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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 2008 Mercury Verado 150HP Outboard on a 20' Boston

Customer Question

I have a 2008 Mercury Verado 150HP Outboard on a 20' Boston Whaler.
The engine drops down to 3000 RPMs when pushed under load.
If I gradually increase the throttle, it will go up to 5,000 RPMs. If I push it any further the engine stumbles, & drops back down to 3000. Also I can't push the throttle from idle, it will do the same thing.
Fuel pressure at idle is 56psi. 64psi at 1000 RPMs, & the pressure jumps up to 70psi just as the engine starts to stumble.
I have already changed one coil to eliminate a dead cylinder, but can't seem to figure the other problem.
Submitted: 2 years ago.
Category: Boat
Customer: replied 2 years ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Charles replied 2 years ago.
Hello, my name is***** you for allowing me to assist you today.
Would you please post the serial number of the engine?
Customer: replied 2 years ago.
Hi Charles,
the serial # ***** *****
Jan. 2008
150XL L4
Expert:  Charles replied 2 years ago.
Do you know any history of the engine? Has it been in the shop for some upgrades?
Customer: replied 2 years ago.
Don't know the history beyond last season.
Had a problem with the lift pump at the first start this season.
I changed the float in the fuel supply module & that remedied that problem.
The fuel pressure is within perameters, except for the jump up to 70 psi at the point of the engine malfunctioning.
Expert:  Charles replied 2 years ago.
on the top of the FSM there are 4 hoses, fuel in, fuel out, Vent purge and the MAP reference hose. That is the one that we want. When viewing the FSM while mounted, it is the one in the center rear. Trace the hose to where it connects, remove the connection,blow back toward the FSM to see if you can move any air or not.
Customer: replied 2 years ago.
I quit work at 5:pm NY time.
so I'm not at the boat now.
I will check the hose in the morning.
I get in at 7:30 AM.
I hope we can resolve this problem.
Expert:  Charles replied 2 years ago.
I am in the CST and am only online in the eve and weekends.
do you have a scanner to see if it is throwing any codes at all?
Customer: replied 2 years ago.
We have a CDI, but it'S not compatible with Verado.
Expert:  Charles replied 2 years ago.
Customer: replied 2 years ago.
The 4 hoses are fuel in, fuel out , vacuum to the pressure regulator, & the vent.
regulator has vacuum at idle, so that's ok.
I can't find the other end of the vent hose, but I can blow through it from the FSM end . Granted I can't blow hard, but it doesn't feel clogged.
Expert:  Charles replied 2 years ago.
So it did move air?

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