Fueling Issues

[ThePunisher]

So I've got a fueling problem I need help with.

1974 CJ5 with a AMC 304 that was sitting for approximately 5 years. I did the usual tune up items, plugs, wires, belts, fluids etc. Cleaned out the old tank, filled it with a few gallons and tried starting it. No fuel.

I figured it was the pump from sitting for so long. Replaced that today and still no fuel. So I blew out the lines and they were clear as a whistle. Tried pulling the line from the pump to the carb at the bottom of the pump, still no fuel. Tried putting a different line from the pump intake to a gallon of gas that I sat on the ground and then on the fender, still no fuel.

Pulled the pump, it had marks on it like the cam fuel lobe is hitting it but still no fuel.

Any ideas?

Also thought about ditching the mechanical pump and going electric but I'm not sure if that will fully solve the issue or not.

Suggestions?

 

[Torxhead]

Maybe try putting a little gas down into the carb to get the pump going by starting the engine or filling up the float bowl. If you were to siphon some fuel up to the pump by removing the inlet hose that could speed things along by getting some of the air out of the line. I would advise continuing with using the mechanical pump also.

 

[ThePunisher]

I already tried the siphoning. Nothing happened. The pump was dry

 

[tarry99]

I already tried the siphoning. Nothing happened. The pump was dry

So you have checked the lines from the pump to the tank and from the pump to the carb? Correct?
Have you tried leaving the line off to the carb and turn the motor over?
Take the gas cap off in case there is no vent and your creating a vacuum.

 

[ThePunisher]

So you have checked the lines from the pump to the tank and from the pump to the carb? Correct?
Have you tried leaving the line off to the carb and turn the motor over?
Take the gas cap off in case there is no vent and your creating a vacuum.

Yeah cleared out the lines with an air hose. They are all good.

I just don't know how to create suction from the pump to the tank.

 

[tarry99]

Yeah cleared out the lines with an air hose. They are all good.

I just don't know how to create suction from the pump to the tank.

I think there is an obstruction..............Did you try taking the gas cap off and try getting fuel forward.......my point is if the vent at the tank is plugged it will create a vacuum while the pump is trying to suck. Could also be an air leak back there at the tank that's allowing it to suck air.
Do you have a complete smog system with the extra line at the fill?
If you were to blow air from the pump intake back to the tank will you hear bubbles?

 

[ThePunisher]

I think there is an obstruction..............Did you try taking the gas cap off and try getting fuel forward.......my point is if the vent at the tank is plugged it will create a vacuum while the pump is trying to suck. Could also be an air leak back there at the tank that's allowing it to suck air.
Do you have a complete smog system with the extra line at the fill?
If you were to blow air from the pump intake back to the tank will you hear bubbles?

No smog equipment thankfully. I didn't try blowing air back to the tank. Going to try a few more of those things on Wednesday.

 

[ThePunisher]

Replaced the sending unit and got fuel! Now I just need to fiddle with my rebuilt 2100 to get her running. She wants to start but too much fuel

 

[tarry99]

Replaced the sending unit and got fuel! Now I just need to fiddle with my rebuilt 2100 to get her running. She wants to start but too much fuel

Replaced the sending unit? ....................at the top of the tank? So was it plugged there?

You now probably have a bunch of debris in the Carb. that got sucked up in the line.
You may have to take it apart and clean the needle and seat and the jets.

 

[ThePunisher]

Replaced the sending unit? ....................at the top of the tank? So was it plugged there?

You now probably have a bunch of debris in the Carb. that got sucked up in the line.
You may have to take it apart and clean the needle and seat and the jets.

