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 Joe Your Own Question
Joe, Marine Mechanic
Category: Boat
Satisfied Customers: 7251
Experience:  ASE, electronics, Marine mechanical and electronics, pwc, wiring, all around repair tech,
Type Your Boat Question Here...
Joe is online now
A new question is answered every 9 seconds

I have a 5.0 mpi that still wont idle after a new iac

Customer Question

I have a 5.0 mpi that still wont idle after a new iac
Submitted: 2 years ago.
Category: Boat
Expert:  Joe replied 2 years ago.

Thank you for your question, my name is ***** ***** I will be glad to assist you with your concern today.

Can you please discribe to me at idle what the engine is doing?

Customer: replied 2 years ago.

Hi Joe

I.m Mike

i just got the boat it ran fine on Fri wouldn't start except by putting in nuetrl and quick shifting into gear on Sat

Ireplaced the IAC (the one i took off looked like a new one)

same problem rund fine but when it hits idle it dies

2003 5.0 mpi

Expert:  Joe replied 2 years ago.

Hi Mike,

I would start by checking the tps - throttle position sensor, which is located on the throttle body, on the opposite side of the linkage attached to the shaft. Using a voltmeter and checking voltage at idle (engine not running but key on) .045-.065 vdc closed throttle and wide open throttle around 4.5 to 5vdc.

Depending on model it may be adjustable, if you find numbers are off and adjustment does not help then it needs to be replaced. Know that first you would remove the flame arrestor and see if it runs better and cleaning it if needed then checking throttle body around butterfly if a dirty ring the throttle can hang and give an incorrect reading/air.

If above is all good and iac counts on a scan tool are correct then move on to checking engine for air leaks with a leak down test, large enough and engine will stall. Also you would want to check fuel pressure to start and no misfires.

Since it does not even idle let alone a problem shifting then I do not suspect a drive cable issue.

Also note if you did not already know even though and iac could be replaced it does not mean that the passage on the throttle body is not the problem instead, a throttle body can sometimes get dirty and require cleaning sort of in the same aspect as a carb just a different unit.

Thank you!

- Joe

Please rate my answer when ready. Bonuses are appreciated.

If for any reason you are not satisfied please reply back to me for further assistance to which I will be glad to help you. The rating system is only to rate me as an expert not the site or the product. If you have any problems for any reason please reply back and let me know.

Thanks again for using justanswer and have a great day!

If you need any further assistance you can reply back at any time for my help.

I'd be happy to answer any other questions you have even if not related.

Related Boat Questions