CJ fuel system

Tobers

Well-Known Member
Joined
Jan 11, 2008
Location
durham
ok so this sunday I finally got the 304 running again... thanks to ken (stockcar). turns out I had the fuel lines mixed up return to send and send to return and did not have the ignition box grounded. so we ran it out of a jar for maybe 1min then connected the fuel lines and ran it for maybe 3 min and it was idling fine then it just stopped. I can get it to start on starting fliuid but not gas out of the tank.. I def have spark and gas. so is it bad gas? idk any ideas... thanks
 
Is there anymore gas in the tank? Might of only been 3 min worth in there or possibly could of sucked some crap into the lines...
I don't know, something to check out though.
 
Need a little more info or we are kinda working in the dark. What carb? Out of a jar? as in jar to fuel pump to carb?
Does the carb have a fuel filter in it?
Were you pulling through an inline filter?
I would change the carb filter if it has one. Then I would take off the inline filter and blow both ways through the fuel line with the air compressor. Then put it all back together, except keep it fueling from the gar, gas can or what ever. Then with it unhooked from the carb, pull the coil wire, and crank it over, if it spits out fuel on the carb end, then you have no issues there. Hook it back up and try to crank it. If no gas in the carb, then you have a float stuck, or the needle and seat is probably clogged. That means taking the top off the carb, or the bowl off it's is a holly and figuring why the fuel isn't going through
Good luck, hope this helps
 
don't know what kind of carb think its the stock one that comes on the 304...
don't think its vaporlock because the fuel lines are on opposite side of the frame than the headers. when I push the gas pedal I can clearly see fuel shooting into the carb. it won't start at all on the fuel only on the starting fluid. good idea on the filter inside, how would I get to that.

thanks
 
upnover said:
Does the carb have a fuel filter in it?
Were you pulling through an inline filter?
I would change the carb filter if it has one.
Click to expand...

Ditto! If you're running the stock MC2100, there's likely a sintered bronze filter in the inlet (under the fuel line fitting) that is always neglected. Pull it out and blow it out with compressed air. If no compressed air, it can be removed temporarily for troubleshooting.

To promote quick & easily diagnosable fuel issues, I've always used the plastic see-through filters (running 2 back to back now). They will tell you several things at a glance. Try doing that with the standard steel fuel filters...

Also, if you look down the carb throat and thumb the butterflies, the accelerator pump should produce a stream of fuel. This is also a quick way to check for fuel at the carb, as most accel. pumps are fed directly from the bowl.
 
Tobers said:
don't know what kind of carb think its the stock one that comes on the 304...
don't think its vaporlock because the fuel lines are on opposite side of the frame than the headers. when I push the gas pedal I can clearly see fuel shooting into the carb. it won't start at all on the fuel only on the starting fluid. good idea on the filter inside, how would I get to that.

thanks
Click to expand...

Sure it's Gas and not water?
 
hmm interesting thought... so you are saying it may be pumping water from the tank... how could I tell water from gas when it is squirting into the carb?
 
Tobers said:
hmm interesting thought... so you are saying it may be pumping water from the tank... how could I tell water from gas when it is squirting into the carb?
Click to expand...

If there's water in your gas tank (from the long sit) it will be on the bottom of the tank... right where the pickup tube can suck it up to be pumped into your carb. You could pull the fuel line from the pump to carb and pump a bit into a clean container. Tilt the container and any water will go to the lowest point and look kinda like an air bubble of sorts.

Be sure to smell the liquid to insure it's not ALL water!

If you have the MC2100, pull the throttle linkage loose, unscrew the air cleaner stud & 4 machine screws and take the top off the carb. Same deal... water or crap in the bowl?
 
ok thanks will do... if I got a little water in the carb could I disconnect the fuel line and pump the water out and then spray starting fluid in the carb and start it a few times to burn off any little amount of water that is in the bowl? or do I need to take the carb apart?
 
Im too involved in the cold medicine to offer much help, except run a standard steel filter between those glass ones and the carb mentioned...Ive seen more than a few come apart and dump the screen into the motor.
 
Tobers said:
ok thanks will do... if I got a little water in the carb could I disconnect the fuel line and pump the water out and then spray starting fluid in the carb and start it a few times to burn off any little amount of water that is in the bowl? or do I need to take the carb apart?
Click to expand...

