So I've working on my xp limited for a few months now and I've disassembled the entire thing and rebuilt it. Now I'm running into some fuel issues. I rebuilt the carbs using a kit from OSD marine. which I believe is a quality kit and has oem spec parts, BUT now that I've started to crank the engine, it's not pulling fuel. I also replaced the fuel lines in full rebuild so it has to pull fuel through about 10 ft of line. I cranked it for awhile and still wasn't getting fuel to the filter that unscrews from the bottom where the lines hook up to. I hooked a hand pump up to the filter out side and pumped fuel in the filter hoping it would speed up the process, but even though there is fuel inside the filter, the pump has not put anymore fuel in the lines or the filter. I looked at a diagram for the vacuum lines hoping I just hooked them up wrong, but I'm pretty sure they are correct. I have the vacuum that comes strait from the tank hooked up to the top double sided connector and the one on the side hooked up to the engine connection underneath the carbs, is this correct? I've also turned it over while feeling the end of the line to see if there is suction in the fuel line, but I could barely feel anything. I'll upload some pictures of the connections in a second post. Any help is appreciated, Thanks!
1998 seadoo xp 951: Carburetor fuel pump barely works
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Noahsfixingbrokedownskis
Member
Did you test the pop off pressure? Also make sure to clean your high and low side adjustment screws. Here is a picture I took of my carb pre cleaning to insure I reconnect the lines correctly.
Grim
Active Member
Several things could be wrong. First, have you tired spraying some oil/gas mixture in the crabs to verify the engine runs? Also, download the repair manual and parts manual, they are free on the web. That is what helped me to verify which lines went where.
After that,
I would start by taking a piece of gas line and running it to the carb from a container of gas...see if the carb picks up fuel and runs, this will tell you if it is a problem from the tank to the carb. If it doesn't run I would take the fuel pump (on the carb) apart and inspect everything. Did you replace anything on the pump when you did the rebuild? Some of the OSD kits have parts for the pump.
Hopefully you used the guide for carb rebuild on this forum...if not go find it and review to see if you did anything wrong.
Report back and we can help more.
After that,
I would start by taking a piece of gas line and running it to the carb from a container of gas...see if the carb picks up fuel and runs, this will tell you if it is a problem from the tank to the carb. If it doesn't run I would take the fuel pump (on the carb) apart and inspect everything. Did you replace anything on the pump when you did the rebuild? Some of the OSD kits have parts for the pump.
Hopefully you used the guide for carb rebuild on this forum...if not go find it and review to see if you did anything wrong.
Report back and we can help more.
Ok I’ll try with a separate container for the gas, I’ve not seen the engine run before, but it has 130 or 140 compression, and spark so it should work. I did rebuild the pump using the carb rebuild guide posted on here. Only thing I can think of that might be failing is the clear plastic discs, maybe I installed them wrong even though I checked the marking side. But I’ll troubleshoot on Monday, I have an event this weekend so I won’t have time.
TheGTIjetguy
Member
In addition, you can also check the engine side pulse nipple on the crankcase. Sometimes they clog or corrode off altogether.
I have tested the carb fuel pumps by putting fuel in a small container below the ski (height doesn't matter much but I want to see the pump pull) . Then I place a clear line into the fuel and connect the other end to the carburetor fuel inlet. Next, I take a nice clean line and attach it to the pump pulse line and place it into my mouth and gently puff my cheeks to make the pulse. The fuel should be drawn right up the line and "not" gravitate back down. The carb pump is very efficient so it doesn't take but a few seconds to verify.
I'm not sure about the 1998 engine but I'll assume they are the same as others. On the bottom of the engine case where you connect the hose to the pulse line for the carb fuel pump, there is another fitting that looks the same. That fitting is for the rave valve system. Make sure the rave line is connected with the check valve operating properly. I don't know how much of an effect it would have on the fuel pump if that line was leaking and allowing a vacuum loss. Just making sure also that you have the pulse line connected to the fitting closest to the mag.
You could also have an issue with your fuel selector valve. I pull a vacuum on the fuel line prior to assembly. I check the fuel selector function and especially the water separator. If you have any leak at the separator that will really hamper pump performance.
Something else...Did you pressurize the carbs to 15 pounds and check for leaks after rebuilding? A small leak on the pump cover will definitely affect efficiency.
Is the pump assembled correctly according to the diagram? I have to look at that thing time and again to make sure I got it right. LOL
Good Luck !!
