1997 BF15 fuel delivery problem or stuck valve/lifter?

[yukonerdave]

Hello

New to this forum and I'm looking for some help diagnosing an issue with my 1997 BF15. The motor runs great 90% of the time but every once in a while I get a hard stutter at start-up, or when coming down from an open throttle. Occasionally it will also happen while putting along at low RPM. It never happens at mid-high RPM. It will often last 5-10 minutes while I try restarting. When it is stuttering it is unresponsive to opening the throttle, except that it will die if I open it too much. Eventually, whatever is causing it will become unstuck and the engine will rev up normally again.

I've replaced the fuel tank, all the hoses, and the filter, and ultrasonic-cleaned the carburetor thinking that dirty fuel was causing a partial blockage, maybe in the carb. The carb is whistle-clean now but I get the same issue. I am starting to think it must be a stuck valve or intake port. I ran some fuel additive through and a valve cleaner product to the crankcase. Didn't help.

I'll add links to 3 videos; one showing the stutter problem, one showing it operating great at high throttle, and another showing it idling properly at low throttle.

I'd really appreciate any thoughts on what is causing the stutter and how to fix it; it is frequent enough that I don't trust the motor to get me home.

https://photos.app.goo.gl/XG29MZfTCA9475248

Thanks a ton

Dave

[racerone]

I think you have ignition / spark issues.----Does spark jump a gap of 5/16" on both leads ?

[racerone]

deleted

[yukonerdave]

I think you have ignition / spark issues.----Does spark jump a gap of 5/16" on both leads ?

Hey thank you for the reply. I put new plugs in but didn't check the gap so I'll look at that and get back to you. I'm curious, though, why you'd think it is an ignition/spark issue? Wouldn't that cause problems at higher RPMs just as much (or more so) than at low RPM? Does it sound like only one cylinder is firing when it is stuttering like that?

[William01]

77

jgmo
Outstanding Contributor

Join DateNov 2009Locationtemecula, ca., usaPosts4,224

Re: 2015 9.9D Not completely broken in

Well, I don't know. Why did you decide to not use the new SE valve? Maybe you should install the new one and try it again.

Other than that, have you tried squeezing the fuel bulb when it's falling on it's face? Being that it's "not broken in yet" it shouldn't have a fuel pump problem but who knows?

I also think you should try doing a "cylinder contribution test".

Here's how:

Pull the spark plug wires from the spark plugs and smear a very small amount of dielectric grease (tune-up grease) inside the edge of both plug wire boots with a toothpick or small screwdriver tip. Reinstall the wires, seating them on the plugs firmly.

Start the engine and then pull one plug wire and note the change that makes. Reinstall the wire then pull the other one and compare the change that one makes to the first.

The engine may die when the wires are disconnected and that's ok but these engines will often run fairly well on only one cylinder UNTIL you ask for some power. I hope you see where I'm going with this.

The cylinder that makes the LEAST or NO difference in the way the engine runs is the weak or non contributing cylinder. Often it's simply a bad spark plug.

Make sure you use insulated pliers or a thick DRY glove or towel to handle the wires to prevent getting shocked. If you have a PACEMAKER, then DO NOT DO THIS! Find someone else to help you get it done though.

Standing by....

A cut and paste from my issues. My plug boot felt loose so I took a screwdriver and gently squeezed the receptacle tighter. Solved the last of my issues.

[racerone]

When testing maximum ignition output you do not use the sparkplugs.----And the sparkplugs are not used when doing this testing.---Sparkplug gap has nothing to do with this test.----You use a testing device.-----But, good luck sorting this out.

[jgmo]

As racerone suggests, a "spark tester" is a good tool to have and they are very inexpensive.

But it's pretty evident that the spark is GREAT when it's not "stuttering"

Makes me think something is loose someplace.

Check the wiring at the kill switch
Check the wires at the ignition coil
Check the wire plugs for the exciter coil (see item 2 in link below)

https://www.boats.net/catalog/honda/...99999/flywheel

Follow the wires from the exiter coil connectors and make sure they are terminated securely at the other ends. That may involve checking the wiring harness (item 7 in the link below). Pay particular attention to grounds such as the one for the eyelet for screw item 9 in the link.

