270 SLX stalled at idle speed

A

Andy O

New Member
Jul 3, 2023
8
Boat Info
2007 Sea Ray 270 SLX
Engines
496 MAG with Bravo III
Greetings! I have a 2007 270 SLX with the 8.1L Mag 496 DTS. 290 hours. Original owner.

Took it out this afternoon on a short trip at slow speed (< 10 mph). Turned it off and sat in the middle of the lake and ate dinner for about 1/2 hour. Started right back up and started heading home…. 5 mph the whole way. About 10 minutes in, it stalled out of nowhere. Wouldn’t re-start. Batteries strong and sounded like it wanted to turn over but didn’t. Tried for about 15 minutes. While the tow boat was on the way I took the throttle out of gear and pushed it up about half way and tried to start it. It fired up. When I pulled back towards idle, sounded like it would stall so pushed it back up. Put it gear and drove around for a bit and it was fine. Headed back to the dock (not going too slowly) and got it in the slip. Didn’t stall. Sat in the dock for about 10 minutes with it running at idle and no problems. Turned it off and on a couple of times and no problem.

Searched the forum and google searches and saw a post about IAC valve - which looks to be an easy/inexpensive fix. Said it was a classic problem on mercruisers but not sure if mine even has it (apparently 8.1S definitely has it - saw a YouTube vid). I guess it could be a million problems (water in fuel?) but any thoughts from the experts?
 
If you truly have DTS, and you should, there is no IAC as the throttle body is digitally controlled. My money is that your cool fuel module is beginning to fail. I had that exact boat but a 2008, and it did the same thing, then the failures became more frequent. It was a failing/then failed cool fuel assembly. I didn’t mess with rebuilding it, just replaced the entire assembly.
 
techmitch said:
Sounds like an IAC, but I'm surprised that you didn't mention any engine alarms. Maybe your boat is not equipped?
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Thanks for the reply. Correct, no alarms.
 
paulswagelock said:
If you truly have DTS, and you should, there is no IAC as the throttle body is digitally controlled. My money is that your cool fuel module is beginning to fail. I had that exact boat but a 2008, and it did the same thing, then the failures became more frequent. It was a failing/then failed cool fuel assembly. I didn’t mess with rebuilding it, just replaced the entire assembly.
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Thank you! I’ll do that anyway. Can’t hurt (except maybe in the wallet…)
 
Chris-380 said:
Just thinking on the cheaper side, when was the last time you changed your water/fuel separator?
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Andy O said:
Thank you! I’ll do that anyway. Can’t hurt (except maybe in the wallet…)
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yes, start with a low cost option if you have not already. Swap out the thimble and disk filter in your cool fuel module, and add a dose of fuel treatment (Merc brand, seafoam, etc). If you have one, a fuel pressure gauge on board will help diagnose a faulty CF module.
A cool fuel module is $1000 ish probably, so a few interim steps to help verify the diagnosis is in order.
 
Chris-380 said:
Just thinking on the cheaper side, when was the last time you changed your water/fuel separator?
Click to expand...
Last time I changed the filter was 2021 (about 30 hours ago). Just pulled and it didn’t look bad but will try that first.
 
paulswagelock said:
yes, start with a low cost option if you have not already. Swap out the thimble and disk filter in your cool fuel module, and add a dose of fuel treatment (Merc brand, seafoam, etc). If you have one, a fuel pressure gauge on board will help diagnose a faulty CF module.
A cool fuel module is $1000 ish probably, so a few interim steps to help verify the diagnosis is in order.
Click to expand...
Thank you. Will do that. Found the cool fuel system and the cheapest I found was $1725 — yikes…
 
Andy O said:
Last time I changed the filter was 2021 (about 30 hours ago). Just pulled and it didn’t look bad but will try that first.
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Make sure you fill with fuel, I have heard it’s ok not too, mine didn’t start without it
 
Andy O said:
Thank you. Will do that. Found the cool fuel system and the cheapest I found was $1725 — yikes…
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Fuel pressure should remain around 40 psi with key on and motor off, or motor running. Shader valve right on the rail so it is super easy to take readings. When mine failed it started dipping into the upper 20, then eventually 0.
 
paulswagelock said:
If you truly have DTS, and you should, there is no IAC as the throttle body is digitally controlled. My money is that your cool fuel module is beginning to fail. I had that exact boat but a 2008, and it did the same thing, then the failures became more frequent. It was a failing/then failed cool fuel assembly. I didn’t mess with rebuilding it, just replaced the entire assembly.
Click to expand...
Just and update: you were spot-on. Had it diagnosed yesterday and getting the whole thing replaced. Thank you all so much for the help!!
 
Andy O said:
Just and update: you were spot-on. Had it diagnosed yesterday and getting the whole thing replaced. Thank you all so much for the help!!
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Glad the forum could help. Expensive repair but hopefully you found it quickly and get it resolved to go enjoy your boat.
 
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