need help honda 90

S

starcrafttom

Active member
The last few trips on the boat the honda has not been getting up to speed. I have always been able to get up to 5400 rpm and 28 to 30 mph wot. now I can only get up to 4900 rpm and 20 mph. I don't know whats wrong. I am not starving for fuel because now I am using more fuel. I have to run 4800 rpm just to keep it at 18 mph. I have had heavy loads on the boat the last few times but not enough to make this big a difference and even with just me on board I can not get wot out of her. can some one suggest what I should look at or should i just take her to the shop??
 
Tom, I've got the same problem with one of my 45's. I replaced the lower unit with one of El and Bill's and thought the gear ratio was different but it wasn't. Found some loose plugs and tightened them but it didn't do much. Replaced the Racor Fuel Filters and that didn't help. Switched the gas lines (mine come from different tanks) and that didn't help. At least it runs good, idles fine, etc. The "bad" engine will only do about 4700 and the "good" one will redline at 6000 if I push it. What to do, what to do? The next thing is to check the linkage with the throttle wire and make sure it's opening up all the way, maybe it has slipped?

Charlie
 
funny you should mention that cable. mine is in the process of breaking right now. the plastic covering has came off at the point that the cable enters the engine. All the braided cableing has started to rust and break. the funny thing is that the engine still runs up to 5800 in nuetral. Iam putting a new one in this week after the sock eye fishing ends and before my eye surgery. I hope this is the only problem. the engine has a 3 year warrenty but not the cable . only one year on that according to les and company. Which reminds me , how long is that cable??
 
Tom-

Sorry to hear about your motor problem.

Sounds like you're laboring the engine, but wasting a lot of energy, can't wind 'er up fully, and getting a very limited top speed.

Outside of an internal engine problem, the symptoms sound like a bent prop.
Have you checked for a suble, hard to notice bent blade or two?

The hub must be good, or you'd be over-reving instead.

I assume the hull's still clean and fair, and you've checked the obvious sources of drag.

Does the prop turn freely in neutral by hand? Folks who troll a lot in crowded areas can ball up a ton of fishing line in front of the prop hidden on the propshaft, although most of the modern outboards have line cutting slots on the housing.

Another very common problem is carburetor or fuel injection obstruction, causing one or two cylinders to not develop power, but you say you're using more gas, so....................?

Are one or more of your plugs fouled? Doess the engine sound out of time?

Hope you get this solved easily and w/o too much cost!

Joe.
 
Tom:

"the funny thing is that the engine still runs up to 5800 in nuetral"

Be careful with the engine reving in neutral. Most all manuals say not to rev over about 2500 rpm w/o a load on the engine. I've heard you can bend or throw rods at high no-load rpms!

Joe.
 
I have not pulled the plugs yet but the engine sounds like it running good. just not getting the speed and power I once did. I did run this prop thru a lot of sand tring to get off a bar last winter but have ran it a lot since then and not had problems until now. It may be the cable, but keep the ideas flowing.
 
Jim here, I recently had an issue with a engine that would not fully rev and peak out on the top. I found a small grain of carbon between the electrode and tip of the spark plug. This has happened before at 2000 feet and required a emergency landing. But something to check. Also I was told by an A&P Mech that using gas with ethanal will loosen carbon from the piston tops cleaning the insides. I stopped using that brand and have had no further trouble.
 
Lots of good ideas here. Tom have you tried replacing with a suzuki? :lol:
Just kidding. I was looking at my outboard maintenance book, and here are some ideas from the author:

Engine speed lower than normal

1. Fuel hose crushed or kinked
2. Fuel filter clogged
3. Fuel contaminated
4. Spark plugs fouled or defective
5. Incorrect spark plug
6. Spark plug gap incorrect
7. Badly fouled prop
8. Propeller pitch or diameter incorrect.

