View Full Version : Hard starting Honda 1999 90 hp BF90

01-14-2010, 02:18 PM
"I have a 1999 Honda BF90 that only has 275 hours. The I bought it used with the previous owner only putting about 175 hours on the motor. It was maintained well, but barely used. I keep regular oil changes, treat fuel in storage, changed plugs, used cleaner in the fuel, and run all fuel out of engine when not in use for longer periods of time. It cranks over a while to get it started if the engine is not warm. It will even turn over it self a few times but then stop and I have to keep trying until it finally holds it's own. I have no problem starting the engine if the engine is warm. In cold temps is seems to take forever to get it to initially start. Once running, it runs smooth and to my satisfaction. Any suggestions on what might be causing this?"

01-14-2010, 04:11 PM
does that model have a manual choke ?

what is your starting procedure ?

01-14-2010, 05:38 PM
"You need to advance the throttle a pretty good amount and activate the choke as you are starting the motor. Also, be sure to pump the fuel bulb until it gets hard. Sometimes you may even have to sweeze it a second time if there is any trouble starting cold.

Depending on your key switch arrangement, you may have a toggle switch or you push in the key switch to choke it. If you do not hear any clicking when you activate the choke (with the key switch or the toggle switch), there is some issue with the choke solinoid.

Many times the plunger gets gooed up and does not move. You can pull it out and clean it as well as the internal part of the solinoid with brake clean and q-tips.

If it starts ok when warm, it is either your method of starting or something faulty in the choke system.

You can bypass the solinoid by pulling out the manual choke on the front of the motor. You still have to advance the throttle to start it cold."

01-14-2010, 05:44 PM
"I think its pretty clear that you have a fuel enrichment problem with the carburetor. Scott's question is to the point. If it has a manual choke, it is out of adjustment. It's more likely though that yours has an electrically controlled "SE" (start enrichment) valve and it may be malfunctioning or the passages in the carb for that circuit are plugged and need to be cleaned. Either way, unless you have a book and are a competent mechanic, it should probably go to a pro for repair.

Heed this piece of advice to prevent future problems. You need to DRAIN the carburetors when putting the engine up. Draining removes any moisture at the very bottom of the fuel bowls in the carbs. Running the engine out of fuel doesn't always get the moisture and sediments that are floating in that moisture out because water is heavier than gasoline and the engine doesn't run on water and will leave it behind. I'm talking MINUTE amounts here. It only takes a spec of mineral that you can barely see without a magnifying glass to clog up some of the carburetor passages.

Also, running your engine out of fuel on a very hot day could actually damage the engine. A lean fuel mixture can cause extremely high combustion temperatures that can damage pistons and valves. Not a good practice.

Also, DO NOT use "starting fluids" (ether) to bypass a cold start problem. You can easily ruin the engine with that stuff. As a mechanic, I would like to see "starting fluid" outlawed for anything other than the direst of emergencies.

Find yourself a good shop and they should have you back enjoying the water in short order.
Good luck."

01-14-2010, 07:20 PM
My bf50 electric choke is activated by turning on the ignition and lifting the fast idle arm until you hear the solenoid click.
At that point cranking the engine over for a few seconds will get a preliminary fire.(usually dies on a real cold day)
With the next attempt you may need to feather the fast idle arm for 10 seconds until motor gets going.

They don't like cold starts very much.

01-14-2010, 07:36 PM
"This 90 HP Honda has the standard choke that closes over the intake to the carburator. All Honda 90's that are carburated have a manual choke and most of the time the choke can also be operated electrically by push to choke, a choke switch, or as Scott said, raising the fast idle arm up all the way, which activates the choke by an internal switch in the shift box.

We just have to wait and see what setup Doug has and how he has been starting it.

If started correctly, the 90hp should hit just like Scott says his 50hp does."

01-15-2010, 05:51 AM
"Thanks for the replies.

This model does have a manual choke. As for the starting procedure, other than the obvious...checking oil, priming fuel bulb, etc., I have tried both engaging the choke either by the key switch and then the actual choke switch on the engine, both with similar results. Although, I have not attempted the engaging of the throttle method; however, the engine will not turn over unless the throttle is in neutral. I have actually been caught short on this one until I realized the throttle was engaged at the time of starting the engine. I will try to attempt to see if this will work during ignition, but prior will not all it to turn over.

