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1999 BF30A running rough and hard to start

S

swebster

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I have a 1999 BF30A that won't idle properly, so I thought I would post my adventures in attempting to fix it for others to benefit from my efforts.

I love and HATE this motor. Will I ever buy a carbureted motor from Honda in the future? Not a chance. I still cannot believe Honda still sells new BF30s today with carbs meanwhile the rest of the world has moved on to FI fuel systems. Anyway I digress. The motor, despite the carb issues, has served me well. I have had it for 21 years and it powers my 13' Zodiac that sits on the back of my boat. Over the years I have torn down and rebuilt the three carbs at least a dozen times, and replaced the #3 carb once.

Tip #1 (and I am sure most boaters already know this) do NOT run Ethanol fuel in these engines (or any small carbureted engine for that matter). Ethanol wreaks havoc on any rubber parts in the carbs and fuel systems in general. I have not used Ethanol gas in mine for years but I am sure some people might still be doing this. So stick with the Ethanol FREE fuel. This is especially an issue if you do not drain the fuel from your carbs after use and you let the engine sit for a long time (weeks, months) without running it.

I had a number of issues with my BF30 that have been festering over the last few years so I decided to spend some time (and money!) trying to fix them.

Issue #1 - Years ago when changing the thermostat, one of the bolts that holds the cover on, broke off in the block. I've noted others on this forum ran into the same issue. I "fixed" mine years ago by using "metal" epoxy to seal up the cover. That worked for a few years, but eventually it gave way and I kept having to replace the epoxy. SO it was time to fix it properly. Bought a new thermostat cover, drilled out bolt holes, tapped them with slightly larger threads and put in new stainless bolts I got from Lowes. After replacing the cover and gasket, I noticed the gasket for the water jacket, behind the thermostat, was also leaking slightly, right behind the thermostat housing. I sealed that as best I could with Red RTV Sealant. The proper way to fix THAT is to remove the water jacket cover, and replace that gasket, however when I tried to remove THOSE bolts, the first one I tried also broke off, and I was not keen or hauling the boat out of the water to work on that bit at this time. I am sure I'd be drilling out and tapping another 6 or 8 holes. That will be a job for the next haul out. (My Zodiac sits on the back of my boat, on a lift, and does not come out very often). During this job, I also replaced the impeller and the rubber hose that runs under the engine for the overboard discharge of cooling water. The cooling system is good now.

Issue #2- The motor was not idling reliably and running very rough, so I figured it was time to deal with the carbs AGAIN. This problem consumed quite a bit of time (I spent the better part of 2 weeks off and on) trying to solve this problem. Below are the things I did in my efforts to solve it.

Step 1 - I removed the carbs. Incidentally, if you are going to clean/rebuild the carbs (on BF25/30) don't do what I used to do, which was to individually remove the carbs from the motor. That approach is a super pain in the ass, and, if the boat is in (or in my case, over) the water, it is a recipe for disaster and lost parts into the drink. It is easier to disconnect the throttle and choke linkages, and then 4 bolts and two nuts on the intake manifold, and presto -- the whole intake manifold, carbs and intake muffler all come off neatly. You can then take the entire assembly home and work on it on a bench.

I dismantled the 3 carbs, cleaned them, cleaned out the jets (yes remove the jets if you are doing this!!) and I replaced all the o-rings and rubber gaskets. Honda has a gasket kit for this (16010-ZV4-005). When cleaning the carbs, take a close look at the float valves to make sure the rubber tips are not worn - that can cause them to stick or, not seal properly. After cleaning and reassembling the carbs, I reassembled the intake system, making sure to use new gaskets (16221-ZW2-000), a new gasket between the intake muffler plate and carbs (17384-ZV5-000), and lastly a new intake manifold gasket (17151-ZV7-000). The goal here is to eliminate air leaks in the intake system, which will cause all sorts of headaches. After doing all this, I put the intake system back on, and.....it ran better, but, still not running properly. I took the intake system back off, and decided to replace all the fuel hoses, and vacuum hoses on the carbs, checked the dashpot valve while I was at it (it was setup wrong) but....still no joy.

Step 2 - While troubleshooting, I noticed when I squeezed the fuel bulb to prime the engine, gas was coming out of the fuel pump. I also noticed the chamber in the pump that fed cy 2 and 3 was not really moving much fuel. Time for a new pump. I found a used pump on eBay and installed that. It fixed that leaking issue, however, the motor still had the same rough idle and would stall and not function at low idle.

