Logo
FULL SITE MENU

New to forum and new to efi with problem

G

Gates

Member
Hi guys. I am just getting back to boating after 15 or so years. I just bought a used 16 foot boat with a 2008 mercury 4 stroke efi. I am having a little problem with it stalling at idle only when cold. Ok so when I take out my boat and let it idle a bit and start off very slow it will stall and also stall if I let off the throttle. Once it is warmed up all is fine. I just changed the plugs, foot oil, oil and filter. I hope someone else has had the same problem and had it resolved. Thanks.
 
Hello, I'm new myself but the first thing I would try is some superduper, fuel treatment like stabil marine or sea foam or some other miricle cure to clean the fuel and injection system hope it helps it can't hurt.
 
How would I use the seafoam. Do I just pour it in my fuel tank. I was looking at videos on youtube but it only shows how to do it to carbureted models. Don't want to waist a can for nothing.
 
Turn key and let it idle. If I don't touch the throttle, it will stall within one minute. If I put it in gear with no throttle, it will stall within a few seconds. It will be fine after running engine at full throttle for about a minute. I bought seafoam (not the spray type) but have not tried it yet.
 
I know it is not much help if you don't have a scan tool, but.....it sounds like a temp sensor problem if the engine is acting up only when not warmed up. The EFI automatically richens the mixture when cold(choke), and then leans out for normal running. If the computer thinks it is at operating temp right on initial start up it will die a few times. Just a guess......other possibilities out there.
 
Merc dealers sell a cleaner and also a fuel treatment...i am running a 60hp efi bigfoot and using them both on every tank...expensive but last a long time if mixed correctly..if the motor is new to you i would double or triple mix the cleaner and single mix he treatment and run the hell out of it for a couple tanks..
 
these merc efi motors seem critical in the fuel pump area..and they are expensive items...something like 750 bucks for my motor....after market they are 450-500...that the reason i say run it with a good cleaner...most times a used boat has been sitting for a while and the fuel system just needs cleaning...
 
Thanks for the reply guys. I will try next weekend to add the seafoam that I bought and see what happens. Thanks. Not sure how much I should add to my portable tank though.
 
papyson said:
double the recommended mix..
Click to expand...

Leave the SeaFoam on the shelf- it does nothing. My thoughts are you have an intermittent sensor problem- usually either the TPS or the IAC. You need to have the outboard scanned for intermittent faults (which usually don't give you an alarm) to find out which sensor is faulty.
 
bilge rat jim said:
Leave the SeaFoam on the shelf- it does nothing. My thoughts are you have an intermittent sensor problem- usually either the TPS or the IAC. You need to have the outboard scanned for intermittent faults (which usually don't give you an alarm) to find out which sensor is faulty.
Click to expand...

Ok I did notice something different with this motor compared to my 25hp merc. The idle does not rise up and back down after first start.

I just took a look at my IAC. Ok so don't laugh. It has two nipples on it but only one has a hose on it and the other is open to the air with no plug at the end. Not sure if that is normal. Would disconnecting something tell me if it is bad.
 
Last edited:
Gates said:
Ok I did notice something different with this motor compared to my 25hp merc. The idle does not rise up and back down after first start.

I just took a look at my IAC. Ok so don't laugh. It has two nipples on it but only one has a hose on it and the other is open to the air with no plug at the end. Not sure if that is normal. Would disconnecting something tell me if it is bad.
Click to expand...

Yep...... the 2 nipples- one has a line that runs to the intake, and measures pressure/vacuum, the other is open to measure ambient pressure. Disconnecting the IAC won't tell you if the sensor is faulty.
 
Ok so I ended up adding a whole can of seafoam in my portable tank and went out yesterday to try it out and it seemed to work immediately. It did not stall at all. Not sure if that stuff is a miracle cure or I just got lucky and my motor did not stall but I hope it is all fixed now. Will only find out for sure on my next trip out.
 
Back
Top