Honda 90

J

Jon - CLou

New member
We have a Honda 90 (year 2002) and I've been having a little problem with starting it in the mornings. This problem happened when it was only about 6 months old and then it went away. Now, the last 3 weekends, it's going thru the same thing.

Here's what it's doing...
Initial startup in the mornings-Turn key, choke engine and the engine starts fine. Choke maybe 1 or 2 more times and leave at high idle (2000 to 3000 rpms). At this point everything is working the way it's supposed to (I think ) and then after about 30 seconds the engine loses rpm's and starts chocking out until it stops. (At this point it doesn't need anymore choke). After starting it about two or three more times(3 to 5 minutes worth), it finally clears out and then runs fine for the rest of the day.

I noticed after I flushed all 4 carburetors by opening the drain valve and pumping the squeeze bulb, it runs fine after that?

I can't imagine it being a dirty carb but it sounds like it. Also, I started out with new fuel tanks, new lines and fittings, internal and external filters, stabil in fuel and always run the engine dry after using.

Any suggestions would be appreciated.

Heading to Newberg Oregon in a few and will return on Sunday.
Jon
 
I have a 2003 Honda 90 and it does the exact same thing when it is being started after not having been run for a week or two. After it warms up it can be shut down and restarted without any problem or hesitation.

It is amazing to me that your engine acts exactly like mine does and it is also frustrating that we are having these kinds of problems.

Would love to hear from Les on this subject.

Jim
 
I think I have come across the problem and solution to the difficult starting situation.

Went to my dealer today (Alaska Mining and Diving) and spoke with the lead mechanic. After hearing the problem, he said it sounds like I don't have installed on my boat a check valve between the engine and the fuel tanks. After priming the engine and starting it with the choke on, the fuel burns out of the carburetor bowls and the fuel in the line (without a check value) runs back into the tanks, leaving a fuel gap the causes the engine to die after a minute or two of running on the carburetor bowls worth of fuel. This made so much sense to me! He gave me a check valve and I went and checked my boat to see if I had one of the these installed. I did not!

So, until I can get my boat into the water (which will be awhile yet here in Alaska!), I can't test out this potential solution. I have great faith that this is the culprit, and by installation the $10 check valve, all will be well.

Jon, perhaps you could give this solution a try?

Jim
 
Some thoughts. First, I don't understand what your doing when you choke the engine "1 or 2 times more". but assume you have two ways to choke. One is the button at the engine (which you aren't using), and the other is at the throttle control, at the helm. It helped me to pull the cover off the engine, and watch how the throttle advances, and when the chokes engage as I pull the helm choke/throttle advance lever up and down. The bottom line is that the chokes don't engage until the lever is almost at the top, and disengage pretty much as soon as the lever begins to drop. If you're using this lever to choke 2-3 times, all you're doing, in effect, is pumping gas into the carbs 2-3 times, and then leaving the chokes engaged when you start. Be sure you're not flooding the engine in all of this. My engine doesn't like to be choked once it starts, but does want some throttle advance as it warms up. So, once it fires, I depress the choke/advance lever to about half way, and do it by feel, from there, depending on what the engine is doing. Sometimes I have to rechoke, but don't keep them engaged for long.

Be sure to hold the fuel bulb so that it's long axis is vertical, with the outlet end higher, so that you don't pump air into the fuel. Listen at the engine while you pump, and be sure you hear gas flowing into . If not, it's either already there, or your pumping is not accomplishing anything.

My Honda certified mechanic, when told of cold start problems, took out his pencil torch, applied heat to the mixture levers on each carb, and richened the mixture slightly. Don't try this yourself. But, mine does start much better after that trick.

If I haven't started the engine in a while, I put "earmuffs" on in the driveway, turn on the water, and get it running and warmed up there. Later that day, or even the next morning, it fires up at the launch ramp without any messing around.

The check valve suggested by others also sounds like a good idea, and perhaps here's how to see if backflow leakage is the source of your problem (and, also, whether your bulb is delivering fuel to the carbs). Pump up the bulb, and then disconnect the fuel line fitting at the engine, using the thumb depress lever. Hold the fitting over a container, and use a clean piece of wood or plastic to slightly depress the ball bearing at the end. Don't use a screwdriver, or you'll scratch the surface, and/or risk a spark. Neither are good ideas. Gas should spew out at first, so be sure not to get any on yourself, or to spray it such that it might ignite. Perhaps right up against an old towel? Remember, gas vapors are heavier than air, so don't smoke, and make sure the cabin door is closed, the automatic bilge is not fused, and nothing electrical is going to happen. It's best to do this while standing behind the boat, and if on the water, while standing on the swim platform. Don't drain gas into the well, or you'll have a "pool" of vapor waiting to ignite. The gas should then drain freely as it siphons from the tank (you need to have the fitting lower than the fuel level in the tank to siphon). If you can't get a siphon going, have someone pump the bulb, with the ball depressed, and confirm that gas comes out the fitting. If you don't learn anything doing this, wait until you have the start problem, and then disconnect the fitting and depress the ball bearing, and see if you have pressurized fuel at the fitting, ready for delivery to the engine. If so, backflow through the line wasn't causing the engine to fail to run.