Step 3 - Thinking I may have contaminated fuel, I replaced the fuel in the tank with fresh stuff, changed the engine-mounted fuel filter, as well as the water separator filter. That did not solve the issue either. I thought the issue could be fuel, because, after all my work, the engine would idle nicely but then after a while it would run very rough and I'd have to raise the idle setting to make it idle. Incidentally, in all of this, I also adjusted the mixture (for best idle) and balanced the carbs with vacuum gauges. Still, no joy - it would work for a while then run very poorly.

Step 4 - Thinking I had eliminated all things related to the fuel system, I decided to turn my attention to the electrical side of the engine. In the past, most of my woes were related to the carbs, hence my initial focus there, but I had done everything I could think of to address that side of the engine with some noticeable improvement, but still not completely solved.

I checked the temp sensor and it seems ok, per the testing instructions in the BF30 shop manual.

Time for a "drop cylinder" test. I ran the engine, and pulled off plug wires, one by one, with the engine running, to see if it made any difference. Be CAREFUL doing this -you can get a good shock, so use a well insulated pliers to pull them off. When I removed the wires from the #1 and #2 cylinders, as the engine was running rough, it made NO DIFFERENCE to the operation of the motor! That told me I still had some issues with those two cylinders not firing. I changed the spark plugs - no improvement. I removed the coil packs from the motor and tested them (per the shop manual), but testing the primary side of these coils (between the two terminals) is tricky - you need a very sensitive ohm meter as the resistance here is only supposed to be around .15 - .25 ohms, and most cheap ohm meters will just read this as a dead short. I took off one of the plugs at the sparkplug side of the coil pack and noticed the wire was very corroded (it was dark/black in color). Next money to be spent therefore was new coil packs - Honda offers a kit for around $70 (30500-ZW2-F01). If you buy them individually it will be $150, so just get the kit. I installed the new coil packs, and PRESTO, the engine ran MUCH better!

So, while the carbs did need cleaning, a key part of my problem was the plug wires being very old and corroded. I am still doing some testing. The motor is running much better, but I am still noticing at times, when it is hot, that the idle becomes rough (too low) again, so I am going to now go back and double check the balance on the carbs, now that I have a much better spark from the new coil packs.

Hope my trials and tribulations are useful to others on this forum. If anyone has other ideas to offer, I am all ears.
 
Just to provide a counterpoint. I work on a lot of the carbed Honda's because they are SO much simpler to work on, preferring them to the injected motors. And I run any fuel that's handy.

BUT

I'm careful about not leaving the motors set too long (2-3 weeks) without fuel treatment or draining the carbs (VERY simple). I would suggest you need to be just as careful when running non ethanol fuel. As far as ethanol based fuel eating up any rubber parts in an outboard, that's hogwash. The engine manf's dealt with that issue MANY years ago.....

If a carbed mid size Honda isn't idling right, MOST times it's about the tiny concealed jet hidden inside the brass tube that runs from the bottom of the float bowl to the top of the carb. Fuel metered through the jets in the carb throat at idle MUST pass through that jet. If it's plugged they are starved for fuel and the engine isn't going to idle. There's more to it, but that's the most common issue. People don't see that jet when cleaning. Noteworthy is the fact that this jet is tiny, not much bigger than a human whisker. That's why it plugs up so easily, especially when not in use.

I would MUCH rather face a set of dirty carbs than an electrical issue, plugged fuel injector, or any of the other myriad of likely characters when dealing with a balky fuel injected motor. The injected motors really run nice, until they don't.....

As far as the broken bolts (it happens, especially in a salt water environment), rarely would I drill them oversize. There's no need, unless dealing with something like a head bolt, which would receive the heli coil treatment.

Broken bolts can generally be avoided with a regular maintenance program where anti seize compound is used on reassembly. It's only when dealing with what I call "break down maintenance programs" that you must deal with those. -Al
 
Hi - thanks for the feedback.

I just find FI engines are less maintenance overall. I find injectors easier to deal with than a carb. That said, I have become pretty good at taking my carbs apart, cleaning and reassembling (and yes I always pull out the jet from under the screw to clean it).

As for the fuel, I have seen first hand the effects of the Ethanol, and not all manufacturers have switched to components that are Ethanol safe, especially on carburated motors - FI motors typically are not affected by the Ethanol. I can post a few pics of the sort of things I have seen with carbs. All that said, as you point out, nothing beats draining the carbs, and/or running them dry (disconnect the fuel feed and let it run till it stops, and then open the drain valves on each carb) before putting the motor away for a period of time. I typically drain mine, but I have to admit there is the odd time I leave and anchorage in a hurry, or get distracted, and bring the Zodiac up, and I do not always remember to drain the carbs.

