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Pump or premix?

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eavega

eavega

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hello all

I have a 97 GTX which I just did a top-end rebuild. Finished assembling, starting, set idle speed, etc and now ready for water trials and hopefully a summer of fun. A quick history - my friend bought this ski last year, with a somewhat unknown history. Typical "it was running when parked, but now it does not" Now someone at some point cared about this ski, because as I was working on it I found evidence that the carbs had been rebuilt at some point, and all the fuel lines had been changed over to black fuel line. Anyway, he ran it without checking carbs because, well, it started right up with fresh fuel. It ran for about a day before the mag piston crown shattered, we are still not sure if it was lean from dirty carbs, too much piston clearance, etc. When he ran it last year, he put premixed fuel in. He assumed the oil injection pump was working, because it seemed to consume the oil he put in the oil tank (based on the low oil light coming on at one point). Anyway, I've redone the top end, rebuilt the carburetors, replaced the oil injection lines, reassembled the motor, and put premix in it since I was told to double oil the first tank of gas to help break it in. It now runs, but I can't get the oil pump to pump oil into the injection lines (Oil injection lines are still pretty empty, with a lot of air bubbles and pulling the bleeder screw doesn't cause any oil to flow out, even if I manually actuate the pump). I've verified the injection pump oil feed line is full of oil, so there is either a blockage or failure with the oil injection pump.
I am going to pull the oil injection pump and bench test it, but assuming that the pump is faulty, should I just cap it and convert the ski to premix, or should I seek out a replacement pump? New OEM I've seen prices online for $200, but I can find used verified working injection pumps for less than $50.

I already have my 95 SPX that runs premix and has the proper block-off plate. Its not a huge issue to run premix, as I do my mixing when I gas up the ski at the gas station.

Thanks for any insight you all can give me.

Rgds
 
Premix and all your problems go away. I just nixed the pump on a 1996 I just bought. I've seen toasted cylinders too many times using injection systems and I 'm not reinstalling a 20 year old oil pump. Good luck, whatever you decide. :)
 
I did a cheap bypass on my pump when I switched to premix. Left the pump on the motor and added a fuel shut off line meant for a lawnmower on my oil feed line. Did not feel like pulling the pump out and buying and installing a block off kit.
 
Luv2Camp said:
I did a cheap bypass on my pump when I switched to premix. Left the pump on the motor and added a fuel shut off line meant for a lawnmower on my oil feed line. Did not feel like pulling the pump out and buying and installing a block off kit.
Click to expand...

Just wondering... what lubricates the oil pump gear if you shut off flow to the pump ? That would be a concern for me. I actually thought about leaving the pump in position but removing the gear. It was easy enough to make a block off plate and gasket so that's what I did. Ride it like ya stole IT !! :D
 
etemplet said:
Just wondering... what lubricates the oil pump gear if you shut off flow to the pump ? That would be a concern for me. I actually thought about leaving the pump in position but removing the gear. It was easy enough to make a block off plate and gasket so that's what I did. Ride it like ya stole IT !! :D
Click to expand...

The gear is on the outside of the engine so if it fails it will not contaminate anything. I figure worst case scenario is the pump siezes and if it does, it only has a plastic gear to strip. I have about 40 hours on premix and no issues with the pump being on the engine.
 
So now I have a couple of question about the injection pump. The manual shows the procedure to open the bleed screw until oil starts dribbling out. Now, I am absolutely sure the line feeding the injection pump is full of oil and it flows freely. My question(s)

1. Does the engine need to be running for that oil to dribble out? I would assume no...

2. If no oil dribbles out, and I am sure that the injection pump feed line is moving oil freely, do I have a blockage in the pump or would there be another reason?

If anyone can answer these questions or provide a reason why I am not seeing any oil come out, I would very much appreciate it!

Rgds

E
 
Well to burst your bubble the oil pumps don't go bad on the seadoo's. As long as you replace the small 3/32" oil lines and use the correct oil you will be fine and use a lot less oil than premix.

If you want to run premix on a 787 all you have to do is remove the plastic drive that runs from the oil pump to the crankshaft snout. There is no plastic gear like on the 720-580 engines.
 
mikidymac said:
Well to burst your bubble the oil pumps don't go bad on the seadoo's. As long as you replace the small 3/32" oil lines and use the correct oil you will be fine and use a lot less oil than premix.

If you want to run premix on a 787 all you have to do is remove the plastic drive that runs from the oil pump to the crankshaft snout. There is no plastic gear like on the 720-580 engines.
Click to expand...

Disagree. I think the statement should be almost all of the pumps do not fail. My pump failed. Would provide oil at idle and under some power but under 3/4 to full throttle it would stop pumping. Caused a lean seize on my brand new rebuild after my break in when I started to spend some time in the upper rpm range.
 
Luv2Camp said:
Disagree. I think the statement should be almost all of the pumps do not fail. My pump failed. Would provide oil at idle and under some power but under 3/4 to full throttle it would stop pumping. Caused a lean seize on my brand new rebuild after my break in when I started to spend some time in the upper rpm range.
Click to expand...

Sorry, LOL. Never say never. There is only a very, very, very small chance the oil pump will go bad. :thumbsup:
 
That son of a gun oil pump ain't going back on mine. LOL Pre mix... yea baby !!
 
Last edited by a moderator:
Well, in any case, I pulled the pump last night. Now I know why it wasn't working. Someone at some point had removed the injection pump drive shaft. Nothing was spinning it. It still wouldn't bleed oil through the screw, so I blew it out with compressed air, and water came out. Probably the water was blocking the pump. In any case, I also tried to test it with a drill, and no oil pumped. I'm assuming this is one of those failed pumps. I'm still pondering whether to replace the pump or not, but for the time being I'm going to run premix in the ski so I can get out on the water.
 
eavega said:
Well, in any case, I pulled the pump last night. Now I know why it wasn't working. Someone at some point had removed the injection pump drive shaft. Nothing was spinning it. It still wouldn't bleed oil through the screw, so I blew it out with compressed air, and water came out. Probably the water was blocking the pump. In any case, I also tried to test it with a drill, and no oil pumped. I'm assuming this is one of those failed pumps. I'm still pondering whether to replace the pump or not, but for the time being I'm going to run premix in the ski so I can get out on the water.
Click to expand...

Note that the oil flow while driving with drill will be very slow
 
Well, change of plans. I started surfing ebay for a replacement pump, and got a good deal. Replaced it today, and worked as expected. Injection lines filled right up. Tomorrow I ride!
 
I have just bought a 98 GTX Limited, and has a new engine. I guy that I bought it from mixes the gas what is no problem, but what about the oil pump? It is showing an low light. Will the motor shut down because of this light. That's for any comments.

Newbie / Tom, Mesa, Az.
 
Nope the light is just an idiot light.
The pump needs to be replaced with a block off plate or the plastic drive removed if there is no oil going to it.
 
To eliminate the light, unplug the sender at tank, and run a jumper wire..itll trick the mpem thinking its full
 
oil by pass shut off?

I to am be mixing my fuel, does the oil pump need a shut off coming from the pump. or can I just let it just stay empty?

Newbie / Tom, Mesa, Az.
 
Tom I removed my oil pump and made a block off plate. My ski a 1996 SPI needed to have a level in the oil tank to feed the bottom end of the engine. This is not advice, just what I did. :)
 
I'd going premix, might as well dump the resivoir bottle and loop the RV line. Either keep the 2-stroke oil in the out drain it and backfill with gear oil
 
The 951 doesn't have a rotary shaft. If you remove the pump you can remove the tank and plumbing.
 
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