I'm not sure about the 1998 engine but I'll assume they are the same as others. On the bottom of the engine case where you connect the hose to the pulse line for the carb fuel pump, there is another fitting that looks the same. That fitting is for the rave valve system. Make sure the rave line is connected with the check valve operating properly. I don't know how much of an effect it would have on the fuel pump if that line was leaking and allowing a vacuum loss. Just making sure also that you have the pulse line connected to the fitting closest to the mag.
You could also have an issue with your fuel selector valve. I pull a vacuum on the fuel line prior to assembly. I check the fuel selector function and especially the water separator. If you have any leak at the separator that will really hamper pump performance.
Something else...Did you pressurize the carbs to 15 pounds and check for leaks after rebuilding? A small leak on the pump cover will definitely affect efficiency.
Is the pump assembled correctly according to the diagram? I have to look at that thing time and again to make sure I got it right. LOL
Good Luck !!
That line you are calling the vacuum line at top is the fuel return line.
This won't affect your fuel flow but did you check the function of the accelerator pump on the carb? I generally don't have issues with the accelerator pump but plugging of the nozzles that spray into carb throats. You'll know if they are working properly as the ski will accelerator poorly or fall on it's face just when accelerating from low speed. Hope it all works out for you. I fought these a lot.
TheGTIjetguy
Member
When the pumps start pulling fuel it will be obvious. It takes my single carb 717 about 10 seconds of cranking to fill the system and feed the carbs. As etemplet said, your accelerator pump is a great way to see if you got fuel at the carbs. The throttle should feel like an empty windex spray bottle pumper when the carbs are dry, than you will feel and hear it pushing fuel through the nozzle of the carb when full.
I made the mistake recently of installing the carbs on the GTX 951 BEFORE installing the exhaust manifold. I've built a number of 951s and when I picked up the exhaust manifold I said.... oh crap... I'll never get those bolts in there. I got them in without pulling the carbs but I wouldn't recommend it.
I know it isn't a big deal to pull the carbs back off but I used RTV on the gaskets for this ski and I didn't want to clean all that crap off... again. I don't like using RTV for that reason but I just didn't trust the surfaces. I was sure hoping for no issues when I put the ski in the water. I hate that crap.
I know it isn't a big deal to pull the carbs back off but I used RTV on the gaskets for this ski and I didn't want to clean all that crap off... again.
I don't like using RTV for that reason but I just didn't trust the surfaces. I was sure hoping for no issues when I put the ski in the water. I hate that crap. Ok so I might have realized the problem just by reading all of the responses! On the fuel module that goes inside the tank, there are 4 nipples, 2 for gas lines and 2 for vacuum/air. I currently have one of those vacuum lines hooked up strait to the carb, on the nipple I circled in the picture that says fuel tank line. Is that correct? I’m starting to think that the line which connects to the air hose with 2 check valves and a 3 way split goes to the carb, is that my problem or is my setup correct currently. I’m about to start trying all of the suggestions listed above, so if this is my problem then it would be good to know now. Another thing, does the pulse line push air out or pull air in from the carb. If I’m going to simulate it with my mouth I need to know lol.
TheGTIjetguy
Member
Hopefully you can find a free service manual online for your ski. That will give you all the fuel line routing information you need. The line from the carbs directly back to the tank is most likely a return line.
The pulse line gets a slight vacuum followed by a slight pressure, quickly back and forth. This moves the “dry” or pulse line side of the diaphragm back and forth creating a pumping action on the “wet” or fuel side of the diaphragm. The two little disk valves are check valves that allow fuel to be pulled into the chamber, then pushed out the feed side to the metering chamber on the other side of the carb.
The pulse line gets a slight vacuum followed by a slight pressure, quickly back and forth. This moves the “dry” or pulse line side of the diaphragm back and forth creating a pumping action on the “wet” or fuel side of the diaphragm. The two little disk valves are check valves that allow fuel to be pulled into the chamber, then pushed out the feed side to the metering chamber on the other side of the carb.
TheGTIjetguy
Member
Definitely look over your fuel line routing per the service manual. Also check for any areas that may leak. The smallest amount of air allowed into the feed line will break the vacuum and not allow it to pull fuel from the tank. If all else fails, take the carb pump side apart and check everything again. One of those little disks not seating can easily negate the pumping action.
