78 cuts out

[AuglyTruckGuy]

I have a 78 Chevy Scottsdale 3/4T 4x4 400cu. Truck has run great and hauled more than I ever expected to and from the house I built, however, recently it has been cutting out and stalling at around 20-25 miles an hour on acceleration. I checked out Chiltons manual and it pointed me towards the ignition module and vacuum advance in the HEI distributor but replacing both of these did not solve the issue. Now Im thinking fuel filter or pump. Any advice?

[madcow75]

Check your coil. Had that problem also. Coil may have a crack. Runs fine cold but when it warms up it truck cuts out. Replaced and never had a problem since.

[Black 'n' Blue]

I recently went through that on a 40s willys. It would run great till you try to drive away, it would stall. It was the fuel pump, it would spin fast enough to keep it idleing but not fast enough to keep up with anything above idle. My bet is the fuel pump. I doubt it's the filter, but there cheap and easy to replace on these trucks so I would change that anyway.

[njlimbaugh]

If the engine cuts out at low RPM but runs OK at higher RPM it ain't the fuel pump or the filter. Fuel starvation is first noticed at highway speeds when the fuel flow can't keep up with the engine's demand.

[78 Chevyrado]

Check the advance weights inside the distributor cap under the rotor.

My 78 did that exact same thing, and it turned out the moving parts underneath the weights had rusted stuck in the full advanced position. it had too much advance for low engine speed, but it was running good at higher speeds. when you figure out how the mechanism works its simple, and it should move EXTREMELY freely.

[motornut]

Originally Posted by 78 Chevyrado

Check the advance weights inside the distributor cap under the rotor.

My 78 did that exact same thing, and it turned out the moving parts underneath the weights had rusted stuck in the full advanced position. it had too much advance for low engine speed, but it was running good at higher speeds. when you figure out how the mechanism works its simple, and it should move EXTREMELY freely.

for sure check this!mine were acting like this too