No start - fuel issue?

[Hatchet54]

1977 K20 SBC, 4bbl carb, no crazy mods. 30gal saddle tanks, I only ever fill the driver side.

About 6 months ago, I was driving my truck up a long incline on the interstate and it experienced a surging/loss of power issue. It bucked and puttered like it was running out of gas. I was doing a lonnnng road trip and I had guessed I was getting close to empty (my fuel gauge had broken on the trip, which is important to this story). I kept it in 2nd gear and when I limped over the crest of the hill, power returned to normal. I got into town a mile later, filled the tank, and had no issues for another few months.

About a month ago, the truck died on me coming into the driveway of my home. Poured gas into the carb bowl and it would start, but refused to hold idle and would only run as long as the bowl stayed full. I did a simple diagnosis and decided to replace my mechanical fuel pump. The old pump was a cheap NAPA part from about 4-5 years ago, so it had lasted way longer than I thought it would. No problem. I replaced it with a Carter pump and the truck started in 5 seconds (before I did so, I added about 5 gallons of gas). Idled strong for several minutes and I drove it around the property in all gears. Seemed great.

Yesterday I go into town to get some groceries and after driving the truck for about an hour on the highway it suddenly begins surging again. Like before, this was on an uphill. I downshift and can get it to crawl for a while like last time, but then eventually it dies altogether and coasts to a stop on the shoulder. It started once more and idled for about 5 seconds, then died and would not start again. I had no choice but to get the truck towed. On the way back to my house I had the driver stop at the gas station and we filled it. It took about 23 gallons, so it was getting close to empty. However, with the full tank it still would not start.

I am going to diagnose what I can today, but at this point in the process I thought I should post and ask for some advice. Is it possible that a carter pump would go bad after less than 100 miles? Are my problems caused by running the tank too low? Or should I be looking elsewhere for the problem? I am assuming it is a simple fuel delivery issue, but I could be way off.

 

[Ricko1966]

Several things could be going on,trash in the tank prevent fuel flow.Fuel pump lobe on cam wiped out. Those are the first I would check. People are going to say oh it can't be the cam lobe or it wouldn't have run with the new,yes it can happen that is exactly what happened to my 85. No fuel put in a pump a month later no fuel,wow this is weird put in another new pump assuming I just got a bum,new pump. Nope fuel pump lobe was worn off the cam.

 

[Memaloose]

That's one of the first things I'd check too, trash or plugged fuel pick up in tanks then work my way forward.
I had an Olds where it would do the same thing, it was the mesh screen in the fuel pickup in the tank.

 

[PrairieDrifter]

Have you changed cap rotor and plugs any time recently? Check them if not.

 

[Buck69]

Fuel filter? Possibly the new pump increased the pressure enough to buy you a little more time?

 

[AyWoSch Motors]

Another thing to think about on top of what has already been suggested, is possibly a massive vacuum leak, and it's been tuned to run with it.

My 86 had a massive vacuum leak on the q-jet I had in it, I tuned it so it would run, and sounded pretty good, but I'd put 5 gallons in it, and itd make it down to the mail box and back about twice before it ran out of gas. Would throw 5 gallons gas in it every time I had to drive it, was absolutely plugging gas. Then I put a brand new edelbrock on it, and it runs perfectly now. I put 5 gallons of gas in it, and it's been on that 5 for a few months. Many trips to the mailbox and down to road, and using it to tow stuff, and show off etc.

Short version is, with the vacuum leak, it was chugging fuel, no vacuum leak, pretty good mileage.

 

[Hatchet54]

Thanks for all the replies guys. I haven't had a chance to look at the truck today but have been thinking about it all day.
Unfortunately, the biggest hurdle I have right now is my geographic location...I'm caretaking for a large ranch in remote New Mexico for the winter and have little to no tools or workspace, just whatever came with me in the truck toolbox and a dirt lot that gets hella windy. So depending on what it ends up being it might be in my best interest to just send it to a shop...

I'm really hoping not to have Ricko's problem of a worn cam...I imagine the only way to solve that would be replacing the cam entirely and that is certainly the last thing I want to be doing right now. I suppose there's no real way to tell if that's the case without opening everything up. The pushrod looked fine when I replaced the pump, for whatever that's worth.

Prairiedrifter no, I haven't looked at the plugs recently, although I did change out my distributor in the last year - I guess it could have gone out of time? I'll pull a plug and see if I'm getting spark. Although the truck will start and run with fuel in the carb.

Buck, the fuel filter was replaced along with my new fuel pump. I forgot to mention that.

