BF130 No Start, Intermittent Spark

Hello to all,

I have been reading through all the threads here trying to find a solution to my problem. There is a wealth of information on here, but I have not been able to diagnose my "no start" with the information in the forums.

I have a boat with a 2002 BF130 which has performed flawlessly up until a few weeks ago. The person I purchased the boat from had to put it in the shop because when we went to test drive it, it was running like crap. Turns out that a dirt dauber had built a nest on the timing belt, causing it to jump. While it was in the shop to replace the timing belts, they replaced the old fuel system with the newer version. I figured with all that work, I would be good for a few years. A few weeks ago, I took it out to meet some folks over at a swimming area. It purred like a kitten, as it always has, on the way out there. I was there for a few hours and when I tried to start the boat, it just turned over, but wouldn't fire. Luckily, someone towed me back to my dock as they were headed that direction anyhow.

This engine has always started as soon as I hit the key. The kill switch has never worked on this boat. I thought that might have been the problem, so I replaced it. When that didn't do the trick, I started searching online for a solution, which is how I found this forum.

I had a local mechanic look at it, and he said it had no spark, but being unfamiliar with Honda engines, he declined to go any further into it. I called another mechanic out to look at it, and he said it had intermittent spark. He replaced both coils, but that did not change anything. He also was unfamiliar with Honda engines and told me I should take it to a Honda shop. As the nearest Honda shop is a 3 hour round trip, I would like to see if I can resolve this myself.

I found the jumper and checked the MIL lights. It is giving me three different codes, 3, 7, and 14. These all appear to be on the intake side. If I am correct, 3 is the MAP, 7 is the Throttle Position Sensor, and 14 is the IAC. I am not aware that any of these would affect the spark.

I got a OHM meter and checked the resistance to the pulser coils. One read 1058 and the other 1062. Those figures appear to be in range. I don't know of a way to test the voltage on the pulsers when the engine is turning as I have heard that will blow most volt meters.

The plugs look good, just soaked with Gasoline. They do not look fouled.

As others have suggested, I went through the wiring harness and checked all of the plugs for corrosion. Everything looked clean. I am now looking for the grounds. I understand that there are several grounds that run to the ECM, but I do know know where they connect to the grounding source. This is where I need help.

Does anyone know where these grounding locations are? From looking at the wiring diagram, I think the 2 grounds for the ignition are the brown/black wires that go to Connector B on the ECM.

If any of you know of any other things I should be looking for, please let me know. I am not all that familiar with outboard engines, but can typically Forrest Gump my way to a solution on automobile engines.

Any help would be appreciated.

I tried to answer your grounding question once, but I guess the post did not take.

Most of the grounds are terminated on the lower front port side edge of the powerhead. You might have to move a few things to get to them.

Disconnect the kill switch. Check for a short to ground on the black/red lead. When you do this, make sure that you turn the key switch to "on". When the key is turned off, the switch shorts the black/red to ground (killing spark).

If your harness is such that you can also disconnect the black/red from the key switch, it would be good to do the rest of your testing with it disconnected.......as long as it is not shorted to ground. It probably does not have to be a hard short.....a low resistance short would have the same result.

Mike

Thanks for the suggestions Mike. It never dawned on me that the kill switch wire itself might be shorted to ground. I will check that and let you know if that solves the problem.

Well Honda dude, you called it. There is a low resistance short on the black/red wire. I disconnected the harness at the engine and the short is on the engine side. When I disconnect connector A from the ECM, the short goes away. I thought it might be passing through from one of the sensors, so I disconnected them one by one. None of them changed the reading until I got to the Oil Pressure Sensor. When I disconnected it, my reading changed, but did not go away. It actually started fluctuating up and down. When I reconnected the wire, it went back to the .14 reading I had before. Is that normal?

I do not know if it is normal.

You said that your reading was .14. What scale is it on? Could it be .14 k ohm...14 meg ohm? It could make a big difference.

Reverse your leads and see if the measurement changes. If it is a real low resistance both ways, then there may be an internal issue in the ECM. Just a guess..

If the measurement does change then in the one direction, you are just seeing the conductivity of the semiconductors inside the ECM and the measurement may not mean anything. The change in resistance by removing the lead to the oil pressure switch, could just be due to you removing a ground (which the switch sends when the engine is stopped) from part of the ECM.

So....we could be looking in the wrong place or the ECM has an issue. The only way to tell for sure is to see if you have a friend who is willing to switch ECM's with you for a test.

Mike

Thanks for the response. I can't remember what the scale was. I'll take better notes next time. Does the oil pressure switch send a ground to kill the ignition when it senses a low pressure condition?

Yes. When there is no oil pressure (when the engine is not running) and if there is actually no or very low oil pressure, the switch does not open and continues to send a ground to the ECM. The ECM then puts the engine to go into limp home mode. The engine should start and run at idle, but when the rpms increase, the ECM says..."no way".

Mike

Ok, so I can rule out the oil pressure switch as a possible cause. Just in case it the no spark isn't related to the black/red ground, I will work my way from top to bottom to check what I can with the multimeter. I checked the ohms on the pulser coils, but I did not on the 2 ignition coils as they were new. I tried to check the output of the pulser coils using a DVA adapter. The instructions for the adapter said to put the voltage at 400V. My tester only had 200V and 600V. The readings were about 20 percent higher on one of the pulsers when compared to the other. I could not find any specs in the service manual that would give me the acceptable output voltage for the pulsers. Would you happen to know what those should be?

