I feel like I messed up bad - new to me truck issues after purchase

[IT Cowboy]

I feel like I done messed up A A Ron

I bought a 72 C10 heritage edition today with a 402. The truck is nice, no rust I could see anywhere and it ran and drove great on the test drive. I didn't take it above 40 on the test drive though.

It was running fine on the freeway on the way home and then it started sputtering and surging after about 15 min on the road. It would act like it wasnt getting enough fuel and surge in rpms and power. If I put it in neutral going down the road and revved it is would rev ok. If I stopped and left it running for 5-10 minutes and then continued it would run ok again for the first 5 minutes or so and the start surging and sputtering again. If I was idling it didn't surge and if I shut it off it would start up right away no problem then idle fine. There is a mountain pass on the way home so I pulled over and found a mechanic shop close by and left it there for them to look at. I might need to have it towed to a classic car mechanic to have it diagnosed

It was not too warm outside today and the heat gauge stayed about 1/2 while moving. I am disappointed with myself and feel like a kid with a new broke toy. I keep telling myself it probably isnt anything to serious or expensive.

So far I am thinking it might be one of these things

fuel tank vent clogged

fuel pump

fuel pump pressure tooo high

distributor

timing

coil

points

plug wires . coil wire

carb body valve (name?)

clogged fuel filter

vacuum leak

manifold gasket

Any ideas on what it could be or things to check out

[57taskforce]

What is exactly did the seller say a heritage edition was? I don’t think that’s a real thing. As for the way it’s running I’d check for vacuum leaks and look over the fuel system first.

[truckster]

I'm guessing it's the fuel sock. It's on the end of the pickup tube, and after so many years it's rotten. It gets sucked in while you're running down the road. When you stop or reduce the demand it lets fuel flow.

It's actually a pretty common problem on older vehicles. The fix is to remove the sending unit, pull off all remnants of the sock, and replace the fuel filter.

[IT Cowboy]

Originally Posted by truckster

I'm guessing it's the fuel sock. It's on the end of the pickup tube, and after so many years it's rotten. It gets sucked in while you're running down the road. When you stop or reduce the demand it lets fuel flow.

It's actually a pretty common problem on older vehicles. The fix is to remove the sending unit, pull off all remnants of the sock, and replace the fuel filter.

Is the sock on the end of the sending unit and do I just remove it from there and not replace it and just replace the one on the carb inlet.

Could I just replace it with an inline filter somewhere?

[57taskforce]

If it is indeed the strainer on the sending unit, you just pull what’s left of the old one off and press the new one on. Definitely change the filter in the quadrajet inlet if present and any other filters that might have been added in the last 50+ years. Also a really good time to replace the sending unit gasket on the tank and rubber fuel lines inside the cab that attach the metal lines to the sending unit. Here is an example of the Strainer.
https://classicparts.com/1967-87-gas...ock-filter-3-8

[IT Cowboy]

More fuel demand causing the fuel filter issue? When I started down the road again it would be ok for a bit longer if I was under 40 mph. If I tried to speed up to 50+ right away then it would start acting up sooner. That maybe equates to fuel demand issue?

[LockDoc]

Originally Posted by IT Cowboy

Is the sock on the end of the sending unit and do I just remove it from there and not replace it and just replace the one on the carb inlet.

If it is the pickup tube sock you will probably have remnants of it in the fuel tank. I would not run it without the sock filter. You may have to disconnect the fuel line at the pump, and at the sender and blow some air through the line to clear any debris out of it. Blow through the line at the tank end but make sure the line is disconnected at the pump. Yes, replace the carb filter too. once you remove the sending unit it will be pretty obvious if the filter is bad.....

https://classicparts.com/1967-87-gas...ock-filter-3-8

Edit: I didn't refresh the thread before I typed my reply so it mirrors the reply by 57taskforce... I guess great minds think alike...
.

[57taskforce]

Originally Posted by IT Cowboy

More fuel demand causing the fuel filter issue? When I started down the road again it would be ok for a bit longer if I was under 40 mph. If I tried to speed up to 50+ right away then it would start acting up sooner. That maybe equates to fuel demand issue?

Yes, that’s exactly why I said to look for vacuum leaks(cheap and easy to find with carb cleaner), and really go over the fuel system. A vacuum leak leans the fuel mixture out, just like not enough fuel running thru the system, or a gummed up carb will do. I’ve seen the strainer get gummed up with old gas before, while not disintegrated, or falling apart it still had to be replaced.

[IT Cowboy]

With the age I wonder if I should just replace the whole tank and sending unit, or is that overkill?

Could I just put a fuel filter on the outlet from the tank

I will probably ask the shop to look at the sock and carb filter and replace it to get me going and then I can replace the tank and sending unit myself when I get it home

[LockDoc]

Originally Posted by IT Cowboy

With the age I wonder if I should just replace the whole tank and sending unit, or is that overkill?

