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496 ho mag driving me crazy

Old 06-01-2020, 02:48 AM
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Default 496 ho mag driving me crazy

Got problems with my 496 mag ho. 1 week ago i was cruising in 25kt. When suddenly it bogged. Down to idle and had a verry harsch idle and hesitated and missed when i tried to rev it in neutral. No trouble acording to my vesselwiew. Cheked the siphon valve removed the fuelfilter. Primed it and suddenly it started running good again. Went home 35NM. Without any problems. Went out at friday for about 6Nm went all good but Yesterday when i tried start it, it started and died direkt. For 3 times then it didnt start at all. No active alarms due to my wesselview. Did the same procedure removed my fuelfilter primed and it started. But running harsch at idle and wobt rev more then 1500. But Did get home in 4.5kt. At dock it walks in idle from low to maybe 1000 rpms. And died everytime i tried to engage gear. When i got it in my doxkingspot i started it again and running at idle harch but more stable. My stupid vesselwiew says its all good. Only thing i noticed is my raw water pressure sensor is much higher then usual use to be at 0.01-0.03 bar. Now it went from dead zero to 0.2 bars at times. Can that sensor cause this ? And put it in limpmode? But no alarms and beeps?
hate problems thats not consistent. I drove ca 50nm from the first time to the second.
feels like a fuel prob.
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Old 06-01-2020, 04:29 AM
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I dont think this will help you, but my 496 is acting strange too.

I have 2 problems that I cant figure out.

1. Its idling at 800 then goes up to like 1200 and then down again. Its acting really strange and I dont know what causing this problem.

2. A knocking sound thats not sounds it is related to any mechanical problem. More like something are loose. One guy told me to check the coupler.

Here is a video of the engine running

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Old 06-01-2020, 04:44 AM
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Originally Posted by JohanSweden View Post
I dont think this will help you, but my 496 is acting strange too.

I have 2 problems that I cant figure out.

1. Its idling at 800 then goes up to like 1200 and then down again. Its acting really strange and I dont know what causing this problem.

2. A knocking sound thats not sounds it is related to any mechanical problem. More like something are loose. One guy told me to check the coupler.

Here is a video of the engine running
https://youtu.be/TZtQdsvyJZY

såg denna på fb häromdagen.
Och av namnet att dömma antar jag att det är samma😉
har du provat att köra drevet på? Tänkte att det lanske avlastar kopplingen/bussningen.

min beter sig typ likadant på tomgång men svarar knappt på gas och utan det klånkande ljudet.
hoppas ddt löser sig!
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Old 06-01-2020, 05:22 AM
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Originally Posted by Fimbultyr View Post
såg denna på fb häromdagen.
Och av namnet att dömma antar jag att det är samma😉
har du provat att köra drevet på? Tänkte att det lanske avlastar kopplingen/bussningen.

min beter sig typ likadant på tomgång men svarar knappt på gas och utan det klånkande ljudet.
hoppas ddt löser sig!
Jaså där ser man 😄
Ja, drevet är monterat på filmen. Har även testat att köra utan. Samma klonkande ljud..

Hoppas att du får en lösning på ditt problem med!
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Old 06-01-2020, 07:33 AM
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Originally Posted by Fimbultyr View Post
Got problems with my 496 mag ho. 1 week ago i was cruising in 25kt. When suddenly it bogged. Down to idle and had a verry harsch idle and hesitated and missed when i tried to rev it in neutral. No trouble acording to my vesselwiew. Cheked the siphon valve removed the fuelfilter. Primed it and suddenly it started running good again. Went home 35NM. Without any problems. Went out at friday for about 6Nm went all good but Yesterday when i tried start it, it started and died direkt. For 3 times then it didnt start at all. No active alarms due to my wesselview. Did the same procedure removed my fuelfilter primed and it started. But running harsch at idle and wobt rev more then 1500. But Did get home in 4.5kt. At dock it walks in idle from low to maybe 1000 rpms. And died everytime i tried to engage gear. When i got it in my doxkingspot i started it again and running at idle harch but more stable. My stupid vesselwiew says its all good. Only thing i noticed is my raw water pressure sensor is much higher then usual use to be at 0.01-0.03 bar. Now it went from dead zero to 0.2 bars at times. Can that sensor cause this ? And put it in limpmode? But no alarms and beeps?
hate problems thats not consistent. I drove ca 50nm from the first time to the second.
feels like a fuel prob.
You should check fuel pressure at idle and under load. That's where I'd start.
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Old 06-01-2020, 12:06 PM
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Originally Posted by underpsi68 View Post
You should check fuel pressure at idle and under load. That's where I'd start.
did that today. 36 psi on idle and moving around with little load.
Goes up to 44 psi when priming and then drops to 36-38 psi starts but doesnt go smooth.
disconected the vacuum to the fuelpressure reg
On the fuelcooler stable at 44 psi on idle and under little load.
removed the reg and going for a new one tomorrow.
Rusty and looking bad.
Hope i found the problem.
Carefully Optimistic
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Old 06-01-2020, 04:00 PM
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Bad fuel sea foam & hi test fuel! Change fuel filters repeat! Try it?
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Old 06-04-2020, 01:40 AM
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Think i finnaly found the problem.
changed the regulator on the fuelcooler. Littlebit more stable att pressure gauge.
took her for a test went fine in 5 min.then started again walking in revs. Harsch idle.
Still stable fuelpressure so i ruled out the fuel prob.
noticed that my vesselview showed 0bar at sea water pressure.
so i messured the sensors and nothing made sense.
then i found the speedsender cable.
the 3 cables connector and that one looked prettybad. With that one dissconected all other sensors got 5v took her for a test drive again and everything works!!
gotta try again today but i honestly think the limit sender is the problem.affecting the 5v to all other sensors..

Last edited by Fimbultyr; 06-05-2020 at 05:34 AM.
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The following 2 users liked this post by Fimbultyr:
AllDodge (06-04-2020), JohanSweden (06-04-2020)

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