pump is weak. Just because it pumps some doesn't mean it is enough for wot. If you are getting air in your lines it is because of a bad hose connection, cracked hose, or bad fitting. Do the primer bulb test first please so we can rule out the fuel pump. If it doesn't change then check all fuel lines for cracks and make sure that they are secured with clamps or zip tied well to the fittings. Once the engine has started your primer bulb will get softer.

 

[bigd5977]

Re: not getting up to full speed

No, the pump & boat does not go faster when you pump up the bulb & as far as fittings go ,, some do not have any clamps or ties but r tight

 

[fireman57]

Re: not getting up to full speed

Okay.Still sounds like spark. If you have a timing light take it and a buddy and check spark with it when it does this.

 

[bigd5977]

Re: not getting up to full speed

ok,, do you mean check the timing of each spark plug to the flywheel??? or just 1 plug & if it is timing,, how do you adjust timing on it?? & i also take it, i need the boat in the water to do this?? or can i use an earmuff on the prop shaft to do it on land ???

 

[CharlieB]

Re: not getting up to full speed

Is this a new problem or is this motor new to you and you have always had this problem since you got it?

Did you recently install this motor on this boat or did you but this problem from someone else?

If you have always had this problem, what boat and what PROP are you running?

 

[fireman57]

Re: not getting up to full speed

Get a timing light and a buddy. Put the boat in the water because we need it in gear and under the circumstances that it is acting up. Make sure someone knows how a timing light works. When it acts up have him check each plug wire separately for spark. You do nothing with the flywheel and you better not change any timing. We are only checking to see which if any coils are bad. If you find a plug wire or two that have no spark then that is your problem. If you find one that is not sparking change the coil with one that you know is working and see if the problem follows. That is if the cylinder that you swapped coils with that used to work doesn't now then you know the coil is bad and you can replace it. Btw the coil is what the spark plug wire runs into. These things sometimes break down under a load but work fine in neutral or no load conditions.

 

[rhaser]

Re: not getting up to full speed

I had this problem also. try taking the cowling of and running it. i had a small exhaust leak and the engine wasn't getting good air. if it runs good thats the prob. but it also does sound like coil and timming. also make sure you have the right plugs in. ive seen them run crappy without champions.

 

[fireman57]

Re: not getting up to full speed

rhaser I agree with the exhaust leak but it would run fine for a while at wot until it ran out of air. He hasn't told us that it does that

 

[mherndon]

Re: not getting up to full speed

I have had the same problem. I bought my boat used and the first day I ran it, it ran for about 3 minutes and then lost almost all power. The bow sat down in the water and we were basically trolling. I checked the primer bulb and it was flat or deflated. I disconnected the line, pumped it, and it ran great... for another 2 minutes. I got home, took the gas tank out of the boat, emptied the last of the gas, and cleaned it out real good. I hooked everything back up and put fresh gas/oil in it and it has ran fine for about 2 months. It started loosing power again yesterday but the bulb wasn't deflated. So when I get home today, I am going to clean the inline fuel filter, the screen in the gas tank, blow out the lines, and check for deterioration on all of the lines. I will probably rebuild the carb soon also.

It didn't sound to me like your bulb was deflated but it could be bad gas or trash in the lines. I also heard something about power packs... but I think that it is a whole different ball game!

 

[lmusashi]

Re: not getting up to full speed

Hey the same thing happened to me today.... the fuel line from the gas tank was reversed, I noticed the arrow was pointed towards the gas tank. When I reversed it so the arrow pointed to the motor it all worked fine.

 

[bigd5977]

Re: not getting up to full speed

it says that the timing is supposed to 16 degrees be4 top dead center, but i wont adjust that till i'm sure the timing is off. believe it or not i'm having a major problem finding a timing light, since most all vehicles anymore do not have a distributor to turn to adj. timing, a lot of places dont have them unless you special order them or unless your an OLD CAR nut,, so now i'm trying to see if any neighbors or friends have 1, that & a compression tester, as far as fuel tank lines, carbs, & hoses took all them off & blew thru them,, clean as a whistle, & NO this motor was not replaced & it ran good when i 1st got it,, just took awhile for it too warm up & get moving good, Still takes awhile to warm up but not running good unless idling or working throttle by hand while not in gear, also on this motor,, what does the Rectifier do, cuz i found a wire from it that is not broken but the red insulation has chipped off & showing bare wire,, little bit corroded but all still in tact & thinking about just repairing the wire if i can, also i found out that the Propeller measured out to 12 diameter,, somebody asked about that

 

[rhaser]

Re: not getting up to full speed

The rectifier is for charging the batt. and should not effect running. check for 12+ volts at the red wire while off then the voltage should go up when started. there is also a screen in the fuel pump did you check that? a hand nut in the middle of the circle the inlet line goes to it. note its position and put it back the same way. did you check to see if an auto parts store has one to loan? or try a local repair shop.

 

[General Lee I]

Re: not getting up to full speed

Fireman
Does he need a timing light or just a simple spark tester?