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Truck runs but then just dies when I press the gas pedal

AbramJ

AbramJ

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Ok, so as I drive the truck is running fine and then suddenly it'll just stop running. I'll turn the key to off, wait a minute, and turn the key and it fires right up. It'll run fine for a while and then it'll happen again.

I just replaced the fuel pump this morning because my old one developed a crack. The truck was running fine before this. Right after I replaced the fuel pump the truck gave me no problems, but then the above described problems started.

Is it possible that while replacing the pump I accidentally knocked some junk into one of the fuel lines and its clogging up the filter or blocking the line when I step on the gas pedal?

(The truck is a '76 Suburban, 350ci with 4bbl carb)
 
did you replace the little rubber line on top of the fuel pump too? if not that would be it unfortunetly
 
Last edited:
shady said:
did you replace the little rubber line on top of the fuel pump too? if not that would be it unfortunetly
Click to expand...

Note that this age of vehicle has a mechanical fuel pump on the bottom of the motor, not the electric pump in the tank found on later models.

For the OP, note that there may be a fuel filter in the inlet at the carb, which are famous for clogging at inopportune times. I would crack that -- you'll need a 1" wrench for the housing plus, hmm, a 5/8" flare wrench, I think it is for the line -- and see if there's a filter in there. It's a little thing, like an inch or so long and maybe half that in diameter. There's a spring and they only work right pointing one way or the other.

I remove these as I hate them and they're hard to get to, and put an external fuel filter (Fram G15 or Wix 33033) in line with the pump IN from the tank (i.e. BEFORE the pump, not after.)

-- A
 
I guess I shouldve included that it is a mechanical pump. Thanks for the replies. I was going to get a new fuel filter at the carb but Autozone had no idea what I was asking for when I was there buying the pump. I'll check the line from the pump to the carb first as the other two looked just fine.
 
I did not see the age:doah: I R STUPID:bow: :D
 
Is it blowing black smoke when you restart it? Do you have to pump the throttle to restart it? Does it just shut down instantly or progressively quit?
 
ktmoutfront said:
Is it blowing black smoke when you restart it? Do you have to pump the throttle to restart it? Does it just shut down instantly or progressively quit?
Click to expand...

I'd have to say the majority of the times it happened today it would just cut out instantly. Never black smoke and didnt have to pump the throttle. I could just turn the key and it would start right back up. Twice it would cut out but catch itself and keep running.

It seemed to happen most when I would drive 40mph or faster.
 
I had a bad distributor rotor cause that in my dads old 68 Chevelle wagon with a 307...it would start in neutral or park and run fine,but DIE as soon as you put it in drive or reverse and tried accelerating...turned out the spark punched a hole thru the plastic rotor and it was grounding out on the shaft of the distributor under a load...luckily the gas station I was near had a used one they gave me so I could get home!..(I learned to carry old tune up parts WITH me after that--and belts too!)..

Another possibility if it turns out its not fuel related,it could be the wires on the HEI pick up coil have broken and are only barely making contact,and when the vacuum advance moves the pick up coil to advance the timing they separate,killing the spark...I've seen ignition modules that will only run an engine at no load and die when put under a load to,the dwell advance circuit in them can fail that way..
 
So tonight I checked to make sure there wasn't anything in the fuel lines, and couldnt find anything. So I was running the truck trying different things to see if I could get it to do it for me.

So I turned on the a/c and ran the truck up to a high idle and let it sit for a bit, then I shut the a/c off and let it go back down and then it spat gas out of the carburator and died. I went in and turned the key and it turned over and died, turned the key again and it fired right up.

My brother thinks the carb needs to be rebuilt. Thoughts?

carb.jpg
 
looks like the acc pump is leaking around it, open that butterfly on the front of the carb with a finger (engine off) and manually stroke the throttle linkage to check for acc pump squirter. It should provide a nice stream of gas into the carb throat when you do this.
If you got gas squirting up the sides of the choke plate maybe the float is too high, or timing is off and trying to backfire?
 
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