UselessATmechanics

I have a 1977 GMC Midas (Chevy 454 Big Block) Motorhome. I went to the gas station to get gas, fueled up one tank, switched the tank selector to the other tank, and then it wouldn't start at all. Finally got it started, and it would only high rev. So I got it towed home. Once home, it wouldn't start at all. I realized there was no gas getting to the carb. I replaced the exterior fuel pump, and still no gas. I traced the fuel line from the fuel pump, to the fuel filter, and changed that. Still no gas. Followed the line further back, to the fuel tank selector valve. I took that off, and am now just running the fuel line direct from the tank, to the fuel filter, to the fuel pump, to the carb. Still no gas. I made sure all the lines are hooked up correctly, no kinks or anything. What else could the problem be? Is there some kind of safety valve or something that may be stopping the gas? I opened the gas cap, and blew air from the fuel filter to the tank, and it blew gas out the tank, so there doesn't seem to be anything in the line? I installed a new fuel pump because I wasn't getting gas from the tank. I installed it correctly, even reinstalled it, and I cant get it to pump any gas. There are no clogs in the line, and all the lines are sealed good. I even tried putting a hose from the inlet line on the fuel pump in a jar of gas, and I cant get it to suck any gas. What could the problem be? I'm 99% sure it's installed correctly, and 99% sure that the camshaft rod is moving, which should be powering the mechanical fuel pump. I even tried filling the carb. bowl to get the motor moving so the fuel pump would start pumping, but nothing. I'm also sure that I have gas in the tank.

I need to get home in 3 days, and I can't afford the $200 to tow it to a shop, on top of how ever much it costs to get fixed.

Any help is much, MUCH appreciated.

RacerX

I dont want to insult you bro, because I m not there so see the car but are you sure you topped up with gasoline and not diesel? The pump you stopped at said 87 or similar right and not 40? Just an idea... But ok, lets start from the top and try a few things:

1. Disconnect the fuel pump from the block and take off the outlet line to the carb. Pump the Cam Rod by hand and see if fuel comes out the outlet on the pump. This will mean fuel is getting to the pump and leaving.

2. Remove the filter and try to get the fuel to run from the line in the tank into a jar to check for flow. Use gravity to help you. Jack up the rear and hold the line lower than the tank. No flow=restriction is in the tank.

3. This fuel line is puncture proof braided rubber hose rated 7-10psi. But it may be the original and the inside walls may have collapsed which is blocking the fuel delivery. The fuel line is cheap like $2/foot but your van is so long you may need 30 feet of it.

4. Now, if the pump, filter and lines are new there should be no restriction. Which leaves us with the sole perpetrator, the fuel sending unit in the tanks. No fuel delivery means that something is impinging the sieve in the sending unit. 1977 Motorhome? 33 years old. There could be something in the tank. I ve seen sugar in the tank that creates a crystalline sheet and clogs the pickup. I ve seen an actual LEAF from a tree in a tank clogging the pickup. You re going to have to check out the sending unit and see if its doggone. Problem! You have 2 30 gallon tanks I presume full of fuel, which will be QUITE HEAVY and almost impossible to drop down open up without losing most of the fuel. Unless you want to run fuel to the carb from a Jerry Can inside the truck using the fuel line and the new fuel pump? Jerry Cans usually dont get bigger than 5 gallons.

4a. Even check the tank#1/#2 switch. It may not be opening or closing completely leaving the system in limbo between tank pickups or something. Its like when an elevator door opens but its not totally on the floor(above or below).

5. Now I dont know if this problem is related to the other problem you posted before, that sounded like a choke issue. But this here, if you are sure you re getting no fuel to the engine can only be 4 things up to the motor: pump, line, filter and tank. After the pump its all carb.

6. Another thing, since I m not there. Are you SURE you re getting no fuel and not NO SPARK? And it does CRANK right but no Start?

MDTAHOE

When you poured gas in the carb did it start at all?