Broken hearted kid and fuel system

[DoubleDingo]

That makes sense. As many times as we've dropped it and put it back, we can do it with our eyes closed. thanks for the insight. You just saved us many hours of frustration and him cussing. lol

Cussing = Bonding

 

[JamesSam]

@medic503 and @jlynn79
If you get the truck running are you planning to cruise to the C10 Fall Revival this weekend? I see y'all are in Roanoke Rapids.

 

[Dryriver1]

jlynn79 said:
"When we connect the fuel pump directly to a gas tank it runs fine. The problem comes when we connect it back to the factory fuel lines. As soon as we do, the truck cuts off and will not run. It will start and idle but that's it. As soon as we hit the throttle, it just cuts off. However, when it is connected to the gas can, it runs and throttles fine."

@jlynn79 Welcome to the GMSB from west Texas!

I have quoted you up there and I would like to ask the GMSB Buddies this question.

"It will start and idle but that's it. As soon as we hit the throttle, it just cuts off. However, when it is connected to the gas can, it runs and throttles fine."
Could it be that there might be a cracked rubber hose that as soon as there is more need for fuel (more throttle) it is sucking in more air than fuel therefore causes the truck to cut off?

What do you guys think?
Please advise.

R.
Dryriver1

 

[Ricko1966]

Some of what you're saying doesn't make sense. If you're putting the line to the carbureator in a bottle of gas that makes no sense because the carbureator will not draw fuel on its own. Are you putting this bottle on the inlet side of the pump and it runs until the bottle is empty? If that's the case everything from the pump forward including the cam and pushrod are not the problem. If not put a can of gas with a hose in it on the inlet side of the pump,see if it runs.

 

[Ricko1966]

If it runs on gas supplied at the pump inlet put a piece of hose on the frame line and blow through it. Can you blow through it? Is it restricted,does the fuel in the tank bubble? If no disconnect the outlet from the fuel switch valve,now blow through the line. Is it clear now blow through the valve is it clear? Blow thorough to the tank is it clear? Does fuel bubble. Answer those questions and we can figure this out. If #64 passed then we need to figure out which of these doesn't pass. And fuel bubbling in the tank is important.

 

[medic503]

Ok, so we didn’t make it Friday. James has walking pneumonia and double ear infection so he’s been taking it easy. But, he was out of school today and did all his chores like I asked so we went and worked in the truck. Here’s what we did and what we found. We dropped the tank rather than going from the top.

Fuel line kinked between the tank and the selector valve. Unkinked it and tried and still no fuel to carb.

All connections checked and tightened.

Realized I didn’t have it connected directly to the tank so disconnected and reconnected directly to the tank. Still no fuel to the carb.

Blew in short fuel line and heard bubbles. Disconnected fuel supply line from the bottom of fuel pump and blew. Heard bubbles. Took a large syringe and sucked from the line and drew up fuel.

Blew from the carb side of the pump and heard bubbles. Used syringe but couldn’t draw up fuel.

When we put the carb supply line in a bottle of fuel it blows bubbles but will not pump anything out.

When starting we primed the carb and it ran fine til the bit of fuel ran out. Then cut off and wouldn’t start. Still not pumping any fuel.

So, we have fuel coming from the tank to the bottom of the fuel pump. If we take the lines off the fuel pump (carb side) and start it with an auxiliary tank, it runs fine. So the issue we have found is the fuel pump. This is the third one we have bought so it’s getting really annoying. I can’t understand how it can blow air matching the turning of the engine but nothing comes out. There’s no way the lines are crossed because they’re two different sizes and one won’t fit the other.

I read that the fuel pump push rod can wear out and that it could be the problem. When we put the most recent fuel pump on I checked and there was a push rod there. It was in some really thick grease and I tried to pull it out (kinda) but it wouldn’t budge. It moved up and down fine but wouldn’t come out. So, we’re gonna replace it. Do yall think we should buy a 4th fuel pump? Any other suggestions? Lol. Those are the only two things left that I can find. We’re gonna try to go back one day this week and try again. Our spirits are a bit higher because we have made more progress today than we have in months. Thank you all for your help and suggestions. We are almost there.

 

[squaredeal91]

With lines hooked up to fuel pump.(pump off of block) By hand push the plunger rod to simulate cam pushrod. See how that works.

 

[Travlr]

Ok, so we didn’t make it Friday. James has walking pneumonia and double ear infection so he’s been taking it easy. But, he was out of school today and did all his chores like I asked so we went and worked in the truck. Here’s what we did and what we found. We dropped the tank rather than going from the top.

Fuel line kinked between the tank and the selector valve. Unkinked it and tried and still no fuel to carb.

All connections checked and tightened.

Realized I didn’t have it connected directly to the tank so disconnected and reconnected directly to the tank. Still no fuel to the carb.

Blew in short fuel line and heard bubbles. Disconnected fuel supply line from the bottom of fuel pump and blew. Heard bubbles. Took a large syringe and sucked from the line and drew up fuel.

