2001 Mercruiser 5.0 flucuates then dies

[shumbard]

This IAC has offset screw holes so it can only be installed one way.

 

[alldodge]

Guess I have nothing, never heard this happening before. Wonder if Sierra is the issue, :noidea: just a guess


Het Fun Times have any ideas?

 

[Pete104]

Makes you wonder. Obviously a buyer at Sierra dropped the ball at some point. How can 1 seller expect to sell "everything" accurately ?

 

[shumbard]

Anyone ever had any issues getting rotor off. That thing is stuck. Screw on top is rusty so moisture may have it stuck.

Also had 2 plugs on starboard that were damp with slight fuel smell.

Started return process on IAC. Will check local Mercruiser shop on way home today to see if they have one. Merc part here is 102 vs sierra at 80. If dealer here is around same price will go ahead and get one and install today when I pry that rotor off.

 

[Fun Times]

I do recall someone somewhere on one of the boating forums experiencing the same issue with an IAC being that the plug connector was opposite of the original and the harness not reaching so honestly I'm not really surprised and I almost said something about making sure to find the correct design...Now I wished I did mentioned something. I tried locating the topic I'm thinking about but no luck though.

There were a few brands and part numbers mentioned in this topic, what brand/part number did you end up buying from and where?
Here's three examples as to be careful with as Sierra part number 18-7704, 18-7705 used on Volvo penta & 18-7697 almost all looks like they may fit too but don't know for certain. https://www.perfprotech.com/catalogs/sierra/page/846 .. http://www.iboats.com/Iac-Motor-18-...6218110--session_id.834612169--view_id.712854


We also need to bear in mind that if the engines from about the end of 2002 - 2008 with 555 ECM's uses a different design IAC than early 2002 on back and the 555 design is the same as you would find on a 2002 ford windstar....Detailed info on this is quoted below and is a copy and paste of two posts combined from same poster.

Since last summer I was having idling problems on my stbd 350 mag MPI. So when our 330 Sig got wet last Tues I decided to fix the problem once and for all. I switched the throttle position sensor (TPI)from port engine to stbd engine and had no improvement in idling. The port engine was still stalling and "hunting". Then I changed the IAC valve from port engine to stbd. My stalling problem went to the port engine. Bad IAC valve. This is where it gets interesting. My first stop was Autozone with part in hand. They couldn't cross reference it but the guy at the counter said "That sure looks like a Ford IAC". huh?" I'm running a chevy sir." Next stop was a mercruiser dealer. They didn't have the part of course but did verify that mercruiser did indeed use a Ford IAC on there 350 mag mpi engines. He said this was because they had only 2 wires left on the ECM for the IAC and chevy IACs are 4 wire. Fords are 2 wire. Now I went to Advanced Auto. Found a guy who was fast on the computer search engine and started looking at every Ford IAC they had. Soon I found an exact match! My mercruiser 350 mag mpi uses an IAC made by Ford for their 2002 Ford Windstar! I purchased it and installed it last night. My 350 mag idles and runs perfectly. Also I might add that the price was less than half of the merc part.
I purchased them at NAPA part #2-166509 and cost 69 deer each plus tax (comes w/ gasket). I was told that merc needed a 2-wire iac for their 350s because that's all the space they had left on the ECM. Whether the block is the same or not doesn't matter because the iac is on its own mounting plate and housing. The iac is only operational at idle and does nothing else. I did notice that the new iacs (ford windstars) contain a small return spring in them to return the plunger whereas the old merc factory iacs did not have the springs. Maybe this part has been improved?

 

[Fun Times]

Anyone ever had any issues getting rotor off. That thing is stuck. Screw on top is rusty so moisture may have it stuck.
when I pry that rotor off.

The complete rotor assembly/Stainless Steel wheel needs to be pried up with a pry bar or two. Without touching the sensor, put a heavy-duty flat screw driver or pry bar under the wheel with the side of the blade vertical and push down on the driver handle and the wheel will come up...Sometimes it may take two pry bars.