Oh, and we have already tried swapping ECMs. No change.

I took more ohm readings over the weekend. When I reversed the leads on the black/red wire as you recommended, the measurement did drop. I set the meter to K ohms and it read 1410 one direction, and 1380 the other.

I took measurements ignition coils. The secondary side on both read .33KO, which was within spec. The primary side read 1.1 ohms, which was much higher than the range in the manual of .60-.72. Since they are new, I decided to pull out the old coils to see what resistance they showed and they also read 1.1 ohms on both. The mechanic that replaced them told me they were out of spec, and I didn't question it. Could the figures in the manual be wrong?

Is there a way for me to test the voltage coming out of the ECU into the ignition coils without damaging the ECU? I could find nothing in the manual or online about that. I don't want to hook up the DVA adapter if it will fry the ECU. I also haven't been able to find any information on the voltage range that should be coming from the pulsers. The ohm readings are within spec and there is not a short to ground on any of the pulser leads.

You had mentioned in an earlier post that we may be looking in the wrong place. Do you have any recommendations on where or what I should be looking for? I have read about the main relay having issues, but I get the 2 second high pressure fuel pump run when the key is turned on, so I assumed it was powering up the ECU.

Any help would be appreciated. I am scratching my head on this one.

The wiring diagram is not clear, as to what the color wire is to the coils. It looks like one is yellow/black. If I am correct, when you turn the key to on, you should get 12v dc all the time at the coil, on that lead..if the main relay is working. That does not mean that the main relay is good, overall. It just means that that portion is operating correctly. Likewise, if there is not 12v there, then the main relay, wiring or fuse are suspect.

With a constant 12v at the coil, the other side gets a pulsing ground from the ECU when the engine cranks.

I do not think your meter will cause a problem if you check for the 12v or watch for pulsing ground with your other meter lead on the positive 12v side....or even directly the positive post on the starter. I am not sure what it will read, but it should be something between zero and 12v.

The manual does agree with what you say the resistance should be. Since the resistance is so small, most meters can not accurately measure that low anyway...so I would not be too concerned about that.

If you want to check the coil, you might be able to set up a small test circuit.

Use the coil that was removed, if you still have it....

Let me see if I can verbalize the connections....keep in mind....I have never tried this.

Use a standalone 12v battery. You need some small jumper cables.

-Connect the positive 12v side of the battery to one primary contact.
-Connect one end of a jumper to the other primary.....you will use the other end later for the test. It needs to be long enough to reach the battery ground terminal.
-Take two spark plugs and plug them into the two secondary leads.
-Jumper both spark plug bases together and also jumper them to the ground terminal on the battery.

Now you are ready to take that loose end of the jumper on the primary side and just, very briefly touch it to the ground post of the battery and then take it off. Do that in a repetitive fashion...simulating rapid spark.

If the coil is good....and if my theory is correct.....you should see spark at the spark plugs.

If you do not see a pulsing ground in the first part of this post, then I would not bother with the coil test.

Mike

One other thing to consider...is the MAP.

As far as I can tell, the initial spark from the ECU is activated by the two pulsers and map sensor. It is then fine tuned by the Intake temperature, Engine temperature, and the Throttle position sensor.

So, make sure that the MAP sensor port is clear. There is a pin hole opening in the Map and it sits over an opening in the throttle body. If plugged with any debris, that might be preventing spark. Just a thought.

Mike

Hondadude, I hadn't had time to work on the motor until recently. I tested the coils using your method, and they did produce spark. I then checked the positive lead going into the coils. When putting the meter on the ground, it read 11.9 to 12 volts. When using the DVA to test the pulse, I was only getting 4.5 volts on one coil, and 4.3 volts on the other. It appears I have found what is causing the no spark, now to figure out the why of it.

Do you know if the pulser coil just acts as only a trigger, or does it charge a capacitor that would send a ground to the coil? I can't wrap my head around the latter being a possibility, but I don't know that much about these. I ask because I am wondering if the pulser coil signal is weak, would that result in a weak ground to the coil? I have searched through the manual and online and cannot find any information on what the output voltage should be on a pulser coil. I checked the OHMS and they were within spec.

I took the MAP out and it looked fine, no obstructions or debris in the tiny hole. Since the ECU is showing a MAP code, it could be defective. They are cheap enough, so I have ordered a new one. Once I get that in and installed, I will update.

Thank you for all of your help so far. I now know more about this engine than I ever cared to know.

I do not know for sure, but I think the pulsers act like a trigger. I also do not know the voltage output, but is probably pretty low. It would be worthwhile to measure their output.

If sounds like you checked the voltage at the two leads at the coil. If there is a voltage drop in the system, it might look like there is not a good ground pulse coming from the ECU.

Before you do a lot of other tracing, check for any startup voltage drop by measuring from the positive 12v side of the coil to a good ground.....while you are cranking. If the voltage goes down, then it is probably not the ECU. It is somewhere in the voltage/ground wiring.

If the voltage stays relatively close to 12v, then hopefully, the pulser output or the map sensor bad.

I would have thought, that the ECU would have defaulted to a standard map value if the map is bad and the engine just would not run as efficiently. This ECU is pretty basic...so who knows?

Mike