Carb not getting fuel

I just rebuilt the carb on my 79 today and put it all back together to find that now Im not getting any fuel from the pump. So I replaced the pump today and turned the truck over for a while and its still not pumping gas. What should I check into next? Is there a chance that its vacuum related? I know there is a small dry rotted spot in the fuel line right below the fuel filler cap. Could that be an issue? Thanks

bvteachey said:

I just rebuilt the carb on my 79 today and put it all back together to find that now Im not getting any fuel from the pump. So I replaced the pump today and turned the truck over for a while and its still not pumping gas. What should I check into next? Is there a chance that its vacuum related? I know there is a small dry rotted spot in the fuel line right below the fuel filler cap. Could that be an issue? Thanks

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Fuel pump turning on? Hole near the filler cap won't have anything to do with it..

Either electircal, a fuse/relay

clogged fuel line?

Really hard to say.. are you getting ANY pressure at all? Something as little as 5psi?

adamdude with a carbed engine, they use a mechanical pump that runs of the cam shaft, so no electrical involved. unless the upgraded to an aftermarket one.

did you pull the fuel line off the carb and turned it over to verify it was not pumping? are the inlet outlet lines on the pump in the right places?

then check fuel line for bend or crimp where it may be restricted, and lastly ensure there is enough fuel in the tank, perhaps the pickup in the tank is clogged?

even with minor leaks in the fuel line its self, the pump is usually powerfull enough to pull some fuel through it. the leak in the filler neck would not affect the fuel lines or pump.

good luck

I did not know that..

Do even EFI motors come with mechanical fuel pumps? My father said ours was changed in 1993 on a trip to Seattle..so according to him, the fuel pump is roughly 17yrs old.. seems like a long time for an electrical fuel pump

nope pretty much all efi's use an electric pump. the difference is in the output that the pump produces. a mechanical pump is ideal for a carbed setup becasue carbs can just dump in raw fuel with the air that flows through sucking the fuel out of the jets. as long as the fuel is there the air will take what it needs. mechanical pumps usually only run from 15 to 30 psi

for efi systems they use injectors that "atomize" the fuel which is they turn it into vapor ( only the fumes of the fuel burns not the actual fuel)

but in order to atomize the fuel they need to use a much higher psi 30 to 150 psi. think of an injector like the handle on a spray bottle, liquid inside but when you pull the trigger it comes out in a fine mist. the computer with all its sensors is the hand pulling the trigger to give the engine as little or as much fuel as it needs for - the demand on the motor( throttle position) - altitude ( air density) - temperature ( air density) - and emission restriction ( keeping the balance of not too rich or too lean)

an electric pump can last for quite a long while, the one in my f 150 turns out was still good, but I replaced it not knowing my computer was fried, and it just turned 21 at the start of this month.

Hmm good to know. I have never delt with a carb'd motor before..so that/this is all new to me to. A learning experince.

bv- you might want to replace the dry rotted hose, I dont think thats you're problem but it needs to be replaced anyway, have you checked fuel filter?

OK, you rebuilt a card but have no experience with one. That leaves me with a couple of questions,

1. Have you just tried disconnecting the gas line at the carb and turned the engine over to see if in fact the pump is or is not pumping fuel?

2. Did you do the preliminary float setting properly?

3. How about the throttle plate vs idle jet setting?

4. Did you soak the carb in a carb cleaning solution to get the gunk out of where you can't see? Like the idle jets and transition slots and inside the metering plate.

Here are some things to check,

1. If all that was done, then turn to the carb. Remove the fuel bowl/s and make sure you did the float adjustment correctly. Once you are sure it was set properly to the preliminary setting, reassemble it and connect the fuel line, (for this procedure, you may eliminate the filter from the system).

2. Another adjustment is the idle jets, the throttle plates need to be adjusted so the idle jets just show below it, (when looking at the carb from the bottom).

3. Also, you need to make sure the idle mixture adjustment is set properly. If you followed the instructions, you gently ran them in to stop while counting the number of turns so that when you put the new ones in you could carefully and gently run them in to stop and then back them out the number of turns you previously counted. That will give you a rough adjustment that can be refined once the engine is up and running. If you didn't do that then the instructions should have a suggestion for how many turns to back it out so you will be in the ball park.

4. If it has a sight plug, remove it and disconnect the ignition, turn over the engine and see if the fuel bowl fills to the bottom of the hole. If no, adjust the fill valve until it just meets the bottom of the hole.

Once the adjustments are set, hookup the ignition, make sure there is no gasoline pooled on the manifold from previous messing around and Oh yes, have a fire extinguisher on hand just in case though with a cold engine the possibility of a fire is low. OH, NO SMOKING!!!! You may want to have a can or something to catch any fuel that squirts out or leaks out while doing the above adjustment.

Once you have established that you have fuel from the pump and the float is adjusted properly, ignition is good, the engine should start. If not, come back and explain how far you got.