Yeah I replaced the sending united. Re-blew out all of the lines and cranked it until it spewed fuel out of the line before the carb. Then I attached it to the old carb with the busted choke and tried starting it. It tried but wouldn't. So I slapped on the rebuilt 2100 and tried again and got closer but ran out of light. Made sure I cleared the lines and ensured the fuel was clean before I swapped carbs

 

[tarry99]

Yeah I replaced the sending united. Re-blew out all of the lines and cranked it until it spewed fuel out of the line before the carb. Then I attached it to the old carb with the busted choke and tried starting it. It tried but wouldn't. So I slapped on the rebuilt 2100 and tried again and got closer but ran out of light. Made sure I cleared the lines and ensured the fuel was clean before I swapped carbs

Have you checked your timing?
Are the plugs old?
Do you have too much fuel going in now? or not enough?

 

[ThePunisher]

Going to mess with all of that on Sunday. I wanted to see if it would fire on the old plugs and it did but it wouldn't stay running. I have new plugs to install and I already installed a new coil, cap, wires and rotor. So now I need to mess with the timing and air/fuel mixture

Do you recommend any certain order of doing this? Like go all the way lean or rich and work your way back? Same with timing, any suggestions? I'm used to PCM controlled vehicles and computer tuning for mods lol

 

[tarry99]

Going to mess with all of that on Sunday. I wanted to see if it would fire on the old plugs and it did but it wouldn't stay running. I have new plugs to install and I already installed a new coil, cap, wires and rotor. So now I need to mess with the timing and air/fuel mixture

Do you recommend any certain order of doing this? Like go all the way lean or rich and work your way back? Same with timing, any suggestions? I'm used to PCM controlled vehicles and computer tuning for mods lol

So if you did not have a Laptop with you I assume you would be hitchhiking? (LOL) Thats a joke!
Internal combustion Engines are pretty simple.......For Timing pull all your spark plugs and if you have a manual switch that you can bump your starter over with rotate the engine slowly with the tip of your finger in the spark hole for number 1 cylinder, slowly..............when it gets to TDC your finger will get pushed off by air from the Compression stroke. The key is to roll up on it slowly. Stop... and check your timing mark on the front cover and pulley.........it should be a few degrees before or after the mark ......pull your Distributor cap and see where the rotor is pointing...........if the rotor is pointing to the contact tip on your cap where #1 is then we can assume that your engine is still in time. If its way off then mark that location and rotate the distributor closer to the point on the cap. A retarded motor will fire up much easier but will not RPM.......an advanced motor will crank over like its struggling.......The key here is just to get the motor running. Once running then put a timing light on it.
Don't mess with the Idle screws yet.........they should be about 1.5 turns out to start and by adjusting them your looking for maximum RPM via that adjustment prior to using the Idle screw adjustment that opens the throttle blade.

 

[ThePunisher]

Great. Thanks a lot man!

I've messed with plenty of them without pcms but only after they were running hahaha. Never had to adjust timing to get one to start. I figured I'd work my way backwards from TDC but wasn't sure if there were any other tricks to these motors. Also don't know diddly about carbs. I've only owned fuel injected motors before

 

[ThePunisher]

Got her to idle today. Turns out it's actually a 73, not a 74. Found that out by the wiring harness setup. It wasn't firing on all cylinders though, left the old plus in on purpose. Going to swap in new plugs and wires next week. Ran out of time today because I had to go to work. Good to know that it's closer and closer though!

 

[tarry99]

Got her to idle today. Turns out it's actually a 73, not a 74. Found that out by the wiring harness setup. It wasn't firing on all cylinders though, left the old plus in on purpose. Going to swap in new plugs and wires next week. Ran out of time today because I had to go to work. Good to know that it's closer and closer though!

Hey good for you.........sounds like your working through the little Issues you had, hopefully everything will work out.

 

[ThePunisher]

Hey good for you.........sounds like your working through the little Issues you had, hopefully everything will work out.

Hopefully. Still working through it slowly. Trying to get things wrapped up in the next month so I can take it hunting!

 

[tarry99]

Hopefully. Still working through it slowly. Trying to get things wrapped up in the next month so I can take it hunting!

Where you going Hunting?

 

[ThePunisher]

Where you going Hunting?

Property my family owns up north. About an hour north of Willits. B4 zone