2001 Mercruiser 5.0 flucuates then dies

[shumbard]

Have owned a pontoon for the last 8 years and decided I wanted something to cruise the waterways. Bought a 2001 Ebbtide with a Mercruiser 5.0 EFI. Have had it out every weekend and has ran great. Even did some tubing and skiing last weekend. Went out today and went down the lake about 10 miles. Ran awesome all day and varied speeds. Came into the boat ramp and it was a little crowded so waited my turn. Swam a little. Turned boat off and on a few times idling into position staying in line to get to ramp. Last time I idled over boat just died. Started again and it idled up to just over 1000 and back down to normal and died again. It did this several times and then would not start. I paddled over to dock and tied off. Boat started... idled up then down a few times and died again. I trailered boat and brought home and placed in garage where I store it. Any ideas what the problem may be?? Couple of post lead me to believe it could be the IAC but all had different symptoms than mine. Please help. Thanks

 

[alldodge]

Howdy

Might be a sticking IAC, it may need to be cleaned. The normal failure rate of the IAC is, it will not idle but the motor can run fine at higher rpms. If its sticking then it could be a bit flakey.

Otherwise we could use your motor serial number to see what your setup is.

 

[Fun Times]

Hi, welcome to iboats!

It could be a failing IAC. One test of a few would be to see if the engine will stay running at a higher RPM by advancing the throttle. Now that you're home, you'll need to see if it's still doing it while running the engine using the garden hose method connected to the stern drive using flushing device (muffs).

Also just to check, pull out a few easy to get to spark plugs to ensure they still look good and not fuel fouled..If they are fouled then "possibly" an MAP sensor issue going on too.

 

[shumbard]

Motor serial number is 0M010150

 

[alldodge]

Remove item 7 in the link below and see what it looks like. Look to see if the IAC has been getting hot

http://www.mercruiserparts.com/bam/subassembly/31846/4856/130

 

[shumbard]

How can you tell if it has been getting hot? Looked at part this morning. It is painted black which would lead me to believe it is original after reading other post.

 

[alldodge]

Yours probably isn't getting hot. I've seen them where there is a slight bit of plastic which welted out around were the wires come out.

 

[shumbard]

So today is first chance to get back to the water. Backed boat in and fired up on trailer. Started and idled normally so I decided to go for a ride. Boat ran great. Came back to ramp and idled as should. Think the IAC may be going bad??

 

[alldodge]

As Fun Times mentioned, pull out a few easy to get to plugs and see what they look like.

If the IAC is failing it will run at higher rpm's but will die or sputter when at idle, that is if the fuel pressure is correct

 

[shumbard]

Will pull a couple of plugs when I get it back home. Thanks for the input.

 

[shumbard]

ok. So I pulled one plug from each side of the engine. Both are dry and appear to be normal according to plug charts I looked at. Tried to attach photos but my file size is to large.

 

[shumbard]

They may have a slight lead foul. Maybe last year or previous and need to be changed. Having just purchased this boat a few weeks ago I have not taken the time to do a full tune up as I normally would after making a purchase of a used recreational vehicle.

 

[alldodge]

Sounds like the plugs are OK, so the issue is the idle as I see it, and not the MAP sensor. Either need to wait for it to start again and verify that higher rpm is good and idle is bad, or replace and hope that was it. The IAC at Rock auto is 23.79 and is a standard GM part

 

[shumbard]

So then auto IAC will work for marine application?

 

[alldodge]

So then auto IAC will work for marine application?

Yes, they are the same part.

 

[shumbard]

Would you happen to know the automotive part number? For my particular boat here on iboat it is 18-7632

 

[alldodge]

Merc number is 805224A1
I googled mercruiser 805224A1 and there is a link for rock auto , then entered 805224A1 and it showed the item

Other numbers listed are AC5
enter iac valve ac5 and others come up

 

[shumbard]

Thanks

 

[shumbard]

So I broke down and went ahead and ordered my tune up stuff here at Iboat. While I was at it I decided to change iac even though the last 2 times out I had no issues. Recieved my stuff yesterday and decided to change plugs, wires, distributor cap and rotor button. Started on port side. Noticed front and rear plugs are a little damp and smell of fuel. Center plugs dry. Taking a break and will tackle starboard shortly.

Pulled old IAC and installed new one. When I went to plug it in found the recepticle on new IAC is facing in opposite direction and wire isn't long enough to plug in. Anyone ever experienced the same issue? Guess I will return for an exchange.

 

[alldodge]

new IAC is facing in opposite direction and wire isn't long enough to plug in

It has 2 screws/bolts on opposite sides of the IAC, remove the two screws and rotate it 1/2 way around and put the screws back in

Or am I missing what your saying?