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Honda BF225 one cylinder not getting fuel.

T

Tolque

Contributing Member
Any suggestions appreciated. I have 2005 BF225 with one cylinder not getting fuel. I have checked compression, replaced the oxygen sensor, swapped injectors, all new plugs etc and the problem cylinder is getting spark. I am down to wires or ECM. I do have the old model ECM 34750-ZY3-013. I see it is now superseded with the 043. Was that ECM known to fail? Would you replace the ECM (less labor more money) or replace the wiring harness (less money more labor)? Are there any other sensors that could cause one injector to malfunction? Thanks for any help!
 
Did you check to be sure that the injector is getting a constant 12v? The ECM sends a ground to fire it. If it does not have 12v, then pick up the 12v from another injector by making a short jumper.

Sometimes, you can use a test light or for sure an analog voltmeter and check for the pulsing ground. Check one of the working injectors so that you can see what the light or meter does with a working injector. If it is not getting the ground, then run a jumper lead from that injector to the lead where it comes out of the ECU. (yellow/blue lead)

If that does not get it to work, then it probably is not the harness.

Mike
 
Will the injector get a constant electrical feed with the engine off and just the ignition on? That is a really awesome idea about the jumper, you might have just saved me a big pile of money. Do these ECU's fail often?
 
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I checked for current at the injectors, all injectors read 12.0 volts. The bad cylinder injector is getting 13.66 volts. It was also the only cylinder that had a black sooty spark plug. Any ideas?
 
Any ideas here are appreciated. I'm thinking of replacing the wiring harness and crossing my fingers. I just wonder if there are any other sensors that could make one injector not fire and have increased voltage. I already replaced the plugs, O2 Sensor, cleaned the EAC valve, swapped coils and plugs, swapped injectors and it is always the number 2 cylinder that doesn't get fuel, no matter what I do. All other cylinders are working fine.
 
Before changing the wiring harness add the jumper, just check the continuity of the wire from the injector connector to the ECU connector. If there is an open, then jumper around the wire and see if that fixes the problem. If so, then you can leave the jumper or replace the wiring harness.

Mike
 
Thanks Mike, I will give that a try tomorrow. I checked the voltage at the ECU for the number 2 injector and it read 12.4 volts. I used the yellow/black as the ground and the red wire as the positive. I just don't understand how it could pick up more voltage and read 13.66 volts in between the ECU and the injector.
 
How does that measurement compare to one of the injectors that are working properly?

Was the voltage not pulsing?

If you used a digital meter, you may not see the pulse.

Did you unplug the injector and measure the voltage there? The injector is like a coil and it could present some extra transient voltages that could give you a different reading than at the ecu. But, who knows for sure?

Whichever way you do it, measure both injector voltages the same.

If you have an old type analog meter, you should be able to see the needle pulsing. A simple test light may show the same....but I am not sure...it has been a while since I tried that.

Basically, you have to determine if you are getting a pulse, not getting a pulse, or getting solid voltage (all the time). If you have either of the latter two, then the wiring harness is either ok, or you have a short (getting constant ground) on the one lead. You probably are not getting a pulse...since the injector or the substitute injector does not fire.

Mike
 
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It appears that the problem injector wire is grounding out since it reads the same voltage if I touch both injector wires or touch the yellow/black wire with the negative probe and the red probe to the engine block. It is a digital meter. It reads about 13.1. All the other cylinders are 12.0. I ran a jumper and had the same result, 13.1 volts. I ordered a new wiring harness, I am afraid the grounded wire could be something in the external wiring harness up to the ignition that is affecting this one injector. The only time I could get the injector voltage to pulse is when I cut the green wires, which also stopped the engine alarm from beeping.

I dont really know but I am pretty discouraged, I will replace the engine wiring harness when it comes in but I'm not sure what to do if that doesn't work.

When i unplugged the plug from the ECU and tested the voltage directly from the ECU to the injector the voltage went down to 12.4. I am wondering if the plug going into the ECU is bad or something else in the harness is making that particular wire ground out.
 
Remove connector for the lead at the ecu and remove the connector from the injector and measure resistance to ground of that lead. If the harness has a ground in it, it may show up....

It is possible that a diode blew in the ecu and it is putting a constant ground on that lead.

