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BF20D: engine quit after running normally for an hour, will not restart

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BarryK3

Contributing Member
Hi everyone,

I have a 2004 BF20D with remote control and electric starter. It was running great today. It started up normally and I ran it for about an hour in the harbor at low speed. It then suddenly quit and would not restart. A friend towed me back to the slip. The starter spins normally but the engine does not fire at all. There is plenty of fuel. I played with the kill switch to see if the clip was loose but that had no effect. It's behaving like it has no spark.

I recently serviced the engine: cleaned the carburetor, replaced plugs, replaced battery cables, cleaned out the water jacket, replaced internal anode and thermostat. The motor is on a 10' Caribe RIB used in salt water.

We had a very heavy rainstorm yesterday, a somewhat rare event in southern California. Maybe that has something to do with it?

I have not begun troubleshooting yet, I am wondering if anyone has had a similar problem.

Thanks,
Barry
 
Where is the fuel tank, built in or external? I would take a sample from the gas tank into a clear plastic container and see if it separates with water.
 
I think Blue_Sky's suggestion is a good one. Especially if your fuel tank sat out in our rare rain last week. Do you leave the vent open? You would be amazed at how much rain water can get into a fuel tank through that.tiny vent.

Have you ever removed and emptied the "fuel chamber"?. It's the black, rubber cylinder attached to the engine oil dipstick tube. That device is intended to keep the supply of fuel to the carburetor from running low during hard acceleration. But it also acts as a water catch and needs to be emptied at least once a season.

Check those things out and get back to us.

Good luck.
 
I think Blue_Sky's suggestion is a good one. Especially if your fuel tank sat out in our rare rain last week. Do you leave the vent open? You would be amazed at how much rain water can get into a fuel tank through that.tiny vent.

Have you ever removed and emptied the "fuel chamber"?. It's the black, rubber cylinder attached to the engine oil dipstick tube. That device is intended to keep the supply of fuel to the carburetor from running low during hard acceleration. But it also acts as a water catch and needs to be emptied at least once a season.

Check those things out and get back to us.

Good luck.
 
Thanks everyone,

The tank is under a flip-up seat. I have a full size Quicksilver fuel filter/water separator. I opened that yesterday and did not find any water inside. I have a tow arranged for today to take it to the launch ramp. Once it is back in my garage I will begin the troubleshooting including a spark test. I will definitely drain the fuel chamber.

Take care,
Barry
 
The same happen to me, I have a 96' Merc 5.7 LX. It will run excellent for 30-45 minutes and then just shut off. I have been chasing this for a while. I replaced the Ignition sensor, carburetor and am considering replacing the fuel pump. My latest thought was it could be electrical and some sort of kill signal. All oil pressure and temperatures are well within range. Im going to take a mechanic for a ride and see if we can test it all after it happens.
 
The factory service manual has a good step by step troubleshooting guide. I will work on this over the next few days.
 
Lemen said:
The same happen to me, I have a 96' Merc 5.7 LX. It will run excellent for 30-45 minutes and then just shut off. I have been chasing this for a while. I replaced the Ignition sensor, carburetor and am considering replacing the fuel pump. My latest thought was it could be electrical and some sort of kill signal. All oil pressure and temperatures are well within range. Im going to take a mechanic for a ride and see if we can test it all after it happens.
Click to expand...
Lemen - I'd start a new thread with your symptoms.. Is it pretty consistent at the 30-45 minute mark, shutting off on-plane or idling?

Barry - Let us now how you make out, double check the angle that your primer ball is when it's laying there, sometimes they invert and make the check ball stop the siphon from the tank. I had a customer with that problem, it would die after he hit a couple waves and the primer wall would now be pointing at the deck. He also only had about 6" of slack to deal with as it was under a console.
 
Boat is in the garage now. I tried to start it and no change, no firing at all. I am going through the troubleshooting list. Opened carb drain screw and clean fuel comes out, no water.

I pulled the plugs. They are clean and looked dry??

I did a spark test with both plugs grounded to thermostat screws. NO SPARK.

I'm taking apart the remote control now to check the kill switch wiring (red/black wire).

Barry
 
I went through the ignition troubleshooting. Kill switch is OK. Key switch is OK. Exciter coil, pulse generator have normal resistance values and clean connectors.

I found fairly extensive corrosion on the ground connection on the ignition coil primary side. Resistance for primary and secondary windings is normal. I cleaned the corrosion fairly well with a dremel and redid the spark test. I saw what I would call weak spark. I had to darken the room to tell if there was spark or not. I tried starting the engine but there was no firing. I tried starter fluid in the spark plug holes and also the intake but no firing. I connected a wire with alligator clips between the engine block and primary terminal but no firing.

I also checked the fuel chamber. It has clean fuel and no debri. The fuel was under pretty high pressure there.

I'm running out of ideas. I guess I will clean the ground connection on the block and run a new wire to the ignition coil. I will also try new plugs, although the old ones are only a few months old and look OK.

Is there any point in opening up the carb and looking for debri?

Basically the engine has not fired once since it died.

