Fueling problem in 1974 Toyota Landcruiser

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Parend40

Parend40

Joined
Dec 2, 2025
Threads
3
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Location
ARIZONA
1974 Toyota Land Cruiser FJ40 – Fuel Delivery Issue
Hey everyone, looking for some advice on a fueling issue I’m having.
I recently replaced my carburetor because the old one was dumping fuel into the intake and running terribly. I installed an OEM Toyota carb, and it ran great for a few days.
Then out of nowhere:
I started hearing a faint humming noise
The engine died while driving
I checked the carb and the bowl had no fuel in it
I’m now wondering if my mechanical fuel pump has failed. It’s about 5 years old, but I believe it’s just a cheaper aftermarket pump (around $70 from Amazon), not OEM.
Another thing I’ve noticed—every time I remove the gas cap, I get a strong rush of air coming out of the tank. I’ve heard mixed opinions:
Some say the tank should be sealed and pressurized
Others say it should be vented
So I’m not sure if I might also be dealing with a venting issue.
My questions:
Does this sound like a failing mechanical fuel pump?
Could a non-venting/pressurized tank cause fuel starvation like this?
Should I be running a vented gas cap on this vehicle?
Any recommendations on a good quality replacement fuel pump (OEM or equivalent)?
Appreciate any help—thanks in advance!
 
As mentioned above, check your oil for fuel.

The fuel system cannot be sealed. See if driving with the fuel cap off/loosened makes a difference (assuming no fuel in the oil). That will check the EVAP system. The factory fuel cap lets air in, but not out. The system needs an air outlet. Is the fuel cap OEM?

Do you have a fuel return from the carb? The OEM carb had a fuel return on it from the factory in 1974. If the fuel return is gone, that will impact which fuel pump to go with if yours is bad.

How old is the fuel filter and fuel tank? Rust/debris could be plugging the line.

Pictures always help.
 
firemanj92 said:
Also, have you checked your oil for fuel, if so then pump is/has failed.
Click to expand...
How do I do this , drain some oil and check? I just did an oil change a few hundred hundred miles ago and have it schedule every 3000, and didn't notice anything but that could of changed.
 
hobbes said:
As mentioned above, check your oil for fuel.

The fuel system cannot be sealed. See if driving with the fuel cap off/loosened makes a difference (assuming no fuel in the oil). That will check the EVAP system. The factory fuel cap lets air in, but not out. The system needs an air outlet. Is the fuel cap OEM?

Do you have a fuel return from the carb? The OEM carb had a fuel return on it from the factory in 1974. If the fuel return is gone, that will impact which fuel pump to go with if yours is bad.

How old is the fuel filter and fuel tank? Rust/debris could be plugging the line.

Pictures always help.
Click to expand...
Okay I will try this dringing with cab loose. And I just restored the 40 so brand new fuel tank, new fuel lines new fuel filter evey 3000 miles. And no the new carb does not have a return line, its the coty racer carb. I have it plugged comming out of the tank next to the battery because when it was off it was gushing fuel out of the old factory metal line.
 
A strong whoosh indicates the fuels system cannot vent. There should be a check valve by the B pillar that holds pressure. About 0.5 psi. You should get a “slight” whoosh when opening the fuel cap when just driven.

Is your charcoal canister hooked up?
 
The fuel separator looks like the photo below. It is behind a metal plate you’ll have to remove to see what’s going on. Compy Fabrication Ltd. - https://compyfab.com/
1775839975922.webp
 
hobbes said:
Behind your b-pillar should be a fuel separator. Do you have that? Is it hooked to the fuel tank on one side? Where does the other side go?
Click to expand...
I do not have a fuel separator the previous owner installed a aftermarket fuel tank in the rear. So I have 2 tanks the tank underneath the passenger seat and a tank in the back behind the rear diff. He put in a valve that allows the tanks to switch from front to rear. No fuel, separator.
 
hobbes said:
Which tank are you drawing from? Try allowing that one to vent.
Click to expand...
The valve will switch from tank to tank. So I run on both but 99 percent of the time I use the front as that has the gauge and the rear acts as an extra that I could use on long overland trips. But Im willing to do whatever to get the think running properly.
 
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