Oil pump issue

SoCal250 · May 13, 2022, 05:12:38 PM

Just finished rebuilding a Yamaha CS5 pump. Disassembled, ultrasonic cleaned, installed new seals and gasket. Works find on the bench, the thumb wheel turns the pump and the plunger moves up and down as expected.

However, when I slip it onto the drive shaft in the engine cover the plunger no longer turns. It seems like it's frozen (binding up on something). This is the case even if it's not screwed down, but just gently slid over the drive shaft. I've taken it on and off several times and it works fine when it's removed and I spin the wheel. Not sure what the issue can be.

I'm wondering if maybe there's something in the distributor gear that's out of sequence or backwards. The gear looked to be straight cut so direction shouldn't matter. There was a washer (shown) in one of the photos that I installed on the tip of the distributor shaft that went into the housing body. Should that have gone somewhere else?

Arrow · May 13, 2022, 05:16:05 PM

Sounds like you got the internal gear the wrong way round. It will free wheel in the other direction if this is the case.

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SoCal250 · May 13, 2022, 05:24:59 PM

Quote from: Arrow on May 13, 2022, 05:16:05 PM
Sounds like you got the internal gear the wrong way round. It will free wheel in the other direction if this is the case.

Thanks Arrow.
Sounds that will involve messing with the 2 little spring-loaded pins again (yeesh).

Arrow · May 13, 2022, 05:31:16 PM

Correct, but take just the large washer off first and you can view the direction of the gear.

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SoCal250 · May 13, 2022, 06:15:15 PM

Should it be flipped around?
Seems like it's in correctly because the prime wheel rotates downward, turning the shaft so the pins engage in the cutouts. Right?

Arrow · May 13, 2022, 06:19:28 PM

No, if the pins engage you can't turn the shaft in the correct direction via the white plastic wheel.

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SoCal250 · May 13, 2022, 06:32:38 PM

Quote from: Arrow on May 13, 2022, 06:19:28 PM
No, if the pins engage you can't turn the shaft in the correct direction via the white plastic wheel.

Ahh, got it. Wasn't thinking clearly about how it functions, now I get it. The wheel turns the pump shaft and the gear is disengaged from the engine drive so it can spin freely, independent of the engine.

So, the gear needs to come out and get flipped 180 and dropped back in. Fun fun fun.

Arrow · May 13, 2022, 06:35:05 PM

You got it.

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SoCal250 · May 13, 2022, 06:51:53 PM

Thanks again for your guidance!

It's great to get feedback from the Master

Arrow · May 13, 2022, 07:15:23 PM

Thank you Sir, you're most welcome.

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Oil pump issue