Blew from the carb side of the pump and heard bubbles. Used syringe but couldn’t draw up fuel.

When we put the carb supply line in a bottle of fuel it blows bubbles but will not pump anything out.

When starting we primed the carb and it ran fine til the bit of fuel ran out. Then cut off and wouldn’t start. Still not pumping any fuel.

So, we have fuel coming from the tank to the bottom of the fuel pump. If we take the lines off the fuel pump (carb side) and start it with an auxiliary tank, it runs fine. So the issue we have found is the fuel pump. This is the third one we have bought so it’s getting really annoying. I can’t understand how it can blow air matching the turning of the engine but nothing comes out. There’s no way the lines are crossed because they’re two different sizes and one won’t fit the other.

I read that the fuel pump push rod can wear out and that it could be the problem. When we put the most recent fuel pump on I checked and there was a push rod there. It was in some really thick grease and I tried to pull it out (kinda) but it wouldn’t budge. It moved up and down fine but wouldn’t come out. So, we’re gonna replace it. Do yall think we should buy a 4th fuel pump? Any other suggestions? Lol. Those are the only two things left that I can find. We’re gonna try to go back one day this week and try again. Our spirits are a bit higher because we have made more progress today than we have in months. Thank you all for your help and suggestions. We are almost there.

If you are sure that the lines are clear and the pump is not sending fuel... it is likely that the cam shaft lobe is worn out. You can try a new shaft, or plumb in an electric pump.

 

[Turbo4whl]

I must ask, when you are installing the fuel pump, do you push the push rod up and make sure the the pump arm is under it? Some times packing with grease will hold it up when you install the pump. You can also reach in with a thin screwdriver and push it up when installing the pump.

Earlier in this thread someone asked if you checked the cam lobe. Did you do that? They explained how to do it.

 

[jlynn79]

I must have missed the part about checking the cam lobe. I have not checked that. I will go back and look at that and check it when we go back. I will also see if I can actuate it manually and see what happens. When we installed this fuel pump, I made sure that the rod was held up and on top of the fuel pump arm as best I could. Each time we have removed the fuel pump, we can see where it pushes on the back of it.

I am sure all lines are clear. We dropped the tank and ran a single rubber fuel line from the top of the tank to the fuel pump and connections were checked and rechecked. We also blew air through it and used a syringe to suck fuel back up with no issues. It's only a problem when it hits the the fuel pump.

If there is air coming from the fuel line that is in sequence with the engine running, could the cam lobe still be messed up?

 

[Turbo4whl]

To check the cam lobe, with the fuel pump removed hold the push rod up with you finger. Have jr. crank the engine over. You should feel the rod pushing down a least 3/8 to 1/2 inch.

Disconnect the battery lead to the distributor first, so the engine will not fire. If the rod barely moves, the cam lobe is worn.

 

[jlynn79]

Sorry, the truck is stored about 45 minutes away from where we live at. It's at his moms house. So we don't get to work on it often. Mainly weekends. But we're getting there as much as we can. We will be there again before the end of this week though. I just really feel were right there at it.

 

[jlynn79]

To check the cam lobe, with the fuel pump removed hold the push rod up with you finger. Have jr. crank the engine over. You should feel the rod pushing down a least 3/8 to 1/2 inch.

Disconnect the battery lead to the distributor first, so the engine will not fire. If the rod barely moves, the cam lobe is worn.

Okie dokie. We will check that first when we go back. If it is working, and there is still no fuel being pumped, could it be that we bought yet another dead fuel pump?

 

[Poodlehead]

Hopefully your fuel pumps come with a warranty so at least you don't have to pay for one each time...

Another thought is IF you all know of someone with a good working FP, try swapping what you think is bad with a known good pump and see what happens on both trucks. I realize you need a real good friend that would help you accomplish that task, but that would solve another piece of the puzzle...

 

[Hotrod46]

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.

This would seem to indicate that you can forget about the cam, pushrod and pump. If the pump will suck out of the bottle, then it is working well enough for now. If you don't have the pump trying to suck out of the bottle. You should. This will prove the pump works.

When trying to diagnose an issue like this you have to isolate and verify each part. Too many variables if you don't.

A couple of things to check.

Did a hose get pinched when the tank was being replaced. I have had that happen. They can get between the tank frame bracket and the frame.

If the truck has been sitting for seven years, the metal line under the truck could have a hole rusted in it. This would prevent the pump from picking up much if any gas.

The vent or return line and fuel line could be switched at the sending unit. You could blow thorough and hear air in the tank, but there would be no gas for the pump to pick up.

I think the problem is definitely in the system from the tank to the pump. As suggested, bypass the selector valve. Make the system as simple as possible until you get the truck running.

If none of this helps. Run a temp hose from the hard line under the cab after the selector valve to a bottle or gas can. Prime the carb with a bottle, start the engine and see if it will pick up gas. This will prove the hardline.

All that's left if the truck runs this way is the tank and associated hoses.

Hope this helps.