1999 yamaha 90tlrx RPMs

[99scout]

Re: 1999 yamaha 90tlrx RPMs

99yam40, it is a C90TLRX....for certain....i spoke to a local marine shop and the guy there said that he thought it was a fuel problem also..he told me to pull the pickup tube out of the tank and inspect it....so after having removed the center console i got the pick up tube out and it looks great but it was not cut at a angle. it had a upside down "V" cut in the end so i cut a knotch out of the opposite side...that way if one side got clogged then maybe the other side would still be able to suck fuel up. also while cleaning the outer tank and inner hall with bleach and purple power i found a hole next to the gas guage float assembly which looks like it occured from salt water laying on the aluminum..i sealed the whole. im not to worried about he hole because it will have the same effect as the vent line(i think)and it was in a place that would not interfer with the pickup tube...hole still does not explain why it will run fine all day then mess up on the way home....i honestly think that something is getting hot (ELECTRICALLY) and is shutting down or shorting out.....That would probably leave me with the Stator,
Powerpak or Coils .........Right? can you give me a call....i would like to speak to you in person 304-483-7308

 

[robert graham]

Re: 1999 yamaha 90tlrx RPMs

The puzzle to me is why the motor will run fine all day and then start this lower RPM stuff on the way back...Your idea of an electrical problem makes sense to me.....99yam40 is pretty handy on electrical issues, so hopefully he can help....Good Luck!

 

[99yam40]

Re: 1999 yamaha 90tlrx RPMs

I do not have a manual for your motor, so I do not have any specs for it.
Jefferson probably has the info, but it would be best if you get your hands on a Yamaha service manual for your motor and a DVA adapter attached to a regular meter and follow the steps for testing the electrical side of it if that is what you want to do.

Make sure you have the proper compression, and then make sure you have good spark,proper timing,and good fuel pressure while problem is happening. Also make sure it is not sucking air and starving for fuel
If all that shows good then it will be the carbs that need to be cleaned.

Testing is a lot easier, faster, and cheaper than trying different things to see if it helps

If you have a hole in the top of the tank there is a very good chance you have water and other stuff in the tank moving around in there and maybe in the rest of the fuel system also.

 

[99scout]

Re: 1999 yamaha 90tlrx RPMs

thank you....few more questions...if i was doping spark would it still idle perfectly? would i be able to rev it at the carbs and reach higher rpms without it bogging or fluttering on itds way up? and can i just get a portable tank and temporaraly hook it up for a day to rull out the boatside tank and fuel lines.....also i have a receipt from a local shop from about a month ago stating that the carbs were just cleaned and i have cleaned the carbs aswell since i put the new water fuel seperator on....also yesterday when i was working on the tank i visually inspected what i could of the inside and it looked brand new inside and the gas appeared to be extremely clean...now of course i was not able to see the gas at the pickup tube hole because it is so small but through the gas guage hole everything was good.....as for the hole i sealed...it was next to the guage assembly hole and i only found it because i was wire brushing it to clean it....it was oxidized but i beleive that the wire brush actually exposed the hole....from my pickup tube through the hose and into the fuel water seperator is a good 3/8 of an inch passage the entire distance so any peices that would stave fuel would have to almost completely clogg the line right...something the size of a pencil lead tip can flow clear to the f/w seperator...thats why i feel that it is not fuel related....the gas tank is a 1999 ezell 24 gallon aluminum tank.....also since i have replaced the f/w seperator i have found no crud or water in the bowl at the bottum of the filter yet....and after the f/w seperator i have a 1/4 see-through inline filter and then the standard filter that mounts to the motor from the factory(both of which a perfectly clean......i am going to check the primer bulb for leaks and the rest of the hoses and there is really nothing else that i can do asfar as fuel goes.....the problem that i am having is soooooo consistant that you can almost set you watch by it....as a matter of fact i am going to time exactly how long it takes to happen on this next test.....i might be leaning more towards the high side of the stator giving way under heat only because the problem only happenes on the way back which is a straight run at a constant rpm until it gives out and drops rpm....im not real sure haow a stator works but i do no that it will idle fine and rev by hand at the carbuerator with no problems but as soon as i put it in gear and go to rev it it will only get to 2000 and fluxuates from 1800 to 2000 rpms.....also it is the c model......thanks again guys and if someone can better explain how the stator works i would appreciate it

 

[99yam40]

Re: 1999 yamaha 90tlrx RPMs

As I said you can play with this and that or you can test things when the problem is happening to see what kind of problem you have. Testing will show what is going on, just saying you do not think this or that does not prove anything

Revving a motor out of gear is not putting any load on it, so I think it would point at a lean fuel issue , but you need to test fuel supply and electrical to be sure.

