only runs if I pour gas in the carb????

[koenig65]

The 1970 521 in question sat for at least 1 year then the previous owner managed too start it and he let it run for a while. The truck would not idle and he said he had too add gas everytime he restarted. My question is where should I start? It appears the fuel filter has been bypassed? ?!!!!??. This truck was headed too the scrap metal yard and I managed too save it. I need to know where to start? thanks

[phlebmaster]

Start with the gas tank...drain the old and put in clean new gas. I would add IsoHeat just for good measure.

Then look over the fuel lines and PUT A FILTER ON IT.

Next, pull the line off of the carb and check for blockage by running a hose over the fender and cranking the motor...you should see gas coming out of the hose. If not..I would look at your fuel pump. Be careful not to pump the gas next to your distributor!! Bad things can happen..lol

If your fuel pump works ok, then rebuild your carb. That is not too expensive and if you take your time it is simple to do. Personally, I would put on a Weber 32/36 and call it good!

Hope this helps.

[240Zilla]

If the problem turns out to be internal in the carb, it might be as simple as the needle valve stuck shut. See if there's any fuel to be seen through the inspection window on the front of the carb. If not or you just can't tell, then take off the cover with the window in it.

Be careful of any small parts such as the little brass spacer sleeve that might fall out and get lost when you remove the cover. You might look for this part on the fulcrum rod that supports the float and remove it for safekeeping.

Then CAREFULLY slide the float out of the chamber and set it aside being careful not to tweak any of the thin metal parts.

Reach into the chamber and find the tiny brass button that pokes down from the top. Tap it sharply several times. If it's not poking down very much but your agitation releases it so that it now hangs farther down then that was your problem.

Put everything back together and see if it runs. This might save you from a complete rebuild of an otherwise perfectly good carburetor.

[koenig65]

Ok it will start and run now but after say 5 min the choke does not seem do any \thing and it wants too stall? I cleaned the plugs(looked pretty new although they were coated in a black sout). once warm the carb seems to be sucking air pretty hard? whats next?

[FrancisCarey]

if it DOES have fuel injection, you do NOT want to do the test described above as high pressure fuel will spray out of thye line; this can be quite dangerous! That test is applicable to carbureted vehicles only. Carbureted fuel systems and fuel injection systems are very different, and have very different test procedures.

__________________________great mud guards for safe drive

[superdanni]

are you sure its not the fuel sender? I think I'm having a problem with mine. i've already had gas tank redone, just put gas in it, and the fuel sender is making a clacking noise. of course, I cant figure out if that noise means the fuel sender is bad or there's still something wrong with the gas tank still (it was recored and I put it back on not too long ago, but it tends to be a long time in between when I can work on the car)