1997 XP 787 Hydrolocking With Gas

[XP8001996]

Hey Guys,

I have a 1997 XP 787. Picked up the ski last year just before the winter. Everything was good except carbs were apart in a box. Looked like they were rusty in the inside. I decided to pick up a good used pair. Got them and completley stripped and rebuilt them with Mikuni rebuild kits. Only thing that wasn't genuine Mikuni were the new needles and seats, which I got from SBT. Anyways, I put the carbs on and it ran good. Now it's started to hydrolock (won't turn over). I was able to get the gas to come out of the plug holes by turning it over without the plugs in, it was definalely gas. But when I took it out again it hydrolocked before I got out of the harbor. Now it seems that I cannot get the gas out of it by turning it over with no plugs in. Have tried pulling pulse line off aswell with no success. So was looking for some advice on how to get the gas out. Also some advice on why it is filling up with gas like this? Any help is greatly appreciated

 

[JJinSC]

The reason it filled up with gas is the aftermarket needles and seats. They are well known for having a reputation for leaking. Use OEM.


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[Minnetonka4me]

Yup also make sure you have that clear diaphram in the fuel pump in the right spot. I had a customer not put that in and it filled that cyl full.

 

[- BiRkS_]

+1 with said above... To get the gas out of the crank case and the crank WONT turn (and you want to ASAP because it will clean the oil right off the bearings) Pull the pulse line out and get a manual sucker pump/fluid extractor. Hook it up to the pulse nipple and see if you can get anything. If not, hold the carbs WOT and get a long skinny tube to slide in past the carbs into the case (assuming the RV isn't covering the hole) Extract as much fluid as you can, then get the engine turning over (hopefully it is not seized).

Then pour 1 tblspoon of 2 cycle oil down each plug hole and rotate over. Rebuild carbs and TEST the pop off and leak down. Then attempt to start. As soon as it does and runs half decently, fog the crap out of the engine to get some extra lube down in the bottom end to wash away any leftover gas down there. Then take it for a nice slow run for 20 mins or so, then go back to having fun with it.

 

[XP8001996]

Sorry I haven't got back lately guys. Been busy with work and other stuff. Thanks for the responses guys I really appreciate it! Anyways, I have taken off the carbs, and I plan on buying some Genuine Mikuni needles and seats and repacing them. Hard to find a place to buy them though. Something else that crossed my mind was that maybe my pop-off pressure is not right. This is my first time rebuilding sea-doo carbs so they very well may not be. I recorded my values before and after rebuilding them and found that the pop-off value that the old needles and seats had before I rebuit the carbs was 39 psi for both the PTO and MAG carb. After I rebuilt them and put the SBT needles and seats in it looks like my PTO carb had a pop-off value of 20 psi and my MAG carb had a pop-off value of 27 psi, I put the same colour spring in that I got with my Genuine Mikuni rebuild kit. This seems low compared to the original value of 39 psi. I think the reason I thought it might be okay is that the Bombardier manual had said that the 1.5 seat with the 65g spring should have a pop-off pressure that is 27 +or- 8. Anyways, could too low of a pop-off pressure cause too much fuel to enter the carb and cause it to be pushed through into the crankcase??? Another big problem I am having is getting the gas out of the bottom end. Feel like i've tried everything. Pulled the plugs out and spun it over...nothing. Covered the intake holes with my hands(the carbs are off)... nothing. Tried using a small tube to suck out the gas from the bottom end... nothing. It's strange because all other threads just say to pull the plugs and turn it over. Pulling the plugs worked for me once, I pulled them and shot lots of gas out of the plug holes, got it running and it stalled before I got out of the harbour. Now I can't seem to repeat that. Thanks again for any responses and I hope we can figure this one out!

PS- Sorry about the novel I have here, just trying to be as descriptive as possible lol

 

[kicker]

The dealer in Harrow should be able to get the NS for you. If not you can order them from OSD http://osdparts.com/index.php?main_page=product_free_shipping_info&cPath=595_602_1&products_id=8533

Even with a low pop off the fuel should not fill the cases.

Also, when checking your pop off be sure to keep the NS lubed up with some inj oil or BRP lube/storage oil. When there is a 7lbs difference in pop and the same NS and spring is used, usually the difference is the result of something that has changed in the testing not the actual parts.

 

[Minnetonka4me]

You know what else it could be....the tank vents might not be releasing air, that puts pressure on the needles and seats.


BUT...if the needles and seats are not sealing that would be it.

I carry ALL needles and seats in stock, I now also have a master jet kit in stock too so I have pretty much every jet.

 

[XP8001996]

Okay cool. I guess the dealer in Harrow isn't going to be carrying Bombardier anymore. That's what they said when I went there a couple of months ago.... But I will see about OSD and maybe get them from there and also see why my pop off is so different. Also, I had figured the vents may be the problem, so I took the one that goes to the left side of the hull (port) off the "T" and blew it out with the compressor. A bit of oily like fluid sprayed out of it, but nothing major. Something I noticed was that I was not able to blow on it by mouth, it would not be enough pressure. I had also read their supposed to hold a certain amount of pressure before it allows ventilation too?


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[JJinSC]

The one under the rub-rail is not a vent. It is a pressure relief valve. It releases pressure above 3-5 psi. If goo came out of yours I would replace it. This could cause your engine to flood if it is not working.


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[XP8001996]

Okay, i'll try blowing out the vent under the seat. Is this the only vent for the tank?

 

[JJinSC]

Yes. It lets air in to equalize pressure but not out. It needs to be checked too, but that one would not be causing your engine flooding issue. The pressure relief valve could be causing your engine to flood if it is not working properly.


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[kicker]

For now, just to rule out the pressure relief and the intake vent issue, loosen that gas cap and see if that cures your problem. Usually if there is a build up of pressure in the tank a little puff of air will come out when loosening the cap off.