-
This site contains eBay affiliate links for which Sea-Doo Forum may be compensated.
Rebuilt jet pump but now will not start
- Thread starter Bjsaleen
- Start date
- Status
Sportster-2001-951C-Stock
Well-Known Member
I assume you blew air into the fuel tank, not into the fuel pump on the carburetor. If yes, the air you heard was from air bubbling up through the fuel in the tank.
If you blew air towards the carbs, you should not be able to force air in there b/c the fuel pump check valves (two of them) should only allow fuel to move in one direction (towards the carbs).
So now I would remove the fuel line supplying fuel to the carbs and try to syphon fuel from the fuel tank, you may need a fitting and some fuel line to do that. If you can do this, then it confirms the fuel lines are flowing towards the carburetor.
If the fuel lines are flowing fuel towards the carbs (into the fuel pump) then you can remove the spark plugs and the fuel return line (disconnect at fuel tank or get some fuel line and connect it to the carbs at the return nipple) then crank the engine and see if fuel is coming from the fuel pump , through the carbs and out of the return line nipple back toward the fuel tank. If yes, the fuel pump is working. If not the fuel pump isn't working (for whatever reason).
The fuel pump has two check valves inside and a diaphragm that moves back and forth. This diaphragm has a wet side and a dry side The diaphragm is actuated on the dry side by pressure pulses from the crankcase impulse hose. As the piston moves up and down this causes a pressure pulse to move up through the impulse hose to the dry side of the fuel pump diaphragm. This pressure pulse actuates the dry side of the fuel pump diaphragm. A negative pressure pulse pulls fuel into the fuel pump on the wet side of the diaphragm, a positive pressure pulse pushes fuel on the wet side of the diaphragm from the fuel pump through the carburetors.
So, instead of actually cranking the engine you can connect a piece of fuel line to the pressure impulse nipple of the fuel pump and "resperate" the fuel pump diaphragm by mouth and make the fuel pump move fuel. You should not get a mouth full of fuel, if you do then the diaphragm has a hole in it (not likely), if you can move fuel this way then the fuel pump is working. If yes, the carbs themselves are at fault and if no, the fuel pump is at fault (one check valve inside might not be working, perhaps cracked, wrinkled, or the rubber grommet has failed).
Of course, if the crankcase impulse line to the fuel pump is ruptured, the fuel pump will not receive the pressure pulses necessary to actuate the internal diaphragm.
So if you've had some of these fuel system lines off while working on the jet pump, you may have misconnected a couple of them perhaps? Or possibly the fuel pump has failed, or maybe the fuel lines are leaking air inward?
It's not unusual to have some air trapped in a fuel filter, sometimes they only fill half full with fuel depending on the type. I see this often.
Another way to leak check the fuel lines is by blowing air backwards from the carburetor connection back towards and into the fuel tank. Most marine fuel tanks have an anti-siphon check valve in the fuel tank outlet but our skis don't, so by blowing in this line you should hear the air bubbling up from the pickup tube in the bottom of the tank. You can shut off the fuel valve and then should not be able to blow air backward b/c the flow will be blocked by the fuel valve.
Last edited by a moderator:
Bjsaleen
New Member
After doing some research I'm beginning to think I may have some water in the motor. Because when I started the sea doo the second time i did the proper procedures motor on water on, but after about 30 seconds of running that's when it died and the water was still flowing. I was at the head of the ski and it took me a few seconds to get to the back and remove the hose. Also thinking back I don't know how level my sea doo was and think the nose was slightly pointed down. I'm hoping this is not the case. Not sure how much water it takes to flood the motor. I'm thinking there's not much in there tho, due to it starting and me being able to kinda keep it going with throttle. I've read all the procedures on how to remove the water, only thing is they say to do it ASAP. Well I work 24 hours at a time and will not be able to get to the ski again till Friday. So hopefully there's not any water in the motor. If there is do you guys think the motor will be shot if I wait till Friday?
