Irregular fuel return

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fasternu_674 · #1 Post by **fasternu_674** » Fri Sep 16, 2011 3:01 pm

I have a 03 cannondale that I am working on for a guy. It is bone stock. It had set outside for who knows how long and he wanted it running again. So I replaced the fuel lines, they were coming apart. Replaced the fuel filter. He wanted to keep the quick disconnects like they were, found both had split and were leaking so replaced those as well. Got it running to find it was running too lean. Hooked it up to D&M and adjusted fuel settings only to find only one injector was firing. Went ahead and replaced them both because they both had varnish all over them. Took apart the fuel pressure regulator, screen was full of rust cleaned it out. Put all back together, retuned fuel settings and it ran great. Good return fuel pressure to the tank. Pulled about 2 holeshots and it started cutting out like it wasn't getting any fuel. Popped the fuel cap, roughly no fuel returning to tank, just a very slow trickle. Had another fuel pump on hand so replaced and tried again. Same thing. It seems like when it is cold I have good fuel pressure but as soon as you ride it for just a few minutes it falls on its face and you can't do anything but limp it back in on idle. I am stumped.

Canniboomer · #2 Post by **Canniboomer** » Fri Sep 16, 2011 3:13 pm

The intake screen at bottom of the tank could be gummed.
A fuel line is creased-bent where it connects to the tank,...often from lifting the tank too high to connect, and then not scooting the lines forward after you push down the tank....or the return line is mis-routed.
Line from pump-out to first injector is too long and creased.
Line from 2nd injector to fuel reg is maybe creased from that cramped and hard-bent stock routing (and no room to insul-sleeve the line anyway)...see picture for alternate routing.
That new fuel filter might be plugged up already. What tubing did you use (or re-use?) inside the tank?...yellow gas tubing OK.
Or maybe need to replace the Fuel Regulator pod.
Misc parts are in stock, good luck and let us know your findings, but too bad the machine is still neutered with stock fittings! (:

kdeal · #3 Post by **kdeal** » Fri Sep 16, 2011 4:34 pm

Did you gut the inside of the quick disconnects and just keep the connectors? If not your problem is most likely the internal o-rings in one of the two disconnect fittings.

beanie$440$peed · #4 Post by **beanie$440$peed** » Fri Sep 16, 2011 9:53 pm

QUOTE (Canniboomer @ Sep 16 2011, 04:13 PM) <{POST_SNAPBACK}>

The intake screen at bottom of the tank could be gummed.
A fuel line is creased-bent where it connects to the tank,...often from lifting the tank too high to connect, and then not scooting the lines forward after you push down the tank....or the return line is mis-routed.
Line from pump-out to first injector is too long and creased.
Line from 2nd injector to fuel reg is maybe creased from that cramped and hard-bent stock routing (and no room to insul-sleeve the line anyway)...see picture for alternate routing.
That new fuel filter might be plugged up already. What tubing did you use (or re-use?) inside the tank?...yellow gas tubing OK.
Or maybe need to replace the Fuel Regulator pod.
Misc parts are in stock, good luck and let us know your findings, but too bad the machine is still neutered with stock fittings! (:

whos frame is in that pick is it powder coat or.paint

Canniboomer · #5 Post by **Canniboomer** » Sat Sep 17, 2011 12:59 am

....former customer's machine in Arizona, powdercoated frame,..I think he rode it for a year and sold it recently.

kstevens · #6 Post by **kstevens** » Tue Sep 20, 2011 12:43 am

i was having same problem...spits and sputters after gets hot, shuts off, let fan run for 5 min and will start and run fine, full power for another 10 min, process starts all over,
i have rerouted fuel lines (new) new fuel fillter, removed guts from quick disconnects, new temp sensor, now fuel is slow in fuel return, starts and idles good but get to about half throttle and it sounds like it is bouncing off rev limiter, about 6" flame out back of exhaust,
can anyone help ? thanks

fasternu_674 · #7 Post by **fasternu_674** » Tue Sep 20, 2011 3:43 pm

QUOTE (Canniboomer @ Sep 16 2011, 10:13 AM) <{POST_SNAPBACK}>

The intake screen at bottom of the tank could be gummed.
A fuel line is creased-bent where it connects to the tank,...often from lifting the tank too high to connect, and then not scooting the lines forward after you push down the tank....or the return line is mis-routed.
Line from pump-out to first injector is too long and creased.
Line from 2nd injector to fuel reg is maybe creased from that cramped and hard-bent stock routing (and no room to insul-sleeve the line anyway)...see picture for alternate routing.
That new fuel filter might be plugged up already. What tubing did you use (or re-use?) inside the tank?...yellow gas tubing OK.
Or maybe need to replace the Fuel Regulator pod.
Misc parts are in stock, good luck and let us know your findings, but too bad the machine is still neutered with stock fittings! (:

I have cleaned out the intake screen in bottom of tank as well as replaced the line running to it.
I checked all fuel lines and all are routed cleanly with no sharp bends or kinks.
Fuel filter is clean, fuel flows well out of it.
Only thing it can be in my mind is the fuel regulator pod.

fasternu_674 · #8 Post by **fasternu_674** » Tue Sep 20, 2011 3:45 pm

QUOTE (kdeal @ Sep 16 2011, 11:34 AM) <{POST_SNAPBACK}>

Did you gut the inside of the quick disconnects and just keep the connectors? If not your problem is most likely the internal o-rings in one of the two disconnect fittings.

Replaced both male quick connect fittings, did nothing with the fittings on the tank.

fasternu_674 · #9 Post by **fasternu_674** » Thu Sep 22, 2011 4:16 pm

Ok so I got frustrated and gutted the fuel fittings with no luck. Still have a fuel flow problem. I am starting to think I have 2 bad fuel pumps. I did a pressure test and priming the system I get 45lbs from the pump. When dale is running it holds at 40 at idle and as the rpm climbs the pressure drops significantly. It then holds at whatever pressure it was at during revs at idle until I shut it off and re-prime the system. Anyone have any other good ideas.

kstevens · #10 Post by **kstevens** » Thu Sep 22, 2011 6:46 pm

QUOTE (fasternu_674 @ Sep 22 2011, 12:16 PM) <{POST_SNAPBACK}>

Ok so I got frustrated and gutted the fuel fittings with no luck. Still have a fuel flow problem. I am starting to think I have 2 bad fuel pumps. I did a pressure test and priming the system I get 45lbs from the pump. When dale is running it holds at 40 at idle and as the rpm climbs the pressure drops significantly. It then holds at whatever pressure it was at during revs at idle until I shut it off and re-prime the system. Anyone have any other good ideas.

i noticed that without the guts in the return line that there is the same amout of fuel but there isnt any pressure, it doesnt "squirt" back into the fuel tank, it just kinda flows