Hello, I have a 5yd 1983 chevy dump truck. It has a 366 gas carbureted engine. It has two gas tanks under the passenger and driver’s seat. I believe the fuel pump has failed. I would hear a pump activate when I turned the key to the on position. But I never paid attention to the location. Now I don’t hear the pump and truck won’t start unless I pour gas in carb. So is this pump inside the tank?? And is there two pumps one for each fuel tank?? Thanks Gary
Should be a mechanical fuel pump on the side of the engine. Trace the fuel line down from the carb and you’ll find it. If it’s been removed you’ll see a block off plate on the side if the engine where the mechanical pump should go. AFAIK none of those trucks until you got to the age of fuel injection had an electric fuel pump, probably someone’s bandaid fix.
Wait, tanks under the drivers seat, As in inside the cab?!?! If thats the case it’s definitely been rigged and probably unsafe. Those trucks should either have a standard gas tank tucked under the floor, passenger side of the cab or saddle tank(s).
Should have step tanks. Owner is probably relaying positioning incorrectly. There is no room for a fuel tank under the seats inside the cab of those trucks which is the 70's square body pickup cab with minor differences.
Back in those years, on some trucks, GM and Ford and maybe IH? used electric in-tank fuel pumps. They were connected through an eng oil pressure switch in some cases if i remember correctly
Saddle tanks outside and both have a step built in to help get into truck
I followed the gas line from carb back to the twin saddle gas tanks. These are big exposed tanks that have a step built in to help enter truck. There is no mechanical fuel pump. It has a block off plate. So fuel lines go to each tank. There is a access plate with wires on each tank. I’m figuring for fuel pump and fuel level sensor???? Before I take tank down to look I thought maybe someone could tell me there is a electric pump in each tank??
I would look on an interior frame rail also for an electric pump and a selector valve if you have a control for right, or left tank selection. Follow your lines from each tank through their respective routing as there were many configurations for that series of truck.
Is there a fuel line going into both tanks' or just a cross over line. I think the old Ford gas jobs had the pump in one tank. Can't see both pumps failing if it has 2 pumps. Might be a power issue. If my father was still alive he could tell you. He was a gas truck man
Ok.. the trick definitely has electric fuel pumps. One in each saddle tank. I pulled the tank out to give me room to apply 12v to terminal on top of tank. When I did gas came out of hose. So it’s a power problem. I guess could be the switch that switches tanks or power wire chewed by mice? But the list is getting smaller. Thanks everyone
You are "drilling down" to conclusion. I've seen dual electric pumps in use, a single electric pump with a selector valve for drawing from a selected tank, along with a pumps in each tank and a frame mounted pump, all three. Hard to know sometimes if you cannot see the problems experienced.
I forgot about the selector switches. I remember seeing them on the floor in some of the old GMs. I love the sound of a good working gas job. Not too many around anymore. I think those pumps are pretty expensive, so a power problem would be best.
I too like the sound of a 366V8, or a 427 "Tall Deck" getting it lungs pulled out. Real workhorses in their day but they'd get the job done. The short time I worked at a Chevrolet dealer in 1982 had a lot of medium duty chassis sold and serviced so seen a plethora of options then. Hated the 3208 Caterpillar, and the 8.2 Detroit as hauled in a lot for troubles. The 5.7ltr GM engine of the light duty pickups; couldn't have enough cherry pickers on hand to handle the swapping duties timely.....
There was a fella here with a topkick. It was gas, but fuel injected. Had never seen one. It was a single axle with a trailing axle. The truck was so light, he could haul more asphalt than his box could hold. One of our tandem internationals with the 466 weighed over 10,000 kgs. I think the topkick was around 8. Didn't sound like the 366 carb though.
The injected engines just screamed without personality. The carburetors roared under a pull wanting to pull the top cover through..... Back in those days it seemed every farm had a single axle grain hauler. Lot's of Cargostar, Loadstar, Fleetstar, IH's around mostly being gas powered. The 304, 392, and 404 were popular engines and almost dead reliable.
Ok well it looks like I stand corrected. I’ve owned chevy, gmc and ford gas powered medium duties from the 70s-80s and all used a mechanical fuel pump on the engine. They all had a single tank so maybe that was the difference. That said, I know on medium duty truck there were so many different options available it’ll make you head spin. I agree with others on the sound of an old big block. I’ve got an ‘80 F600 with a 429 4bbl. Sure sounds good through those dual 2.5” glasspacks pulling the dozer up a long grade...
Probably a low pressure pump in each tank. Low pressure because its carburated. Ed