Yamaha 90hp outboard help - Pirate4x4.Com : 4x4 and Off-Road Forum
 
Pirate4x4.Com : 4x4 and Off-Road Forum  

Go Back   Pirate4x4.Com : 4x4 and Off-Road Forum > Miscellaneous > Outdoor Sports and Recreation
Notices

Reply
 
Share Thread Tools Display Modes
Old 05-08-2012, 08:06 AM   #1 (permalink)
Registered User
 
Join Date: Dec 2003
Member # 25321
Location: Central VA
Posts: 175
Send a message via AIM to myndphuct
Yamaha 90hp outboard help

Anyone familiar with Yamaha outboards?

I'm trying to help my Dad get his boat going as he is no longer physically able to participate in his normal summer obsession, golf (he has cancer, incurable, but they give him a couple years).

The boat has been sitting in the barn for a few years, ran rough the last time he used it and it hasn't been much of a priority since. He also said the last time he used it it would idle and rev fine, but fell on it's face when you put a load on it.

I pulled it out the other day, pulled, cleaned, and re-assembled the carbs. I can get it to start pretty reliably, but it idles really rough and dies after 10-20 secs of idling. If i give it throttle I can sometimes get it to run, but the rpm's seem to run away til i cut it back then it idles and dies.

This motor has the oil injection system, and I'm noticing a lot of 2-stroke oil in the water tank, as well as the spark plugs being heavily coated in oil.

Any idea where I should start on this thing?

I'm thinking part of the problem may be over-oiling from the injection system. I put a couple of gallons of pre-mixed 50:1 gas in the tank, pinched off the oil line from the reservoir, cleaned the plugs and it was able to idle for closer to a minute before it died. I'm going to get new plugs this week and possibly get a new fuel pump since it's pretty cheap, just to eliminate that as a problem.

I've also noticed that it will not start without the motor cover on unless I give it a shot of ether. then I can see fuel being sprayed from the jets when I increase throttle, but it will not idle at all without the cover.

Is not running without the cover normal? I'm not really familiar with outboards or 2-stroke engines in general, but I have an old 9.9hp evinrude that does the same thing.

Sorry for the long post.
__________________
89 yj, AMC 360, TF727, Stak D300 RAC, Waggy 44 front/mini spool, Toy 8" locked rear. 35" Krawlers.

Last edited by myndphuct; 05-08-2012 at 08:07 AM.
myndphuct is offline   Reply With Quote
Old 05-08-2012, 08:44 AM   #2 (permalink)
Registered User
 
Join Date: Oct 2000
Member # 1899
Location: Tacoma, Wa Where you can drink the water, but don't breath the air
Posts: 12,449
Check the choke. Sounds like it's malfunctioning.
__________________
What?
HighHooder is offline   Reply With Quote
Sponsored Links
Old 05-08-2012, 08:59 AM   #3 (permalink)
Rock God
 
robert stone's Avatar
 
Join Date: May 2000
Member # 985
Location: roseville,ca
Posts: 1,713
Blog Entries: 1
Send a message via Yahoo to robert stone
sounds like fuel pump and or line/filter
robert stone is offline   Reply With Quote
Old 05-08-2012, 09:09 AM   #4 (permalink)
Registered User
 
Join Date: Dec 2003
Member # 25321
Location: Central VA
Posts: 175
Send a message via AIM to myndphuct
ok, downloaded the manual online. Looks like there is a valve beside the middle carb that can be switched on to enrichen the fuel mixture. There doesn't seem to be an actual choke, at least there is no mention of it in the manual.

I'll check that out when I get back down there. I pulled the fuel filter and checked it, it looked very clean (two piece design) so I don't think that's the issue.
__________________
89 yj, AMC 360, TF727, Stak D300 RAC, Waggy 44 front/mini spool, Toy 8" locked rear. 35" Krawlers.
myndphuct is offline   Reply With Quote
Old 05-08-2012, 11:28 AM   #5 (permalink)
Registered User
 
Join Date: Aug 2002
Member # 13467
Location: Lafayette, Louisiana
Posts: 3,736
Check the coil packs. There should be test procedures in the manual. If the coils aren't strong, that'll throw everything else off. If the coils are good and the fuel enrichment valve isn't stuck, do a compression test.

A friend of mine has a yamaha 115 4-stroke that he just bought that had been sitting for years. It still didn't want to run right after cleaning the injectors, replacing fuel and filters, checking plugs, etc. So he brought it to the shop and it turns out the compression was down to about 30%. Before they tore the motor apart, they mixed up some kind of concoction and ran it at idle for a few hours. It must have been really gummed up valves because that's all it took and the boat runs like a champ now (supposedly, it still hasn't been picked up).

