01 srx 700 not getting enough fuel to run after warmed up

srxz

srxz

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Jan 4, 2004
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Location
Georgian Bay
I haven't been here for a while but could use some ideas on this as it's turning into a nightmare lol!

Last year near the end of the season after a long wide open pull on the lake the sled starts to lose power.....getting off the gas to slow down and pinning it again there is full power once again only until you hold it wfo for some time does it start to bog........replaced fuel pump with used one to try.....no change...end of season!

This year I checked all the fuel lines, vents, new filter, another set of carbs and another fuel pump and the problem is getting worse.......float bowls are nearly mt when i check after the sleds starts to fail and will only run on full choke.......it starts fine still and runs good till its ridden for about 5 minutes.....also i experimented with an electic fuel pump temp set up to make sure the floats were full and sled ran fine with no issues!!

Thats 3 fuel pumps i've tried and 2 different sets of carbs so not sure why else it would run low on fuel in the bowls unless not getting enough pulse from engine but the line looks fine and it will fill the bowls from dry on a cold start!!??


Thanks guys if you have any ideas I don't what else to check??
 
I know you said you replaced the carb rack but did you check and clean the top-hat filters behind the needle and seat?

What kind of pressure were you seeing with the electric pump set up?

I'm not real clear on your symptom. Will it start and idle okay - say, for 10 minutes or do you have to use the choke even at idle.
 
You're sure vent line is clear? Nothing in the tank obstructing the filter? and like snomofo said, top hat filters? and will it idle for 10 minutes on it's own, can you just putt around without it acting up?
 
Are you shure the moter is not hurt as in a crankseal or a hole in the block?Hole in a piston ?Start looking for something else that would give you a low vacuum .
 
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I did clean the top hat filters and thought that was the problem at one point Bc they were dirty but that didn't help either........the sled will start and idle fine and you can ride it around slow with no issues it's just when you ride at higher speeds that it acts up!! I did a compression test it's 120 on each cylinder and sled pulls hard and works well when I tried the electric fuel pump set up! Idk what the spec is for pulse line vacuum but I'm going to put a gauge on it and monitor while I'm running it with the electric pump.......I can't see how the motor would be damaged to cause low vac as it runs awesome until the bowls get low on fuel but it's possible......
 
This is another direction but my Viper has been doing the same thing for the past couple of seasons. When you are WOT for about a half mile or so it looses power, slow down to 50 or so and it takes right back off. It started intermittently a few years ago and got to the point where it was every time last season. I thought it was the power valves initially and then the carbs but rule them out. Several of the members suggested I look at my clutches. I rebuilt both the primary and secondary this summer and it seems to be fixed but I have not had a chance to really hold it open. I am going to the UP this weekend and will know for sure once I get on a rail bed.
 
what test did you do to think its a fuel problem?

when it acts up what happens if you slightly lift up on the choke lever, does it run good again at high speed?

honstly you describe a stator problem to me, but I am interested in hearing how you camr to the conclusion its the fuel, thats why i am asking.
 
Thanks for the replies!
I know it's a fuel problem because I rigged up an electric fuel pump on a battery with a Jerry can of mixed gas to feed the carbs directly and disconnected the sleds fuel pump and it runs perfect with that set up!! Never bogged or stalled even at high speed!! The choke did help keep it running for me to limp the thing home from the lake when it did act up on the machines own fuel pump the last time I tried but didn't make it better at high speed!! I have new gas filter and blew through all the vents and unscrewed the gas cap at speed to see if that helped also??? Does anyone know how much vacuum the pulse line should have?? Thx again!
 
You check your float height? If your not getting enough gas maybe you float height is set to high (They're measured upside down). You don't have a fuel shut off do you? Read somewhere someone put a yamaha fuel shut off but it was 1/4" and wouldn't flow enough gas at high speeds.
 
srxz said:
Thanks for the replies!
I know it's a fuel problem because I rigged up an electric fuel pump on a battery with a Jerry can of mixed gas to feed the carbs directly and disconnected the sleds fuel pump and it runs perfect with that set up!! Never bogged or stalled even at high speed!! The choke did help keep it running for me to limp the thing home from the lake when it did act up on the machines own fuel pump the last time I tried but didn't make it better at high speed!! I have new gas filter and blew through all the vents and unscrewed the gas cap at speed to see if that helped also??? Does anyone know how much vacuum the pulse line should have?? Thx again!
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the part that doesnt fit in is, its fine running , then after 5 mins it does this.......thats why seems to not make much sense its a fuel problem as the pump and stuff is a fixed set up.

if your convinced its fuel, then you need to look at the needle and seats, o ring for seat, and the float level. those are the only things that limit the fuel but they dont work for 5 mins and then not work.
 
