Truck Troubles

[TheSeeker]

Hey everyone, I have a 1970 c10. Pretty much all stock and I have been using it as a daily driver right now as im fixing it up. Everything was running fine and dandy till about 2 weeks ago. I noticed everytime I stopped at a red light my truck acted like it was running out of fuel, and sometimes it would choke out and die. So when I got it home, I parked it and started checking things out. Fuel filter is clean, spark plugs are not fouled. I pulled the top end off the carburator and I did replace the float, accelerator pump and top end gasket. Now it fires right up and idles well, but when driving it it still seems to feel like its running out of gas. The good news it is that it does NOT die on me now. Any one with ideas? The carb in question is a stock 70 qjet. I was maybe thinking mixture screws, or timing at this point... Thanks in advance for any help

[70jnktrk]

one thing that I discovered on my 70 was the sock on the fuel pickup had/was dissolved...D

[kevmic28]

Sounds like the same problem I am dealing with. You said you checked the fuel filter, the one in the carb inlet? What about fuel pump?

[TheSeeker]

Well, this truck was my grandfathers service truck, so over the years it has taken some abuse but its always been taken care of. The fuel filter is an inline filter up next to the carb. Not the one that originally was in the carb inlet (paper or some kind of copper i believe?) And I should have mentioned the the first week I had it I replaced the sending unit and had the tank boiled out and cleaned and everything. I wouldnt think its the fuel sock on the sender but I can always check. And the fuel pump is also less than 3 months old. I could check that as well.

[So.Cal.Super]

Fuel Pump?

Mine started dieing under heavy acceleration, then it felt like it was running out of gas at 65, now its more like 55 or if I take the back road to my buddies (heavy grade) it doesn't want to make it. I have checked everything and am thinking the Diaphram in the fuel pump might be toast. I ordered a new one from summit for for around $40. and i'm adding a regulater and fuel pressure gauge. should be done when I get some time in a few weeks.

[smallblockchev]

do you have rubber fuel lines at all? maybe they are getting old and kinked. I would change the fuel filter anyways because they are cheap and give the carb a good cleaning. maybe some gunk worked its way in there. Did you check to see if the floats were set at the right level?

[TheSeeker]

I will inspect the fuel lines in the morning. And I did check the carb out fairly well, the float is brand new now, set correctly and the metering rods etc, were all in good shape. The jets were clean and undamaged as well. Ive been scratching my head all night on this haha.

[kevmic28]

Have you checked the cap and rotor?

[Rat Bastid]

timing maybe?

[TheSeeker]

Tomorrow morning im going to do as suggested and go over everything with a fine tooth comb. I dont understand this issue but im going to start with the most inexpensive parts first, and work my way up from there.

[cdowns]

those lazyman rubber fuel lines sure burn up things good

theres a section of small rubber line under the cab passenger side see if it's cracked or kinked

[kevmic28]

keep us up with what you have done so we know what works and not.

[kevmic28]

Any updates???

[TheSeeker]

Yes, Sorry busy day haha. I did go out and inspect the fuel lines. The rubber ones look fairly new and surprisingly are in great shape. I tested the fuel pump, everything is ok there. The carb is working properly and I had my buddy tune it for me. After he test drove it, his idea is that the culprit is the 100 plus degree heat, the 190 degree thermostat and the steel fuel line going to the carb. He thinks its heating up causing the fuel to boil, leading to vapor lock. I dont know if this is the sure fire problem, but seems likley right now haha. And he checked the timing while he was here and it was good too. So im still guessing, but at least headed in the right direction

[SOUTHERN917]

I have the exact same problem as kevmic28 and theseeker.....I have also traced, checked, and tried all of the same....I did switch vac adv from ported to full manifold vac, and it improved slow idle when in gear. My next guess is timing, I'm going to spent the time to find "true" TDC, I have a sneaking suspicion that it's off, and setting it at 10BTDC is really more like 8....