9.9 evinrude runs but will not hit high rpm

[greg1973]

i have a 1976 9.9 evinrude. it ran great last year this year i took it out it was hard to start and wood not stay running at idle unless i used the choke on it and when i put it in gear it ran like it was not getting gas till i gave it full throttle it wood run at half the rpm then it wood act like it wood jump up for a split sec and then cut out like it was running on 1 piston or starving for gas so this is the stuff i did so far on it.
i check both pisttions they are 120 and 119 the plugs are sparking 1 plug look nice and clean other looked black put 2 new plugs in it and same thing. so i had carb rebuilt no chang only thing i did not do is rebuild the fuel pump but this is why i did not do this it is getting gas or it wood not run but if the pump is week will it still run i do not know this this is what i am asking wood the fuel pump do this or is there some thing i am missing that wood make my moter do this and it is only running like this under load out of water it runs fine high rpm but in water under load will not hit the rpm runs half at best

 

[Daviet]

Re: 9.9 evinrude runs but will not hit high rpm

Compression, fuel and timed spark is all it takes to make youe engine run. Sounds like the compression is ok. You should check the spark with a air gap tester to properly check spark. Usually if you have to use the choke to keep the engine running, you have a fuel delivery problem. Check the fuel pump and see if it is pumping fuel to the carb. If so I think you have carb problems.

 

[greg1973]

Re: 9.9 evinrude runs but will not hit high rpm

carb rebuilt spark is great new coils on it as of last year but wood a fuel pump make it seem like it has no power if so i will get new fuel pump to see if it works i just am getting mad do to i replace every thing and not a thing helped so i am trying to make shore i get the right thing this time but on the other hand it has all new parts or rebuilt parts on it but it is 35 years old

 

[Daviet]

Re: 9.9 evinrude runs but will not hit high rpm

You can bypass the fuel pump by pumping the primer bulb when the engine is running, it should stay firm.
When you overhauled the carb, did you remove the core plug on top of the carb and clean the passages underneith? Did you remove the orifice plug and make sure it was clean?

 

[OptsyEagle]

Re: 9.9 evinrude runs but will not hit high rpm

I don't think the fuel pump would cause your symtoms. I am a little confused. You first said that it was hard to start and you needed to use the choke a lot and at the end you said "it is only running like this under load, out of water it runs fine high rpm". When it runs fine out of water (I assume in a bucket or on muffs) is it hard to start?

I will tell you about my 1975 9.9Hp which is pretty much the same design as yours. When I pull the choke, position the throttle and pull the starter rope it fires in 1 or 2 pulls. If I do not push in the choke back in soon, it will stall. Immediately after I do, I many times (usually colder weather) have to pull the choke back out a bit and a few seconds later I push it all the way back in, etc. After 45 seconds of this it will pretty much run fine all day without the need of any choke. I have been doing this for years and consider it almost normal, or not necessarily abnormal.

My next comment are on the spark plugs. The latest OMC specification was for Champion UL81C spark plugs. When I put those plugs in, my motor would start pretty well (like above when very cold) and idle fine. When I put it in gear and hit the throttle, it would surge and bog down and surge and bog down. Obviously a cylinder was cutting in and out. Let's just say I tried many things to address this problem and then one day by fluke I put in the NGK equivalent spark plugs (B7HS) and the problem went away. This made no sense to me so I put the Champion plugs back in and my problem came right back. Since it still didn't make any sense I then put brand new Champion UL81C plugs in it and had the same problem.

Needless to say, I now use NGK B7HS spark plugs and have just written off trying to figure out why. I do use Champion plugs in other motors without any problem, but if you search this site you will come across quite a few others who recommend the NGK plugs in the 1974-1976 9.9/15Hp motors. If you do a lot of trolling the B6HS might be a better suggestion.

 

[greg1973]

Re: 9.9 evinrude runs but will not hit high rpm

thanks for the help
ok i will try to clear up what it is doing
i took it out on a fishing trip i had a hard time starting it and keep it running i had to use the choke on it to keep it running if not it wood shut down i put it in gear gave it full gas and it wood not build up speed and wood not rev up and as soon as i left of the gas it wood shut down and i wood half to choke it to get it started and hold the choke to keep it running till i put it in gear to give it full gas but it never build up rpm it wood jump up like it was trying but it was for a split sec and drop back down .

so i got it home got it to the shop they rebuilt the carb and told me that was the problem this wood fix it.
i took it out on the water same thing hard to start had to use choke no rpm build up.

now when it is out of the water in a bucket for test run when i get it started it will rev way up high rpm but this is not under a load it is just a bucket of water so it don't over heat but when it is in the water under load it will not hit the rpm for it this is why i am asking this
to learn this stuff to fix it with out getting riped of from a shop fixing it

so i got 2 new coils for it new plugs i got ngkb6hs plugs had the cham plugs in it but got rid of them i took it back out same thing happen hard to start no rpm.

so now it only lets the fuel pump it is the 2in 2 block pump i was told this pump leaks inside and it wood leak fuel but i do not see fuel leaking from it and i don't trust the shop i took it to the fixed some thing that was not wrong with it and are telling me it is this and this and this so i am doing it myself now and i know how to work on car engine's so this can not be to hard to do i just got to learn it

i test the pisttions that was good spark is good carb is good lower unit is good and free

so i wood like and pointers on what you think may be wrong and i will check and see if that is it if it is the fuel pump i will get 1 for it i can not find a rebuild kit for it so i got to get a new unit if it some thing else you can think of let me know thanks for all your help

 

[OptsyEagle]

Re: 9.9 evinrude runs but will not hit high rpm

When you say that the spark is good. Is that testing it with an external tester and getting it to jump at least a 3/8" gap on both cylinders? Holding it against the block and seeing a spark on the plug gap is not sufficient.