Could I just put a fuel filter on the outlet from the tank

I will probably ask the shop to look at the sock and carb filter and replace it to get me going and then I can replace the tank and sending unit myself when I get it home

I remove the tanks, empty out as much of the gas as I can, and take them to the car wash and pressure wash them with soap, then a good rinse with clear water. I then take them home and vacuum out as much of the water as I can with the shop vac and put a heat gun in the sender/fill holes and run it until the tank is dry on the inside..... Works good. Then it is easy to tell if there is any heavy rust in them.
.

[IT Cowboy]

My wife behind me thought it smelled like fuel and was running rich? Possible getting too much fuel.

I should have mention this too but I touched the coil to dist. cable while running and got a shock. Isnt it supposed to be insulated and that not happen? I was checking the plug wires were attached tight. The truck would sputter and backfire while under load too. - bad ignition coil and wires?

[LockDoc]

Originally Posted by IT Cowboy

My wife behind me thought it smelled like fuel and was running rich? Possible getting too much fuel.

I should have mention this too but I touched the coil to dist. cable while running and got a shock. Isnt it supposed to be insulated and that not happen? I was checking the plug wires were attached tight.

There is a lot of juice right there so if you are grounded good it will zap you through the coil wire.....

[57taskforce]

Originally Posted by IT Cowboy

My wife behind me thought it smelled like fuel and was running rich? Possible getting too much fuel.

I should have mention this too but I touched the coil to dist. cable while running and got a shock. Isnt it supposed to be insulated and that not happen? I was checking the plug wires were attached tight. The truck would sputter and backfire while under load too. - bad ignition coil and wires?

I bet a doughnut it’s running lean, backfires under load is a tell tale sign.

[IT Cowboy]

Originally Posted by 57taskforce

I bet a doughnut it’s running lean, backfires under load is a tell tale sign.

LIKE - this makes me feel a bit better and it might be an easy cheap fix.

I might just have a new HEI dist. and ignition sytem put in since they are fairly cheap. I am going to put on new plug wires with the ceramic boots and a fresh set of plugs.

It was also getting terrible fuel mileage.

[KQQL IT]

When I brought old blue home.
Ran like crap.
Hei cap
Rotor looked even worse

[dmjlambert]

Congratulations on your purchase. Don't panic. Sounds like you got the right truck. It may need some minor fixing, welcome to the tinkering. I suggest ask here on the forum lots of questions as they come up, and post lots of pictures of what you have and especially what you're asking questions about, and the fine folks here will give plenty of info to help you out and make recommendations if you want to hear them.

[IT Cowboy]

[IT Cowboy]

Originally Posted by dmjlambert

Congratulations on your purchase. Don't panic. Sounds like you got the right truck. It may need some minor fixing, welcome to the tinkering. I suggest ask here on the forum lots of questions as they come up, and post lots of pictures of what you have and especially what you're asking questions about, and the fine folks here will give plenty of info to help you out and make recommendations if you want to hear them.

Thanks for the encouraging words. I did panic a bit and it was mostly because of lack of sleep and just spending a crap ton of money. My self-calming pice of mind is that these motors are fairly simple mechanical air pumps and there is not a lot of things to go wrong and it isn't anything major. In the IT world I am used to digital reliability not analog. Leaving a new purchase 100 miles away was tough too as I was planning on polishing it out tomorrow. Patience was never my strong point. It will all be ok and was probably a blessing that it acted up on me before I went up the pass.

[57taskforce]

I see you’ve got the NL2 aux fuel tank. You need to verify which tank it is pulling from. There should be a manual valve on the drivers floor near the bottom of the door, kinda between the door and the side of the seat. The valve will allow you to select between the cab tank and the tank below the bed. You won’t be able to properly diagnose this until you find out which tank it running on.

[geezer#99]

In your list of things to check you left off the obvious one to me.
Considering your elevation and ambient temperature it could just be carb icing.

I’ve had that happen. a few times.
Worst time I had an actual ball of ice around the carb.


https://en.wikipedia.org/wiki/Carburetor_icing

[IT Cowboy]

Originally Posted by 57taskforce

I see you’ve got the NL2 aux fuel tank. You need to verify which tank it is pulling from. There should be a manual valve on the drivers floor near the bottom of the door, kinda between the door and the side of the seat. The valve will allow you to select between the cab tank and the tank below the bed. You won’t be able to properly diagnose this until you find out which tank it running on.

The 2nd tank was removed many years ago and the fill cap is just there for show.

[HO455]

Congratulations on your new truck! She a looker! We'll be expecting more pictures of it.

Here is a link to a thread on fuel tanks. Post 20 has a good run down on the fuel tank.

https://67-72chevytrucks.com/vboard/...d.php?t=732963