Last edited by a moderator:
Luv2Camp
Active Member
If it was only a few seconds, and the fact that you have had the motor running while pouring fuel into it leads me to believe you are ok. Still should check. Being that it stalled out to begin with and now will not start on its own leads me to believe it has nothing to do with water. Also since you can get the engine to run when you squirt pre-mix into the carb indicates you have spark and combustion. This leaves the fuel as the missing link. Being you just replaced your fuel lines, odds are you have crossed one of them and are not making the complete fuel circuit. Yes, there could be other issues causing BUT you need to look at the fact that before you worked on the fuel line and the pump it ran fine. Being that it ran for about 30 seconds when you were done working on it indicates to me it is not an issue with a pinched thrush washer on the pump. This leaves the only other most probable issue being your fuel line connections. It is REALLY easy to connect one of the lines to the incorrect nipple on the fuel baffle or the fuel knob.
Sportster-2001-951C-Stock
Well-Known Member
I think it would probably take about a minute or more for the exhaust to fill and back up with enough water to enter the cylinders, this sounds exactly like fuel starvation especially considering you can get it to fire off with a shot of fuel into the carbs.
BTW, no need and preferably not, for hose water if run time is kept less than 30 seconds. I never do connect mine to water, but if you have a long trip or busy ramp I can imagine you might desire longer than 30 seconds for testing purposes after doing some service.
BTW, no need and preferably not, for hose water if run time is kept less than 30 seconds. I never do connect mine to water, but if you have a long trip or busy ramp I can imagine you might desire longer than 30 seconds for testing purposes after doing some service.
Sportster-2001-951C-Stock
Well-Known Member
Here's a link to a drawing, not sure it shows enough detail to really help though.
The fuel baffle nipples are labeled next to the nipples, return, reserve (pickup at very bottom of tank) and fuel, or something like that. You may have to blow air through to confirm the goes into's and comes out of's are connected in the correct locations.
http://partsfinder.onlinemicrofiche...asp?Type=18&make=seadoopwc&a=303&b=7&Action=O
The fuel baffle nipples are labeled next to the nipples, return, reserve (pickup at very bottom of tank) and fuel, or something like that. You may have to blow air through to confirm the goes into's and comes out of's are connected in the correct locations.
http://partsfinder.onlinemicrofiche...asp?Type=18&make=seadoopwc&a=303&b=7&Action=O
Bjsaleen
New Member
I appreciate all the help guys! I'm gonna look over the fuel lines and MAKE SURE they're going the way there meant to go. Makes me feel better with you guys saying most likely not water in the motor
I must have not looked hard enough at the top of the fuel baffle because I couldn't see where it's stamped where the lines are supposed to go. I will look harder and hopefully that's my problem!
Sent from my iPhone using Tapatalk
I must have not looked hard enough at the top of the fuel baffle because I couldn't see where it's stamped where the lines are supposed to go. I will look harder and hopefully that's my problem!
Sent from my iPhone using Tapatalk
Sportster-2001-951C-Stock
Well-Known Member
Another little trick to test if the fuel pump and carbs are working, you'll need a piece of fuel line and a small gas can filled with fuel. Connect the piece of fuel line to the carburetor fuel pump and drop it into the small gas can and see if the ski will fire off and run.
Make sure the gas can isn't very large and there's some space in the ski's fuel tank, b/c the fuel pump will be transferring fuel from the gas can to the ski's fuel tank while the engine is running.
FWIW, The fuel pump pumps more fuel than the engine uses, this extra fuel is returned through the return line back to the fuel tank. This feature was designed to help purge air from the fuel lines and make fuel pressure stable, so keeping the fuel return plumbed as intended is necessary, that part of the fuel system shouldn't be eliminated (not that you were considering that). Also, the return fuel line often has a flow orifice restrictor inserted in the line and this restrictor is easy to overlook while replacing fuel lines, so hopefully if you changed that fuel line you didn't fall into this trap of inadvertently throwing away this restrictor????
Make sure the gas can isn't very large and there's some space in the ski's fuel tank, b/c the fuel pump will be transferring fuel from the gas can to the ski's fuel tank while the engine is running.
FWIW, The fuel pump pumps more fuel than the engine uses, this extra fuel is returned through the return line back to the fuel tank. This feature was designed to help purge air from the fuel lines and make fuel pressure stable, so keeping the fuel return plumbed as intended is necessary, that part of the fuel system shouldn't be eliminated (not that you were considering that). Also, the return fuel line often has a flow orifice restrictor inserted in the line and this restrictor is easy to overlook while replacing fuel lines, so hopefully if you changed that fuel line you didn't fall into this trap of inadvertently throwing away this restrictor????
