How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Charles Your Own Question
Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3981
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
67216606
Type Your Boat Question Here...
Charles is online now
A new question is answered every 9 seconds

I have a yamaha 100 4 stroke. When I start out it runs fine.

Customer Question

I have a yamaha 100 4 stroke. When I start out it runs fine. After a bit it starts missing. RPM doesn't seem to matter. As soon as I turn it off and restart it runs fine for another 15 - 90 seconds, then begins missing again. I changed the fuel filter and have put several cans of Sea Foam through it.
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Marine Mechanic should be aware of?
Customer: NOt that I can think of
Submitted: 3 months ago.
Category: Boat
Expert:  Jason replied 3 months ago.

Hello my name is ***** ***** am I speaking with? I read what you wrote. Do you have the year and model number on the outboard available?

Expert:  Jason replied 3 months ago.

It looks like you read my response. Are you still here?

Customer: replied 3 months ago.
I am here
Expert:  Jason replied 3 months ago.

I never received a response from you. Do you have the year and model number on the outboard available?

Customer: replied 3 months ago.
Not sure of the year or model. I can go look on the engine if I need to
Expert:  Jason replied 3 months ago.

Well... At minimum I would need to know if the engine is carbureted or fuel injected. Do you which it is?

Customer: replied 3 months ago.
Let me go get a model #. Where is it located?
Expert:  Jason replied 3 months ago.

It's on a sticker on the clamp bracket. Are you near the outboard now to go check for this, or is it going to be a while?

Customer: replied 3 months ago.
10 min
Customer: replied 3 months ago.
I don't have phone service here
Expert:  Jason replied 3 months ago.

Okay i'll wait for 10 minutes

Customer: replied 3 months ago.
OK I'm back
Customer: replied 3 months ago.
100 hp 4 stroke fuel injected
Expert:  Jason replied 3 months ago.

Okay what was the model number?

Customer: replied 3 months ago.
67F L 306688 are the numbers on the plate
Customer: replied 3 months ago.
Yamaha F100TLRY
Customer: replied 3 months ago.
The TLRY is partially obliterated but I think that's right
Expert:  Jason replied 3 months ago.

F100TLRY is a carbureted engine, not fuel injected. Is there a history on this engine, have you ever personally seen it run correctly or make full power? Is it missing at all RPMS or just idle? How old is the fuel itself?

Customer: replied 3 months ago.
The hood says fuel injected. I bought the engine rebuilt last year from a place called Blackbird Industries. It has run well until now.
Customer: replied 3 months ago.
When I restart it it will run for a time period (30 seconds to several minutes) just fine, from an idle to wide open. Then it starts running rough and the RPMs drop. At WOT it runs fine, as it does at idle.
Customer: replied 3 months ago.
Turning it off and restarting seems to reset it.
Customer: replied 3 months ago.
I have put about 150 hours on it since March 2016. We had an issue with the trim motor but no other problems
Expert:  Jason replied 3 months ago.

C​lick this link, these are the carburetors for model F100TLRY - http://www.boats.net/parts/search/Yamaha/Outboard/2000/F100TLRY/CARBURETOR%201/parts.html

You either have the wrong hood or the wrong model number. Do you want to take a couple of pictures of the engine so we can see exactly what you have?

Customer: replied 3 months ago.
Fuel was purchased 2 weeks ago from a reputable marina
Customer: replied 3 months ago.
I topped off the tank yesterday morning with the top grade
Customer: replied 3 months ago.
Is there an email I can send you a picture of the plate?
Expert:  Charles replied 3 months ago.

Hello, my name is***** will assist you from here. You can use this link for instructions on how to post a pic here, or email to customer service address on the page and tell them that you are working with me and they will forward them to me. Once I see exactly which set up your engine has, I will be able to assist you in getting it running again.

http://ww2.justanswer.com/help/how-do-i-send-photo-or-file-expert-0

Customer: replied 3 months ago.
After i chatted with you folks l realized my primer bulb was leaking so I replaced that. However that didn't fix the problem. I also replaced the filter
Expert:  Charles replied 3 months ago.

Thanks, ***** ***** turn the engine so that I can see the other side of it, that is where the intake is. The top cowling is the same for the carb and the FI, only the sitckers are different. Since you bought this rebuilt, I want to make sure that you have.

Customer: replied 3 months ago.
Does this work?
Expert:  Charles replied 3 months ago.

Yes it does. This is a carb engine. Was is sold to you as an EFI?

Customer: replied 3 months ago.
I'm not sure actually.
Expert:  Charles replied 3 months ago.

When the engine bogs down, would pumping the primer bulb over and over help it to run better?

Customer: replied 3 months ago.
No. Has no effect. That's how I found out the bulb was leaking
Customer: replied 3 months ago.
Nothing makes it run smoothly except turning it off and restarting
Expert:  Charles replied 3 months ago.

How is the oil level in the engine right now? Low or high?

Have you pulled the plugs to look at the tips of them?

Have you serviced the cooling system since you bought the engine?

Customer: replied 3 months ago.
Oil is in the normal range. I have not pulled the plugs. I had the local marina do a service this spring but I'm not sure if they serviced the cooling system
Customer: replied 3 months ago.
If it would be helpful I can pull the plugs and look but it will be several days until I'm back at my boat
Expert:  Charles replied 3 months ago.

Yes it would be very helpful. It would also help if it can be on a trailer, as there are other items that may need to be looked at, and it is much easier to check them standing behind the engine rather than hanging over the back of the boat.

Customer: replied 3 months ago.
OK I'll do that and respond back. Thanks! For future reference, I'm assuming the EFI is a better system?
Expert:  Charles replied 3 months ago.

Yes, the EFI, or electronic fuel injection is a much better system than the 4 carbs that you have on your engine. It burns less fuel and gives less issues than carbs. My guess is that the place that built the engine had the cowl for your engine was broken, so they threw this one on it. Or they were trying to pass the engine off as something it is not.