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Ted G.
Ted G., Rigger, Diagnostician
Category: Boat
Satisfied Customers: 6095
Experience:  40 years boating, Safe boating instruct., Offshore Race promoter, Failure Analysis, Expert Witness
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I have a 2004 yamaha 250hp outboard model #Z250TXRC I lose

Customer Question

I have a 2004 yamaha 250hp outboard model #Z250TXRC I lose spark on cylinders 2 and 3 after engine starts so engine is running on 4 cylinders so far test wires going to coils from computer tested coils with wires from good cylinders that do lose spark and coils are good even swaped computer with sister engine on boat same 2 cylinders lose spark checked harness for broken wires swaped temperature sensors from sister engine even checked shift interupter to make sure that wasent stuck causing slow mode dont know what to do next need help
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** I will be helping you today. On the problem engine. Pull the emergency stop switch clip out. And then attempt to start the engine. (It obviously will not start) Does the alarm beep at you when you do this?
Customer: replied 2 years ago.
I have been using a jumper box so I dont use the clip.
Expert:  Jason replied 2 years ago.
We need to have a way of knowing if the alarm system on the engine works or not. How would you like to do that?
Customer: replied 2 years ago.
Thought we had a fuel issue so replaced fuel filter and the screen in the fuel pump canister took it for a test drive and engine would stall when you gave it gas and then alarm would beep when engine stalled
Customer: replied 2 years ago.
Tried to use diagnostic software but could not establish link with the computer to check for engine codes
Expert:  Jason replied 2 years ago.
Can you establish a link with the other engine that is working?
Customer: replied 2 years ago.
no I have been on phone with company that sold it to me and still have problems establishing link work for a marine shop and other mechanic has hard time with 2 strokes all the time seems only to work with 4 stroke yamahas
Customer: replied 2 years ago.
Have you ever had aN OUTBOARD THAT LOSES SPARK ON CYLINDERS 2 AND 3 BEFORE BECAUSE i HAVENT AND dont know what to do next driving me crazy
Expert:  Jason replied 2 years ago.
Do you have a DVA to measure pulser coil outputs?
Expert:  Jason replied 2 years ago.
Have you ever had aN OUTBOARD THAT LOSES SPARK ON CYLINDERS 2 AND 3 BEFORE BECAUSE i HAVENT AND dont know what to do next driving me crazy
Yes of course I have, but that can happen for a dozen different reasons. It's not like if you are missing spark on 2 and 3 then the problem must be "XYZ", it doesn't work that way. You can loose spark on those cylinders for a number of reasons.
Customer: replied 2 years ago.
using spark tester can see spark jumping on good cylinders and can even pull the spark plugs wires off and hear no change in engine on dead ones took wire leads coming from good cylinders and have good spark from coils that werent firing before have continuity on wires from computer to effected cylinders have no wire harness problem that i can see computer lists for around 1600 dollars so even swaped the computer from good engine with same results no spark on those 2 cylinders
Customer: replied 2 years ago.
You can see spark jump on first start up but dies shortly there after
Customer: replied 2 years ago.
if you do spark test on none running engine you would think you have spark on all cylinders but you lose it as soon as engine starts and there is no audible alarm going off
Expert:  Jason replied 2 years ago.
Is that no on the DVA?
Customer: replied 2 years ago.
I guess not sure what that is?
Expert:  Jason replied 2 years ago.
If you don't know what it is then you won't have one.
Here is kind of where we are at. The website advertises ask a mechanic get an answer. You seem to be wanted to troubleshoot the engine yourself. But you do not have the tools to do so. Realistically speaking without the tools the engine can not be troubleshot. Seeing as I can't give you what you want. Is there anything I can help you with that would give you some sort of satisfaction?
Customer: replied 2 years ago.
Nope I guess not sorry to waste your time Just thought you could suggest something to test that I havent thought of myself
Expert:  Jason replied 2 years ago.
Good luck!
Expert:  Ted G. replied 2 years ago.
Hi, let's see if I can help here. The CDI depends on the charge and pulser coils to create proper spark. So you need to check voltage output from those coils. Here is a diagram and the voltage values you are looking for. Since you are losing two cylinders and not all I suspect you will find the pulser coil bad.
Here is the link : https://www.dropbox.com/s/0xlyri4igslogxb/yampulser.JPG?dl=0
Let me know if you need more help.

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