10hp starves for fuel.. 2-line system

[kbait]

qd-20 10hp, pressure tank system. Great spark, good pressure tank system and fresh fuel. Primed carb w/primer on tank and it starts fine, but dies due to starving out of fuel (sneeze). Even at higher rpm's than idle, where the low speed side wouldn't matter if it were clogged up (it should stay running). If I primed it again, it'd start again, and die after about 4 seconds. I then cleaned the carb (yes, all passages.. set the float even w/carb body, etc. Opened the high speed jet 3/4ths turn, and low speed 1.25. Hooked it back up and same result. Pressure builds fine in the tank, and it'll stay running as long as I push the primer, but dies immediately when I stop pumping it. Kinda got me scratching my head, as I've worked on these for years, and this is a new one! I'm sure it's not spark, and compression is good. Thanks!!

 

[tashasdaddy]

Re: 10hp starves for fuel.. 2-line system

check air hose for leak. all the way to the block. also could be loosing crankcase pressure.

 

[F_R]

Re: 10hp starves for fuel.. 2-line system

qd-20 10hp, pressure tank system. Great spark, good pressure tank system and fresh fuel. Primed carb w/primer on tank and it starts fine, but dies due to starving out of fuel (sneeze). Even at higher rpm's than idle, where the low speed side wouldn't matter if it were clogged up (it should stay running). If I primed it again, it'd start again, and die after about 4 seconds. I then cleaned the carb (yes, all passages.. set the float even w/carb body, etc. Opened the high speed jet 3/4ths turn, and low speed 1.25. Hooked it back up and same result. Pressure builds fine in the tank, and it'll stay running as long as I push the primer, but dies immediately when I stop pumping it. Kinda got me scratching my head, as I've worked on these for years, and this is a new one! I'm sure it's not spark, and compression is good. Thanks!!

Now wait a minute---you say it keeps running as long as you pump the primer but stops when you quit pumping? AND there is pressure in the tank? OK, the only thing I can think of is-- does that one have a sintered fuel filter on the bottom of the carburetor? If it does, betcha it is plugged up. Try taking it out temporarily and see if it keeps running. Some how, some way, there isn't enough fuel pressure actually getting to/into the carburetor.

 

[kbait]

Re: 10hp starves for fuel.. 2-line system

Hey FR.. It does have the glass bowl underneath the carb. I'll try that first thing! Thanks for making sense.. My thought was hooking up an elevated single line tank directly to the carb intake petcock and seeing if it'd keep running... but I bet it wouldn't, as your diagnostic sounds really feasable.. thanks, and I'll re-post the result.

 

[samo_ott]

Re: 10hp starves for fuel.. 2-line system

That is odd as those two situations are usually mutually exclusive. You're sure the cap is tight and it's holding pressure? How do you test the pressure? Just crack the cap after running?

 

[kbait]

Re: 10hp starves for fuel.. 2-line system

It was a clogged filter in the glass bowl under the carb bowl.. Thanks FR!

 

[jbjennings]

Re: 10hp starves for fuel.. 2-line system

I can't believe F-R got that one right. One-in-a-million for sure!

 

[F_R]

Re: 10hp starves for fuel.. 2-line system

I can't believe F-R got that one right. One-in-a-million for sure!

Actyally, it has been my experience that it is fairly common.

 

[coolguy147]

Re: 10hp starves for fuel.. 2-line system

wow man i would have first thought pressure tank wow man great job