300 verados choking out
03-09-2015 | 10:29 PM
#1
Thread Starter
Registered User
Joined: Dec 2005
Posts: 53
Likes: 2
From: CT
300 verados choking out
I have triples and the center motor is breaking my balls
Scanned all 3 motors no fault codes and reset smart craft and re-sicronised
Changed spin on fuel filter
It has good 91 octane gas
The motor starts and idles fine but won't rev over 2,000 rpm under load (it chokes out) and I can't figure out why it's been to 3 different mechanics so far
Could it be throttle position sensor?
Drive by wire communication issue?
Feul delivery problem?
Scanned all 3 motors no fault codes and reset smart craft and re-sicronised
Changed spin on fuel filter
It has good 91 octane gas
The motor starts and idles fine but won't rev over 2,000 rpm under load (it chokes out) and I can't figure out why it's been to 3 different mechanics so far
Could it be throttle position sensor?
Drive by wire communication issue?
Feul delivery problem?
03-09-2015 | 11:29 PM
#2
Banned
Joined: Jul 2011
Posts: 9,594
Likes: 45
From: Ft. Worth TX
it chokes out as meaning the engine stalls - or engine sputters but stays running at only 2000 rpms no matter how much throttle you apply ?
Fuel pressure reading taken - what are they ?
Spark on all cylinders ?
All fuel injectors have power and pulsing ?
possible fuel injectors needing flow testing and cleaning.
Post your serial # of your engine and year. it is mandatory for proper service procedures and proper parts installed per Merc build from engine serial # runs.
Fuel pressure reading taken - what are they ?
Spark on all cylinders ?
All fuel injectors have power and pulsing ?
possible fuel injectors needing flow testing and cleaning.
Post your serial # of your engine and year. it is mandatory for proper service procedures and proper parts installed per Merc build from engine serial # runs.
Last edited by BUP; 03-09-2015 at 11:36 PM.
03-10-2015 | 10:18 AM
#5
Registered
Joined: Mar 2013
Posts: 1,102
Likes: 11
From: Granger, Indiana
Please don't laugh - I am no where an expert by ANY means -- but in the geometry of your boat and engine placement are you sure that the center engine is getting enough air??? Underway it is possible that the center engine is somehow being starved of enough air to effect good combustion.
PLEASE -- I am no expert but if the engine scan is negative - there is something else screwy going on
Sorry if this is wasting your time
3pointstar
PLEASE -- I am no expert but if the engine scan is negative - there is something else screwy going on
Sorry if this is wasting your time
3pointstar
03-10-2015 | 10:30 AM
#6
Banned
Joined: Jul 2011
Posts: 9,594
Likes: 45
From: Ft. Worth TX
Fuel pressure readings and how about compression numbers is always the first start to any running problems dianostics. Surely all 3 shops did this form of testing. When a Merc tech calls in to OEM Merc for assistance - the first questions they ask the tech are fuel pressure readings and compression#'s and fuel samples taken ? If no to anyone of these answer - Merc replies are - when you get all those #'s and sample of fuel call us back, Just saying.
Sounds like possible fuel pressure problems and or injectors need to be flow tested & cleaned
Is this a saltwater app ?
Sounds like possible fuel pressure problems and or injectors need to be flow tested & cleaned
Is this a saltwater app ?
Last edited by BUP; 03-10-2015 at 10:34 AM.
03-10-2015 | 02:40 PM
#7
Airking
Joined: Aug 2004
Posts: 452
Likes: 0
From: Stafford Va.
Plenty of info here.
http://www.veradoclub.com/
Also read under fuel pressure trouble shooting chart in this Merc FSM service bulletin info. A lot of problems are associated with FSM. I have had a couple issues with floats and reference hose myself.
http://www.marinemechanic.com/merc/d...leshooting.pdf
The regulator
in the FSM has a reference hose connected to it and the other end is
connected to the FSM cover. From the cover, it is then connected to the
intake. Check the hose from the FSM to the intake manifold. If alright,
remove the FSM cover and inspect the line from the cover to the
regulator. If the line inside the FSM were to split, or become
disconnected, fuel will be drawn into the intake causing the engine to run rich.
Ethanol in fuel breaks down plastic hose, also floats, and with no reference to pressure regulator it over fuels motor. I always keep a float assembly in stock. I have had 3 fail so far. You can change one out in about an hr or so. My engine stopped running with no codes when float did not activate lift pump twice. When one float sunk and kept lift pump running then tripped vent switch code and engine kept running.
http://www.veradoclub.com/
Also read under fuel pressure trouble shooting chart in this Merc FSM service bulletin info. A lot of problems are associated with FSM. I have had a couple issues with floats and reference hose myself.
http://www.marinemechanic.com/merc/d...leshooting.pdf
The regulator
in the FSM has a reference hose connected to it and the other end is
connected to the FSM cover. From the cover, it is then connected to the
intake. Check the hose from the FSM to the intake manifold. If alright,
remove the FSM cover and inspect the line from the cover to the
regulator. If the line inside the FSM were to split, or become
disconnected, fuel will be drawn into the intake causing the engine to run rich.
Ethanol in fuel breaks down plastic hose, also floats, and with no reference to pressure regulator it over fuels motor. I always keep a float assembly in stock. I have had 3 fail so far. You can change one out in about an hr or so. My engine stopped running with no codes when float did not activate lift pump twice. When one float sunk and kept lift pump running then tripped vent switch code and engine kept running.
Last edited by Boater8987; 03-11-2015 at 12:18 PM.