I'm a little foggy on the fast idle arm, but if it is the lever next to the throttle and key switch used during ignition, I do not have this on my boat.

I have not used starting fluid. I've only used fluids to treat the fuel during storage and carb cleaning additives.

I should also mention, when inspecting the spark plugs, one plug was noticed to have more carbon build up than the rest. It wasn't an alarming amount, but was considerably more than the rest. The other three were in good condition based on the amount of hours ran at the time.

I was unaware of the of draining of the carburetors, so this could very well be a potential suspect into the problem. I will make this a common practice in the future."

01-15-2010, 03:34 PM
"I have to go on the assumption for now that you carbs are ok...since you said it starts good and runs good when it is warm.

You need to figure out how to advance the throttle without engaging the gears.

It will be very hard to start unless you advance the throttle!

If it is a Honda shifter, there is probably a black button at the bottom of your shift lever that you can push in (when you are in neutral). If you hold it in while you advance the throttle, the gears should not engage.

If you do not have an owner's manual, you can download one for free from Honda at http://www.honda-marine.com/owners/OwnerManuals/OM.aspx?modelGroup=BF90 ("")
Pick the one based on your serial number. It has several examples of shifters and how to start it with each.

One other thing...once the engine hits, you will need to release the choke and then give it short chokes, until the starts running smoothly. Give it plenty of throttle...but be ready to bring it back once the engine gets started so the engine does not overrev."

01-16-2010, 01:51 PM
Thanks for the info. I'll post my findings as soon as the issue is diagnosed.

01-20-2010, 08:10 PM
"if you need a factory manual, email me"

01-21-2010, 01:50 PM
"I have a manual that the previous owner gave me, but it seems more general and not specific to that type of motor nor setup."

01-21-2010, 04:29 PM
Take a picture of your shifter and your key switch assembly and post it(them). Then we will know how to tell you how to start it more accurately.

I really think it is just a starting procedure problem and probably not an engine problem.

01-22-2010, 01:21 PM

Will do. I am out of town on business at the moment. I'll be sure to post the pics late next week."

01-31-2010, 07:22 PM

I've tried numerous times to post the photo of the shifter, but it won't allow me due to file size issues. Any suggestions?"

01-31-2010, 07:49 PM
"Try emailing to me [email protected] ("")"

02-01-2010, 02:10 PM
"OK...for anyone else who is seeing this...Doug has a Honda S type shifter (made by teleflex) and a standard push to choke key switch.


At the bottom of your shift arm on the left side is a flat round rubber grommet about an inch in diameter. Grab the shift arm with one hand and giggle it back and forth while you push in on the rubber grommet (button). At some point you should feel the button go in little more and the shift handle release and you can push the shifter forward without shifting into gear. If you can not get it to release, there may be a problem with corrosion...and the motor will not start easily.

To start the motor....You need to push that button and advance the throttle about 1/2 to 3/4 of the way. Make sure the fuel bulb is squeezed hard. Turn the key to on and push in the key to operate the choke. You should hear a click from under the motor hood. If you don't hear it...push it a couple of times until you do. If you still don't...take the hood off and have someone watch the carburators when you operate the choke. There is a black plastic rod connecting all the carburators that should move up and down when you operate the choke. If that doesn't happen, pull out the manual choke on the front of the engine...that should operate it.

While still having the throttle advanced, continue to hold the key in to choke while you turn the key to start. The motor should try to start within a couple of seconds.

Once it starts, you may have to push the choke in a couple more times briefly and/or adjust the throttle before it runs smoothly. You may even have to squeeze the fuel bulb again.

Since you said that the motor starts and runs good when it is warmed up, I am assuming the motor in general runs ok...therefore, these starting proceedures should get you going."

02-03-2010, 07:22 PM
"It worked! Cranked over the first time.

When I bought the boat, the original owner didn't show me the proper procedure, but did display that the boat was in good working order. I was unaware of the rubber grommet's function.

Thanks for all the help!"

02-03-2010, 08:39 PM
Thank goodness for the simple things!!!

Happy boating.

04-23-2011, 01:19 PM
Can you describe the procedure of servicing or replacing the electric choke on the BF-90. Thanks.