If all of that seems good, I'd bypass the oil injection. On my Johnson, it's just a matter of pulling the electrical connector and oil lines and plugging the ports. It's probably something similar on the yamaha. I'm sure it's been discussed on the internet; it's a pretty common thing to do.
__________________
[QUOTE=Willyswanter's Dad;8398776]I'm trying to find spinner caps that will fit the wheels so when I'm stuck it will look as though I'm still wheeling[/QUOTE]
Ben Segrest is offline   Reply With Quote
Old 05-08-2012, 02:31 PM   #6 (permalink)
Registered User
 
Join Date: Dec 2003
Member # 25321
Location: Central VA
Posts: 175
Send a message via AIM to myndphuct
on the yamaha the oil pump is mechanically driven. I've found a few threads about guys switching over to pre-mix and eliminating the injection. There is also a sensor in the oil reservoir that sets off a buzzer if the oil gets low. I think it will also prevent the engine from exceeding a certain rpm, so I'll have to look into that before eliminating the injection system. I'll take my compression tester over there too, can't hurt to check.

I've got some sea foam I plan on running through the fuel system too, might not hurt to run some through the oil system as well.
__________________
89 yj, AMC 360, TF727, Stak D300 RAC, Waggy 44 front/mini spool, Toy 8" locked rear. 35" Krawlers.
myndphuct is offline   Reply With Quote
Old 05-08-2012, 05:21 PM   #7 (permalink)
Registered User
 
Join Date: Feb 2010
Member # 153567
Posts: 290
Yamaha oil injection rarely gives any problems, I'd leave it there. Start with a compression test, then use a spark checker to insure you are getting spark on each wire. Pump up the primer bulb and squeeze it pretty hard, does it go down? are you getting any fuel dripping around the carbs?

What did you clean the carbs with? Yamaha carbs have extremely small orifices in them. I use an ultra sonic to clean most of the crud off, then dunk the carb bodies in "Yamaha carb cleaner" for at least a few hours. @ qts in a folgers coffee jug works just fine. Then back in the final ultrasonic to final clean, blow them out good with air and reassemble. The enrichment circuit use stator voltage to heat a wax pellet inside the needle assembly, when the wax is cold, it holds the needle off the seat, allowing extra fuel to enrich en the circuit. Once the wax heats up and melts, it moves the needle closing off the extra gas,

Sounds like to me you need to have another run at the carbs, I have to go back once in a while to clean them a second time. Don't use old school chem dip on those carbs. The Japanese carb manufactures use soem really crappy aluminum to make carbs, teh alumiun is sometimes poures, they coat the carbs with some kind of clear coat to prevent internal air leaks. Thats why they look kinda shiny. Post up the engine model and I'll see what teh idle screws are supposed to be set at
sparepartsdave is offline   Reply With Quote
Old 05-08-2012, 08:10 PM   #8 (permalink)
Registered User
 
Join Date: Feb 2005
Member # 43727
Location: North Louisiana
Posts: 766
Clean the carbs first as in completely disassemble them and clean every orifice, jet etc. Make sure the oil tank is full as some of them have a low oil sensor that puts the motor in limp mode. Make sure the oil tank caps are in good shape and not cracked since a tiny amount of water in the oil system will cause a toasted motor.

Sent from my A500 using Tapatalk 2
whistle pig is offline   Reply With Quote
Old 05-09-2012, 02:59 AM   #9 (permalink)
Registered User
 
Join Date: Dec 2003
Member # 25321
Location: Central VA
Posts: 175
Send a message via AIM to myndphuct
the engine is a 90tlrb, I've give the carbs another go with the cleaning.
__________________
89 yj, AMC 360, TF727, Stak D300 RAC, Waggy 44 front/mini spool, Toy 8" locked rear. 35" Krawlers.
myndphuct is offline   Reply With Quote
Old 05-09-2012, 05:30 AM   #10 (permalink)
Hillbilly Houndsman
 
SilverZuk's Avatar
 
Join Date: Aug 2002
Member # 13420
Location: Kenna, West Virginia
Posts: 7,103
On old motorcycles (70's), we ran mixed two stroke gas to eliminate the unreliable oil injection systems.
__________________
The penalty for punching someone in the mouth is way too high in our society.

www.MountaineerOffroad.com
SilverZuk is offline   Reply With Quote
Old 05-09-2012, 07:03 AM   #11 (permalink)
Registered User
 
FrankenToy's Avatar
 
Join Date: Oct 2004
Member # 36822
Location: Toyotaville, just west o' Denver
Posts: 2,113
I've worked on any number of Yamaha motorcycles (never on outbooard, though). It sounds like your ignition system may not be functioning correctly, as stated previously. That's where I would start. Yamaha oil injection system is damn near bullet-proof. Another thing to consider is the brand of two-stroke oil you're using. Are you using "black death" 2-stroke oil (cheap Wal-Mart-esque 2-stroke that sells for $5/ocean-going-tanker full) or are you using a good (i.e., expensive) synthetic, like Golden-Spectro or similar that actually works? Can't tell you the number of spark plugs I seen fouled/ruined by running black death 2-stroke. In the long run using cheap oil is WAY more expensive.

