Engine Stalls at idle - Mercruiser 5.0 MPI

[chyanke]

Need some help diagnosing a problem with my Mercruiser 5.0 MPI. I have a 2005 280 Sundancer with twin 5.0MPI Bravo III’s with 260 hours on the engines. At the end of last season, I put STA-BIL fuel stabilizer into the tank at the ratio stated on the back of the bottle. I ran the boat at cruising speed for 30 minutes and then came into the marina to put the boat on the trailer for the winter. Approaching the marina, I slowed to no wake speed and the Port engine stalled. Never any problems prior to this incident. It would not restart in the neutral idle position. I was able to start it in neutral by revving the engine to 1k RPM. As soon as I backed it down to the idle position, it stalled. I repeated this a few more times and it stalled at idle each time. The Starboard engine ran fine with no issues. I put the boat on the trailer and forgot about it since it was the last trip of the season.

Fast forward 6 months to this weekend, I hooked the water up to the engines to start and change the oil. The Port engine would not start again. In neutral, I gave it some throttle and it fired right up. Back it down to idle and it stalled. I started it again by giving it some throttle and let it rev at 800 RPM for 5 minutes to warm up so I could change the oil. About the time I was ready to shut it down (5 minutes running) I noticed some white smoke coming from behind the air intake cover. The white smoke got thicker in a matter of seconds and I immediately shut down the engine. Upon inspection, the white smoke left some white residue next to where it was billowing from. In the pic below, I identified where the smoke came from. Starboard engine started and idled just fine with no issues.

Does anyone have any idea what the problem is? I always use fuel stabilizer at the end of every season with no problems but could it have affected the engine? Is the stalling at idle related to the white smoke? The location where the white smoke came from, what is that part called and what does it do? Any help would be greatly appreciated.

 

[Ididntdoit]

Iac

 

[jason78]

Iac

I'll second the IAC. Very common issue with the Small Block MPI engines and you have the classic symptoms. It appears yours is still painted black meaning it has never been changed. Can't believe it made it that long. Be sure you change the IAC mufflers too. Many here carry a spare on board.

See post #8 here.

http://clubsearay.com/showthread.php/36072-Impeller-IAC

 

[my DOG HOUSE]

You can get the IAC from your local Advance Auto Parts Store. Save big $. The only kicker is you will have to reuse the rubber gasket. I have had no issues doing that. The muffler being clogged is the primary cause of the IAC failing and if you remove it and keep it out it will last much longer. According to my SeaRay tech it only serves to reduce noise at idle and I cant hear it with the hatch closed. The noise with out the muffler sounds like an air hose at idle only as the valve closes above idle.

YMMV?

 

[ZZ13]

Deleted

 

[ZZ13]

You can get the IAC from your local Advance Auto Parts Store. Save big $. The only kicker is you will have to reuse the rubber gasket. I have had no issues doing that. The muffler being clogged is the primary cause of the IAC failing and if you remove it and keep it out it will last much longer. According to my SeaRay tech it only serves to reduce noise at idle and I cant hear it with the hatch closed. The noise with out the muffler sounds like an air hose at idle only as the valve closes above idle.

YMMV?

So all that dirt that is on my filter/muffler when I replace it is irrelevant to the IAC?

 

[my DOG HOUSE]

So all that dirt that is on my filter/muffler when I replace it is irrelevant to the IAC?

Just as irrelevant as it is to your motor. You do know that there is no air filter on the motor, right?

The IAC's fail because of the reduced airflow (cooling, as air passes through it) caused by a clogged muffler. The same engine in a car has the same IAC without the muffler and you do not hear it because if the air filter.

At idle the IAC solenoid energizes (thus creating heat) to open the passage for idle airflow and it is cooled by that airflow. The IAC is fail - closed, that is why the engine runs normal above idle.

As I understand it from my SeaRay tech. If I am wrong, please explain.

