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2003 50b air injector issue

oneeyemike

New member
I have a 2003 50b serial #16268xc that has been hard to start for a few weeks. If the engine has not been run in 24 hours it takes 8-10 tries to get it started. If it has set for less than 24 hours it will crank right up. Today while operating it went into safe mode with three lights flashing. Turned off motor and wouldnt start back. I used the factory manual and from what it says I have a faulty air injector on the #2 cylinder, tach at 2000 and b&c lights on. My question is are these prone to going bad, and if so should I replace all three? Looks like they are about $250 each, so I will check the resistance and function before I replace, but was curious about the experts opinion on this. Also, im assuming the #2 cyl is the middle one? I searched the manual but never saw a definite answer on which cylinder is #2. Thanks for any help
 
So to clarify, it sounds like you have a TLDI, an MD50B. No, the injectors (both air and fuel) are pretty reliable. If indeed you did diagnose an injector issue using the charts in the Factory service manual, then it is time to whip out the ohm meter and test to confirm a problem.

That said, Tohatsu issued a Service Bulletin in June 2011 covering the 2010 MD50B2 with serial numbers between 003989AX and 044507AX. However, your serial is from 2003, and should not be affected.

Yes, cylinder 1 is on top, then 2, and the bottom is 3.
 
Thanks Paul for your input. From the diagnostic chart in the manual, it says faulty air injector #2, but from the way I read it that the "b" light should have not been on. Both "b" and "c" lights were on and tach at 2000. Is this correct? I also have a concern because it appears the hours are not showing correct when I go into diagnostic mode. When I got the motor 3 years ago I checked it and it had between 250-350 hours on it. When I checked it yesterday the tach went to 5000 with no lights, which from the manual says 4-5 hours, which I know is not correct. Am I missing something? I will pull the boat out of the water this afternoon and test the injector. Is it possible to test it on the motor or do you advise pulling the air rail? I will check the resistance and apply power to see if I hear the click like the service manual says, I assume if it checks good, it would be a wiring or connection issue, correct? Can you clean air injectors if they test good? Thanks again for your help.
 
Something is wonky with those readings. I would go through the diag mode once more. I would also reset the TPS initial value to be sure that the throttle is synced with the TPS sensor. Yes, you can ohm it out while installed. Just be careful with your connections; some ohm meters have pretty big test leads.
 
Something is wonky thats for sure! Checked it out again this evening and this is what I found. The air injector checks good when checking resistance. Reads exactly the same as #3, 1.8 - 1.9 ohms. Tried clearing the dignostic codes but cannot get rid of the #2 air injector code. So I unhooked both the #2 and #3 air injectors and spun the motor over a few times. Got the same #2 air injector code with b and c lights, and a # 3 air injector code but with only light c. Left them unhooked and cleared codes but still have the #2 code, even without trying to start motor. It will not clear the #2 injector code. According to the chart, the C light should be on, and it was for the #3 code , but why does the #2 code have both the b and c lights on? Why would it not clear out? After looking at the schematics, I noticed that the blue wire is common to all the injectors, so I dont figure that is the problem, so I checked the light green and white wire all the way to the ECM and it has no resistance so I know that wire is in good shape all the way to the ECM. I did reset the TPS, just for kicks but it didnt change anything. I also connected another battery in parallel just to make sure it wasnt a battery issue. No change, but I use a 1000 CA battery so I didnt figure it would. Im about out of ideas here. Only thing I havent done is physically checking grounds, but all are tight and appear to be in good condition. Is there a way to reset the ECM? Could this be a faulty ECM? Im going to settle in and study the manual some more, but Im about out of ideas. Just cant figure out how I can clear the codes with both injectors unhooked and it will delete the #3 and not the #2. What am I missing here?
 
Just to make sure, I just checked the resistance of the air injectors again because I was in the blazing sun at about 90 degrees when I checked this afternoon. It is now about 77 degrees and they all read 1.4 - 1.5 ohms. I know that the book says 1.29 at 68 degrees so thats why I rechecked it. I just dont feel like its a faulty injector since the #2 code wont clear.
 
Also the hours still show at 5000 on the tach with no lights, which according to the manual means 4-5 hours, which I know is incorrect
 
Resetting the TPS also resets the ECU. See p9-44 of the Factory service manual.

In diag mode 1, the tach operation gets verified. It automatically goes to mode 2, engine hours. Yes, 5000 and no lights is 4-5 hours, which we know is incorrect.

However, once you get to mode 3, you cycle through all the tests (see p9-34 of the FSM). 5000 and no lights means a CPS malfunction, usually accompanied by at least the C lamp, possibly the B lamp.
In mode 3, a faulty #2 air injector would show 2000 RPM, A off, B off, C lit.

When in mode 3, you can reset codes by removing the stop clip and then pressing in the key for about 3 seconds, until it beeps 3 times. This does not delete engine hours. See p9-35 of the FSM.

Before you spring over $1700 for a new ECU, I would disconnect and reseat all connectors (in case there is any oxidation on the contacts). While disconnected, inspect the contacts to make sure they are clean. I would also verify all the grounds (an often overlooked problem).
 
It only shows 5000 and no lights in mode 2. In mode three, it shows 2000 and B and C lights on. It will not reset this code. When I unplug the connector for the Air injector number 3, spin it over a few times to set code, it shows the same 2000 and b and c, and 3000 with just the c light on. I can reset the codes and the #3 injector fault will reset but the #2 remains. Why would the b light be on with the 2000 code and why cant it be cleared? I think if I can figure that out, it will be right. Could a weak battery cause issues like this? I have a 1000MCA battery that is three years old. Im going to have it load tested today and possibly go ahead and replace it just to make sure. I will check all connections and grounds this evening. Thanks for taking the time to help me Paul. I really appreciate it.
 
That code is an impossible combination, so it may have nothing to do with the #2 air injector. It should clear no matter what. The only thing that should remain is the engine hours. 2000 with B and C lights sounds like hours between 100 and 200. You may possibly have a bad ECU if it won't reset. Weak batteries do cause all sorts of weirdnesses because while cranking, the voltage to the ECU is too low, and it doesn't initialize properly.
 
It pays to read the manual! I was mistaking the initial tach sweep to 5000 as my engine hours. So I have spent the past three days trying to get the hours reset. LOL. Turns out my battery was bad and I had a bad spark plug. New battery and three new plugs and she runs like a top. Thanks Paul for taking the time to give your input on my situation. You helped me about three years ago get this motor running when I got it and again your experience and knowledge has helped me out again. Thank you again!
 
Well I have run the boat a couple of times and heres what I have. It runs great, it is just hard to start after it has sat for more than about a day. If I crank the boat within about 24 hours, it will fire right up. But if it sits any longer, it will fire for a second and die. Then it takes 8-10 tries to get it started. Then runs great, until it sits. I have been reading other posts about draining the vapor separator, which I have never done. I feel like its drawing air or losing fuel as it sits. Would this be a possibility? No water in the fuel filter/water separator, but I feel this is a fuel issue. I checked the air pressure with a tire gauge and it had around 100 psi. I didnt figure I should try to measure fuel pressure with that... lol.
 
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