It sounds like it could be an intermittent cylinder. With one cylinder running they can usually start OK but if the good one is week to begin with you may need more throttle and more choke and it would definitely prevent you from gaining top RPM. If it cut in you would get a surge and it would bog down as soon as it cut back out.

Other then that, I would say that the carb was not cleaned well enough. Let me know about the spark.

 

[greg1973]

Re: 9.9 evinrude runs but will not hit high rpm

i have spark coming from the plugs and jumping to the block of the plugs i wood say it was good and stong it was a bright spark but when i pulled the plugs out 1 plug seem to be clean like no gas getting to it and other plug was nice and damp with gas in it this makes me think the carb was not rebuilt right at the shop or the fuel pump is not giving it the gas it need i think i will get a new pump and see if that will do it if not i will be taking it back to the shop to have them fix the carb right that they rebuilt

 

[jbjennings]

Re: 9.9 evinrude runs but will not hit high rpm

It's been suggested you test the spark with a tester to see if it will jump at LEAST a 1/4" air gap with a hot blue spark. If it won't, then you won't get spark under compression. The reason one plug is nice and damp with gas is because it's not firing.
Then again, I could be wrong......
BUt, I'll 3rd the suggestion, and hope you post back what the problem was. I have noticed that these motors foul plugs a lot, so it could be that simple. But I still think the problem is spark and not fuel related.
JBJ

 

[Rayzor]

Re: 9.9 evinrude runs but will not hit high rpm

Is the gas your using fresh?

 

[Midnight Krawler]

Re: 9.9 evinrude runs but will not hit high rpm

The 1976 Johnson/Evinrude has point drive ignition. Have you check or replaced them?

 

[OptsyEagle]

Re: 9.9 evinrude runs but will not hit high rpm

i have spark coming from the plugs and jumping to the block of the plugs

Greg. Unfortuneately, that test does not confirm sufficient spark. A week ignition can spark in regular air, but it needs a much stronger charge to spark in a compression environment like inside your motor. Your symtoms relate to a spark problem so I would either get a proper spark tester or make one. In air it should be able to jump a 1/4" minimum gap and I like to see 3/8" gaps being jumped.

 

[Suzi55Jet]

Re: 9.9 evinrude runs but will not hit high rpm

A shot in the dark. Do a compression test, if for no other reason than ruling it out. Or did I miss that above somewhere?

Sputtering? half power, won't run at load, only runs fully choked, just rebuilt a carb?

This happened to me when I had a carb set too lean. It burned a hole in the piston and had the exact symptoms.

One day it ran great, I limped back to the ramp the next day.

 

[jmendoza]

Re: 9.9 evinrude runs but will not hit high rpm

Assuming you have spark, If it's not a dirty set of points, or a bad condensor, or the timing is way off (adjust points) then maybe it's over cooling and not warming up...possibly a stuck open thermostat. A chunk or the water pump impeller could get in there and do that.

 

[greg1973]

Re: 9.9 evinrude runs but will not hit high rpm

points are set at .20 carb rebuilt has 1/2 jump from plug to block fuel pump is new i am at a lost with it so i took it to a new shop to see what they had to say and he told me the high rpm point is not firing there is a low and a high in the points and the high is week is what he told me the problem was i never hard of this but i am getting new points for it now to put in will let you know if this works every thing else is new on it
thanks for all the help on this matter will keep you all updated on this

 

[OptsyEagle]

Re: 9.9 evinrude runs but will not hit high rpm

Anyone else heard of points not firing on high RPM but working on low RPM? This sounds new to me, but I am currently (on another thread) having some problems with a mid-range miss after I changed and gapped my points on a '75 9.9Hp Evinrude.

In any event, since I was leaning towards a spark issue on your motor and most likely caused by dirty or worn points, this may very well fix your problem. Please let us know how it all works out.

 

[jbjennings]

Re: 9.9 evinrude runs but will not hit high rpm

points are set at .20 carb rebuilt has 1/2 jump from plug to block fuel pump is new i am at a lost with it so i took it to a new shop to see what they had to say and he told me the high rpm point is not firing there is a low and a high in the points and the high is week is what he told me the problem was i never hard of this but i am getting new points for it now to put in will let you know if this works every thing else is new on it
thanks for all the help on this matter will keep you all updated on this

Huh???? SOunds like total nonsense on behalf of your mechanic about points for high and low speeds. Anyway, like you I'm super interested to see how it turns out!!
Later,
JBJ

 

[OptsyEagle]

Re: 9.9 evinrude runs but will not hit high rpm

In any event, since I was leaning towards a spark issue on your motor and most likely caused by dirty or worn points, this may very well fix your problem. Please let us know how it all works out.

and just so you understand my thoughts on your motor. The point problem I suspected had nothing to do with RPM. I suspected that one of your points were working fine and the other was either dirty or worn, making that cylinder not work and and this would eliminate your ability to achieve high RPMs and be a little harder to start.

If there is a low RPM vs high RPM (and in my case mid-RPM) level for points, I would love to hear it. Good luck to you.

 

[Daviet]

Re: 9.9 evinrude runs but will not hit high rpm

I have never heard of such a thing either. When you install the new points use some emory cloth and polish the base of the points that contact the mag plate ( mag plate also) to get a good clean contact.