 

[jason78]

You can get the IAC from your local Advance Auto Parts Store. Save big $. The only kicker is you will have to reuse the rubber gasket. I have had no issues doing that. The muffler being clogged is the primary cause of the IAC failing and if you remove it and keep it out it will last much longer. According to my SeaRay tech it only serves to reduce noise at idle and I cant hear it with the hatch closed. The noise with out the muffler sounds like an air hose at idle only as the valve closes above idle.YMMV?

What assurances do I have that the IAC from Advance Auto Parts is Ingition protected for use on a marine engine? The practice of using various automotive parts to save money has been discussed here a number of times and in some cases makes sense but not sure I would want to do this with an electrical component unless one can be absolutely certain it is the exact same part. Some risks are not worth saving a few bucks.

 

[paulswagelock]

There are no assurances that it is a non-incendive device. That said, I have not seen anywhere that the Merc part is either.
It is $55 versus $120, so you need to weigh that against the unknown.

 

[kkalsch]

What assurances do I have that the IAC from Advance Auto Parts is Ingition protected for use on a marine engine? The practice of using various automotive parts to save money has been discussed here a number of times and in some cases makes sense but not sure I would want to do this with an electrical component unless one can be absolutely certain it is the exact same part. Some risks are not worth saving a few bucks.

I too have used the Auto Store version- the only reason I did (other than half the price)....was because I gave them the Mercury part # and it was a direct interchange .So do you think that company would take a risk by providing a direct interchange for the Mercury part -if it was not the same?..that's a pretty big liability if its not.

 

[jason78]

There are no assurances that it is a non-incendive device. That said, I have not seen anywhere that the Merc part is either. It is $55 versus $120, so you need to weigh that against the unknown.

I have been able to find the Merc IACs online for under $100 so for $45 every couple years I guess I'll keep using the Merc branded ones to be on the safe side. Although you are correct about the Merc ones not being labeled as such, I can't see them selling a part for a marine engine that was not safe to operate on it. What it all comes down to is as you said, weighing the potential cost savings with the unknown.

 

[jason78]

I too have used the Auto Store version- the only reason I did (other than half the price)....was because I gave them the Mercury part # and it was a direct interchange .So do you think that company would take a risk by providing a direct interchange for the Mercury part -if it was not the same?..that's a pretty big liability if its not.

As many times as I have been misguided by employees of Auto Parts stores and their systems, nothing would suprise me. It very well could be the same part but not worth the risk to me personally unless of course it could be verified, nullifying the risk. If we were talking about hundreds of dollars and something that I had to replace several times a year, I would certainly take a closer look but as I said before, a 40-50 dollar savings on something I might replace every 2 years just does not make sense to me.

 

[Dave S]

I am with Jason on this one.

Buy the Mercury branded part. Look on line f you want to save a few bucks. Make sure you do get a new gasket as well since the old one will sometimes tear when you remove the IAC. And always carry a spare IAC on board along with the proper size allen wrench. You can change the IAC in 10 minutes or less even when you are on the water. And change your IAC filters on both engines. The filters are dirt cheap and my advice is to change them annually.

Single engine guys should always carry a spare as you will likely not be able to dock the boat with a bad IAC. (don't ask me how I know this.:smt043)

 

[my DOG HOUSE]

There is no such thing as an IAC filter. It is a muffler, check the MerCruiser service/parts manual.

But Dave's advice to SE boaters is spot on, trying to dock with a bad IAC would be an accident waiting to happen.

 

[Dave S]

Just for the record, that little piece of foam acts as both a filter and a muffler. When it is clogged with dirt from filtering a lot of air as the hours chalk up on your engine, it can prevent the right amount of air getting thru to the IAC itself and can prevent the IAC from working properly. It also acts as a muffling device. With the engine idling and no filter/muffler in the TB intake, the roar form the engine is real loud if you have to work on the engine with it idling. And underway you may notice a whistle too. But just hearing how loud it was at idle with no muffler while trying to work on the engine, I decided to go the replacement route. The filter/muffler costs less than a dollar, so I see no reason not to change it.