EDIT---> Also check the crankshaft seals. Believe or not, these have a BIG effect on how a 2-stroke runs, along with reed valves (if your outboard has these).
__________________
Seems the fools are in charge now and they demand a high tariff... Me

Last edited by FrankenToy; 05-09-2012 at 07:09 AM.
FrankenToy is offline   Reply With Quote
Old 05-09-2012, 07:53 AM   #12 (permalink)
Wheeler
 
hogcat's Avatar
 
Join Date: Nov 2005
Member # 61545
Location: Close to I-10
Posts: 317
Take it to the dealer and get a quote on fixing it. Tell them you can not afford it now. Might cost $100.00 or so, but do the fixin yourself.
hogcat is offline   Reply With Quote
Old 05-09-2012, 08:35 AM   #13 (permalink)
Registered User
 
beyondhelp's Avatar
 
Join Date: Oct 2002
Member # 14423
Location: Port Saint Lucie Florida
Posts: 273
I had similar issues when the CDI box died on my OB. Weak intermittent spark would let it run for up to a minute if it started. Replaced the box and it runs better now. You can check them out with a dvm, I eliminated every other possibility first then replaced it.
beyondhelp is offline   Reply With Quote
Old 05-09-2012, 11:56 AM   #14 (permalink)
Registered User
 
Join Date: Dec 2003
Member # 25321
Location: Central VA
Posts: 175
Send a message via AIM to myndphuct
Stopped by the local boat shop on my lunch break. Went in looking for a fuel pump, talked to the counter guy/mechanic who said if it's starting and idling at all the fuel pump is fine. Recommended doing the carb soak and said the same thing that SparePartsDave did about soaking the carb and small orifices etc. So I picked up some of the yamaha carb cleaner and will be taking them back apart and giving them a thorough cleaning. I'll update after that.

Also picked up the yamaha brand 2-stroke oil, which is what has been used in it since he got it (bough used so I don't know what the previous owner ran).

Thanks to everyone for the help so far, I've got to get this thing going. If this doesn't work I may go ahead and have them look at it and just deal with my wife being pissed at me for footing the bill.
__________________
89 yj, AMC 360, TF727, Stak D300 RAC, Waggy 44 front/mini spool, Toy 8" locked rear. 35" Krawlers.
myndphuct is offline   Reply With Quote
Old 05-10-2012, 07:57 AM   #15 (permalink)
Registered User
 
Join Date: Jul 2011
Member # 194896
Posts: 32
I had the exact same symptoms on my Yamaha 50 tlra. It ran like shit at idle. It was missing on the top cylinder. I turned the enrichening valve to the middle position and it was fine. It turned out that the idle jet was clogged.
TBailey is offline   Reply With Quote
Old 05-10-2012, 06:39 PM   #16 (permalink)
Registered User
 
Join Date: Dec 2003
Member # 25321
Location: Central VA
Posts: 175
Send a message via AIM to myndphuct
Ok, pulled the carbs again today, disassembled (including jets/small parts) and soaked them for an hour or two while I changed the lower unit oil, changed spark plugs, put another 5gal of gas in the tank, then I went and fixed a couple of tires on my dads riding mower.

Used compressed air to blow out everything really well and then re-assembled and installed the carbs. She idles great now!

Thanks again to everyone. Hopefully Monday or Tuesday we'll be able to put her in the lake down the road and see if everything else is running good. Surprisingly all of the lights on the trailer were working good, I had to re-wire it the last time he used it, mice had chewed up the wiring.
__________________
89 yj, AMC 360, TF727, Stak D300 RAC, Waggy 44 front/mini spool, Toy 8" locked rear. 35" Krawlers.
myndphuct is offline   Reply With Quote
Old 05-16-2012, 06:05 PM   #17 (permalink)
Registered User
 
Join Date: Dec 2003
Member # 25321
Location: Central VA
Posts: 175
Send a message via AIM to myndphuct
Just a quick update:

Got it out on the water today, motor ran great. No excess oil consumption, no high rpm knock, plenty of power all the way to full throttle.

Thanks again to everyone, seeing my dad stick his cane into the fishing rod holder and open the throttle with an ear to ear grin was priceless.

Today was just a quick shakedown run, hopefully we'll hit the bay in a week or two.
__________________
89 yj, AMC 360, TF727, Stak D300 RAC, Waggy 44 front/mini spool, Toy 8" locked rear. 35" Krawlers.
myndphuct is offline   Reply With Quote
Old 05-16-2012, 06:34 PM   #18 (permalink)
Registered User
 
beyondhelp's Avatar
 
Join Date: Oct 2002
Member # 14423
Location: Port Saint Lucie Florida
Posts: 273
Awesome! I fish with Dad almost every weekend.
beyondhelp is offline   Reply With Quote
Old 05-16-2012, 06:51 PM   #19 (permalink)
Registered User
 
Join Date: Jun 2005
Member # 49169
Posts: 1,205
If that wax pellet enricher gives you any trouble, pull it and freeze it for 12 hours, reinstall and it'll act fine for a few years.

Also, those things hate ethanol. run the blue shit from West Marine in it. It'll thank you for it.
__________________
A little chaos is good for the soul. SSJ
Rat~Man is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 11:25 PM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0 ©2011, Crawlability, Inc.