Broken hearted kid and fuel system

[medic503]

Ok yall, Ive got a situation and I cannot figure it out. I am not a mechanic by no means but hoping someone here can point me in the right direction. My son was gifted a 1984 Chevy K10 with a 350 motor by his grandfather. For those that work at a parts store, yes its four wheel drive. It has the regular quadrajet carburetor on it. The problem is, we cannot get gas into the carburetor and I cannot figure out why. We have been working on this thing for months and each time we discover something new, he gets excited because we finally think we have found the problem. We fix the issue, and it still doesnt work. Last night we worked for three hours just to try to start it til the battery died. He just hung his head and started crying and its killing me. I love working with him on it to help him restore it but im also tired of throwing time and money at something and getting nowhere. Fuel is not getting into the carburetor and i cannot figure out why. His grandfather said it ran before, it just needed the carburetor cleaned because it had been sitting for about 7 years and the fuel tank selector switch needed replacing. Here is a list of everything we have done.

- When he first got the truck, the carburetor was taken off and given to a mechanic to clean. He cleaned it and did a few other things to it and we got it back. Wouldn't work.
- bought and installed a new fuel tank selector switch, didnt work.
- dropped the passengers side tank and cleaned it out, put in a new fuel sending unit. didnt work
- Bought a new mechanical fuel pump for it and put it on, it ran for 4 minutes and then didnt work. There was fuel in the pump when we removed it.
- Bought new spark plugs and wires, didnt work.
- Found out my son didnt get all of the water out of the gas tank before the tank was put back on so we dropped it again cleaned it again and got ALL water out. It was dry as a bone. Replaced everything and filled with gas, ran for 2 minutes, wouldnt start.
- Bought a new mechanical fuel pump just in case water messed up the first one, still didnt work. There was a little fuel in the pump when I removed it.
- Ran a line from the carb to a bottle of fuel, works fine.
- Blew air through all the lines and there was no fuel anywhere. I couldn't hear any leaks, but there was no fuel when I moved my finger off the hose and I felt the air.
- just in case, all rubber fuel lines were replaced. still didnt work.
- Tried the bottle thing again, ran fine. However, no fuel in the lines that I could see.
- Replaced the tank selector valve, no gas anywhere, still wouldnt start
- Checked the rotor cap and its clean and replaced just as it was. Ran fine off a bottle.
- Found out about a push rod that makes the fuel pump work (had never heard of this before) but went and bought a new one. When we pulled the fuel pump off, I there was one already in there and I could tell that at the bottom of the arm on the back where the rod had been hitting it at the tip. So Im assuming that is working properly.
- Last night we replaced the metal fuel line with a rubber one on the front of the motor. That is literally the only part of the fuel system left that had no been replaced (except for the metal lines) on the passengers side. Still wont start.

Just for ***** and giggles last night, I read about priming the carb. We poured a total of an entire 20 ounce bottle of gas down the carb choke side and it would run until the gas was burned and then cut off. We tried starting it until the battery died and when it died, so did our ambition.

So, what else could it be that is causing the fuel not to get into the carburetor. I did pull the fuel filter last night and it was pretty clean, there were some black dust looking things on it but otherwise it was clean. It had fuel on it but not as much as I imagined it should be. The check valve was installed on the nut side of the carb. Is that backwards? What am I missing? Just an FYI, all of the work was done on the passengers side. We have not touched the drivers side. We wanted to get one tank working and then focus on the other one. Could that be the problem? I am so tired of throwing time and money into this thing and not getting any results. I only have 3 months until he gets his license and I dont have a lot of time to work on it. Someone please help!!!!

 

[DoubleDingo]

It sounds like you have done everything that I can think of. The only that came to mind was the fuel lines to the valve. Were matched up to the correct ports? The valve on mine has a bunch of ports and I could see getting hoses hooked up wrong if one wasn't careful when replacing them. The other thing comes to mind is maybe a kinked hose between the sending unit and valve. Or maybe the sending unit tube and or sock is plugged.

 

[Paladin]

Once again, a easily solved problem. Your 5th sentence says it all. Get a HOLLEY!!!!

 

[rusted nuts]

Sounds like the fillter in the carb is pluged if it has one , or the needle valve is stuck shut, try tapping carb with small hammer where fuel line goes in

 

[medic503]

It sounds like you have done everything that I can think of. The only that came to mind was the fuel lines to the valve. Were matched up to the correct ports? The valve on mine has a bunch of ports and I could see getting hoses hooked up wrong if one wasn't careful when replacing them. The other thing comes to mind is maybe a kinked hose between the sending unit and valve. Or maybe the sending unit tube and or sock is plugged.

Thank you for the reply. The valve on mine has 6 ports. 4 on one side and 2 on the other. I took them off and replaced one at the time with the same size hose to make sure I didn’t get anything crossed up. Looked all over to make sure and there were no kinks anywhere that I could see. Last I looked sock was just as white as the day I bought it. Guess I can drop the tank again and check and see.

 

[medic503]

Sounds like the fillter in the carb is pluged if it has one , or the needle valve is stuck shut, try tapping carb with small hammer where fuel line goes in

I’ll get a new filter and see if that changes anything. Would cleaning the carb fix the needle and seat issue? Could it mess up after it was cleaned?