Thanks,
Barry
 
Also, you are supposed to be able to tell if the plugs are wet or dry to determine if fuel is reaching them. It certainly smelled like gas after cranking the starter but the plugs did not seem that wet.
 
Hi Barry,
Hmmm...
This is a bit of a puzzler for sure.
But after reading your last post I am still leaning toward no fuel delivery.

The Honda twins don't put out the crisp, blue spark that you would get from a car ignition system. So the fact that you do see spark, even though it looks "weak" could be normal.

The curious thing to me is that you wrote about the fuel chamber being pressurized. I don't think it should hold much pressure at all so that could indicate a restriction downstream or the float being stuck closed.

The fuel pump only delivers around 2 to 3 psi tops but I suppose that might seem like a lot if it jumps out at you all at once.

You said it didn't fire on starting fluid and you would think that if the spark is adequate that it should at least cough.

But I don't like the use of starting fluid because it is so explosive and can damage an engine very easily. It also evaporates quite quickly and that can make getting the proper "dose" applied to fire a given engine without blowing a chunk of ring land off of a piston a tricky exercise.

When I am trying to prove fuel starvation I use propane gas. It really is the safest, most reliable way of running an engine on artificial enrichment. If you feed it propane correctly and it won't run then it's bound to be no/weak spark, lack of compression or the timing is off.
 
I got all of the corrosion off of the ground lead between the block and the ignition coil, both ends. Less than 1 ohm from installed spark plug bolt back to primary side of coil. The spark looks brighter now. Still won’t start and plugs look dry. Carburetor will come off soon.
 
I cleaned the carburetor. Nothing major, I had rebuilt it about 6 months ago. The accelerator pump piston was stuck and not working so I replaced those parts (I did not take that apart last time). I reinstalled the carb and still no firing. I tried propane and starting fluid but not a single cough.

I checked the compression and it seems fine. I don't have the proper adapter for the 10 mm plug holes but I have a rubber tipped tester and it seems OK.

I rechecked my numbers for the ignition components. I got 0.6 ohms for the primary side of the ignition coil. I forgot to account for the resistance in the multimeter wires. A Youtube video pointed this out. When I touch the leads together I get 0.3 ohms in the wires alone. So the net for the coil is 0.6 -0.3 = 0.3 ohms! The spec for the coil is 0.8 - 1.0 ohms. So, I must have an internal short in the coil resulting in weak spark. It is probably too weak to fire during compression??

So I will order a new coil.

Have I missed anything?
 
Sounds like you have done pretty much everything. It very well could be an ignition problem. It cutting off so suddenly and not firing on propane, along with the coil resistance not being to spec. definitely points in that direction.
I hope your new coil has you back out boating real soon.

One question I have is about the accelerator pump spray nozzle.
These engines need that nozzle to be completely clear for them to start and run properly.
When I clean one of these carbs I check and clean the nozzle while the float chamber is off by propping the throttle plate wide open and spraying cleaner through the accelerator pump tube passage in the main body. I look for a stream to exit the nozzle and shoot about 8 feet out the engine side of the carb throat. If it doesn't pass that test, cleaning the nozzle is mandatory.

Also, did you clear the main and idle air jet passages? They often get overlooked but cause plenty of problems if clogged. The passages are the horizontal drillings that are above the carb throat on the front (air inlet) mount flange of the carb.

Those and and the air vents seem to escape scrutiny quite often.

While I think of it too...
Did you check and clear the passages in the floor of the float chamber while you had it off?
There are 3.
One feeds the carb drain screw.
One feeds the accelerator pump piston chamber.
And the third feeds the cold start enrichment dip tube.
Those can have "mud" packed in them because of their location. Wire cleaning is often required in that case.

One last carb item is the high speed jet. It is located in a dip tube that extends into the float chamber opposite the enrichment well. It gets plugged and can cause severe loss of power.
It can be very difficult to clear once plugged so keeping it clean is very important since it is not a serviceable part. If it can't be cleared, carb replacement is the only solution.

Anyway I'm hoping the new coil gets you going.

I only mention the carb stuff because I want to make sure that you have that information if you aren't satisfied with the engine's performance.

Buenos suerte!
 
So I received the new coil which includes the new spark plug cables and boots. I checked the primary resistance and it is similar to the old coil, maybe 0.4 ohms, lower than the spec. I was worried that I missed something else, maybe the CDI box. But, I connected it and checked the spark, it looked much brighter. I installed the plugs, pumped the bulb, and it started in about 1 second and ran perfectly. Go figure!

Barry
 
That's great news Barry!

I'm really glad you got it figured out and working.

I've said it many times....
...boating can be FUN....

...just as soon as you're through with all the maintenance!

Now it seems that you should be ready for SPRINGTIME!
 
Thanks everyone!

For this puzzle, the factory service manual was very helpful. There are step by step troubleshooting guides. You can download a copy from various sources and they are not that expensive. In this situation it was hard for a novice to tell a weak spark from a normal spark. This led to confusion over whether it was a fuel delivery or an ignition problem. The lack of a single cough when trying propane, a squirt of gasoline, or starting fluid argued that it had to be an ignition problem.
 
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