*IF* you find water in the bowl, that means it either came from the jar you used *OR* your fuel tank (the larger problem here).

A tiny bit of water shouldn't be a show stopper if it was just in the bowl, but likely has invaded the idle circuit. That will require some disassembly ** I RECOMMEND YOU REMOVE THE CARB TO DO THIS AS THERE's TOO MANY SMALL PARTS THAT COULD FALL DOWN THE CARB THROAT! **



SkyHiK5 said:
Im too involved in the cold medicine to offer much help, except run a standard steel filter between those glass ones and the carb mentioned...Ive seen more than a few come apart and dump the screen into the motor.
Click to expand...

Would NEVER make it past the sintered filter in the carb inlet
 
Caver Dave said:
*IF* you find water in the bowl, that means it either came from the jar you used *OR* your fuel tank (the larger problem here).
A tiny bit of water shouldn't be a show stopper if it was just in the bowl, but likely has invaded the idle circuit. That will require some disassembly ** I RECOMMEND YOU REMOVE THE CARB TO DO THIS AS THERE's TOO MANY SMALL PARTS THAT COULD FALL DOWN THE CARB THROAT! **
Would NEVER make it past the sintered filter in the carb inlet
Click to expand...

would if I removed the clogging bastid :flipoff2:
 
haha yeah both filters through the carb and parts down the throat sound no fun... assuming it is water it def came from the tank because I saw the fuel in the glass jar and it was fine. I think I'm going to try to disconnect the fuel line after the fuel pump and try to pump out any water if there is still some in the tank. then I'll start it a few times with starting fluid and then recconect the line and try again. If this doesn't work I'll tackle taking the carb off... lets hope it won't go that far:rolleyes:
 
Tobers said:
If this doesn't work I'll tackle taking the carb off... lets hope it won't go that far:rolleyes:
Click to expand...

After you do it a couple times (great practice) it will take LESS THAN 15 minutes to pull the carb, strip it down, blow it all out (with compressed air), reassemble, & reinstall.

Here's a pictorial rebuild of a 2100. At this point, I'd skip the accel. pump & power valve portions, you can visit those later. Just focus on the jets, idle circuit, and booster venturi.

Also, if for some reason you don't have the sintered filter in the inlet, you may have screen UNDER the needle seat.
 
ok worked on it a ton today... the carb is fine and the filters look fine... if I disconnect the fuel line right before the pump and run a line to a gas can it pumps fuel like mad, starts first try, and then idles perfectly... on the other hand I couldn't get the pump to suck up gas from the tank... If i reconnected the line It would run for a while off the the gas in the lines then stumble and quit.

I thought it might be cracked rubber lines so I replaced those and when I disconnected the line after the filter it seems to be pumping some gas but not as much as it needs to.... so I ran it off the jar again and then reconnected. it ran perfectly for 5min then quit. so I'm guess it is getting some gas but not enough. any ideas? thanks
 
I would dop the tank and pull the sending unit out. Sounds like your sock filter is clogged. How much fuel is in the tank?
 
If your tub is shot, instead of dropping the tank, you can just cut a hole above the sender and pull it up thru the tub. It was a little sketchy with the cutoff wheel throwing sparks on the gas tank, but I didnt get blown up, YMMV :bounce2:
 
yeah I just repaired the tub so that isn't going to happen! ok good idea on the filter would I need to buy just a filter or a whole sending unit...
 
Are you sure that your fuel lines are routed correctly? Sounds like maybe you might be pulling fuel, but there isn't enough vaccum release and the fuel pump can't implode the tank. Try running it with the tank cap off.
 
tank cap is off.... already tried that, thanks though. and after checking manual, rechecking the lines... and re-doing the soft lines I am 100% sure the lines are right.
 
Ok finally fixed it!!!! well almost... blew air through the lines backwards and couldn't hear any bubbles in the tank so I dropped the tank and sure enough there was no filter assembly on the sending unit so even though I had like 4 gallons in the tank the plain copper tube without the filter wasn't picking anything up... I took the sending unit out and stuck it in a jar and sure enough everything worked fine!! thanks for the help.
 
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