Conquest 8x8 w/ 20hp Kawasaki carb flooding, fuel pump doesn't shut off.

[kjac3585]

My 8x8 Argo Conquest with the 20hp Kawasaki FD620D engine hasn't been used for a couple years so I rebuilt the carb and flushed the old fuel out of the lines. After putting it back together I noticed the fuel pump never shuts off and I'm assuming it's flooding the carb/engine because the engine will only start up and run for about 1-2 seconds before it dies. I know the carb is getting plenty of fuel as it pours out of the drain plug when opened. It's an aftermarket fuel pump, however it's worked fine in the past. I put a new float valve in the carb and the float appeared to be fine as well. Any ideas on what I should look at?

[Supermag]

If you think it is flooding, try to cut the power to the pump after the engine starts. You could also install a manual shut off valve to see if it runs until it runs itself out of fuel. I would double check the after market pump to make sure PSI and flow ratings are compatible to the OEM pump. You may be bypassing the float valve with excessive fuel pressure. Check out Rock Doctors video on YouTube on the conquest (Kawasaki) carb cleaning how to. It is a good video on the basics of the FD620D carb.

Dave

[plott hound]

make sure needle is seating properly.easiest way to test that is turn carb upside down,and see if you can blow through fuel inlet.

[kjac3585]

If you think it is flooding, try to cut the power to the pump after the engine starts. You could also install a manual shut off valve to see if it runs until it runs itself out of fuel. I would double check the after market pump to make sure PSI and flow ratings are compatible to the OEM pump. You may be bypassing the float valve with excessive fuel pressure. Check out Rock Doctors video on YouTube on the conquest (Kawasaki) carb cleaning how to. It is a good video on the basics of the FD620D carb.

Dave

I can get it to start with or without the pump, but it dies within a couple seconds regardless. I've seen the Rock Doctors carb rebuild video, it was definitely informative, but it's not helping much with my issue I don't think. The aftermarket fuel pump ran fine for a year, so I'm doubting it's a PSI issue.

make sure needle is seating properly.easiest way to test that is turn carb upside down,and see if you can blow through fuel inlet.

I didn't want to take the carb apart again until I could rule out the fuel pump, however it looking more and more like a float or float needle problem.

[ARGOJIM]

try to carefully remove the shut off solenoid ( without breaking the very fine wire) and check for any drag in the needle, if there is any drag it may not be opening enough to supply fuel. Unplug the fuel pump, hook up the wire and ground the solenoid and watch for good travel and return. If there is any drag and cleaning it with gum cutter does not free it, nip the tip and if it cures the problem get a new one.
The solenoid is about 75-100 so try to free it first.

[kjac3585]

try to carefully remove the shut off solenoid ( without breaking the very fine wire) and check for any drag in the needle, if there is any drag it may not be opening enough to supply fuel. Unplug the fuel pump, hook up the wire and ground the solenoid and watch for good travel and return. If there is any drag and cleaning it with gum cutter does not free it, nip the tip and if it cures the problem get a new one.
The solenoid is about 75-100 so try to free it first.

I just put a brand new fuel shut off solenoid in, so I'm hoping that's not the problem. I know the engine is getting gas because I can start it repeatedly, however it dies shortly thereafter. It's my understanding that if one of these fails it prevents any gas from getting into the carb.

[ARGOJIM]

Yes if it sticks closed no fuel, if it only slightly opens not enough fuel, if it is known good than look elsewhere. Or if you still have the old one, nip the tip and give it a try to rule out the solenoid problem. But as you stated could also be the inlet needle, we also had a problem once where the inlet tube had a restriction we could not free.

[kjac3585]

I disconnected the fuel line from the carb and crimped the line to test the fuel pump and the pump still ran continuously. Aren't these pumps supposed to shut off after reaching a few PSI? I know it's getting fuel because I unplugged the fuel line and the gas pumped out steadily. I'm going to go buy a new pump, but if anyone knows anything about these pumps and how they are supposed to behave please fill me in.

[rodp]

Some diaphragm pump motors run continually although the motor isn't actually moving the diaphragm when pressurised.

[Supermag]

I can hear the fuel pump on my conquest pulsing continuously as soon as the ignition is turned on.
One more thing you can try is to gravity feed some gas to the carb fuel inlet using a small funnel and hose from about 3.5 to 4 feet above. Once the gas is in the funnel wait a while to see if it drops indicating a bad needle or seat. If the level remains constant when the engine is turned off try to start it. Weather or not it runs will give you a good indication on where the problem is and may save you from buying a new pump.

Dave

[kjac3585]

I can hear the fuel pump on my conquest pulsing continuously as soon as the ignition is turned on.
One more thing you can try is to gravity feed some gas to the carb fuel inlet using a small funnel and hose from about 3.5 to 4 feet above. Once the gas is in the funnel wait a while to see if it drops indicating a bad needle or seat. If the level remains constant when the engine is turned off try to start it. Weather or not it runs will give you a good indication on where the problem is and may save you from buying a new pump.

Dave

I went ahead and put in a new pump since the old one was 4-7psi and the specs call for less than 4 psi. The problem still persists however, so I can pretty much rule out fuel for now. I changed the spark plugs as well, but that didn't solve the problem. I was trying to avoid it, but I guess I'm going to rebuild the carb again and see if there is some issue with the float needle or clogged jets. Also, since you have a conquest, are you familiar with the gas vent tube location? I noticed one in the parts diagrams, but I can't find it on mine anywhere.

[plott hound]

the line comes off the filler neck and runs to the back of machine.if you suspect that is the problem,remove the cap and see what happens.i had a similar problem with my conquest,cleaned the carb 3 times and still had an issue.finally i bit the bullet and bought a new carb.

[kjac3585]

the line comes off the filler neck and runs to the back of machine.if you suspect that is the problem,remove the cap and see what happens.i had a similar problem with my conquest,cleaned the carb 3 times and still had an issue.finally i bit the bullet and bought a new carb.

I've already tried starting with the gas cap off, but no luck. When you say the line runs to the back, where exactly? Is it slid under something or would it be apparent? I've got all the floor panels out and I don't see it. There is a 4 inch long by 1/4" piece of copper tubing spliced in between the 1/4" rubber fuel line about a foot down from the fuel pump... I was thinking that might be where the previous owners bypassed the vent hose, but that's just me speculating.

[plott hound]

vent line comes off a little fitting thats brazed onto the filler neck.the vent hose runs bettween the upper and lower bodies to the back centre of the machine.there you will see a thru hull compression fitting.

[kjac3585]

vent line comes off a little fitting thats brazed onto the filler neck.the vent hose runs bettween the upper and lower bodies to the back centre of the machine.there you will see a thru hull compression fitting.

I see it now, the line has been removed, but the fitting on the rear is still there. Seems like an odd place for an air vent, I'd figure water could get in there pretty easily when floating.