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F150 low rough idle


dabear

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First time in 40 years of having a boat that I took one to a dealer for engine work. My F150 has 130 hrs. Has new fuel filters ,new spark plugs a rebuilt and tested set of fuel injectors . Oil and filter fresh . It will idle all day long in the drive way on the hose put the boat in the water and it won't idle rpm drops and stalls at idle. Anything past 900 rpm runs normal. Cruises normal has not lost any wide open RPM or speed. Had to take it to someone with Yamaha Dia.testers. Call Paul at Family Boating he has a Yamaha Tech named Curtus a certified Yamaha tech for over 20 years with all the information and testers needed . Dropped the boat od this morning feels strange having a shop work on your boat but didn't want to buy test harness and Dia equipment to try and trace the fault. Empty garage looks a lot bigger.  Joe R

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Outlaw it isn't anything that I could see with out Yamaha  Dia. Equipment, The two sensors that I thought could be out od range are not cheap two to three hundred dollars each.  Plus they have to be adjusted to specs after replacement. I didn't want to start changing parts that may be ok so I took it to a trained Yamaha mechanic Curtis at Family Boating I was told that he was the best around. I have never had a car or boat I owned worked on by somebody else but on today's hi tech outboards you could replace things that are not the root cause of the problem . If you don't have the correct testers to pin point the fault you could turn into a parts changer In a second and not fix it. When I get it back I will post what parts repaired the idle problem.  Joe R

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Modern outboards are great money makers for educated mechanics!

 I hope they get it lined up for ya.  Throwing parts at an unknown problem is never fun. Diagnostic will tell them some but not all.  I'd lean toward TPS or IAC (lean mixture at idle) just off your description, but honestly it could be a number of different things.  Good luck!

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9 hours ago, dabear said:

Outlaw it isn't anything that I could see with out Yamaha  Dia. Equipment, The two sensors that I thought could be out od range are not cheap two to three hundred dollars each.  Plus they have to be adjusted to specs after replacement. I didn't want to start changing parts that may be ok so I took it to a trained Yamaha mechanic Curtis at Family Boating I was told that he was the best around. I have never had a car or boat I owned worked on by somebody else but on today's hi tech outboards you could replace things that are not the root cause of the problem . If you don't have the correct testers to pin point the fault you could turn into a parts changer In a second and not fix it. When I get it back I will post what parts repaired the idle problem.  Joe R

 

Money well spent....simple stuff.....plugs, filters, impellers, etc....I do myself...anything requiring "real" knowledge goes to the 5 start yamaha mechanic at Boat Center...they have NEVER let me down....

 

dc

 

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The fault that is causing the low rough idle is a minor exhaust leak between the power head and exhaust . The bad thing is the power head has to be removed to inspect what parts need to be replaced to repair the leak. What seems to be happening is when the boat is in the water at idle it  the exhaust comes out between the power head at the base filling the cowl with fumes causing the sensors not to read correct.When the RPMs get higher the exhaust is stronger and it exits out the prop and stops filling the cowl with fumes. I will have to wait until next week and see how bad it is. The tech said the boat ran fine when the cowl was off. I hope this Information may help others with the same.complaint. Curtis at Family boating did a great job finding the root cause that was making the engine idle drop and run rough.   Joe R

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1 hour ago, dabear said:

The fault that is causing the low rough idle is a minor exhaust leak between the power head and exhaust . The bad thing is the power head has to be removed to inspect what parts need to be replaced to repair the leak. What seems to be happening is when the boat is in the water at idle it  the exhaust comes out between the power head at the base filling the cowl with fumes causing the sensors not to read correct.When the RPMs get higher the exhaust is stronger and it exits out the prop and stops filling the cowl with fumes. I will have to wait until next week and see how bad it is. The tech said the boat ran fine when the cowl was off. I hope this I for may help others with the same.complaint. Curtis at Family boating did a great job finding the root cause that was making the engine idle drop and run rough.   Joe R

what year? Is it under warranty?

dc

 

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I looked at the hours and assumed it was only several yrs old.Glad you found the problem.  Do you flush the motor after each use?  With the boat sitting a long time it should be flushed.  Use is good for all outboards.  Make sure you keep the fuel treated to prevent water and separation from happening.

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Out of warranty. Low hrs because boat is used about every other week fishing 20 mins from ramp. Motor is spotless and is ALWAYS flushed. Yamaha has had a exhaust corrosion problem on many F225 and on some F150's. I had not heard about this corrosion problem until after it happened to my motor.  There are a few pictures of this problem area on line the pictures on line show corrosion from the inside of the exhaust turner and port area seems like it was not a big problem on two strokes because the exhaust ports are coated with oil build up from 2 cycle oil unlike the dry exhaust on four strokes. Oh well I guess this is not my lucky day.  

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Jason I just retired and am going to be able to use the boat much more and I was thinking that this motor would be my last and that I could put hundreds more hours on it with out any major repairs. (😢) Now I am thinking about maybe trading the motor in on a new SHO 115 or SHO 150  .  Not the way I wanted to start retirement  . After I see the out the door price with my trade I will have a better idea what is best for me. Anyone know what speed they are getting with the SHO 115 on the 2010 style 18 HPX hull ?  Joe R

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Fsusteve, was your repair done as a warranty repair ?   Did the repair last  ?  I have pics of some one else's motor with the same condition that I found on line showing the area that didn't seal on the exhaust and the metal that was corroided or washed away. I am not sure how to post the pics. Did anyone ever tell you of a way to stop the inside of the exhaust from doing this ? It is not a water jacket area that can be flushed. Joe R 

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This was a few years ago, I had read it somewhere on line as a possible cause, similar issue that you're having. It also turned out I had a head gasket issue and the motor was out of warranty, my mechanic ended up tearing the engine completely apart, it was pricey. It was a 2001 motor which was when they had a lot of problems with the four strokes. Repair was permanent, although I never felt confident with it after that, sold it less than a year later.

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