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Honda BF50A Trouble restarting after running great for hours

B

B Fleck

New member
Hello @ Marine Engine Forum,
I've been struggling with the twin Honda BF50A motors that power my 19' 1997 Arima Sea Ranger. The boat also has a Honda 9.9 hp. All three motors feed off the same onboard/internal 48 gallon fuel tank off a seperator with a filter. The serial numbers on the 50 hp tags if it's of any relevance are BAZL-1002135 and BAZL-1008666. My issue is the motors will always fire up immediately, 1st turn of the key at the dock. They will run flawlessly, sometimes for hours. When I turn them off, be it for a minute or a half hour or an hour, they will refuse to restart. Thinking I may have had a fuel line issue, I replaced all three with new primer bulbs and new couplers to the motors. I've changed the filter seasonally the last two years.

A bit of history on the boat. I'm the 3rd owner. I bought it from my Dad who owned it since 1999 I believe. It's been in the garage and used very little in the grand scheme of things for most of it's life. If it ever was used in salt water, it was in the late 90's and very little.

A local motor mechanic suggested the next thing I should replace should be the anti-syphon valve(s) on the fuel lines. I'm not entirely sure I'm looking at the right part and was hoping someone could confirm they are in the brass fitting going out of the filter in the attached image.

I've had others suggest I should check the water pumps. All of them have great streams of outgoing water pressure when running so I don't think they're struggling to get cooling water.
Beyond this, can anyone please assist what I should troubleshoot next?
 
Hi,

Jusr letting you know that no photo was attached to your post. I find that I usually need to reduce the file size to 40% or lower to post pictures here. It doesn't seem that doing that harms the picture quality much at all.

It wasn't clear to me, from reading your post, if the no start issue is with all three outboards or just the two 50hp. ???

Another thing that's confusing to me is that it seems as if you use three different supply hoses with primer bulbs to feed each outboard from that main tank. Could you please clarify how you get fuel from the big tank to each outboard?

I'm no Honda 50 expert. I've never even worked on one.
But the only "anti siphon" or one way check valve I'm aware of in a 50A fuel system is the one in the fuel supply hose primer bulb. That check valve CAN allow "drain back" to the tank if the flow arrow isn't pointing slightly upward so that gravity helps the valve fully seal when the pump isn't pulling fuel.
 
Hello Jgmo. The image I tried to attach was from a filter that is fed from the onboard 48 gallon tank. I tried to attach again for reference. All 3 motors feed from this same filter. (1 50hp and the 9.9 are spliced to feed both). Only the 50hp motors are the ones giving me grief. I've made sure the arrows all go the right way towards the motors and the issue is pre and post replacement of all fuel lines, primer bulbs and couplers to the motors themselves.
 
Contact the administrator about the trouble loading pics. They arr friendly and helpful. There's been some recent marketing spam so it could be something related to preventing that.

Those primer bulb arrows need to point upward to ensure the check valve always works properly. They don't need to be vertical. Just angled up slightly should work. But if yours are already angled up slightly, then trying to get a bit more upward tilt might improve things some. Worth a shot anyway.

Make sure there's no chance that air could be getting pulled in someplace. Fittings and that filter could be suspect. I don't know.

Good luck.
 
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Thank you. I know the fuel lines are a bit longer than the perfect length. I will make it a point to orient the arrows in an upward position and keep checking boxes.
 
You're welcome.
Yes, checking boxes is about all you can do to find the cause.

I know the Keihin carbs on these pretty well and have studied the Honda carb manual. I have two editions.

While this does sound like it could be fuel starvation problem. It doesn't sound like a carb issue to me. I'm not always right of course.

Thinking about what your mechanic suggested, you may want to inspect the acceleration enrichment/anti stall dashpot check valves.

Those don't handle fuel, they control air flow to and from the carburetor's main well to provide for accelleration enrichment when going full throttle and throttle delay when rapidly closing the throttle to prevent stalling.

I wouldn't think that they might cause your no start but your guy may know something I don't.

Item 40 in link. Yours should be black and silver with the black side receiving air from the throttle dashpot and the silver side delivering that air to the carb wells via the anti-stall pipe (38) and bulk fuel hoses (49) (50)....they're really air hoses but need to be fuel resistant.

When blowing air lightly into the silver side, there should be no flow allowed.

A puff of air to the black side nipple from the dashpot diaphragm when the throttle linkage is opened quickly should exit the silver side nipple.




Besides that, a "check the box" suggestion I have is to verify valve clearances. Especially if you don't know when or if they were ever checked/adjusted before.

I'm trying to think of things that would effect both ouboards at the same time. While it is enrirely possible something like this could be electrical or even cooling related, niether would be likely to happen simultaniiusly to both engines.

However, the engines being the same age with identical service lives made me think of the valve lash wear on both being the same.
 
J,
Thank you for all the additional information! I had a look at my new fuel lines when I got home. Being a little longer than necessary, the are by default with the arrows on the primer bulbs aiming down. Something I've never thought about running outboards my whole life being an issue. I did pull the extra hose through the bulkhead so that when connected to the motors they should stay in more of a vertical position.

I will have a look at the diagram and comp it to my motors and try the test you mentioned as well. Not sure if it matter but my serial numbers are a lot lower than the 3000001 series it references but I would think mostly similar components. I can practically guarantee NO valve work has ever been done on these motors. My Dad ran the boat more than I likely knew about since he's been retired but because he has other boats and is a baby boomer that abhors buying fuel, has primarily always fired the 9.9 from the launch for us to fish with. If I had to bet, the 50s probably have less than 1,500 hours on them in their 30 years.
 
Yeah, the outboards are older than the hull then. My mistake.

Here's the page for your vin #s
As you can see, pretty much the same.stuff.


1500 hours isn't much so my valve clearance theory might not hold up.

But I would check them anyway because enough wear could take place enough to change things.

A large amount of wear can take place during break in hours if the oil isn't right or if run too hard.

I agree about the check valve angle.

Theoretically they should work in any position. But I found out the hard way that there are different designs and quality. A replacement might not work as well in many cases.

I never paid any attention to it until it became an issue with a particular boat. That's when someone else suggested pointing it up and the priblem went away. Point them up ever since.

How long the hoses are could be a factor too. I'm no hydraulic flow expert but I'm sure there's a formula about supply line diameter and length.
 
The filter feeding the engines from the tank is likely a water separator, spin on. Anytime you check it, drain it’s contents in a clear container to check for water or dirt.

Many running issues are caused by fuel being old or full of water or dirt. In addition, using a fuel additive like sea foam once a year can clean out varnish type crap in your carbs and the valve train.
 
You might consider runinng the 50 that's not fed adjacent with 9.9 on a portable tank to see if the problem changes for that unit.

The fuel pressure specification for the 50A is listed as 2.8 lbs. That indicates that the "lift" or suction value of those pumps is likely quite low too. So, again, their sensitivity to supply hose restriction and friction is a question for me.

Are you positive the gas your're running is ethanol and methanol free? Carb manual lists 10% maximum (E-10) is allowed for Honda engines. 5% methanol is allowed too but it has to contain certain lubrication additives and corrosion inhibitors. I would avoid both if possible.
 
When I get my hands on the spare tank from my Dad, I'll test it on the starboard motor first for sure. It gets the dedicated line (un-spliced) from the filter.
Also, although I occasionally buy 5 to 10 gallons from a dock side pump or otherwise that has some ethanol, I make a point to source No E fuel for these motors and any other small engine. I know they're not a Top Tier fuel, but my only option for this locally is usually Maverik stations.
 
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