These are the top 8 most common causes of engine speed being lower than normal. Obviously, #8 isn't you since the prop worked great for some time. You said you changed all the fuel filters in april, so that shouldn't be it, and your kicker is plumbed off your fuel seperator right? But I wouldn't mark it off. So what I would try first would be to use a small kicker tank to take the whole fuel system out of the mix. If you have the same symptoms then you can check #'s 1-3 off your list. That basically leaves you with spark plugs or your prop being too dinged up or warped. Beyond that you know my mechanical ability so... By the way you must have come and picked up your boat today right? :wink: I know, thats not funny. See you tuesday.

Sark
 
your right, thats not funny. :moon For the rest of you, my boats at sarks place in the water. I will have to check the spark plugs as the rest of the listed items have not changed since the problem started.
 
Tom,

I would check to see if the throttle plates in the carbs are opening fully.

With the motor cover off (ignition OFF), put the control handle into gear and push the handle to the full throttle position. Then check the carbs to see if the throttle plate levers are in the fully open position. The bad cable could be preventing the carbs from opening completely.

When shifting with the motor not running the prop needs to be turned slightly to let the gears engage.

If the boat is in the water, start the motor, put into gear (at idle) and turn off the ignition (with the control in gear). Then you can push the throttle to wide open to check the carbs. (with the motor NOT RUNNING).

I hope this helps.
 
Sea Wolf":1bgkup5y said:
Does the prop turn freely in neutral by hand? Folks who troll a lot in crowded areas can ball up a ton of fishing line in front of the prop hidden on the propshaft, although most of the modern outboards have line cutting slots on the housing.
Click to expand...

That's something that came to my mind when I saw this. It just takes a minute to pull the prop and check. I had a bunch of mono wrap the prop hub at the base and it sort of wedged between the prop OD and the skirt around it on the lower unit housing. I didn't really notice it dogging so much, but I knew something was haywire on the way back in. I found the prop was very hard to turn by hand. The line melted into a solid chunk of plastic and I had to pull the prop to get it off. Someone on here said a while back that it can even swell up to the point of splitting the housing. Even if you don't see signs of it on the outside, I suppose it could get onto the shaft behind the prop and tighten up the thrust washer back there. It's free to check it.
 
I don’t know how the choke operates on the Honda 90. Don’t know if you have one or four (one on each carburetor) but a partially closed choke will cause your symptoms. Check to make sure the choke is not stuck partially closed.
 
You folks up there aren't undergoing a gas reformulation, are you?

The new E-10 gas has caused a lot of fuel problems because of it's ability to make water soluible into the gas and also loosen up tank deposits, although this is a grteater problem in an older boat.

Joe.
 
Joe,

I think that is happening here in WA. I have had problems after two fillups in June and July( at fuel docks). The last three fuel dock fillups have been good, though.

I read that MTBE gas and E 10 don't mix well and can cause running problems. The article also said that the new E 10 gas doesn't store well (not over 30 days). They recommended leaving tanks low to empty in storage and using a fuel stabilizer.
 
stopped by the boat tonight and used a spark plug checker on all cylinder and they checked out just fine. the prop spins in neutral just fine, i removed some line a few months ago when I lubed the prop. I did not check the travel on the throttles but will after work tomorrow.

The one thing I did notice was the fuel line coming off the fuel filter and going to the "y" between pumps was soft and collapsed. It did not seem to matter at idle but might suck down at wot. I will check it tomorrow with the boat moving and may even just cut a new piece and install. depends on how the fishing is.. Thanks for all the advice and I will keep you posted.
 
Susan E:

I suggest you pull the entire fuel line, and after draining it out, place it on a workbench, and use a sharp razor blade or tool to slice it down the middle, from one end to the other, rather than just cutting across the soft spot. It would be nice to have a look at the inside of the tube, along its entire length, so you could see if you're just dealing with a weakening, or if you also had parts of the fuel line lining breaking off, and heading upstream to your motor. If that's the case, you'll want to replace any separate filters, such as a Racor, as well as the Honda filter which is on the starboard side of the motor, just below the carbs.

Let us know, but it looks like you're on the right track.
 
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