Luv2Camp
Active Member
I changed out my fuel lines two seasons ago on my 95 GTX and do not recall this either. Here is a thread stating this is only a straight line fitting. Maybe more will chime in about this. Even if you missed it, I would think you would have enough fuel making it to the carb to at least start.
http://www.seadooforum.com/showthre...stion-on-fuel-line-restrictor-in-a-95XP-96SPX
Yep, I ditch it on every ski. It was just there for easy installation at the factory. You can see how most plumbing is hanging there. Thanks sabr for the video.
Sea-Doo XP assembly: https://youtu.be/iQj1D4xYsOg
Sent from my SGH-T889 using Tapatalk
Sea-Doo XP assembly: https://youtu.be/iQj1D4xYsOg
Sent from my SGH-T889 using Tapatalk
soccerdad
Well-Known Member
I agree with the above. You can prove it with hanging a small gravity tank, like Sportster suggested. My favorite tool to prime it is a hand vacuum pump like this from Harbor Freight. http://www.harborfreight.com/brake-bleeder-and-vacuum-pump-kit-69328.html This will instantly get you fuel and tell you if you have it plummed correctly and if you have any vacuum leaks in the supply side. These systems must be vacuum tight though all fittings, fuel selector and filters so it can suck the fuel to the carbs. Try it, you'll like it! Saves you tons of guessing and cranking. Oh, and there won't typically be much back pressure on the return line. It just goes back to the fuel tank above surface.
Bjsaleen
New Member
Soccerdad, could you walk me through the procedure you use when using the vacuum pump to prime your fuel lines and check for leaks?
soccerdad
Well-Known Member
Pretty simple. Just remove the incoming fuel line at the carb or at an inline fuel filter if you put one in there. Connect it to the hand vacuum pump. Pump until you have fuel coming into the trap container attached to the pump. If the fuel gets there, you have it plumbed correctly (at least on the supply side). When you pump it, you can watch it fill the water trap filter and then it will come over to carbs. If you have a bad vacuum leak, you won't get the fuel to pump over. Then just remove the hose from the pump and reconnect. Your ski should have gas in the carb in just a couple of seconds of cranking.
Bjsaleen
New Member
Have not had a chance to look at the fuel lines yet. I'm gonna try and get to them Monday. I will keep you guys updated, the weather has turned and it's mid 60's to 70 this coming week and want to get it on the water!! With all your guys help I'm sure I can accomplish this!
Bjsaleen
New Member
Yeah that sounds really simple and I will be headed to harbor freight and picking the hand pump up. Thanks for the great tip!
Sportster-2001-951C-Stock
Well-Known Member
You can pull fuel out of the tank and prime the fuel pump (thus pull fuel into the feed side of carbs) by pulling fuel up via the return line too.
Bjsaleen
New Member
Ok a little update! First off happy Easter. Ok I got a chance to mess with the seadoo a little bit today. What I did was remove the inlet fuel line that's headed to the carbs. I removed it from the inline fuel filter sprayed some pre-mix fuel into the carbs and placed the end of the line in a bottle filled with fuel. The seadoo fired right up and ran great for 15-20 seconds until I hit the stop button due to not being on a hose. So that mLes me feel really good about the situation. I then hooked the fuel line backup to the fuel selector and with the fuel that was in the line I fired it up once again. It ran great and that's until it died. I looked at the inline fuel filter and it was bone dry. So my conclusion is there is a routing problem (like you all said there was) somewhere from the fuel selector back to the fuel baffle. Now I just need to figure out the right way to route these fuel lines and we should be up and running and in good shape. My question to you guys is, where on the fuel baffle is the markings for which line goes where? Is it on the nipple themselves or on top of the baffle somewhere? Because if it's on the top of the baffle I must be missing something because I cannot see anything that tells me which line goes where. Help is much appreciated!!!
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
Bjsaleen
New Member
I appreciate it!!
- Status
Similar threads