Mike
 
I tested the ground possibility in the wire between the injector and the ECU with the leads off. There is no ground in that particular wire. If I measure voltage from the injector right to the ECU on the pin, it reads 12.4v constant, a ground would read higher so there is some resistance in that pin. If I plug the plug that includes the injector wire back into the ECU and measure the voltage, then it appears to be grounding out. Only when it is plugged into the ECU does it ground out. So, I am hopeful the ground is coming from somewhere else in the harness but realize I may be buying an ECU also. I just hope it isn't something up in the ignition wiring that caused a short and potentially a failure in the ECU. The dealer swore to me that ECU's never go bad. I find that hard to believe. It will probably be a week before I see the wiring harness since I am in Alaska.
 
That part number is actually the third supersession. It could be that the ECU was improved or it could be they changed the vendor who makes the ECU.

I have not heard of one failing, but anything can fail....

Mike
 
There are a few on Ebay ending in 013, like mine. I will probably buy a new one, they end in 043. The dealer told me that as motors get older they make changes to the ECU and thus change the serial number. Who knows? If the 013 model was a dud, I doubt if Honda would be advertising the fact, unless there was a safety issue. This "miss" came on slowly though, for the past year or so right when I left the harbor there would be a rough idle, a little miss coming up onto a plane but then it would clear up. It stopped "clearing up" last time I went out. That is why I think a wire finally wore thru somewhere. Hopefully it is in the harness and not up in the boat somewhere.
 
Replaced wiring harness today, no change. One cylinder still not getting fuel. Swapped out ECU with one I bought on Ebay for $199, the engine wouldn't run at all. It is a $1000 gamble or wait 2 weeks and have the dealer jerk me around and say it runs fine.
 
Skooter, I haven't been able to pull any codes, nor do any of the alarms go off. I know one cylinder that is not getting fuel. I replaced the O2 sensor, replaced the wiring harness, swapped injectors, swapped coils, replaced plugs, checked compression, and finally have ordered a new ECU. If it isn't the ECU, I really don't know where to go after that. The dealer here in Alaska is going to keep my boat for probably a month if I take it in and chances are probably 50/50 it will be fixed when I get it back. It starts fine but you can tell one cylinder is not firing by the way the engine wobbles when idling. Then when I pull off the plug wire there is no change in idle characteristics. When I crank the engine while doing a compression test there is no fuel odor in that one cylinder. The injector is not firing and like I said, I swapped injectors with the same result. However, it is getting spark. The voltage to that injector is 13.67, all the other ones are 12.0. This is even after replacing the wiring harness which is why I think something has gone wonky with the ECU. I don't know of any other sensor that would affect only one cylinder. If you do, please let me know. Thanks for your response, this thing is really kicking my butt, (and wallet). Compression is 182 on that cylinder cold, throttle open.
 
The new ECU has shipped, I should have it in 3 days. Hopefully I didn't just throw $855 out into the wind. Has anyone heard of an ECU going bad on a 2003 BF225? I'm just wondering if part number 34750-ZY3-013 has known problems since it has been replaced with 34750-ZY3-043.
 
I've been active on this forum for at least the last 6 years. There have been very few posts (if any) where the operating problem was due to a failure of the ECU.

Having said that, if you go through the diagnostics for a fault code thrown off by the ECU, then the default for each diagnostic procedure, and nothing else is discovered, is to change the ECU.
 
Thanks CHawk. The problem is, I'm not getting any codes. I just have one injector that is not firing and has a higher voltage than all the others. I would think the ECU is grounding out or generating the wrong voltage somehow. That same cylinder had the only spark plug that was really black with soot. The plugs were fairly new. Perhaps the ECU was over injecting fuel prior to it's failure. If the injector was bad, it would have thrown a code or been resolved when I swapped injectors. The "miss" used to happen when I would first leave the harbor, then it would clear up. It was almost like when we had carburetors and the engine would run cold. The last time I went out it didn't clear up.
 
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I agree that is a strange situation. Hopefully the new ECU will fix the problem. You have eliminated the injector, the plug, the coil and the wiring, so the ECU is the only thing left, it seems. If you can track down the exact pin coming from the ECU the grounds the injector to activate it, then it could be right there.
 
It wasn't the ECU. Bummer! Time to take it to the dealer and see if they can work a miracle. On a more positive note, I caught a limit of salmon fishing the Kenai River today in my waders so to hell with this boat. :rolleyes:
 
This is a really screwy problem. I went back over this entire thread and cannot see any hint at what could be causing the problem, so I would suggest that you start over. Here are the questions that come to mind...

Check again to make sure you are not getting any fault codes.

You said that you replaced the ECU, replaced the wiring harness, swapped injectors, swapped coils, replaced plugs, and checked compression. Is that correct?