Check your see-through filter and the filter on the engine to make sure that you're getting fuel through. If you had pressure and flow when you depressed the ball bearing at the fitting, you don't have a see-through filter problem, or at least not one that would affect anything at idle speeds. I can send you a copy of the shop manual procedure for checking the built in filter.

And, when the eigine won't restart, try pulling the engine cover, and cracking the drain screw on the bottom of the float chamber of the lowest carb. If gas flows out, you might not have a fuel problem after all.

Good luck, and let us know what works for you.
 
Hi All,

Ok, I'll see what I can add to the mix here...

There are check valves in your primer bulb; that's the way it works. If those are in good shape (if they're not replace the bulb) there is no need for other check valves and the fuel will not "drain" out of the engine. Once fuel is in the carb float bowl there are only three ways out; it either gets sucked through the fuel nozzle while the engine is running, it evaporates through the overflow circuit or the drain screw at the bottom of the bowl is opened. Leaving back the way it came through the fuel line is not an option (or physically possible). The fuel also can't flow 'backwards' through the fuel pump. Unless you have a great deal of air in the system the fuel pump will pass it and the fuel in the bowls will keep the engine running far longer than necessary to clear it (ever pulled the fuel line off an idling BF90 to run it out of fuel? Takes a long time!).

The Honda BF90 has a very strong mechanical fuel pump; if there is enough gas in the carbs to get the engines started it will pull fuel from the tank unless it's an awfully long run (it should be about 2 or 3 feet to the fuel/water separator). On a new boat I routinely run the engine on a portable tank to start with; once fuel is in the main tanks I just switch hoses and the engine pulls fuel from the tanks with no priming (and with a dry fuel/water separator).

The are a couple of different types of remote controls that are used with the BF90s. If you have the 'standard' side mount (black box) controller with the key switch and warning lights built-in then your choke is only actuated when the fast idle/choke lever is all the way at the top (it has to be pressed against the spring pressure); the mechanical choke plates on the carb are actuated by a solenoid which is either energized or not (there's no 'in between') and this solenoid is activated by a micro-switch at the top of the arc of the fast idle/choke lever.

If you have a top-mount (binnacle) controller then the choke is activated by pressing in on the key switch (normally).

The are no accelerator pumps on the Honda BF90 carbs; you can push the throttle back and forth or lift the fast idle lever all day long and you will not feed fuel to the carbs. The only thing getting fuel to the carbs is the fuel pump; so if the engine isn't turning over nothing's happening.

It's almost impossible to flood the BF90; the only way I know to do it is to crank a cold engine without the choke engaged or without the kill switch clip installed. The reason the choke microswitch is at the top of fast idle lever's travel is to ensure that the throttle plates will be open enough to start the engine. If you have a top mount controller you must push the shift release button and advance the throttle to get consistent starts from the engine. If you crank long enough you will get the engine to start without throttle (the cylinders finally warm up) but it's a long process and good for nothing.

Jon...

Have you tried bringing the fast idle/choke lever all the way back up the choke position again after the engine dies at 30-seconds? It's not nearly warm in that length of time; it takes quite awhile to heat up the block and 4-1/2 quarts of oil. I suspect the engine is leaning out (it's certainly not flooding out). I've gotten in the habit of not letting the engine die; as soon as it seems like it's going to drop off I run the fast idle lever into the choke position for another shot of 'juice'. The only hard starting issues I have ever had on the BF75/90 are from lack of enough fuel (never flooding) and Nippon Denso plugs (YMMV but we've never had a good experience with these).
 
Les, my choke is at the top of the fast idle lever (all the way lifted up) and yes, I have tried to choke it again when it starts to die. This usually kills the engine faster than not using it at that point. I have plenty of fuel in the carbs, because the prime bulb is still hard when it starts to die and like you said, it takes awhile for the carbs to run dry after initially filled. I don't want to believe that it's bad gas or gunk in the carb, because I think it would do this more often.

The P.A.Honda shop set up my fuel system as follows: Fuel line between a 13 gallon Tempo tank and the external fuel filter/ water separator. Another fuel line and prime bulb (less than 2 feet) from the external filter to the motor.

I did have a venting problem before (almost 2 years ago) and fixed that by changing the quick disconnect fuel fitting that attaches to the Tempo tank fitting. That was pretty easy to find once I found that the prime bulb was soft (sucking in ).

Les, what do you think. Try changing the prime bulb and see what happens? Maybe it has a bad valve inside?

