2003 496 HO Mag update
07-27-2018, 06:46 PM
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2003 496 HO Mag update
folks,
Here what ive learned so far. This is the boat with 2 year old fuel that lays down at 4000 rpm.
i ran it on an auxiliary fuel tank. 90 octane ethanol free gas. Still laid down at 4K rpm absolutely no change in performance. Checked fuel pressure by cycling the key 3 times 40 PSI. It does not hold 40 psi it bleeds down pretty quickly maybe 7 -10 seconds. In plug the fuel pressure regulator at idle pressure goes to 42.
Take it out on the water pressure stays at 40. Even when it's missing and losing power pressure is rock steady at 40. Pulled the plugs and they all look good. Actually really good. Changed them anyway because.
my next move is to remove the high pressure pump cool fuel gen 2 and check for restrictions. In the screen under the regulator unless you guys tell me otherwise.
Let me k ow what you think.
kevin
Here what ive learned so far. This is the boat with 2 year old fuel that lays down at 4000 rpm.
i ran it on an auxiliary fuel tank. 90 octane ethanol free gas. Still laid down at 4K rpm absolutely no change in performance. Checked fuel pressure by cycling the key 3 times 40 PSI. It does not hold 40 psi it bleeds down pretty quickly maybe 7 -10 seconds. In plug the fuel pressure regulator at idle pressure goes to 42.
Take it out on the water pressure stays at 40. Even when it's missing and losing power pressure is rock steady at 40. Pulled the plugs and they all look good. Actually really good. Changed them anyway because.
my next move is to remove the high pressure pump cool fuel gen 2 and check for restrictions. In the screen under the regulator unless you guys tell me otherwise.
Let me k ow what you think.
kevin
07-28-2018, 07:53 AM
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496’s are great engines but require a little work. Before you do anything else you really need to get them scanned. The engine may be in guardian mode reducing available power to 70-90% if you are getting to 4000 rpm. There are multiple things that can put the engine in guardian mode. With out a scan or any other issue we would all be simply guessing at what may be the issue. It could be the tps sensor, IAC, bad spark plug wire, bad dirty fuel injector, etc. Also to help us all out with the specific 496 we need you to post your serial number. There are several variations in the 496......did you replace the fuel filters?
07-28-2018, 08:01 AM
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is it like you hit a wall at 4000 or is it roughly 4000 spitting and sputtering....if it is hard locked stops at 4000 then I would have to agree its a guardian function...if it spits sputters and bounces around 4000 I would have to lean towards a fuel supply issue but could possibly be spark related I guess
agree with quest...get it scanned and see if there are codes
agree with quest...get it scanned and see if there are codes
07-28-2018, 08:18 AM
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496 Fuel Pressure
Your FP should not bleed down that fast. Possible leaking injector, internal bypass of fuel pumps, leak on your test equipment. 40psi KOEO is also 2-3 psi low. Gauge accuracy comes into play as well.
Definately dig some more in the fuel system.
Scanning is always a good idea. Yet, on a functional Merc gaurdian system he would be getting beeps, solid alarms if he had a current fault or was in gaurdian mode.
Definately dig some more in the fuel system.
Scanning is always a good idea. Yet, on a functional Merc gaurdian system he would be getting beeps, solid alarms if he had a current fault or was in gaurdian mode.
Last edited by Ryan00TJ; 07-28-2018 at 08:25 AM.
07-28-2018, 09:20 AM
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496 Fuel Pressure
Your FP should not bleed down that fast. Possible leaking injector, internal bypass of fuel pumps, leak on your test equipment. 40psi KOEO is also 2-3 psi low. Gauge accuracy comes into play as well.
Definately dig some more in the fuel system.
Scanning is always a good idea. Yet, on a functional Merc gaurdian system he would be getting beeps, solid alarms if he had a current fault or was in gaurdian mode.
Your FP should not bleed down that fast. Possible leaking injector, internal bypass of fuel pumps, leak on your test equipment. 40psi KOEO is also 2-3 psi low. Gauge accuracy comes into play as well.
Definately dig some more in the fuel system.
Scanning is always a good idea. Yet, on a functional Merc gaurdian system he would be getting beeps, solid alarms if he had a current fault or was in gaurdian mode.
07-28-2018, 04:37 PM
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Hi All; I purchased a Rinda Techmate Pro and used it to find a clogged injector ( non firing cylinder #7) and as it turns out this is the position on the end of the rail. The last injector. skipping all of the steps, it was loaded with rust particles from the fuel rail. After cleaning them all I got my RPMs back.. I had previously replaced the fuel pump ( was seeing 36psi) and the IAC (starting issues). You cannot assume the injectors are working. You have to know by puling them and sending them out.
07-28-2018, 06:42 PM
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496 Fuel Pressure
Your FP should not bleed down that fast. Possible leaking injector, internal bypass of fuel pumps, leak on your test equipment. 40psi KOEO is also 2-3 psi low. Gauge accuracy comes into play as well.
Definately dig some more in the fuel system.
Scanning is always a good idea. Yet, on a functional Merc gaurdian system he would be getting beeps, solid alarms if he had a current fault or was in gaurdian mode.
Your FP should not bleed down that fast. Possible leaking injector, internal bypass of fuel pumps, leak on your test equipment. 40psi KOEO is also 2-3 psi low. Gauge accuracy comes into play as well.
Definately dig some more in the fuel system.
Scanning is always a good idea. Yet, on a functional Merc gaurdian system he would be getting beeps, solid alarms if he had a current fault or was in gaurdian mode.
Hi All; I purchased a Rinda Techmate Pro and used it to find a clogged injector ( non firing cylinder #7) and as it turns out this is the position on the end of the rail. The last injector. skipping all of the steps, it was loaded with rust particles from the fuel rail. After cleaning them all I got my RPMs back.. I had previously replaced the fuel pump ( was seeing 36psi) and the IAC (starting issues). You cannot assume the injectors are working. You have to know by puling them and sending them out.
kevin
07-28-2018, 08:36 PM
#9
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A bad check valve internally in the fuel pump will cause the bleed down as well.
To add Very common on cheap fuel pumps that are bought online to have check valve failures within a year or 2. I see this alot currently especially from the knock off fuel pumps..
To add Very common on cheap fuel pumps that are bought online to have check valve failures within a year or 2. I see this alot currently especially from the knock off fuel pumps..
07-28-2018, 08:42 PM
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Is airtex , by chance the OE ,manufacturer ? Please say no,
