'03 90hp outboard surging issue

[coreman80]

I have a 03 Yamaha outboard I'm about to unbolt and drop it in the ocean!
It will run perfectly fine for about 15min, get me nice and far from the boat launch then drop back from 4500rpms to 1500-3000 surging sputtering when I drop it to idle, sometimes when I restart the motor or kill all power it will get back to normal for another 10min or so, or just limp back to the boat launch just above idle. Ive gone thru the fuel even hooking up a portable tank to ensure its not a fuel system problem. I have had the carbs cleaned, I replaced to cdi (with a used one from ebay) problem hasn't changed I'm going crazy over here, anything else I should try?? This seems like a common problem but with 100 different solutions.

[CatCam]

I have a 03 Yamaha outboard I'm about to unbolt and drop it in the ocean!
It will run perfectly fine for about 15min, get me nice and far from the boat launch then drop back from 4500rpms to 1500-3000 surging sputtering when I drop it to idle, sometimes when I restart the motor or kill all power it will get back to normal for another 10min or so, or just limp back to the boat launch just above idle. Ive gone thru the fuel even hooking up a portable tank to ensure its not a fuel system problem. I have had the carbs cleaned, I replaced to cdi (with a used one from ebay) problem hasn't changed I'm going crazy over here, anything else I should try?? This seems like a common problem but with 100 different solutions.

I'm waiting for Rodbolt to chime in but me thinks it is your fuel pump. 20/20 hindsight but I would have changed this out long before I started changing out the CDI.....is this the 2 stroke or 4 stroke 90?

Did you try pumping the ball when this happens?

[coreman80]

I checked the fuel pump, it had good pressure I went to order one anyway and everyone I talked to said didn't seem likely at all? at this point anything is worth a try

[zenoahphobic]

It would be one problem with one solution. You may have to do many tests, don't keep throwing parts at it, because often than not you will have a fuel flow issue. So do one thing at a time positively eliminating each.

Did pumping the primer bulb, as suggested make a difference?

[rodbolt17]

two ways to fix it.
1 stand back 10 ft and throw wads o cash at it.
2 simply trouble shoot it.

when its broke test spark at each cyl.

then test the fuel system.

[99yam40]

Rodbolt,
Does the 90 limit RPM by retarding timing or dropping cylinders?
This might give him something to test for

[rodbolt17]

it limits by misfiring cylinders.
it is also unique that the CPS makes spark for #2 cyl.
it only has 1 pulser coil for 3 cyl.
the stator also has a high and low speed charge coil.

[99yam40]

Not sure if the limit RPM you gave ( misfiring cylinders/plugs) was for over speed or the alarm reduction I was shooting for but did not explain well.

I believe my C40TLRX 3 cylinder retards timing to limit RPM if overheat alarm comes in but misfires cylinders if you hit too many RPMs

Just trying to see if he needs to be watching timing when this problem shows up or not.

Also I thought the 93 90 2 stroke used 2 pulsers 1 for #1 and 1 for #3, but #2 is created by the CDI, but I could be way off base as you called it CPS

[rodbolt17]

the 93 90 uses 1 two wire pulser,wire colors w/r-w/b, to fire 1&3,cyl two is sparked by the CDI based on CPS inputs.
84-91 uses two pulser coils and #3 is made up by the CDI and CPS.

[robert graham]

So the surging is most likely electrical or fuel related?....Just curious since I have a similar motor....

[rodbolt17]

dunno
without proper testing with the proper equipment AND training. this could go on forever.

its also way some threads have been posting that NO training is nessasary to work on outboards.
\

[bajakeith]

outboards,I/O's,V-drives,gas,,diesel,,bird shit !!

Any and all need a trained tech for diagnostics.. problems.. in this biz,,very few are trained and with the skill and "Touch".....A pretty paper on the wall dosnt mean the guy has "What it takes" IMHO...I get a lot of "Rework" that Yahoo at the shop with the big sign and bill,, that just tossed parts at the motor/system hoping to hit something.......

[bajakeith]

outboards,I/O's,V-drives,gas,,diesel,,bird shit !!

Any and all need a trained tech for diagnostics.. problems.. in this biz,,very few are trained and with the skill and "Touch".....A pretty paper on the wall dosnt mean the guy has "What it takes" IMHO...I get a lot of "Rework" that Yahoo at the shop with the big sign and bill,, that just tossed parts at the motor/system hoping to hit something.......

[zenoahphobic]

Does not the paper on the wall mean they are trained?

[zenoahphobic]

The problem sometimes is that what is one to do, the system says go to the guy with the "paper". It is only after sometime you realise that there are idiots out there, and if one has the intelligence you quickly realise that one could do just as well relaying on untrained self.

Fine go to a competent technician but where do you find that particular list?

I will always encourage to train oneself in the absence of decent technicians. Don't settle for medioka .