Demon Carb Trouble...help runs for

[TCullen]

Demon Carb Trouble...help

My setup is a mildly worked over 302 HO with a Speed Demon carb. When I got it, the carb was already tuned for the motor and it ran great.

Then...the eccentric that pushes the mechanical fuel pump broke off. So I replaced the pump with an electric model. She started up fine, then the carb flooded so badly that the car would barely run. I thought the problem was just the electric pump, so the eccentric was replaced and the original pump reinstalled.

Now the carb is flooded again, when it starts it only runs for a few minutes, knocks when it does run, and on top of that it won't restart. There is probably an elementary answer to this problem but I've always had EFI and don't know how to fix.

 

[zookeeper]

You kinda answered your own question without knowing it. You likely are not running a pressure regulator between the pump and carb. That's a major boo-boo, get an adjustable regulator and set it around 4 lbs with the motor running and I'll bet it runs a lot better. Electric pumps really put out the pressure and it's almost always enough to push the needle and seat of a carb open, flooding the bowls and shoving the excess fuel into the carb throat, flooding the motor. Manual pumps put out 5-7 lbs, but I've found that throttling electric pumps back to 4lbs pressure keeps everything happy.

 

[10secgoal]

Zookeepre is right. It's definetly flooded. Some companies suggest taking the needle and seats out and making sure they are free of packing material when a new carb is installed. When my needle and seats acted up, it was off and on.

 

[TCullen]

first of all, thanks for your help. i see what you're getting at. but when i've swapped out the new electric pump for the original mechanical pump it still floods. coulld it be that the float is stuck or something of that nature?

 

[Shakin66]

Anytime I work inside a carb. I after I get it remounted I whack it with a dead blow hammer (not too hard) to make certain the needle valve is closed. This comes from my Motocross background but it cant hurt.

 

[Max Power]

I saw that you had gone back to the original setup, TCullen, and my guess is you dislodged some debris and it is keeping the needle from seating. I think it is still flooding, but not from fuel pressure anymore.

 

[TCullen]

Max power, i would tend to agree with your assessment. but how would i go about fixing it?

 

[iskwezm]

sometimes when the needle/seat dries up it will stick. Just remove the nut from on top of the float bowl,remove the need assembly blow off and reinstall,set float and should be ok.

Mine stuck real bad one time so bad it locked the engine and took the needle out several times and then it just worked and has been fine since.

 

[TCullen]

you all have helped me immensly. without your advice, i'd be inclined to do something ridiculous like taking the car to a professional. i'll clean out the needle tomorrow and let you know how it goes. thanks again for the expert council.

 

[SoCalCruising]

Check closely for any residual shavings from the CNC work. Demons have been known to be shipped with some of this kind of debris.

 

[D.Hearne]

Anytime I work inside a carb. I after I get it remounted I whack it with a dead blow hammer (not too hard) to make certain the needle valve is closed. This comes from my Motocross background but it cant hurt.

A large plastic screw driver handle does the same job, but it's a LOT easier on the carb.

 

[D.Hearne]

Also, pull the spark plugs, clean em, roll the engine over a minute or so without the plugs, then put em back in. It'll start then. You've likely got the cylinders full of fuel and soaked the plugs in gas.

 

[D.Hearne]

OOPS...................Triple post.

 

[TCullen]

you guys were dead on. the engine was full of gas. she started right up after i cleared it out and dried the plugs.

thanks