280DA port engine sputter

S

saltshakr

New Member
Jul 3, 2016
9
Buzzards Bay
Boat Info
2003 280 Sundancer
Engines
twin 5.0 mercruiser, w/Bravo III
03 280da, twin merc 5L mpi. Port motor started sputtering on way home, 45 min ride. It died as approach no wake and would crank but no start. Next day started up no problem but sputters when you goose the throttle. Any ideas?
 
Typically, an IAC (Idle Air Control) only causes issues at idle. Was the initial "sputtering" at idle or cruise? I read your post as being the 45-min part was at speed? It will cause issues trying to start, though - if you then advance the throttle and it starts fine, then yes, most likely it's the IAC. Yes, you can swap.

You only have one gas tank, so it's not a venting issue. It could be a partially clogged pick-up tube... also could be the filter or the rubber lines leading to the assembly. If it's been a while since the filter was changed, it's a good idea to start with that, regardless. Checking fuel pressure when the issue is happening would be my next step to help narrow things down.
 
dan313 said:
Change the IAC valve. They are known to go.
Click to expand...
Swap them out and see what happens. A guy on the dock had the same thing happen to him two weeks ago. Changed the IAC and the problem went away. Another guy on the dock was getting an alarm. And the boat ran fine. Turned out to be the IAC valve. Like I said they are known to fail.
Good Luck
 
I just came back from changing fuel filters. The engine was hard to start, but idled fine. If I throttle up in neutral it sputters. Sometimes the idle got stuck around 2000. Anyway, I tested the iac by checking for 10 - 14 ohm, found that test online. Iac had 10-11. Not sure if that's a good test for an iac.
 
Hi All, Thanks for the responses. I swapped the IAC from Stbd to Port engine. the port engine cranks but won't start.
 
saltshakr said:
Hi All, Thanks for the responses. I swapped the IAC from Stbd to Port engine. the port engine cranks but won't start.
Click to expand...

Wait......so you are having a issue with your PORT engine, right?

You swapped your IAC from your working fine starboard engine to your PORT engine. Now your PORT engine will not start?

Thats does not make sense. Are you sure you plugged the wire connector back onto the IAC?

Did you try taking your PORT engine out of gear, move the throttle forward, then try starting it?
 
@doug u are correct. Swapped IAC from Stbd (good engine) to the Port engine. Yes, plugged the connector back in. Port won't start. I tried pumping throttle in neutral and attempt start. No luck. Just cranks.
I hear fuel pump each time ignition switch goes to ON position. I also tested for spark with in-line tester. Seems fine. Could this be more of a bad ignition sensor? Both engines were tuned last summer (wires, plug, cap, rotors). I don't recall if the sensor was replaced. I suppose I could try swapping with bad engine.. Any thoughts? Is there an easy test for fuel psi?
 
saltshakr said:
@doug u are correct. Swapped IAC from Stbd (good engine) to the Port engine. Yes, plugged the connector back in. Port won't start. I tried pumping throttle in neutral and attempt start. No luck. Just cranks.
I hear fuel pump each time ignition switch goes to ON position. I also tested for spark with in-line tester. Seems fine. Could this be more of a bad ignition sensor? Both engines were tuned last summer (wires, plug, cap, rotors). I don't recall if the sensor was replaced. I suppose I could try swapping with bad engine.. Any thoughts? Is there an easy test for fuel psi?
Click to expand...

Sorry for being picky about your wording....

Did you:

A) Pump the throttle forward and back, return to neutral, then try to start the motor

Or

B) Take the motor out of gear, and as you have the throttle advanced, say half way to wide open, try to start the motor

We need you to try “B” to defeat the IAC.
 
If you’ve ruled out fuel, then the next step would be ignition. Try swapping things from the starboard motor to the port to see if you can narrow it down to something through process of elimination.
 
Update.. Mechanic found corrosion with Cap and Rotor. Cleaned it. Starts on 1st crank now. Recommends replacing. Unfortunately, both engines were tuned last year. I guess saltwater and engines don't mix well. :)
 
saltshakr said:
Update.. Mechanic found corrosion with Cap and Rotor. Cleaned it. Starts on 1st crank now. Recommends replacing. Unfortunately, both engines were tuned last year. I guess saltwater and engines don't mix well. :)
Click to expand...

Glad you have it sorted.

I should have thought of the rotor and cap. Mad at myself. Thinking of it, swapping those parts would have been a reasonable thing to try.

If you ever do it yourself, number, photograph make a little cheat sheet for yourself on what wire goes where then move one wire at a time.
 
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