87 30hp evinrude wont run at full throttle

[wannagofishing]

hi everyone i am new to the forum and working on boat motors. i have been reading some of the post trying to figure out what is wrong with my boat, but i am still a little stumped. the motor will crank and idle just fine, when i push the choke up it revs up and runs fine at high rpms and when i put it in gear and push the throttle in runs ok up to about half throttle then it wants to spit and die. i can put my hand over the carb and block air coming into the carb and it will run fine even and full throttle but when i take my hand off it dies. i had the carb rebuilt last year but i did let the boat sit over the winter without being winterized which i know i should not have done, but i have pulled the carb off and cleaned it thoroughly and still it wanted to die at full throttle. i have read that it may be my fuel pump, if so should i rebuild it or buy a new one? and i am having a little trouble understanding what the electric fuel primer does because my boat has a primer bulb and i thought thats how the fuel system gets primed. anyway i am sorry for such a long post, and thanks in advance for any input

 

[tashasdaddy]

Re: 87 30hp evinrude wont run at full throttle

without being winterized< BAD BOY!!
Primer Solenoid
the primer replaced the old choke butterflies in the carborators, pushing in the key activates it, like the old choke plates, but injects fuel directly into the intake.
The red handle is used when your battery is dead, and you have to rope start. You move the handle 180 degrees.
Normal operating position is with the handle back over the body of the solenoid, like in the picture below.

99% chance you have clogged high speed jets, they sit in the very bottom of the float bowl. activating the primer gives it the gas it needs to take off. Cleaning, and Rebuild instructions are in the TOP SECRET FILE.

also replace all fuel line with Alcohol resistant lines. Ethanol deteriorates, the rubber lines, then they start to sluff off on the inside, going directly to the carbs. settling to the bottom of the bowl. contaminating the carbs high speed jets.

always use carb rebuild kits.

 

[wannagofishing]

Re: 87 30hp evinrude wont run at full throttle

thanks for the reply. do u think i should get a fuel pump repair kit as well as replace all the fuel lines and rebuilding the carb?

 

[Mas]

Re: 87 30hp evinrude wont run at full throttle

Try pumping the fuel line bulb when the motor is acting up. If you do not see any difference (better or worse) it likely isn't fuel pump related....save your money.

MAS

 

[Robj]

Re: 87 30hp evinrude wont run at full throttle

I would start by cleaning the carb as TD suggested. See if that solves your problem, if not then repost and go from there.

Good luck and have a great day

Rob.

 

[tashasdaddy]

Re: 87 30hp evinrude wont run at full throttle

change fuel lines then and Rebuild carbs, with a kit. as per directions.

 

[puddlesplasher]

Re: 87 30hp evinrude wont run at full throttle

Hi all,

I to have the same problem. WOT = 2500rpms thereabouts and that is with my needle starting at 1000rpms in the off position.

8 knots on a 16ft Microplus Explorer, 2 up and full fishing kit.

6 Months ago the O/B was overhauled by a Johnson dealer. Occasionally the O/B will cut out for no reason until I became aware of a change in the O/B engine noise. The engine changed from its normal pitch to something like a vibration but a squeeze of the primer bulb resolves it.

This I suppose will be an issue with the fuel pump?

But what is causing the lack of revs?

Thanks all.