Mercruiser 5.0 stalling out!

[edsmax]

When starting my 2002 5.0 EFI (Throttle Body injected) motor, I need to give it some throttle to get it started. It will not start with the simple turn of the key like it did last year. Once started, it idles and revs in neutral just fine.

However, this past sunday, I went to take it out for its first ride of the season and it stalled repeatedly as soon as I put it in forward and gave it a tiny bit of throttle. It stalled 6-8 times as I limped it back to the slip.

This spring, I changed the inline fuel filter, the water seperator filter, and I did an oil change. Anyone have any suggestions?

Ed

 

[tdappleman]

Has the throttle body ever been cleaned? Could be something as simple as a dirty throttle plate, potentially a sticking throttle plate due to deposits or dirty injectors. I'd spray the plate and body really well with an air intake cleaner (not carb cleaner) and make sure it's good and clean. Lubricate the throttle plate and all linkages with a dry type of lubricant so it doesn't attract dirt. I'd then add a couple of ounces of Seafoam or Berryman B12 into the fuel/water separator and pour the remaining product to the tank to complete the cleaning.

 

[Presentation]

Does an EFI engine have a IAC (idle air control valve) like a MPI engine?

Anyone?


If the engine was a MPI I would say its your IAC.

 

[edsmax]

Does an EFI engine have a IAC (idle air control valve) like a MPI engine?

Anyone?


If the engine was a MPI I would say its your IAC.

Thats an excellent question as I thought of the same thing. Does anyone know this off the top of their head? I will have to review my Mercury maintenance CD in a few minutes to find out.

Ed

 

[tdappleman]

I don't think they have an IAC - may have an idle screw adjustment instead.

 

[Dave S]

EFI motors do have an IAC valve but it is a lot different than the one found on TBI engines.

You could replace it but if that is not the problem then you are out some $$$$. You may be better off letting a Merc mechanic with a scan tool have a look at it to diagnose the problem.

Dave

 

[tdappleman]

I'd certainly start with the simple things. You're looking at $10 in parts and about 15 minutes of your time to do it all.

 

[edsmax]

EFI motors do have an IAC valve but it is a lot different than the one found on TBI engines.

You could replace it but if that is not the problem then you are out some $$$$. You may be better off letting a Merc mechanic with a scan tool have a look at it to diagnose the problem.

Dave

You are correct (of course) the EFI engine does have an IAC attached to the throttle body. I called my service dept and told him what was happening. The first thing he mentioned was the IAC. They are scheduled to send a mercury certified tech with the scan tool to diagnose her tomorrow. I am going to look at it tonight and make sure it is not something simple as the IAC becoming unplugged somehow. Will keep you posted.

Ed

 

[edsmax]

Marina service department already called me this morning and confirmed it is a faulty IAC. They are ordering the part today and installing tomorrow...

 

[Nehalennia]

Marina service department already called me this morning and confirmed it is a faulty IAC. They are ordering the part today and installing tomorrow...

I had similar symptoms on my 5.7 EFI early last season, IAC swapped out and back in business. Glad you figured it out early.

 

[Presentation]

Marina service department already called me this morning and confirmed it is a faulty IAC. They are ordering the part today and installing tomorrow...

Thank you.

Can you please do us a favor and post a photo of the EFI IAC and its cost?

Also, once swapped could you please post a follow up letting us know that all is well now?

This thread will become a valuable thread at CSR. You will help others.

We have quite a bit of threads about the IAC and its issues with MPI engines. I even carry a spare IAC onboard.

With the MPI engines, the replacement IAC part is about $100 and it’s a easy do it yourself swap. Dave (I think it was Dave) posted a step by step guide with photos.

 

[edsmax]

Thank you.

Can you please do us a favor and post a photo of the EFI IAC and its cost?

Also, once swapped could you please post a follow up letting us know that all is well now?

This thread will become a valuable thread at CSR. You will help others.

We have quite a bit of threads about the IAC and its issues with MPI engines. I even carry a spare IAC onboard.

With the MPI engines, the replacement IAC part is about $100 and it’s a easy do it yourself swap. Dave (I think it was Dave) posted a step by step guide with photos.

The photo that someone posted earlier in the thread is exactly what it looked like.

I went to look at it last night in the hopes that it simply might have been unplugged from the harness (it was not). According to the Mercury manual, on the EFI (TBI) engine, you have to remove the throttle body in order to swap out the IAC. Upon inspection of the IAC last night, I didnt see why removing the throttle body was necessary.

According to the service advisor, the new IAC is approx $100.

My plan is to go to the marina later this week and see if that fixed the problem. I will keep you all posted.

Ed

 

[tdappleman]

Good deal - glad it's being fixed!

 

[Scottzzzy]

My '05 220 was doing exactly the same thing you described. Changed out the IAC and went ahead and did the impeller and she ran better than before.

Inexpensive peace of mind!:thumbsup:

 

[edsmax]

Yes, the IAC was the culprit. Starts right up now and ran great with no stalling on my first outting last Saturday.

Ed

 

[STIHLBOLTS]

Same thing happened to me but under way a few years ago. Had a nice long tow back to the marina. :grin: That little controller is the number one thing to look out for if you get those symptoms.