Good luck,

>-

I had the same prob when i replaced the electrical pump the PO had on mine with a mechanical. Are you sure you have the gas lines hooked up correctly at the pump, inlet and outlet? The pump for mine wasn't labeled (460) and the way we first had it was actually backwards. Since it didn't have a mech on it b4 I didn't have anything to go off of. You can also run an airhose into your gas filler neck with a rag over it to push the fuel from the tank up to your pump with the gas line disconnected to rule out any blockages. I had to prime mine a couple times to get the gas from the pump to the carb and after that it has worked great. If you haven't already buy an inline fuel filter and put between the carb and pump so you can get a visual on the gas flow. I had nothing but problems with the electrical pump.

Thanks for the input guys, the problem is not gonna have anything to do with the carb. The problem is before the carb, I took the fuel line off before and checked it. I did use a factory replacement mechanical fuel pump, so there's nothing electrical. I also took off the fuel filter and turned the motor over without the lines hooked up but still nothing. the truck was running fine right before I took off the carb so I don't see how any lines would be stopped up. Is there possibly another in-line filter under the truck I haven't come across yet?

Run a short piece of rubber gas line into a small gas can and run it to your fuel pump and see if it will run that way. Try to keep the tank at the same height or slightly higher than the tank on your Bronco. It doesn't make alot of sense that it ran before and not now.

Hey how long was it sitting with the line disconnected?It might just have to be cranked long enough to re-prime the pump.I cant see any other thing but that causing this problem.Try cranking it longer itll have to eventually pump some gas.

I believe I am gonna have to go with Sea Bronco on this one. With the jets screwed in all the way and the floats not set it won,t get gas. ALSO ,THE DEAL OF air-ing up the tank.(haha) Yes, I tried it this year to see if I could get gas to go through the line and I thought the tank was gonna blow up.(haha) Scared the **** out of me.Oh, I had even tried a new pump and still no gas---------then I compared it to my OLD PUMP------the clerk gave me a BIG BLOCK PUMP------FOR MY SMALL BLOCK.------So if you had made all the correct carb adjustments and put on a NEW PUMP---DOUBLE CHECK TO SEE IF YOU WERE SOLD THE CORRECT PUMP AND LOOK ON THE PUMP BEFORE YOU PUT IT ON --TO MAKE SURE YOU PUT THE CORRECT LINES IN THE CORRECT PLACE-------I--STANDS FOR INLET--GAS TANK SIDE AND OUTLET GOES TO THE CARB.-------The fuel pump on a 351 or 400 are the same--bolt patter-----on the small and big blocks they are the same pattern-but the flang that rides on the cam are different.

Ok, although all of this info is definately valid the main concern is the fact that there is not any fuel comming from the pump to the carb. First check and insure the line comming from the tank has fuel, there are a number of ways to get this done i just put a long piece of fuel line on the metal line and attempt to siphon the fuel out, its a good idea to have some water and some clean rags handy cause even the most careful one will get a mouthfull of gas sometime. once you have verified that you have fuel TO the pump connect the fuel line to the INLET/suction side of the pump now disconnect the fuel line at the carb and using a bottle can or long hose and bucket to catch the fuel spin the engine over for about 30 seconds this should be enough time to get the fuel from the pump to the carb end of the fuel line. If you have proven that 1 you have fuel TO the pump 2 you have the line connected to the INLET/suction of the pump (the fuel pump on my truck cant be hooked up wrong due to the connectors being different) you should have fuel to the carb hook it up and run to adjust the carb or you have NO fuel this would indicate a problem with the pump and as mentioned before you need to verify you have the correct pump installed correctly.

Elmo said:

Ok, although all of this info is definately valid the main concern is the fact that there is not any fuel comming from the pump to the carb. First check and insure the line comming from the tank has fuel, there are a number of ways to get this done i just put a long piece of fuel line on the metal line and attempt to siphon the fuel out, its a good idea to have some water and some clean rags handy cause even the most careful one will get a mouthfull of gas sometime. once you have verified that you have fuel TO the pump connect the fuel line to the INLET/suction side of the pump now disconnect the fuel line at the carb and using a bottle can or long hose and bucket to catch the fuel spin the engine over for about 30 seconds this should be enough time to get the fuel from the pump to the carb end of the fuel line. If you have proven that 1 you have fuel TO the pump 2 you have the line connected to the INLET/suction of the pump (the fuel pump on my truck cant be hooked up wrong due to the connectors being different) you should have fuel to the carb hook it up and run to adjust the carb or you have NO fuel this would indicate a problem with the pump and as mentioned before you need to verify you have the correct pump installed correctly.

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I have to agree 100%

There was never an inline filter on the frame from the factory, however many people put them in. Check to see, one of my rigs had that dinky little one that threads into the carb, hose clamped inline. :huh: Took it out and problem fixed.