Rebuild the carbs OR replace them?

[Todd in NY]

I fogged my 1986 Evinrude 90hp V4 today. When spraying fogging oil into the top carb, the engine would almost stall out. When fogging the bottom carb, the engine barely fluttered. The boat sat for 2 years before I bought it, so most of this year has been spent working on the boat rather than fishing from the boat (6 trips since July). The boat is winterized now, so I won't worry about it until April, but how do I know whether to rebuild the carbs or simply replace them? The boat runs good now, but It started out with idle issues. I have the idle adjusted up because it absolutely hated running at low RPM. I always suspected dirty carbs, even though the spark plugs burn at the right color.

 

I've used fuel system cleaner and K-100 in it this year, and I am storing it with a full tank of ethanol free premium, marine Sta-bil, and Sea Foam that I ran through the engine before fogging it. The boat has a 24 gallon tank.

 

What factors determine when to replace rather than rebuild the carbs?

[tuffishooker]

Depends on your level of mechanical skills ; IMO rebuild carbs , get a good kit and manual . I have done carbs on a 1983 70 hp. OMC and now works fine IF that is your problem : Clean up ALL electrical contacts with dielectric grease esp. the GROUND wire at the back of the power pack [ one trick that worked for me was to run the engine in the dark and check for sparks ]

Check compression with a gauge that screws directly into the block ie. no hose ! Let us know how you made out .

[finsntins]

if the motor runs good except at idle,i would check compression like what was stated by fish hooker.2-strokes need at least 100 psi or better and all cylinders should be within 10% of each other.

[Todd in NY]

Thanks! I'll check the compression to see where the cylinders are at. I put dielectric grease on the usual connections. I have the shop manual and owners manual for the engine, and I'm mechanically inclined enough to do the carb rebuild correctly. The rebuild kits are under $18 each, whick is cheaper than a used carb on the auction sites.

I'm making a checklist of things I want or need to do to the boat, but none of it will happen until April. We've had at least 20 ft of snow for the past 2 winters(each winter), and record breaking cold, so April is my goal to start my boat prep. I'll also be replacing all lower unit seals and gaskets before I replace the lower unit oil. These maintenance steps next spring will allow me many more years of fishing before I have to worry about doing it again.

Edited November 12, 2015 by Todd in NY

[Todd in NY]

Forgot to mention that it runs great at idle now.

[finsntins]

if you have not changed lower unit oil,you should do that NOW,before winter.if something is leaking and you have water in the gear case,it will crack and you will be replacing the whole lower unit in the spring.

[Todd in NY]

Easy enough, I'll change the lower unit oil this weekend. I'm curious about water being in the lower unit because there was a little in there when I bought the boat. It wasn't a lot, but I replaced the O-rings on the drain and fill plugs before I refilled the lower unit. Maybe the PO didn't replace those O-rings the last time he changed the oil. I even pumped the 2-stroke oil out of the VRO tank because it was over 2 years old and I didn't want to burn that old oil through the engine.

 

The motor runs great now. Fully loaded, it does 32mph on my GPS (Hummingbird Helix 5 DI GPS unit). It's the 19ft aluminum boat in my avatar. That was with the motor trimmed all the way down on an inland lake, and I ran out of room before I could experiment with different trim positions to see if it would go faster.

[Xxx]

I did the carbs. On my Evinrude 88-88spl, if they are the same which I woud suspect, the direction will read you need to drill out areas that are capped off from the factory, it will say to remove jet so& so but you don't see it, because this is where you need to drill the aluminum out so you can get at the jet. At first it seems a little intimidating but you will be fine, just match the drill bit to the sunken area in aluminum use a cordless drill on the slowest speed and you will be fine, I think I had to on each carb. Good luck take your time and it will turn out just fine. I had no one to inform me of such and yours might be already done, but if not you have an idea of what to do. Pap.

Edited November 13, 2015 by pap

[rolmops]

New carbs are good, buying used ones is risky. The other possible way to go is having a professional rebuild done.

[Todd in NY]

Thanks for the info Pap. After pricing new carbs, I would only go that route if I absolutely had to.

[Xxx]

Thanks for the info Pap. After pricing new carbs, I would only go that route if I absolutely had to.

You are very welcome, if you have a little mechanical experience and are not a person that thinks Rome was built in a day, this job isn't in need of a masters degree in natural aspirated motors. Do one at a time so you have a pattern to follow should you get lost. Maybe purchase a repair manual of your motor/lower unit, that will tell you where the presets from the factory are, and if you don't have already a torch tip cleaner. This has all the different size wire cleaners in it, I'm sure there's a much fancier carb cleaner kits but that's all I ever used and served me fine. I've rebuilt carbs from snowmobiles to chainsaws to Holley 4 barrels, the only carbs that tried my patience was the Chrysler lean burn carbs. You will be fine, and make absolutely sure there is no dirt where your working!!! Good luck

[Todd in NY]

Thanks Pap, I'll add one of those torch tip cleaner tools to my shopping list. I have the Clymer shop manual for my 90hp motor, so no worries. Plus I have a neighbor who has rebuilt his carbs before too. I'll tackle the project on my reloading bench, plenty of light and a clean work area. The boat and motor are covered for the winter, so I'll dig into it in early April. This is when I wish I had a heated garage or shop.

[Xxx]

Thanks Pap, I'll add one of those torch tip cleaner tools to my shopping list. I have the Clymer shop manual for my 90hp motor, so no worries. Plus I have a neighbor who has rebuilt his carbs before too. I'll tackle the project on my reloading bench, plenty of light and a clean work area. The boat and motor are covered for the winter, so I'll dig into it in early April. This is when I wish I had a heated garage or shop.[/quote

LOL I hear you on the heated garage. I'm sure between the two of ya's your motors will run smoother than ever!!

[Todd in NY]

Absolutely, and already looking forward to fishing season next spring.