Mercury 150EFI Won't go above 2800RPM

[jrpotts01]

Hello Guys,
I'm new to this Forum. I have a 1996 Mercury 150EFI. Past few trips the motor will idle good on start up and has full rpm range in neutral. Primer bulb is staying hard, but on take off boat will not go over 2500-2800 rpm and 6.5MPH. after about 10min or so it will clear up and have full speed. After fishing for about an hour at a spot, I will start it up to move to another spot and it will do it again, but only for about 10-15 sec. I think something in the engine temp is controlling this, because of the problem time issue, engine is still somewhat warm. I have a CD manual and one possible problem is the stator. The stator has 1 high speed and 1 low speed coil for the switch boxes. The low speed coils provides primary voltage for the switch boxes from idle to approximatly 2500 RPM. The high speed coils provides primary voltage from 2000 RPM to max RPM the engine is capable of achieving. Has anyone had of fixed this problem. Please help, I cannot afford to throw parts at it. thanks Guys.

 

[jrpotts01]

Re: Mercury 150EFI Won't go above 2800RPM

I spent a few hours troubleshooting and may have found the problem. According to my maintenance CD, the Trigger is the problem. I have no spark on Cylinders 3 and 6. I swapped the coils with known good ones and still had no spark on 3 or 6. swapped a pair of trigger wires from inner switch box with trigger wires on outer switch box to rule out the switch box and problem was still there. According to the troubleshooting tips, a bad trigger will cause a loss of spark on 2 plugs one from each bank. Any thoughts?????

 

[shadowcrest5]

Re: Mercury 150EFI Won't go above 2800RPM

Hello Jrpotts01,
You have now joined a HUGE..and growing club. The "where is my power club". I too have a thread on here (Sep. 24th.) "Where is my power...Fuel restricted". Same Problem you have. Runs great in neutral...or in the drive way with water muffs on. Yet on the lake, anthing after 1000 rpm or idle...forget about it.POWER IS GONE!! I can only get aprox. 3000 rpm. Yet even than it boggs the entire time.
I did bring it in to a marine mechanic he ran a few tests.....and found nothing obvious.It had new gas, new plugs,new oil,new fuel filter....prior to taking it in!! He took a reading on the fuel pump and it was right to specs.His final statement was that he"could not find anything wrong with it". Even a small ..."well lets TRY replacing this or that"....can add up fast.
I did read another thread that talked about this same problem.He...like you mentioned the stator.He replaced his...he than said after that it ran great.It was 9-23-09, by rrrandy "115 hp merc. no high speed power". About page 20 is where I found this. My motor is a 2005 115hp efi 4 stroke.
I will keep my fingers crossed for us to find the problem....good luck.
Shadowcrest5

 

[Faztbullet]

Re: Mercury 150EFI Won't go above 2800RPM

Looks like you found it as 3 & 6 are on same coil in trigger as are 2 & 5 and 1 & 4. Also ohm the trigger wires, should be 1100-1400 ohms to verify its failure.


shadowcrest5 check your spark as I am going to bet its running on 2 cylinders. It will sound great in neutral on 2 cylinders.

 

[jrpotts01]

Re: Mercury 150EFI Won't go above 2800RPM

Thanks for the support guys. I have a 1990-2002 Mercury outboard service manual on CD that I bought off Ebay for $10. It has saved me lots of time and money. I called a outboard mechanic and told him everything I found and he agreed that it was probably the Trigger. I am taking it to his shop Thursday after work for him to hook up his DVA connection to verify it is the Trigger. If it is the Trigger he is going to charge me $65 to replace it. The part is Under $200. Get one of those CD's if you don't already have one, I can do all the troubleshooting myself so they don't charge me those hours at the repair shop. I found the problem in less tham three hours. The CD gives you step by step troubleshooting. I will let you know what he says Thursday.

 

[Out of Bounds]

Re: Mercury 150EFI Won't go above 2800RPM

that is a fair price for the repair. we have one in the shop with the same thing what we found was the fuel pressure was boncing a around but with inn spaec. we replaced the low pressure pump and seems to have fixed the problem. werd same semt just diferent out come. you my have him check fuel pressur just to be safe.

 

[jrpotts01]

Re: Mercury 150EFI Won't go above 2800RPM

Hey Guys,
I took the boat to a local outboard mechanic and he hooked up his DVA meter and confirmed it is the Trigger. He didn't even charge me. I ordered the part new off Ebay for $125 and he is going to charge me $65 to install it. I'm happy it wasn't a more expensive Switch Box or Stator. Be back to fishing next week.

 

[shadowcrest5]

Re: Mercury 150EFI Won't go above 2800RPM

Hi Jrpotts01,
You stated that you felt your problem was the trigger.And that you replaced it. Did you get to take your boat out on a body of water.....to BE SURE? Or did you run it in your drive-way with water muffs on?
I've been having this same power loss problem. Do you remember the person or site that you bought your trigger from...on E-Bay.........................
Thanks ...Shadowcrest5