carb problems?

[RobH]

Hi guys I haven't posted in a couple of days. I'm gonna post more when I get a chance to use the computer more.

I have a strange problem with my carb (i think). The longer I prime the carb the longer it runs -- even if I hold the throttle down. It's starving for fuel. If I understand this right a little exhaust is expelled out the tube that leads frrom the muffler to the tank. This puts pressure in the tank. This pushes the fuel out the bottom of the tank, through the fuel filter and to the carb. I thought maybe the tube going to the top of the tank from the muffler was bad so I replaced it. No change. I thought maybe the line to my carb was bad or my filter was plugged. I ran a direct line from the tank to the carb (no filter). Same problem. When I put a piece of gas tubing on the tanks top nipple and blow into it, ,the car stays running as long as I keep putting pressure on it.

I think my carb is plugged.

I should get a little bit of fuel comming out the line from the exhaust to the tank right?

I'm thinking something got into my carb somehow even with my air and fuel filters on. I think I have to take the carb apart see what the deal is. What do you guys think?

This one has me looking like this:

-rob

 

[x_789]

Sounds like you may have an air leak look at the second post I made in this thread for how to check for air leaks https://www.rcnitrotalk.com/forum/showthread.php?s=&postid=26850#post26850 possibly a tank issue with or lines. Check that first...X

 

[RobH]

x, that guys problems seemed to be with the pickup tube in the tank. Sounds like he got a new tank and was done.

I did the following:

my tank is off my truck so I plugged gas tubing into the top and bottom holes. I pinched the bottom line and blew with all my might. No leaks. Even the lid is air tight.

I filled the tank like 1/3 full (not to wast much gas). The fuel just poured out the bottom line. I gave a little blow on the top line and the fuel came flying. If I push the primer button, gas shoot out like a water gun. I think my pick and my gas are fine. If you read the original thread I replaced all the gas lines to check. Nothing changed it.

Takes us back to the carb right?

The thing should not be that boogered up. It's only got 1/2 gallon or so run through it.

-rob

 

[mjime714]

I'm a little confused. the longer you "prime" your engine, the longer it runs? Prime means to put fule in the carb so that the engine can start.

Let me see if I got it straight. You are not getting enough backpressure from the fuel pressure tube to push the fuel into the car.

You may have a clogged fuel filter (like you stated). Try feeding some denatured through the fuel tube from the carb side to the tank. Use a syringe. Make sure you clean out the Heroine.

Check for cracks in the fuel tank. Clean up your carb.

 

[RobH]

by "prime" I mean pushing the button on the top of the fuel tank.

I took the filter out of the loop as part of my trouble shooting. I put BRAND NEW fuel lines top and bottom WITH NO FUEL FILTER. same problem.

how does one "clean up his carb"?

-rob

 

[mad sceintist]

clean up your carb prolly means rebuilding it.or just inspecting it.

take it off the engine and disassemble and clean all the parts and put it back together.

what engine is it and if you know what carb?

 

[RobH]

i got it figured out! 8-0

remember those primer pump things everyone takes out and replaces with expoy and screws? .... i just found out why ... if I hold that f*cker down, it runs. If I let go, it dies.

problem solved thanks guys

 

[mquejr]

i still didn't understand the question

 

[RobH]

next time, I'll be sure to type really slow for ya mquejr

 

[FastEddy]

Primers are often the cause of loosing fuel pressure. I'm glad you found it.

In the future you will want to keep an eye on the fuel lid gasket as well. You can adjust it with the screw on the bottom side of the lid, don't go to tight.

 

[Candyman]

Good job! Finding problems is a bitch on these things sometimes. Those primers have a poor history. You're better off without it...

 

[RobH]

i had read about these things being a problem. I was just hesitant to try it as I didn't understand how the fuel system worked. This has really been an eye opener and a good learning experience.

Now I just have to plug up the hole in the top of my tank. I kinda messed up and made the hole too big. I think it's fixable though. I'll be sure to post when I have it figured out.

-rob

 

[nitro dave]

What I don't get is why do manufacturers still insist on putting primers in fuel tanks. Nobody I know likes them, they cause nothing but problems. There are other easy ways to prime an engine. You would think that manufacturers would get this, but some just do not.

 

[RobH]

yeah I was curious if anyone sold a tank without a primer pump. The exhaust pipe trick works faster then the dumb a$$ pump anyway.

I can't wait to get home and mod my tank. I have to go help my father in-law with his PC. Then, I have to go get my hairs cut. I'll be lucky if I get to work on it tonight. The weather has been so sweet lately too -- such a tease.