Thanks all, for your response.
Jon
 
Honda perventive maintenance schedule calls for replacing the fuel lines every two years (or so) so you're due for a new line it seems.

Our Honda 50 died, or at least struggled like described above one (1) time. I never did figure out what caused it, but she fixed herself after 5 minutes of running. Fuel filter/separator showed no foreign substances.

-- Chuck
 
Hi Jon...

Guess I'm going to have to come over a whoop on the muther! Ain't right having a BF90 not starting right; especially one just around the corner.

It's not a matter of the carbs running dry; it's about the air/fuel ratio going into those cold cylinders. Because the BF90 idles on so little fuel (say .2 gph, and that's divided by 4 carbs) the idle circuits are very small. As I said before the choke plates are either open or closed...there's no partial setting. When the engine is cold it has to have more fuel to start (the prime start and EFI systems do the same thing) and the only way you can do that with your carbs is to cut down the mount of air reaching the cylinder (i.e. close the choke plates). My suggestion to get back on the choke then isn't to get more fuel in the bowls but to get the choke plates closed and richen up the mixture again. If you lift the fast idle lever when the engine starts to "fall off" you've got to make sure and get all the way back into the spring pressure and energize the choke solenoid; if you don't hit the choke microswitch then the situation is getting worse as the fast idle lever adds more air to the mixture as it gets raised...just the opposite of what we want to happen (unless we get to the choke switch).

I find if you tilt your head slightly to the right and blink three times it always works. When I see you in person I'll tell you what I say during that period of time (can't type that here :wink: )!

[The above was a joke! I've had several BF90's on our own boats; some of which have sat way longer than they should have and they always start immediately (and keep running).]
 
Hey Nerds,

Someone delete the extra postings for that last reply please...apparently my server isn't talking to your server out in the open 'cause it looks like nothings getting posted on my end when I hit 'Submit'.

'Puters! :evil:
 
Hi Les & Jon
I have the same problem on my BF90. Cold start, won't hold an idle. I've tried playing with the throttle / choke control to keep the RPMs up just over idle. Around 1500 RPM. However, when I'm just starting the motor, there are a hundred other thing to do to get the boat ready to go. What I've found works for me is to pull the choke lever on the motor, let it warm up a few min. then it holds the idle with out stalling.
 
Ok, I got a couple things I'm going to try. But first, what is the correct fuel supply line and prime bulb for a 90 Honda, 5/16 or 3/8?
When I had my fuel system installed at the P.A Honda shop, they ran a tee on the outgoing side of my external fuel filter like I requested. The thing that confuses me is that, one line going to the kicker is a 5/16 line and the line for the 90 starts out as a 3/8 nipple and fuel line on one side of the prime bulb and is reduced to a 5/16 on the other side of the prime bulb.
What the heck, I'm not a plummer but that doesn't sound right. I think the one prime bulb might be bad, so I'll try that first. When I can find out the correct fuel supply line and prime bulb, I'll give that a shot. I'm determined to defeat this problem! :smile
Jon
 
Jon,

Do you have a shut off valve on the kicker fuel hose at the tee?

This has been discussed before and its possible for the main to suck air back thru the kicker hose( plugged in to the kicker or not).

It is possible to change the valves in a primer bulb so as to have 3/8" in and 5/16" out.

Hope this helps some,
 
Larry, I don't have a shut off valve on the tee for the kicker. If it has been discussed that one is needed for this application, then I'll get one in.
I'm almost sure now that it's an air mixture issue, and a few quick changes should do it.
 
Hey Jon,

You've got a simple problem! Happens all the time, so go take a vacation and Cyndy Lou and I will take care of it. :wink:

Seriously, I'd block the 8 hp motor at the valve -- the simple way probably is to just make a direct connection to the main. Your problem could go away. If you still have the problem, I'd try a NEW hose and bulb on an aux. tank -- and if THAT doesn't solve it, give me an email and I'll come on over. Need an excuse anyway.

Dusty
 
Jon,

Here's one way to check a fuel system for air leaks.

Temporarily replace the portion of the fuel hose between the primer bulb and the motor connector with clear vinyl hose(from the hardware store).

Now run the motor( on a flusher) and watch the hose to see if air is being sucked into the fuel system. A few tiny bubbles are ok, but large air bubbles or pockets indicate a leak into the fuel system.

Be sure to replace the original rubber hose before using the boat.

I don't know if this will apply to your situation, but this simple test can rule out air leaks as a cause of your problem.

If you do find large leaks, check all the clamps, fuel filters, and hoses.
 
Thanks guys for all the trouble shooting ideas. My first test was installing 2 check valves at the tee and replace the questionable prime bulb. I started it up and it ran perfect, this time. :smile

I already had one check valve on the kicker line but none on the main line. I didn't know that the check valve was internal to the fuel line nipple fitting, so if I sounded confused before, I probably was. :embarrased

We'll see what happens, Jon
 
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