Cutting out/dying while driving

[Brysonsproject]

My 1978 K20 just started hesitating a lot and often dying when driving uphill when I have to hold the throttle, even less than half open for more than 10 seconds. 350 engine with brand new Holley carb. Little Edelbrock red fuel pump and a fuel filter with a return line. The filter and pump were on the truck when I bought it in May but I have replaced everything else in the fuel system. Both tanks work and the cutting out happens no matter which tank I'm using. I think I'm gonna replace the filter tomorrow and I hope that solves it. Any other thoughts on what it could be? I'm thinking it could possibly be that the way I plumbed all the hoses used a lot of hose and maybe it's hard for the pump to push the fuel that far? BTW the pump is pretty close to the tanks, which I've heard is better. Thanks.

 

[Rusty Nail]

My money rides on the connection to the HEI distributor.
Betcha money half of that clip is broken/missing and the wires pull tight enough to force the connection to lose contact.

That's my bet EVEN THOUGH you didn't state that is easily restarts after it dies.


Noob.

 

[legopnuematic]

As Rusty said, definitely check the power at the distributor. On my 76 I had the male spade part of the terminals (from the coil) pushing into the cap, even though the female connector was seated in the cap, it was barely making a connection and wasn’t mechanically interlocked.

Idle was fine and low speed cruising but would cut out when under heavy acceleration.

 

[fast 99]

Check fuel pressure and volume.

Inside HEI on pickup coil there are 2 small wires, look very closely for damage or wear to the insulation close to the pickup. What happens is the vacuum advance turns the coil plate, opens up the circuit if either of the wires are broken. Can gently pull on those wires too, if broken will probably separate.

From description sounds more like a fuel issue.

 

[dvdswan]

Is the distributor loose? Was the new carb "tuned" by someone when installed? Was the timing messed with?

Did you put new gas caps on? possibly creating a vacuum in the tanks?

 

[Brysonsproject]

My money rides on the connection to the HEI distributor.
Betcha money half of that clip is broken/missing and the wires pull tight enough to force the connection to lose contact.

That's my bet EVEN THOUGH you didn't state that is easily restarts after it dies.


Noob.

The truck always starts up fine after AND always does well when I give it WOT whether from a stop or starting to go up a hill. its just when I give it gas for a while that it starts to bog. Does that still sound like an HEI issue?

 

[fast 99]

That's why I recommended checking fuel volume. Vehicles with volume or pressure problems can be fine on level ground but if fuel demands increase [such on a hill] they run out after fuel in the lines and bowl are depleted. You need to do some diagnostic testing. Until then it's a poke in the dark.

 

[Ricko1966]

You can buy,maybe borrow IDK, a fuel pressure tester that has a volume function. I can test fuel pressure and bleed fuel through the relief on my gauge so I can check pressure and volume while watching for an unacceptable drop in pressure.

 

[Brysonsproject]

That's why I recommended checking fuel volume. Vehicles with volume or pressure problems can be fine on level ground but if fuel demands increase [such on a hill] they run out after fuel in the lines and bowl are depleted. You need to do some diagnostic testing. Until then it's a poke in the dark.

What does it mean to check fuel volume? like how fast its flowing? and what tool do you use for that?

 

[WFO]

My 1978 K20 just started hesitating a lot and often dying when driving uphill when I have to hold the throttle, even less than half open for more than 10 seconds. 350 engine with brand new Holley carb. Little Edelbrock red fuel pump and a fuel filter with a return line. The filter and pump were on the truck when I bought it in May but I have replaced everything else in the fuel system. Both tanks work and the cutting out happens no matter which tank I'm using. I think I'm gonna replace the filter tomorrow and I hope that solves it. Any other thoughts on what it could be? I'm thinking it could possibly be that the way I plumbed all the hoses used a lot of hose and maybe it's hard for the pump to push the fuel that far? BTW the pump is pretty close to the tanks, which I've heard is better. Thanks.

If the fuel filter doesn't help, I'd check the float level.
Sound like it's starving for fuel under a load.

 

[Brysonsproject]

If the fuel filter doesn't help, I'd check the float level.
Sound like it's starving for fuel under a load.

What is the float level and how do I check that?

 

[Ricko1966]

What does it mean to check fuel volume? like how fast its flowing? and what tool do you use for that?

Fuel volume is how much fuel it pumps in a given time I'd look for a 1/2 cup in 30 seconds. If you are burning more than you are pumping you will have your problem

 

[Rusty Nail]

If it restarts "fine every time" WHY would you say fuel volume?
Maybe you can learn me somethin.

I may put some money on the rotor bug too.
pull the cap and take pix junior??

Yeah, I wanna split.
half on the distributor plug and half on the rotor.

 

[fast 99]

If it restarts "fine every time" WHY would you say fuel volume?

Because fuel requirements at idle are much less than under heavy load, think gallons per hour.

 

[Rusty Nail]

That makes sense. You guys are gonna fix it.
But hey junior, ever heard of the "flag rate"?
There are other trucks outside and they got customers in the Lounge maybe.

You gonna pay cash or credit? It's two different prices...