I agree with it doesn't make sense lol!
I checked and doubled checked the float heights, needle and seat and screens......on two sets of carb racks!! They both had the same result......very little fuel in the bowl when I took them apart after running the sled! There is no fuel shut off.....it will run fine for longer than five minutes if you don't go wide open throttle......but it will bog after about 10 seconds of wot??.....then it won't run right and even stall unless you let it sit for quite some time!! Going to try something now and check the pick up like and filter again......wil let you know
 
srxz said:
Thanks for the replies!
I know it's a fuel problem because I rigged up an electric fuel pump on a battery with a Jerry can of mixed gas to feed the carbs directly and disconnected the sleds fuel pump and it runs perfect with that set up!! Never bogged or stalled even at high speed!! The choke did help keep it running for me to limp the thing home from the lake when it did act up on the machines own fuel pump the last time I tried but didn't make it better at high speed!! I have new gas filter and blew through all the vents and unscrewed the gas cap at speed to see if that helped also??? Does anyone know how much vacuum the pulse line should have?? Thx again!
Click to expand...
Did you ever try to hook up stock pump to the "jerry can"? If not, may worth a shot just to try narrow it down.?
 
srxz said:
Thanks for the replies!
I know it's a fuel problem because I rigged up an electric fuel pump on a battery with a Jerry can of mixed gas to feed the carbs directly and disconnected the sleds fuel pump and it runs perfect with that set up!! Never bogged or stalled even at high speed!! snipQUOTE]

I'm picturing a 20L Jerrican on one running board and a battery on the other. Must have been quite a ride.

With this set up you've by-passed the pump and tank.

In-tank filter is in place (hose isn't floating)?
No cracks in the tank hose and clamped ends are tight?.
Good flow through the fuel tank flange?
No obstructions in the line between the tank flange and pump?

Checked pulse line with a gauge and compared to another like sled? I've never tried it and it may screw up the gauge you use but I'd guess a 0-30 psi or 0-30 inHg gauge would work.

I've never monitored fuel pressure either but I'd guess the carbs see 4-8 psi and I'd caution against using a pump that pushes much more than that. Even low pressure pumps deliver over 20 psi.
The Cat and Polaris EFI pumps were around 40 psi which would be way too much for carburetor.

Good luck.
Click to expand...
 
Last night I set up the electric pump again and plugged a vacuum gauge to the pulse line to see if anything changed there when it gets hot and there seems to be lots of steady vacuum there even when hot.......I emptied a one gallon Jerry can going up and down the river till it ran out of gas!! Maybe I should just strap a 20 liter can to my back and ride around for the day to get my fix? lol!!
One thing that I don't get is that the sled wouldn't start with the electric fuel pump even after I plugged it in and filled the bowls up in the carbs??? I had to put some gas in the top of cylinder to get it to fire and then it ran great!?

Tonight I'll try it again with stock pump now that I replaced the pick up line and filter in the tank.......the line that was in there was quite stiff and that's the only thing I haven't changed yet in the fuel system! Although it seemed to be sitting in the fuel ok and was clear and without cracks or damage......
 
is the pulse line from the engine to the fuel pump the original grey color heavy rubber wall line or has it been replaced? if it has been replaced i have seen people use aftermakrket line thin walled and it will collapse.
 
The pulse hose has never been replaced and looks in good condition......the pick up line in the tank was original......I've replaced that last night and gonna try it after work today......
 
Not sure what to think here now......I changed the pick up line in the tank but had to put an inline filter on the end of it till the stock filter comes in at the dealer.....hooked the stock fuel pump back up and fired it up no problem and road around slow for a while then went out on the bay back and forth going fast but not wide open as it was rough then went up the road wide open and back and all was good no issues was very happy bit after about half hour of running it it started to bog again and eventually stalled!!!!!

Would not fire until I walked home and got some gas to bring back to spray in spark plug holes then fired right up and ran fine all the way back to the house!!??? Unless there is something in the tank that I can't see floating around I'm out of things to try......gonna fill the tank back up and see how far it will go on the trail this weekend when I get my try our trails free pass this weekend!!
 
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