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Anyone have 25 or 30 HP staring issues? ECU? erratic Tach?

Jethronone said:
Thanks. Should I also disconnect the ground from the ECU and earth it to the block? Unfortunately I won't be where the outboard is for a few weeks so won't be able to try until then.
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you only need to disconnect the 2 wire plug at the hp pump. This disconnects the + and - between the pump and ECU.
 
hi. This topic would also be interested in me. I do not go to the ECU from the FFP .. Going out of the outside. The ECU does not switch the body. However, the normal power consumption of the FPP?
 
szia.Mekkora a nagynyomású szivattyú áramfelvétele? Az ECU nem adja ki a testet, így nem működik. Az FFP külön tápegységen működik.
köszönöm a választ
 
hi. i also have a problem with the ecu. does not output the (-) body. Maybe the current consumption of the pump is high? What is the current consumption or output of the pump? thanks for the reply.
 
I am back at the outboard now and was going to direct wire the fuel pump after cutting the ECU wires as suggested. I thought I would try just cutting the earth and directly earthing the fuel pump first and bingo away she went! The motor seems to be running well on the muffs but haven't tried under load. Very happy to have fuel, spark and a running motor. Wondering what you think about still putting the relay in and cutting out the ECU altogether from the HP pump?
Figure I have a few options now:
Take it out as is and see if it goes ok under load? (bit worried it might be just a temp fix and I will be rowing again!)
Install a direct wire relay switch to take the ECU out of the fuel pump equation?
Invest in the genuine Mercury fuel pump?
Any input appreciated.
 
It certainly was a temporary fix as I tried a few hours later and it wouldn't start (no spark) and lots of fuel is coming out of overflow tube. I have direct wired a switched cable to the battery and fuel pump as suggested and now have spark but it just kicks and then dies with fuel still overflowing. Any suggestions what next?
 
Update: must have been a problem having a switch between the battery and pump as now I have removed switch and pump is running and so is motor. I assume overflowing fuel was because mechanical fuel pump was still pushing fuel to VST when I was cranking it but HP Fuel pump was not running so fuel had to go somewhere. I will try boardhaulers 12 volt relay fix now.
 
Another update; fuel kept overflowing from the VST until I changed the fuel pressure regulator. I have also put in a genuine high pressure fuel pump and the motor runs ok on the muffs but struggles to get to full revs when in the water under load. I am thinking maybe the MAP sensor is faulty but any suggestions welcome.
 
Hi Jhop unfortunately only partially resolved. Firstly the outboard now gets to full power no problems. The source of this issue I think was a small air leak from the copper fitting that comes out of the side of the intake manifold and then connects to the small rubber tube that goes to the MAP sensor. The little copper connection from the tube was broken and must have been slightly leaking so I have fixed that and the motor runs fine 90% of the time.
Unfortunately I have a second problem in that if I stop to go fishing after running the motor for 20 minutes or half an hour it wont restart or just starts and dies. I have started a separate thread on this but don't have any feedback yet. I was using an aftermarket fuel connector so will be trying an original Mercury connector when I next get back to the boat. See the other thread if you want more details.
 
@boardhauler and others, Hey man, So i did the relay fix after I bought the engine and found out afterwards the previous owner put a aftermarket in it via Yamaha mechanic. After relay fix, It ran good for about 30 Min. Then It will start but die 20 seconds later. Pulled VST and found that the little yellow connector with pins had some shorts. Was two free pins. Switched the wires to other pins in connector on both sides. I'm up and running but still quitting out after 60 seconds or so. I'm gonna pull that pump and submerge it along with connector and run it see if overheating or something. I assume if thats not it, I should be looking at ICV? Just checking in with you and others and see if i should consider other possibilities. Is anyone running a relay in this setup with out issues? I just can not see paying 1200 for ecu and 800 for pump and if that would solve it. 2K sounds like down payment to me. I know boating is money but this one got me pretty hard, any help from others, private message or open appreciated.
 
Got A 2008 ,25 hp mercury , turn key to start, if it beeps, eng will start, if it does not beep, eng will not start, if i tap on the ECU ,beeps when I turn key, & eng will start... Thinking we need to buy that expensive ECU ??????
 
Scott@oldschool said:
Got A 2008 ,25 hp mercury , turn key to start, if it beeps, eng will start, if it does not beep, eng will not start, if i tap on the ECU ,beeps when I turn key, & eng will start... Thinking we need to buy that expensive ECU ??????
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Scott did you get this resolved? I am currently experiencing this exact issue.
 
Jhop said:
@boardhauler and others, Hey man, So i did the relay fix after I bought the engine and found out afterwards the previous owner put a aftermarket in it via Yamaha mechanic. After relay fix, It ran good for about 30 Min. Then It will start but die 20 seconds later. Pulled VST and found that the little yellow connector with pins had some shorts. Was two free pins. Switched the wires to other pins in connector on both sides. I'm up and running but still quitting out after 60 seconds or so. I'm gonna pull that pump and submerge it along with connector and run it see if overheating or something. I assume if thats not it, I should be looking at ICV? Just checking in with you and others and see if i should consider other possibilities. Is anyone running a relay in this setup with out issues? I just can not see paying 1200 for ecu and 800 for pump and if that would solve it. 2K sounds like down payment to me. I know boating is money but this one got me pretty hard, any help from others, private message or open appreciated.




Your thorough diagnostic work is commendable. Given the symptoms and your extensive testing, a malfunctioning ECU seems plausible. It's essential to address it, and it's promising that you've identified a potential solution. Imagine this: A world of exciting casino games is at your fingertips as you enjoy your coffee in a comfortable cafe. In 2023, it will be the allure to find more Canadian mobile casinos. It is no longer necessary to visit actual casinos or be linked to a desktop computer to enjoy your favorite games. With mobile casinos in Canada, the gaming experience has advanced significantly. Now, whether I'm on a coffee break or just relaxing at home, I can immerse myself in a world of fantastic games directly from my smartphone.
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Any update?
 
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