If it is a lean fuel issue and you keep running it that way it will pop a piston

 

[99scout]

Re: 1999 yamaha 90tlrx RPMs

should i not test it every time i replace or fix something? if not how will i know if i have the problem fixed or not....i do not have the tools or the knowledge to do these tests...can you guide me through the process of using a timeing light to test the plugs for a drop in voltage? i was looking today about inline spark testers and also fuel line pressure guages tobuy for this problem and any future issues...also using the clear tube to check for bubbles-should i run the motor or just pump the primer ball when checking for bubbles? is there a websitre where i can purchase a new PLASTIC tank or should i look into another aluminum tank

 

[99yam40]

Re: 1999 yamaha 90tlrx RPMs

Apparently you still do not have a service manual for your motor or you have not read it and I believe you have not read the post on testing fuel systems I mentioned earlier. A motor can not suck air or even fuel if it is not running

Have you ever used a timing light before on a car or truck? Hook it to the spark plug wire and battery and then pull the trigger while motor is running the light will flash if there is spark going to that plug

You can pick up these tools at an automotive parts store and they will lone them out at some places

 

[robert graham]

Re: 1999 yamaha 90tlrx RPMs

O.K., I 've re-read your last post, and I understand you have a Fuel/Separator type filter, is it a 10 micron or a 2 micron? I understand the 2 micron types can be restrictive and the 10 micron is preferred. You also have a 1/4" see-through filter between the Fuel/Water separator and the motor, plus the motor-mounted filter? Maybe you've got too many/restrictive filters and it's slowing the fuel flow? Maybe bypass the Fuel/Water separator and the 1/4" see-through filters, run fuel line directly to motor-mounted filter and give it a try? When/if you do this, put in some clean/fresh spark plugs and after your trial inspect the plugs carefully to check for carbon/fuel fouling on a plug that may not be firing correctly. Just some ideas. Good Luck!

 

[robert graham]

Re: 1999 yamaha 90tlrx RPMs

99Scout, I'm just checking if you ever found out the reason for your reduced RPM's? I'm especially interested since your motor is the exact same size and model as mine. Good Luck!

 

[jeffersondodson561]

Re: 1999 yamaha 90tlrx RPMs

Jefferson probably has the info

 

[robert graham]

Re: 1999 yamaha 90tlrx RPMs

99Scout, Any more news or thoughts on your RPM problem? Good Luck!

 

[Home Cookin']

Re: 1999 yamaha 90tlrx RPMs

even though you all are looking at way more sophisticated fixes, the "choppy water syndrome" interests me. Be sure your ground wire on the battery is pliers tight. May as well go through all your connections. This was recommended to me for my 2003 150 TXRB when it was acting stupid at times; mechanic said it was typcial and the engine electronics are sensitive that way.

 

[199675hpforce]

Im going through a similar problem on 2000 90tlry oil injection motor

Im going through a similar problem on 2000 90tlry oil injection motor

Ok im only getting 4000 rpm at lake. Just pulled fuel pump off and inspected. When I cracked it open there was not fuel humm been pumping new bulb and cleaned out carbs. Seems the original diaphram is in need of replacing after 11 years hard use maybe commercial. Have not lake tested but think i found problem. You might want to try and tighten down 3 philps screws and two 10mm screws. Part i ordered sierra 18-7787 fits 40-90hp yamaha and some Mariners. Think it's old part number off 1990 older outboards. I cant see any difference bettween it and new parts correct me if im wrong please. Spent $5 buck's for whole diaphram kit. Yamaha does not list diaphram kit only new pump unit and each seperate. Iboats store does not show my motor 90tlry. Also if you look at pump on back side there is hole in center for low psi pulse. Make sure there is correct gasket mounted up and sealing. Funny how your post is getting all these answers and question but not right ones lol.

 

[robert graham]

Re: 1999 yamaha 90tlrx RPMs

even though you all are looking at way more sophisticated fixes, the "choppy water syndrome" interests me. Be sure your ground wire on the battery is pliers tight. May as well go through all your connections. This was recommended to me for my 2003 150 TXRB when it was acting stupid at times; mechanic said it was typcial and the engine electronics are sensitive that way.

Home Cookin' might be on to somethin' with the loose ground wire, or something dead simple and obvious, rather than some tricked out electrical problem. Good Luck!

 

[199675hpforce]

Re: 1999 yamaha 90tlrx RPMs

Na im going fuel problem!