Took my Zodiac for another series of runs this morning at all throttle settings. My BF30 is running beautifully once again.
 
Point, counter point.
Good stuff guys!

I would like to say that I like both fuel strategies. Today's fuel injected engines are very reliable and actually pretty simple to maintain and troubleshoot for the most part. But fuel injection requires that you run a 12 volt battery with associated charging system.

A small outboard with carb or carbs, doesn't even need a charge coil to run and, in certain applications, that can be a real plus. Like waaaay off grid for example.

As far as cleaning carbs go, I've never seen "ethanol eaten" rubber parts in Honda carbs I've worked on. Maybe I'm just living right?

I find mineral deposits from condensate water to be the biggest culprit in carb problems. All fuel contains SOME water. And, not draining the float chamber on a carb that's not going to be used for a time is just asking for problems from mineral deposition.

Most folks CAN'T properly clean these carbs. The reason is that they don't have a THOROUGH knowledge of how they function.

Take the main jet dip tube Alan references. Not all the carbs have those but, if they do, they typically get overlooked.

The slow air and high speed air feeds don't get cleaned properly, if at all, either. Along with (for carbs equipped with them) accelerator pump circuits.

I can say these things because I have made just about every mistake cleaning Honda carbs that can be made. And I too used to tear them down, clean them (sonic cleaner...check).put them back and....take them off again to find what I missed. ????
.
UNTIL a famous guy on this forum....hondadude....told me to buy the HONDA MARINE CARBURETION MANUAL.

Now, like all Honda manuals, this one too leaves some questions unanswered. But it is comprehensive enough that, if you read through it a time or two, you can get a Honda carb completely clean in one sitting and not 3 or 5 or 15.
 
Man, would love to say I can clean a set of carbs and have them run right first time every time, but it would be a flat out lie. Though I am pretty good with them nowadays (about 3 hours start to finish), it darn sure didn't start out that way. A carb rookie needs patience! With patience, there's no rocket science involved. Absolutely possible for a DIY'er.

I started doing Honda carbs when I was working on the old 70's and early 80's Honda Goldwing motorcycles. Exact same issue, with the same symptoms, with an absolutely tiny idle jet in each of their 4 carbs - that plugged just as easily! You can't leave one of those sitting for several weeks either! -Al
 
I bought a Honda CB 250 when I was living in Panama. I knew ZERO about most things mechanical being only 20 years old. But, with the rain that starts every day with such punctuality that people set their watches by it, the humidity effect on equipment, especially those old Honda carbs, made a quick study of me in order to stay mobile.

Those carbs had these "pistons" that would float as the throttle was opened. I'm still not clear on the exact concept or terminology behind them but I quickly learned, that when I lost power in one cylinder, I needed to stop and take the top of the chamber off, remove the piston and clean it of moisture to keep it from sticking in the bore.

Being not too bright, I thought one day that I would make them smooth by sanding them to help them move easily. And....it WORKED! For a while anyway. But....they began sticking more frequently.

Well, it wasn't obvious to me at the time that I had altered the piston to bore clearance with my "good ol' boy" fix but I figured it out eventually and bought new pistons. THAT was difficult back in 1970. No easy way to get anything shipped to Panama back then!
 
Ethanol gas will put water in your fuel tank/float bowl if allowed to sit for say 6 months, unless treated. Ethanol will eat rubber in old carbs, say pre 1980’s. The newer stuff is ethanol resistant, but the water is still an issue. It is also an issue if the boat marina selling you fuel hasn’t been taking good care of their fuel. No issues with ethanol in any motor used regularly, but you can’t let it sit around long.

One product I use on any gaskets being reinstalled is Hylomar Ultra Blue. It seals gaskets and never hardens like a RTV type product. Use it on both sides of the gasket, since it doesn’t harden, you can easily remove parts previously sealed. Plus, any excess Hylomar internal will dissolve instead of hardening like a RTV whose small bits will clog screens or passages. In most cases, you can reuse the gaskets if you have to remove a part at some point in the future.

Evinrude supply small packages of Hylomar Ultra Blue with their gaskets.
 
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A really thin layer of wheel bearing or dielectric grease applied to both side works pretty good too. Pretty much eliminates gaskets from sticking. I would NOT use anything on a head gasket though.....
 
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