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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15858
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have a 2001 Yamaha 150 direct injection outboard. Having

Customer Question

I have a 2001 Yamaha 150 direct injection outboard. Having problems when you go for power. Starts and idles perfectly but when you go to open it up it loses power. Like it's not consistently getting fuel. Had all filters changed, new fuel line, primer ball ect. This problem is also intermittent. Sometimes the boat will run perfectly. Any idea what may be the issue?
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** am I speaking with?
Have you tried running it off of a portable fuel tank to see if the issue still happens?
Customer: replied 2 years ago.
Yes. It still happens. Only happens when the engine has been running for awhile. Had a mechanic look at it and he was saying it may be an electrical issue. Some sensor or module that is attached to each cylinder.
Customer: replied 2 years ago.
My name is Jon
Expert:  Jason replied 2 years ago.
Hi Jon, did the mechanic hook up a scan tool to check fuel pressures while the problem is happening? Has he duplicated the problem and done a cylinder drop test? It doesn't sound like you are working on this yourself, what kinds of questions did you have?
Expert:  Jason replied 2 years ago.
Also, does this happen every time. Or is it intermittent?
Customer: replied 2 years ago.
It's is intermittent. Not sure about the scan tool. I can find that out. The boat was passed on to me by a friend and he was having these problems and had a mechanic looking at it.
Expert:  Jason replied 2 years ago.
I can give you some tests that need to be done by the mechanic. But because it's intermittent I won't be able to give you any kind of answers here. I don't know if you will find that helpful or not. Did you want to continue or call it quits?
Customer: replied 2 years ago.
We can continue. Because this engine is fuel injected does it make sense that the issue is electrical?
Expert:  Jason replied 2 years ago.
Not always, the HPDI injectors can go bad, and become sticky. What the mechanic needs to do is 2 things. First he has to duplicate the problem. And once the engine is acting up, 1. Check fuel pressures - If they are low the fuel pumps/system need to be gone through in order to figure out why. But if that looks good 2. Do a cylinder drop test. - A cylinder drop test is the mechanic being able to turn off any cylinder he wants with the lap top. The way this works is each time he turns off a cylinder, there should be a drop in rpms. So if he turns off #1, and there is a drop in rpms. He would turn 1 back on, and then turn 2 off. He would go through all 6 cylinders. What he is looking for is to see if there is a cylinder with no change. Lets say he turns off #4, and there is no drop in rpm. Then you know the problem is on the #4 injector or the #4 coil. From there you can swap the coils and injectors to other cylinders that you know work okay. And see if the problem follows the coil, or follows the injector. And that will tell you which part the issue is. Does that all make sense?
Customer: replied 2 years ago.
Wow. Yea that does make sense. I will go ahead with what you have suggested here and see what happens. Thanks
Expert:  Jason replied 2 years ago.
You are most welcome and I was glad I could help.If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank. Questions do not close out, so if you have to come back tomorrow or next week with follow up questions to this you still can even after doing a rating. And if I have saved you quite a bit of money, or saved you a trip to the dealer, tips are always greatly appreciated.Thank youJason

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