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 James Your Own Question
James, Marine Mechanic
Category: Boat
Satisfied Customers: 4111
Experience:  12 years Certified marine mechanic, performance boat builder
Type Your Boat Question Here...
James is online now
A new question is answered every 9 seconds

how to test a switch box on a 1988 70hp mercury outboard

Resolved Question:

how to test a switch box on a 1988 70hp mercury outboard
Submitted: 5 years ago.
Category: Boat
Expert:  James replied 5 years ago.

Hello, welcome to JustAnswer.


If your motor runs, but the idle has to be all the way up, the problem isn't the switch box.

Where did you adjust the idle all the way up?

What is your motors serial number so I can bring up any diagrams we may need?

This is likely a fuel delivery problem, probably a plugged up carb or two, but it could also be a fuel pump issue though that is not as likely.

Customer: replied 5 years ago.
Serial Number: 0B260953
Adjusting idle lever by the T handle control
Motor was running fine and basically shutdown
Expert:  James replied 5 years ago.

Have you checked for spark on each cylinder? I am sorry, I assumed you had when you changed plugs. I should have asked.

If you haven't, you need to do so. We need to know if each cylinder is getting a good spark.

Customer: replied 5 years ago.
will double check and get back to you
Expert:  James replied 5 years ago.
Very good, I am here all day, they never let me go home, lol.
Customer: replied 5 years ago.
have good spark on all plugs one more thing the motor had to warm up before it would run right
Expert:  James replied 5 years ago.



Did the motor end up running correctly? Was this just a start up issue, after witch the motor ran ok?

If it was, tell me what you did when you started the motor. What was your start up procedure?

Customer: replied 5 years ago.
the motor would start and idle fine but when you put it in gear it would only let you run maybe 1/4 throttle and it ran fine but try to give it more throttle it would bog down until it warmed up then it would run fine after that it would do this every time it was started the temp outside did not make a diffrents
Expert:  James replied 5 years ago.

Yep, this is a fuel issue.

Have you tried priming the motor with the primer bulb prior to starting? I know you should only have to do that on the first start up of the day, but trying it can help us get the problem narrowed down.

You can also try squeezing the primer (well, having a helper do it) while trying to accelerate to see if this allows you more get up and go.

You may be having a problem with the fuel draining back into the fuel tank when you shut down the motor, but I think you might need to rebuild the fuel pump on the side of the motor.

Customer: replied 5 years ago.
ok will try that tomorrow and let you know thank
Expert:  James replied 5 years ago.
You are welcome.
James and other Boat Specialists are ready to help you

Related Boat Questions