Logo
FULL SITE MENU

Honda BF15D, intermittent can't re-start, primer bulb only 80% hard after many squeeze

H

Honda_boy

New member
The engine can start from cold crank smoothly in the morning. I turned it off for 5 minutes in the middle of lake. When I wanted to continue cruising, it can't be started for no reason. I noticed that the primer bulb can only be squeeze up to 80% hard, not fully hard as I firstly prime. We rested for around 2 hours in the middle of lake, then everything be fine again. Such intermittent starting failure happened three times in the last week. By the way, the fuel line, primer bulb, fuel filter are all newly replaced. Can anyone shed lights on this issue?
 
I don't know a thing about that engine. But what you describe sounds like vapor lock. Is that engine carburated or fuel injected?
 
Shouldn't have to touch the primer bulb, you could be flooding it. Only other thing that can cause that is insufficient valve clearance, could be holding valves ever so slighly open when hot.
 
Was it doing this "behavior" BEFORE the fuel supply components were replaced? If not, then the problem may have been introduced during that work. Have you drained all the fluid from the fuel chamber? Item #2 in the link below.
If not, do so. That device collects water over time and can cause starting and running problems.

Honda Outboard 15HP OEM Parts Diagram for Fuel Pump (1) | Boats.net

Buy OEM Parts for Honda Outboard 15HP Fuel Pump (1) Diagram
www.boats.net www.boats.net

Check that fuel tank vent is fully open and clear. Check the fuel tank pickup tube for cracks.

When the problem occurs, take off engine cover and look for any gas leaks at carburetor and fuel pump.

Make sure that gasoline is not entering the engine oil. If so, change oil and filter immediately and determine source. A failing fuel pump will leak gas inside the engine.

Good luck.
 
jgmo said:
Have you drained all the fluid from the fuel chamber? Item #2 in the link below
Click to expand...
How do I drain fluid from the fuel chamber? I only know drain fuel from carburetor by adjusting a screw. Is it the same procedure?
By the way, since the primer bulb is only 80% hard, can't squeeze it to fully hard, do you think it is something related to fuel pump, which is item #1 in your link above?
 
There is a black water separating chamber down in the pan below the carb mount in a rubber holder which is secured by the dip stick tube.It needs to be removed and emptied using compressed air. I would still check valve clearances, particularly since you say it runs fine until you turn the engine off.
 
Yes,
Do what Ian says. Take the chamber off and empty it completely. Compressed air like he says or shake it , shake it, shake it until it's dry.

I also agree with checking the valve lash. If the valves have never been adjusted, there's a very good chance that one or more is tight and that's never good.

While your under the rocker cover is an excellent time to inspect the fuel pump for possibly leaking.

You will likely need a helper to check the pump.

With all the fuel lines, fuel chamber and carb hooked up normally, squeeze the primer and watch for fuel leaking inside the engine from the end of the pump. With the primer bulb still being gently sqeezed, rotate the engine as slowly as you can while watching the camshaft lobe depress and release the the plunger for the pump. If you detect any leakage there, replace the pump and change the oil and filter.

Sorry, I should have asked before....
What year is your outboard?
Pull start only or electric?
Remote control or tiller?

Good luck.
 
It is 2003 Honda BF15D, pull start only, tiller, carburetor.

Let me recap the issue: It is fine with cold start, but not hot start.

As Ian and Jgmo mentioned above, I have checked no fuel leak around fuel pump, have taken out and emptied the fuel chamber, have drained out old fuel in carburetor, new fuel filter, new fuel line with primer. But I haven't checked valve clearances as I am not sure how to do it yet.

It is still hard to hot-start so far, however if I turn throttle wider to 1/3, it can hot-start successfully. (I turned throttle back right after it starts.)

Is it a good or temporarily solution to hot start by turning throttle wider? Should I continue to check valve clearance?

Thank you everyone.
 
Ok....that added bit of info from you has me thinking I may have a solution for you. But more about that later....

Again...
Valve adjustment...
....has that EVER been done on this 20 year old outboard?

If you don't know then it at LEAST needs to be checked.

And, yes, you're right, you need to learn how to do it because it's VERY important. Not hard, but important.

If the valves get too "tight" due to wear, the engine could be badly damaged.

You'll probably need a service manual to do that. And, with all the slipshod, fly-by-night, flat out rip-off, so called "repair shops" out there STEALING people's money and RUINING their outboards....
...I urge you to get that manual and do the work yourself.

You can buy the AUTHENTIC shop manual here:

Honda Marine | Shop Manuals Publications | Honda Power Products Support Publications

publications.powerequipment.honda.com publications.powerequipment.honda.com

The manual is expensive but worth every penny if you care about maintaining that sweet 15 and staying out of the clutches of the flim-flam outboard repair pirates.