Alright so I’m coming back here with my carburetor pump taken apart, I tested the pulse and it was pushing air firmly out so I figured it couldn’t be that. I put the pulse back on and took the fuel line off, then I turned the engine over while holding my finger on the fuel nipple and it had zero vacuum. When I opened my pump I found that there is a clear plastic gasket in between the pulse line nipple and the pump! I’m guessing it does not belong there, and either something else does or nothing should be there. I’m just wanting some confirmation before I go through all the pain of putting the carb back on the engine. I’ll link a picture to what I’m talking about.
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TheGTIjetguy
Member
Sounds like you found it. Awesome. Not sure that you could get the pump disk and rubber plug separately.
FYI it has been proven time and time again on this form that genuine Mikini carb kits are the only way to go.
Also, I see you have gray fuel lines running between the carbs in the picture. You need to get all those off the ski asap. They worked good back in the day, but the ethanol fuel degrades them internally. This will fill your newly rebuilt carbs with green goo in no time.
Remember, the fuel system is worth your time and effort. Higher horsepower two strokes require fuel to cool the piston domes. Running lean due to an carb/ fuel issue will risk the engine.
The sticky thread on carb rebuilding has all the information you need
Hope you get her running! Old skis are great! (Until they aren’t)
Edit: I see that you already replaced the lines. My apologies
FYI it has been proven time and time again on this form that genuine Mikini carb kits are the only way to go.
Also, I see you have gray fuel lines running between the carbs in the picture. You need to get all those off the ski asap. They worked good back in the day, but the ethanol fuel degrades them internally. This will fill your newly rebuilt carbs with green goo in no time.
Remember, the fuel system is worth your time and effort. Higher horsepower two strokes require fuel to cool the piston domes. Running lean due to an carb/ fuel issue will risk the engine.
The sticky thread on carb rebuilding has all the information you need
Hope you get her running! Old skis are great! (Until they aren’t)
Edit: I see that you already replaced the lines. My apologies
I actually found osd marine selling them separately, so I put an order in for a disk and plug. It only cost me $15. I’ve replaced all the grey lines, I don’t know where you saw it in the picture, the only line in it was black. (from autozone) When I first rebuilt it about 6 months ago it was filled with green goo, and I had read all about the grey lines. So thanks for the heads up anyways! Hopefully when my parts come the pump will start working.
I see some WHITE stuff under your valve. If that is not sealing the pump wont work properly. Looks like some corrosion in the picture. I made a tool to lap that surface. It is something I do only when needed. I'm not saying that is your problem. Do you have the carb assembly diagram? It is a bit of a pain for me to read and it looks like you have it assemble correctly for that model carb.
Here is a picture. You don't need the tool but my method is always overkill. This tool insures the surface remains flat and the correct grit compound can remove minor surface imperfections. The extended piece on the bottom of the tool hold it in position when lapping.
This diagram isn't the full page. It tells you further on the left which parts do not belong on the 46 Carb. I don't believe part labeled No 6. applies. Good luck.
Here is a picture. You don't need the tool but my method is always overkill.
This tool insures the surface remains flat and the correct grit compound can remove minor surface imperfections. The extended piece on the bottom of the tool hold it in position when lapping.This diagram isn't the full page. It tells you further on the left which parts do not belong on the 46 Carb. I don't believe part labeled No 6. applies. Good luck.
Yeah I’ve got the diagram, and I’m positive it’s assembled correctly. I could see just by looking at it, that my disk wasn’t sealing because it was warped and because the plug wasn’t holding it down enough. Not sure about the corrosion, I’ve tried to clean it so as far as that goes I think I’ll take my chances. If it doesn’t work, then I’ll look into doing something like you did to get the corrosion off.
On a side note, I save those check valve discs from the kits because they are easy to damage and lose. They are critical and I don't like having to stop my work for lack of a part. I find some of them come a bit larger in some kits even though they are Mikuni kits.
They reason I do the fuel test I do sometimes is to insure the valves are holding and the fuel doesn't flow backwards. The pumps work great when they are working properly. Good Luck !! Welcome to Seadoo issues.
They reason I do the fuel test I do sometimes is to insure the valves are holding and the fuel doesn't flow backwards. The pumps work great when they are working properly. Good Luck !! Welcome to Seadoo issues.
You should be able to remove the corrosion without my rocket science. LOL It's just difficult to get in there to clean it. I'd try scotch-brite with some WD-40. As long as it is clean you'll be good.
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