I also recommend unplugging and spraying contact cleaner on the CDI contact terminals. Gently clean any corrosion you find being very careful as few to none of these parts are available.

https://www.boats.net/catalog/honda/.../ignition-coil

In addition to those things you may want to locate the wire plug connectors for the pulsar coil. That coil is located under the camshaft pulley. Item 5 in the link below. It's no big deal to remove the cam pulley as long as you pay attention to the engine timing while doing so. Removing the pulley and checking the pocket that the pulsar coil sits in for water, dirt buildup or rust could become necessary if you can't locate the problem someplace else.

Getting late...if I think of anything else I'll get back to you.

Good luck.

https://www.boats.net/catalog/honda/...99/timing-belt

[jgmo]

I forgot (slap the forehead) to say that William01 could very well be right about a loose spark plug connector and that should have been #1 on my "check for loose connections" list. (Slap forehead one more time).

Also, I see that the wire end caps (items #6 in link) are still available should you need them.

https://www.boats.net/catalog/honda/.../ignition-coil

Good luck.

[yukonerdave]

I went through most of the electrical connections and everything looks clean and tight. I'm assuming the coil and exciter coil are located under the flywheel but I'm having trouble pulling it. I have the main bolt off. Should it come up and off? I could pry or pull it with something but I don't want to try that if there is something else to do first. Any chance anyone has a PDF of the service manual for this model?

[yukonerdave]

Alright here's an update.

I got it started to test the spark plugs, and it started with my problem stutter. Pulling either plug cap made it die immediately. I tried several times with both to be sure. THEN, I tapped on the CDI with a screwdriver and it immediately started idling properly and revving up. I like to try that a few more times but I need to wait till it goes back to stutter mode now. Now when I start it, it starts and idles normally. With it running normally I tried pulling the plugs one at a time. It runs with either one removed, but it sounds very different when running on one cylinder as opposed to my stutter problem. So that all makes it look like a bad CDI right? Too bad it is a $160 part...

[yukonerdave]

4 times out of 4 now, tapping on the CDI fixes the problem. Of course now that I started doing that, it seems that I am getting the problem more frequently. Anything else I should think about or check before replacing the CDI? I'm assuming they can't be fixed, and like I said, it looks like the connections are all clean and tight.

[jgmo]

Well, that's a bummer if it's the CDI.

But, keep in mind, when they made those they encapsulated them in epoxy to make them pretty dang hearty. Of course it also makes them impossible to repair.

Before condemning tha CDI, check and double check that each wire is solidly connected to it's connector socket and that the pin fit between pin and female socket has an absolutely snug fit. It's about all you can do to make sure you are spending the money wisely.

Good luck and please keep us informed.

[racerone]

Well----I thought it was a spark issue in post #2

[William01]

Service manual possibly. I found an “A” and “D” series service manuals. Unfortunately they don’t supply much information on which manual covers what years.

https://www.selffixer.com/outboard.motors/honda/

[jgmo]

All the 1997's are "A" models.

[jgmo]

Your manual is the 13th one down in the scroll list in the link below. It is a "combo" manual for the 9.9hp as well as the 15 hp A models

https://publications.powerequipment....hp--3-body-01a

[jgmo]

You DO NOT need to pull the flywheel for this problem. The fact that it runs ok at times indicates that the exciter coil is ok.

If you ever need to pull the flywheel though, you will need a wheel/gear puller. The puller works by pushing on the crankshaft while pulling on bolts threaded into the two holes in the flywheel located on either side of the center hole.

When doing this "operation" you need to be cautious because it is possible to damage the flywheel or to be injured. Sometimes the flywheel and tool will "jump" up when it releases and that could hurt you if you're not prepared.

[yukonerdave]

One more thought on this. I changed the oil when I noticed that it was a little low (less than half on the dipstick, but still above the "low" line. Got me thinking that my problem only ever happens at low RPM, and at low RPM maybe the oil pressure drops enough to cuase an issue? Does the CDI on these engines force a limp mode if the pressure gauge registers low oil pressure (or if it overheats)? The green oil light has always been on as far as I can remember, but it does flicker at low RPMs.

[jgmo]

Well, I can't say for sure about that year engine but I know that later models don't shut down the engine because of low oil pressure.

The later outboards de-rate the power to a maximum of 1800 rpm during a low oil pressure situation but the engine will continue to run.

Ironically, the same outboard DOES shut down during an overheat event.

I have always wondered about why they decided to do it that way.