The "discount alternative" manuals like Seloc, Haynes, Clymer and others aren't worth the powder it takes to blow them to Washington D.C. so don't be tempted.

Besides information you will need a standard set of feeler gauges and a very tiny adjustable wrench.

Read what I wrote about checking the pump for leakage in post #8 of this thread. You do that while the rocker cover is off and AFTER checking/adjusting your valves.

Now, back to your hot start problem.

When you say opening the throttle helps that indicates that it may be in a "partial flood" condition. That says to me that there's a problem with the "choke".

I put quotation marks around choke because this carburetor doesn't have a conventional butterfly type choke. It has a cable actuated "enrichment valve" instead. The "valve" is nothing more than a pellet bonded to the end of the choke cable.
I don't like this system because, when the cable housing gets worn the valve won't work properly. You cannot adjust it either. The only solution is to replace the entire cable assembly.

And, to top it off, the parts book is misleading. It shows the cable....item 17 in the link below and the "valve set, starter"....item 11... as being just the housing.
But....if you buy item 11, you get the housing AND the cable as an ASSEMBLY.

Believe me! ONLY BUY ITEM 11!

DO NOT buy item 17!


Honda Outboard 15HP OEM Parts Diagram for Carburetor (Manual) | Boats.net

Buy OEM Parts for Honda Outboard 15HP Carburetor (Manual) Diagram
www.boats.net www.boats.net

I can tell you from experience that the cable (item 17) can NOT be easily mated to your existing "housing". Anyway, your housing is likely causing this problem as it is so trying to reuse it with a new cable would be futile. Just purchase item 11 and carefully install it.

I say carefully because the threads are plastic and are easily stripped. So don't overtighten.

You asked if starting the engine with 1/3 throttle would hurt and I will say probably not as long as you immediately close the throttle on start up.

But....running the engine rich all the time with the choke partially open will eventually cause issues with carbon build up and plug fouling. That along with excessive fuel consumption and the hassle of fiddling with the throttle every time you want to go makes replacing item 11 worth the trouble and the $26.48 + tax+shipping.

BF15D....one of the BEST twin cylinder outboards ever produced! You own a GEM!

Good luck.
 
Thank you so much Jgmo for the informative reply. The motor is new-to-me last month. I will definitely buy the service manual you recomemended and learn to adjust the valve clearance.
 
Great! Please don't forget to update us with how it goes.
You really did make an excellent choice buying that outboard. But, even diamonds need a good polishing once in a while.
 
Hi Jgmo, I eventually made the adjustment on valve clearance based on the instruction from the shop manual this afternoon. Unfortunately the hot start still be hard. The temperature is 12 degree then. I pulled the recoil rope to cold-start with choke closed , just one pull can make it start. I turned it off after kept it running/idling for 3 minutes. Ten minutes later, I tried to re-start, with choke open/closed/half open, but it was never successful. Just wondering (1) what else I can check for easy-cold-start, but hard-hot-start issue? (2) How to determine if choke should be in full open/full closed/half open to match with throttle turn in different scenario ? Is it experience based judgement?

(P.S.: Honda 2003 BF15 4 stroke 2 cylinder, carburate type, manual tilt, pull start, new fuel line, new fuel filter, fuel chamber shaked and drained, valve clearance adjusted)
 
As you guys mentioned about vapor lock, what should I do to solve vapor lock? I already drained the fuel chamber, and adjusted the valve clearance adjustment.
 
Hi,
I don't think this is vapor lock.

I've never seen any Honda D model twin engine vapor lock and I live in Southern California where it often gets above 100° Fahrenheit.

Since you say it starts first pull with no choke in cooler weather (12°C) my best guess is that the START ENRICHMENT valve (choke) isn't completely closing.

This would explain that as well as the hot hard starting. The enrichment valve not closing will have the engine running rich and possibly flooding when trying to hot start..
That explains why you can often start it by opening the throttle because that's exactly what you do to clear a flood condition.

Those enrichment valve components wear out and need replacement after a few years.

If it were mine, I would remove and clean the carb and replace the enrichment valve parts. It's a real PAIN but I think that will fix the problem. At least I hope so.

See items 17 and 11 in the link below.


I said before to only replace item 11 but I have since learned that is wrong. You should buy both 11 and 17 and replace as together. Honda doesn't sell the two items pre assembled any longer so you have to assemble the two yourself. A REAL PAIN!

BUT, before doing anything, check to see if the enrichment valve is firmly held in place where it screws into the top of the carburetor. The threads are made of plastic and wear down. I have snugged them up for a temporary fix by wrapping in Teflon tape.
Eventually though, you likely would still need to replace.

I say clean the carb because the other thing that might cause these same symptoms would be a float that is sinking or is mal-adjusted.

Good luck.
 
Back
Top