 

[CountKrunk]

If you hook up a 5g gas tank, and bypass everything else. Does that work?

 

[medic503]

If you hook up a 5g gas tank, and bypass everything else. Does that work?

Yes. I can put the carb supply line in a bottle and it runs fine. But when I connect it back to the fuel pump, it won’t do anything.

 

[squaredeal91]

Not sure what to add because just about everything has been discussed lol. I have been there before and sounds allot like the problems I had with my first truck, also at age 14. If you do end up dropping tank be sure it can't be Sucking air at any hose connections. Also check everything els to be sure hose clamps are tight. Just last month I was working on that truck again and removed the fuel pump to find one of the hoses I just put on was Sucking air and not priming. I double checked and tightened all connections and got it to prime and start.
I hope you get some results soon, I know how frustrating this can be.

 

[squaredeal91]

And maybe if still nowhere try bypassing selector valve and run it straight from tank to eliminate that as a possible cause.

 

[CountKrunk]

Yes ive read the dual tanks can be a big problem. I assume on my truck it was a big problem, as the passenger side tank was ripped out at some point. Everything else seems stock. Have you tried operating from the driver side tank?

 

[Grit dog]

Yes. I can put the carb supply line in a bottle and it runs fine. But when I connect it back to the fuel pump, it won’t do anything.

Ok, cheer up and tell your kid he’s about to have the baddest ass truck in class!
From what I’ve read, carb, filter in carb and engine are fine. It runs off a bottle. Great news. It runs. But how?
Your description is lacking. Are you letting the fuel pump suck out of the bottle or just bottle feeding the carb?
If the latter, stop and do the same thing but let the fuel pump pull gas out of the jug. If it won’t pull gas out of a can then the problem is the fuel pump or surrounding the fuel pump. Options:
-3 bad fuel pumps, the original and 2 replacements. Not too likely but possible.
-wrong pump. I “think” there were a couple different types but I’ll let someone else confirm whether I’m tracking here or not.
-Improper install, but you said you can see where the pushrod was hitting the pump arm properly so likely not the case.
-Wiped cam lobe. A real possibility on an old unknown engine. May look like the pump is working but not providing enough lift to stroke the pump arm enough. You can diagnose the last 3 by disconnecting the line to the carb and see if it pumps fuel well, just cranking the engine over.
-Lines hoses, tank selector valve, sending unit etc if you can disconnect feed line into the pump and blow bubbles back into the appropriate tank then that’s not the problem.
-Water? Could be some residual somewhere. Water is a bitch to get out. But if it’s pumping out of the pump then there’s nothing. Wrong with the “system” and you could investigate water but likely past that.

Sounds like you’re not getting fuel to push through the fuel pump.

 

[Grit dog]

One cheap easy way to bypass the mechanical pump is get a cheap Amazon $25 electric fuel pump. Bypass the mech pump and use it. If it pulls gas from the tank and sends it to the carb which it should, it eliminates all other possibilities and it’s something with the fuel pump, cam lobe or pump pushrod.
If you find it’s the cam lobe you can use an electric fuel pump but not up in the engine bay. I and others can help you through how to do that properly. And not too expensive. Way cheaper than a cam.

 

[medic503]

Ok, cheer up and tell your kid he’s about to have the baddest ass truck in class!
From what I’ve read, carb, filter in carb and engine are fine. It runs off a bottle. Great news. It runs. But how?
Your description is lacking. Are you letting the fuel pump suck out of the bottle or just bottle feeding the carb?
If the latter, stop and do the same thing but let the fuel pump pull gas out of the jug. If it won’t pull gas out of a can then the problem is the fuel pump or surrounding the fuel pump. Options:
-3 bad fuel pumps, the original and 2 replacements. Not too likely but possible.
-wrong pump. I “think” there were a couple different types but I’ll let someone else confirm whether I’m tracking here or not.
-Improper install, but you said you can see where the pushrod was hitting the pump arm properly so likely not the case.
-Wiped cam lobe. A real possibility on an old unknown engine. May look like the pump is working but not providing enough lift to stroke the pump arm enough. You can diagnose the last 3 by disconnecting the line to the carb and see if it pumps fuel well, just cranking the engine over.
-Lines hoses, tank selector valve, sending unit etc if you can disconnect feed line into the pump and blow bubbles back into the appropriate tank then that’s not the problem.
-Water? Could be some residual somewhere. Water is a bitch to get out. But if it’s pumping out of the pump then there’s nothing. Wrong with the “system” and you could investigate water but likely past that.

Sounds like you’re not getting fuel to push through the fuel pump.

Gotcha. So we replaced the fuel pump with the exact one that was in it before. There are two types for his truck, one short and one tall. It had the short one on it.

We can put the line from the fuel pump to the carb in a bottle of gas and it will run off that gas til empty. It will also run if we pour gas down the choke side of the carb and soon as it’s gone, it stops. It seems like it’s surrounding the fuel pump. When it’s taken out of the equation, everything works.

 

[CountKrunk]

+1 to an electric fuel pump bypassing it all.

Different but similar, i have a 91 craftsman lawnmower. Carb on it. It’s bypassing the mechanical fuel pump with a little electric one with no problems.