As for the vacuum leak, it's certainly possible, although I was getting pretty consistently good MPG on my road trip before the problems started, so I doubt it.

First order when I get the chance is to pull the line off the fuel pump and see if I get any gas coming out. If not, I guess I'll plan on pulling out the sending unit and sock - if I can figure out a good way to get the bed off by myself. I do have a tractor...

At this point I'm thankful that the consensus seems to agree it's a fuel delivery issue, which by all accounts is not the end of the world.
Thanks everyone for the input. I am convinced not to two this truck to the shop if at all possible.

 

[rusted nuts]

Put a gauge at the carb to see what Your psi is, Should be around 10 psi , Also could be filter in carb or pin hole in fuel line between engine and tank, Also could be fuel tank switch stuff.

 

[AyWoSch Motors]

Thanks for all the replies guys. I haven't had a chance to look at the truck today but have been thinking about it all day.
Unfortunately, the biggest hurdle I have right now is my geographic location...I'm caretaking for a large ranch in remote New Mexico for the winter and have little to no tools or workspace, just whatever came with me in the truck toolbox and a dirt lot that gets hella windy. So depending on what it ends up being it might be in my best interest to just send it to a shop...

I'm really hoping not to have Ricko's problem of a worn cam...I imagine the only way to solve that would be replacing the cam entirely and that is certainly the last thing I want to be doing right now. I suppose there's no real way to tell if that's the case without opening everything up. The pushrod looked fine when I replaced the pump, for whatever that's worth.

Prairiedrifter no, I haven't looked at the plugs recently, although I did change out my distributor in the last year - I guess it could have gone out of time? I'll pull a plug and see if I'm getting spark. Although the truck will start and run with fuel in the carb.

Buck, the fuel filter was replaced along with my new fuel pump. I forgot to mention that.

As for the vacuum leak, it's certainly possible, although I was getting pretty consistently good MPG on my road trip before the problems started, so I doubt it.

First order when I get the chance is to pull the line off the fuel pump and see if I get any gas coming out. If not, I guess I'll plan on pulling out the sending unit and sock - if I can figure out a good way to get the bed off by myself. I do have a tractor...

At this point I'm thankful that the consensus seems to agree it's a fuel delivery issue, which by all accounts is not the end of the world.
Thanks everyone for the input. I am convinced not to two this truck to the shop if at all possible.

Whereabouts in New Mexico are you?

 

[Hatchet54]

Whereabouts in New Mexico are you?

Whereabouts in New Mexico are you?

Put a gauge at the carb to see what Your psi is, Should be around 10 psi , Also could be filter in carb or pin hole in fuel line between engine and tank, Also could be fuel tank switch stuff.

I'm about 10 miles outside of Galisteo (Santa Fe county).

The tank switch is a very real possibility. When I trip it, I can hear it go "thunk" beneath the floor, so I always assumed it worked, but it very well may not. I've only ever used the passenger tank twice since having the truck...if gas ever gets cheap again maybe I'll fill it again, but I just can't afford that ****

 

[AyWoSch Motors]

I'm about 10 miles outside of Galisteo (Santa Fe county).

The tank switch is a very real possibility. When I trip it, I can hear it go "thunk" beneath the floor, so I always assumed it worked, but it very well may not. I've only ever used the passenger tank twice since having the truck...if gas ever gets cheap again maybe I'll fill it again, but I just can't afford that ****

Im about 10 miles outside of Las Vegas. Not too far away.

 

[rusted nuts]

If I remember right the switch may have o rings in it, May not. But if it does one may be leaking and sucking air instead of fuel.

 

[PrairieDrifter]

This last year I've developed a random misfire under heavy load, so like going up hills, half to wot. My cap was well used up, it would run great cruising and revving it up/idling. But give it any beans going up hill it would start to hard miss. Just check your cap and rotor and plugs.

 

[Ricko1966]

I am assuming you primed the carb? My first guess is you sucked trash into the screen and pickup by running low. You could run a few feet of fuel line from the pump inlet into a gas can next to the truck,see if it starts and continues runni.g then. If it runs that way you know the problem is between the tank and pump. If it wont start and run it's from the pump forward.
Okay plenty of misinfo here but I'm not going to point it out. So not to start any arguments. If your cam lobe went flat its easy to check,pull the pump and the plate behind the pump.Remote start switch, or a trusted friend disconnect the power wire at the cap and crank while pushing the pushrod up with your finger you should feel the pushrod move in and out about a half inch. If its not moving you can put an electric pump back by the tank,if the truck runs acceptably with the electric pump you can run it that way indefinitely.