My 74 C10 (400sb) idle's and runs great but is cutting out/stalling sometimes at speed. I changed fuel filter's no change acts like vapor lock never had problem befor.
like everything else, it has to start sometime. an ugly but effective shade tree check is to line as much of the metal fuel line as you can with wooden clothes pins. they will act as a heat sink. if this helps the problem, replace the pump and filter houused in the carburetor fuel inlet.
y'know lookin 'pon the fuel system DO not see a fuel pressure regulator....it suggested the fuel pump may be faulty~
if you find a fuel pressure regulator on a 74 c10 you may have the only one.
it also steered toward a throttle body injection~ http://www.autopartswarehouse.com/sku/Chevrolet/C10_Suburban/Holley/ Fuel_Injection_Kit/1974/H1950220S.html? apwcid=productads&003=27846857&010=apwH1950220S1974chc1sufu inki&gclid=CLTC6NKv8bkCFeYWMgodJC0ACg
the heat riser may be chokin' at speed...check this temperature controlled device...maybe the spring is broken, and you just didn't notice it~
the vacuum advance also has a diaphragm that can leak, increasing idle speed and NOT advancing the spark~
summitracing.com has them to fit your Truck~---- http://www.summitracing.com/search/department/air-fuel-delivery/part- type/fuel-pressure-regulators/? SortBy=Default&SortOrder=Default&autoview=ProductName
I'm sure these are principally used with the TBI throttle body injection systems~
if you choose to install a high performance mechanical pump you may need to install a regulator. definetly will need one with an electric pump just to be sure you don't overpower the needle valve and cause a flooding problem. stock replacement pump shouldn't require a regulator. their are low pressure electric pumps but you don't see them much.
Sounds exactly like my 74 C20 454 and it was the fuel pump on the engine block. Replaced and it ran like it always did.
Hey tennisshoes...the judge is alive and operator_13 now...Mick and people who want to shoot me or chop my head off will be disappointed that the judge is NOT HOME~
If none of the above fixed the problem, check the Ignition Start Switch mounted on the steering column inside the cab and actuated by a push rod attached to the key. This switch supplies 12 volts to the distributor coil in the start and run position. The contacts can get oxidized or simply worn out. If the switch was ever replaced it can be set slightly out of alignment and if there is "slop" in the key position detentes it would cause this intermittent behavior. At $11 it's best to just replace this switch. This switch has a history of going bad in various ways.
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