The rotor is and should be Loctited back down with red Loctite but using blue Loctite is typically sufficient enough as it's supposed to help keep the rotor wheel from lifting at high RPM. If there's a screw on top then it may be after market.

Hope you bought the whole rotor assembly like the image below....Also see item number 5, http://www.iboats.com/Distributor-A...218110--session_id.727159004--view_id.1683233
If the rotor don't look like this then we'll need a photo of what you have to help better.

 

[shumbard]

I have a 2001 5.0 Mercruiser. I purchased the part here at Iboats.com. 18-7632 is the part number.

I did buy the whole assembly like the one you have pictured on the rotor.

 

[Fun Times]

If you've been cranking over the engine without starting then you may get a few wet plugs with fuel. Lets hope it's not water as that will be damaging.

To test you will want to disconnect the 2 injectors on top of the throttle body and crank the engine over to see if they appear to be leaking fuel under pressure from the fuel pump.

Also have all 8 spark plugs removed, connect the garden hose up to the drive with the drive in the down position, put some cardboard covering the spark plug holes the best you can and crank the engine over for about 15 seconds to see if the cardboards on either side is getting wet...The spark plug holes should not be spitting out water of fuel if the injectors are disconnected. See injector item number 13, http://www.iboats.com/Throttle-Body/dm/cart_id.266218110--session_id.727159004--view_id.1683238

Let us know, good luck.

 

[Fun Times]

I have a 2001 5.0 Mercruiser. I purchased the part here at Iboats.com. 18-7632 is the part number.

I did buy the whole assembly like the one you have pictured on the rotor.

Don't know if this will help out any but you could also try calling up iboats and explain the situation and reference this topic to see if they'd be willing to check into it further and allow a return for possibly the correct one.

The first full link below is going to be your full parts guide/catalog through iboats newest OEM parts look up for your engine model/serial number posted by you earlier...Just for reference, Your Mercruiser OEM parts catalog part number is 90-80950099

http://www.iboats.com/5-0L-EFI-GM-305-V-8-1999-2001-0L331631-THRU-0M299999/dm/view_id.1683216

The OEM IAC through iboats would be item number 7 805224A1 Motor Assembly, Iac,
http://www.iboats.com/Throttle-Body/dm/cart_id.266218110--session_id.727159004--view_id.1683238

 

[shumbard]

I have already started a return on their website.
Thanks for all the info. It is a big help.

 

[shumbard]

Stopped by my local Autozone and Advanced Auto and looked at the auto equivalent.... both were oriented same as sierra model.

 

[Fun Times]

Stopped by my local Autozone and Advanced Auto and looked at the auto equivalent.... both were oriented same as sierra model.

If still possible, could you try posting a photo of both next to each other for future use.

 

[shumbard]

I tried but photo file size exceeds limits here. I could email a copy.

 

[alldodge]

Use photobucket

 

[shumbard]

I sent ro your email. I will get photobucket on my computer soon so I can post.

 

[alldodge]

Don't know which is which but think the new (Sierra) is on the left....

 

[alldodge]

BTW I have a photobucket account but don't use it much. I like to resize my pics and upload

 

[shumbard]

The new sierra is on the left.

 

[alldodge]

OK, in most cases the pin is extended out and the new one shows in held in. Pics of new ones for sell show a retention wire holding the pin. If the IAC coil inside the unit goes out, it is then unable to pull it back in so the extended probe would seam to me to close the port off and kill the motor. Guess this one doesn't work that way.

Would you mind taking a pic facing head on with the pin, and the connector in the rear facing the same direction. This way we can see the different offset

 

[shumbard]

Reinstalled old one. Finished my tune up and already had boat back in water. Had no issues with idle and boat ran great. I could really tell a difference in its performance with the new plugs, wires, rotor and cap. I can take a pic of the new one from thise angles.