 

[my DOG HOUSE]

Dave, I agree in principal. But some people go on and on about how it filters, as in you are running your engine without a filter by eliminating it. Its sole purpose is noise and the engine has no intake air filter in a marine application. Somewhat semantics and if you keep spare mufflers and change them, your IAC will last longer just as it will if you just remove the muffler. That is if the noise is not a problem. I can't hear the added noise with the hatch closed.

Now, what do you know about the ARRIVAL OF SUMMER?

 

[Dave S]

Now, what do you know about the ARRIVAL OF SUMMER?

Maybe we are heading for one of these.............. http://en.wikipedia.org/wiki/Year_Without_a_Summer ........but I hope not.

 

[chyanke]

Thanks to everyone who contributed to my question. I ordered the IAC, gasket, and muffler/filter for about $105 from wholesalemarine.com and replaced the IAC and muffler on my Port engine. The engine fired right up after the repair and successfully idled. Thanks for saving me an expensive trip to my local SR dealer. I did not replace the working original IAC in my Starboard engine but I order an extra to carry on board in the event that it fails too. Thanks again...now headed to Lake Mead for the Easter Weekend. It’s supposed to be 85 degrees and sunny.

Now for an unrelated question that has probably been covered at some point on this site but I was unsuccessful in a search of the topic. When I change the engine oil in both my 5.0MPI’s, I am only able to extract 3.5 quarts from each engine, although the specs say that it holds 5.5 quarts. I have tried extracting the oil in each of the following ways:
1) using Jabsco pump, pump it from the remote oil drain tube connected to the bottom of the pan.
2) using Jabsco pump, pump it out from the connection at the top of the dipstick tube.
2) using Jabsco pump, push the small tube through the dipstick channel and hit the bottom of the pan.

Each method extracted more or less the same amount of oil...about 3.5 quarts. The boat is on the trailer when I do this and I crank the trailer tongue up trying to make the angle close to waterline level. Does anyone else with the same engine experience the same amount when they extract oil for an oil change? If you get more out, what is your process? Thanks!

 

[JimFromMD]

Thanks to everyone who contributed to my question. I ordered the IAC, gasket, and muffler/filter for about $105 from wholesalemarine.com and replaced the IAC and muffler on my Port engine. The engine fired right up after the repair and successfully idled. Thanks for saving me an expensive trip to my local SR dealer. I did not replace the working original IAC in my Starboard engine but I order an extra to carry on board in the event that it fails too. Thanks again...now headed to Lake Mead for the Easter Weekend. It’s supposed to be 85 degrees and sunny.

Now for an unrelated question that has probably been covered at some point on this site but I was unsuccessful in a search of the topic. When I change the engine oil in both my 5.0MPI’s, I am only able to extract 3.5 quarts from each engine, although the specs say that it holds 5.5 quarts. I have tried extracting the oil in each of the following ways:
1) using Jabsco pump, pump it from the remote oil drain tube connected to the bottom of the pan.
2) using Jabsco pump, pump it out from the connection at the top of the dipstick tube.
2) using Jabsco pump, push the small tube through the dipstick channel and hit the bottom of the pan.

Each method extracted more or less the same amount of oil...about 3.5 quarts. The boat is on the trailer when I do this and I crank the trailer tongue up trying to make the angle close to waterline level. Does anyone else with the same engine experience the same amount when they extract oil for an oil change? If you get more out, what is your process? Thanks!

Glad to see this question... I get about 3.5 quarts out of my starboard engine and about 4.5 quarts out of the port engine. Always drives me nuts every time (twice so far). I use one of the jabsco bike pump looking deals and go with the small tube through the dipstick to the pan. I've even gone as far as to seal the dipstick and tube together with electrical tape trying to prevent any suction loss, and still not much more.

 

[kevin27]

Check to see if you have an oil drain hose attached to the oil pan. Mine did and I just shoved the hose out the drain plug hole and empted into a bucket. No mess inside the boat. I think they came from the factory with them. I have not worked on a 280 but with the smaller engine room than my 300 you may have not seen them. I had to get down low in the eng room to find them.