2004 Johnson/Suzuki 4stroke 90 losing oil pressure

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venuspie

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Jun 22, 2014
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I have an 04 Johnson 4 stroke 90. I was told it was a Suzuki engine. The model number is J90PL4SR. Has only 270 hours on it. Has sat for a few years so I recently replaced the entire fuel system. Runs great but after a minute or so of 4-5k rpm's, the no oil light and warning beeper goes off. You would think it was a bad sensor but unfortunately it is not because immediately the engine begins knocking....really no oil pressure. Shut it down and give it a few and same thing. You get maybe 30 seconds of run time. Seems to idle fine but will not run even at 1/2 throttle without losing oil pressure. New filter and oil. Double checked oil level and perfect. Can these oil pumps really go bad? Is there a relief valve somewhere? Any ideas are greatly appreciated! Thanks in advance.
 
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venuspie

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Jun 22, 2014
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boobie said:
Sounds like a bad oil pump...........
Click to expand...

That's what I was thinking but hoping it wasn't. If I dig that far into the engine, are there any other maintenance items I should change? I know there is a oil pressure regulator that I will change. It actually may be the problem but it is right beside the oil pump, so may as well change both. ANY thing else it could be before I remove the power unit? Really not looking forward to it. Thanks
 
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racerone

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Dec 28, 2013
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Great motors when they run.---These motors were never designed / built with the idea of major afforable repairs at a dealer.----If you can do it yourself maybe , but it will be frustrating.
 
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venuspie

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It only will knock when the oil pressure drops. Let it sit a while and it will run quietly for a minute or so until oil pressure drops again. Maybe knock is too strong of a word. Top end noise from lack of oil. Only runs for a max of 3-5 seconds as I shut it down as soon as I get the alarm.
 
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venuspie

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Bad news. Drained the oil and golden flakes came out.....I'm thinking spun bearing. Looks like a full rebuild is coming. :mad::mad::mad:
 
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venuspie

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Jun 22, 2014
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Spun rod bearing on the #1 cylinder. A lot of sludge in the oil pan and mid unit. I'm thinking that is the cause for the oil starvation. Off to the machine shop I go to redo crank and all rods...Luckily it was a rod bearing instead of a main bearing and block is safe!.....Compression on 2, 3, and 4 were 225-230lbs....#1 was 215..seemed odd. Does anyone know iwhich cylinder is the last to receive oil? I am assuming 1 (the one farthest from the timing chain)
 
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