The problem is in number 2 cylinder. Are you absolutely and unequivocally sure you are getting spark on that cylinder? You never described how you came to that conclusion. How are you sure of that?

You said that when you initially pulled the # 2 plug it was black and sooty. That indicates to me that it was firing previously, indicating a failing plug, coil, or injector. When you run the motor now, is that new plug totally dry?

When you swapped injectors, are you sure that the O rings on each end are installed correctly and that there is no blockage? (The fuel rail itself is not likely the problem since # 1 and # 3 are firing correctly.)

(This is the really screwy part for me.) Are you still getting 13.66 volts at the injector, and 12.4 volts at the #2 injector pin on the ECU? Test this again, making sure that the injector lead is not going through the harness clip.

As Mike suggested, did you test the 2 P lead to the injector while cranking to see if you are getting a constant 12 V+ on the hot lead and a ground pulse on the negative lead? (You need an analog voltmeter for that.)

Did you test the ground wire to the injector (the one that pulses to fire the injector) to make sure it is not grounded when the key switch is on?

If all of that checks out, then I'm at a total loss too.
 
I brought it to the dealer this morning. They guy at the counter, who is not a tech tried to sell me maintenance package that included synching the carburetors for $750. I politely reminded him it was fuel injected. Ugh. They said they would get to it in 2.5 weeks.

So to answer your questions CHawk, and thanks for taking the time to think about this.

You said that you replaced the ECU, replaced the wiring harness, swapped injectors, swapped coils, replaced plugs, and checked compression. Is that correct? Yes

The problem is in number 2 cylinder. Are you absolutely and unequivocally sure you are getting spark on that cylinder? You never described how you came to that conclusion. How are you sure of that? I put a little gasoline in the spark plug hole and it runs normal for a few seconds. Also, I put 3 different new plugs in that cylinder. Same result.

You said that when you initially pulled the # 2 plug it was black and sooty. That indicates to me that it was firing previously, indicating a failing plug, coil, or injector. When you run the motor now, is that new plug totally dry? Yes it is and there is no odor of fuel. I also swapped coils, and injectors.

When you swapped injectors, are you sure that the O rings on each end are installed correctly and that there is no blockage? (The fuel rail itself is not likely the problem since # 1 and # 3 are firing correctly.) Yes, I actually swapped them twice to be sure.

(This is the really screwy part for me.) Are you still getting 13.66 volts at the injector, and 12.4 volts at the #2 injector pin on the ECU? Test this again, making sure that the injector lead is not going through the harness clip. I'm not sure I understand this one. I replaced both the wiring harness and ECU so it should have solve any grounding issues. I know that I got exactly 12.0 volts when measuring the voltage at the plug that plugs into the injector itself on all cylinders, except the #2 cylinder, it read 13.66. Then when I measured it at the ECU pin it read 12.4. It is possible I got the wrong pin.

As Mike suggested, did you test the 2 P lead to the injector while cranking to see if you are getting a constant 12 V+ on the hot lead and a ground pulse on the negative lead? (You need an analog voltmeter for that.) I wasn't able to do the test while cranking.

Did you test the ground wire to the injector (the one that pulses to fire the injector) to make sure it is not grounded when the key switch is on?
I think these last two would also be resolved by a new wiring harness and ECU. I wasn't able to do the test because I have a digital voltmeter.

The guy at the dealer said the ECU needs to be paired up with the motor using the Honda software Is that true? The motor runs identically with either ECU.
 
OK. Well, I'm stumped. The 13.66 volts makes no sense when the other injectors are getting only 12 volts. There is just no logical explanation for that.

On your last question - I'm not sure whether any adjustments need to be made with the ECU for any particular motor. That does seem a bit strange. Other folks on this forum with dual engines have swapped their ECU's between engines with no problem, but presumably, these engines would be of the same model year.

Hopefully, someone on this forum can give you a definitive answer. Just seems strange to me.

I will be very interested in the resolution of this issue, as I'm sure others will be.
 
Skooter, not according to the parts diagram for my model and serial number. It just seems that anything other than the ECU or wiring harness would affect more than one cylinder. Maybe the TPS is sending a bad signal to the ECU but then you would think I would get a code. I also cleared the codes to be sure using hondadude's jumper technique but it didn't make any difference.
 
Prob not tps, I have a similar situation and I swapped mine over from my other motor and nothing changed. I am going to replace my wire harness, thats really the only thing I have changed out
 
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