Fuel Path in a Non-US FJ (I have pressure build up) (1 Viewer)

[mark248am]

Hey everyone, I've been going through my fully restored FJ fixing or replacing things the shop was lazy to do or didn't and one of the things I just did was replace the old fuel cap with cracked rubber with a brand new one (77310-14070) yesterday. I was seeing what looked like fuel residue below the fuel door so figured fumes or maybe even fuel was getting out of the cap and leaving staining on the side of the car which is what got me to change the cap.

Today I took the car to work (its hot around 36 degrees Celsius) and when I got back home I decided to check if there was any pressure build-up in the fuel tank. So I opened the cap and right away there was a long and fairly loud hiss of air being released.

When I was building my Datsun there were two fuel line setups, the US version with an evaporator tank and a non-US version that vented outside the car. Since I live in the Middle East and the car is GCC spec we don't have any of the EPA-friendly add-ons. All the fuel layouts I found in the forum included evaporator tanks. Does anyone know where I can find a fuel line layout for Non-US vehicles so I can trace mine and see what the shop might have done wrong? I have a 1980 FJ.

 

[HoundDog]

I also own a non-usa 1980 FJ40 and just re-ran all my fuel lines and vents. Your truck should have fuel vapor separator under the panel on the passenger side. There should be three 1/4" hoses going from the tank to the vapor separator. A fourth hose runs from the vapor separator to the charcoal canister in the engine bay. This circuit vents the tank allowing pressure to equalize and also keeps the truck from stinking like gas by venting to atmosphere. You can find vapor separators on ebay if yours is missing.

Look for the three vents on the fuel tank on the passenger side and see what the shop did. If they simply capped them off then your tank will have no way to vent as the temperature rises and falls except through the gas cap. They make vented gas caps but that solution will stink like gas and potentially leak some fuel out the gas cap when fuel sloshes up the filler neck. Good luck figuring it out.

 

[flx]

Vapor separator was added at different dates depending of countries/markets.
If the truck doesn't have a vapor separator then the fuel system is very simple, you just need a vented cap (both ways).

 

[hobbes]

OEM fuel caps generally only vent into the tank. On the NA trucks when you open the fuel cap, there should be a "slight" pressure release after driving if everything is setup stock. Think a couple psi. Not sure about your situation.

If you know the build option of your truck, you can try the below link to see if you can dig out a diagram.

TOYOTA LAND CRUISER 40 45 55FJ40L-K - BODY - FUEL TANK TUBE | Japan Parts EU

TOYOTA LAND CRUISER 40 45 55FJ40L-K , FUEL TANK TUBE

www.japan-parts.eu

 

[mark248am]

I also own a non-usa 1980 FJ40 and just re-ran all my fuel lines and vents. Your truck should have fuel vapor separator under the panel on the passenger side. There should be three 1/4" hoses going from the tank to the vapor separator. A fourth hose runs from the vapor separator to the charcoal canister in the engine bay. This circuit vents the tank allowing pressure to equalize and also keeps the truck from stinking like gas by venting to atmosphere. You can find vapor separators on ebay if yours is missing.

Look for the three vents on the fuel tank on the passenger side and see what the shop did. If they simply capped them off then your tank will have no way to vent as the temperature rises and falls except through the gas cap. They make vented gas caps but that solution will stink like gas and potentially leak some fuel out the gas cap when fuel sloshes up the filler neck. Good luck figuring it out.

Thanks I'll lift the car up this weekend and check and see. I previously only looked at the front of the tank and seen two hoses, but now looking at the drawings @hobbes shared it looks like the vents you mentioned are towards the side of the tank. I have an old picture I had taken when the car was previously on the lift and doesn't look like there is anything coming out of that area but will take a better look this weekend.

 

[mark248am]

OEM fuel caps generally only vent into the tank. On the NA trucks when you open the fuel cap, there should be a "slight" pressure release after driving if everything is setup stock. Think a couple psi. Not sure about your situation.

If you know the build option of your truck, you can try the below link to see if you can dig out a diagram.

TOYOTA LAND CRUISER 40 45 55FJ40L-K - BODY - FUEL TANK TUBE | Japan Parts EU

TOYOTA LAND CRUISER 40 45 55FJ40L-K , FUEL TANK TUBE

www.japan-parts.eu

Thanks, this diagram is exactly what i was looking for

 

[flx]

Show us a picture of your fuel door and cap, and a picture from inside showing the filler area, this is where the vapor system would go if you have one.

Edit: And the old fuel cap, it-it the same than the new one?

 

[mark248am]

Show us a picture of your fuel door and cap, and a picture from inside showing the filler area, this is where the vapor system would go if you have one.

Edit: And the old fuel cap, it-it the same than the new one?

Yeah same fuel cap, well same style, the one i got is OEM, the replica is Chinese

 

[mark248am]

Ok, quick update, I shoved my iPhone camera under the car and to my surprise, I do have 3 lines coming out of the fuel tank AND they're connected to hoses. I have no idea where the hoses are going but the fact that they're connected to hoses and not blocked off leads me to believe they're probably connected to something at the other end I presume my fuel tank is breathing and that the loud and long hiss sound when I opened the fuel tank is normal.

 

[ToyotaMatt]

Ok, quick update, I shoved my iPhone camera under the car and to my surprise, I do have 3 lines coming out of the fuel tank AND they're connected to hoses. I have no idea where the hoses are going but the fact that they're connected to hoses and not blocked off leads me to believe they're probably connected to something at the other end I presume my fuel tank is breathing and that the loud and long hiss sound when I opened the fuel tank is normal.

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View attachment 3321663

NO the outward venting of fuel vapors when u open the OEM 14070 cap is NOT normal


- do u have a Charcoal canister and fuel vapor recovery system still> ?

i have NEVER seen a import from south america still have it in place is why i ask ?

 

[mark248am]

NO the outward venting of fuel vapors when u open the OEM 14070 cap is NOT normal


- do u have a Charcoal canister and fuel vapor recovery system still> ?

i have NEVER seen a import from south america still have it in place is why i ask ?

I don't think we ever got the charcoal canisters here but based on the fuel diagram that @hobbes shared it looks like my lines go up to a seperator although i couldn't see it from underneath the car.

 

[sggoat]

OEM fuel caps generally only vent into the tank. On the NA trucks when you open the fuel cap, there should be a "slight" pressure release after driving if everything is setup stock. Think a couple psi. Not sure about your situation.

If you know the build option of your truck, you can try the below link to see if you can dig out a diagram.

http://http:/www.japan-parts.eu/toy...j40l-k/6_791210_058_/body/7751_fuel-tank-tube

if you say the caps vent "into"the tank--not sure how that works--if that were true,how would the removal of the cap possibly result in pressure leaking "out" of the tank?--seems contradictory to the vent system function--

 

[mark248am]

I have a 2022 Hilux and when I get to the fuel station and open the fuel cap I get a hiss as well. If the hiss wasn't so long and loud on the FJ40 I wouldn't have thought much of it, would have assumed it was normal.

 

[hobbes]

if you say the caps vent "into"the tank--not sure how that works--if that were true,how would the removal of the cap possibly result in pressure leaking "out" of the tank?--seems contradictory to the vent system function--

On FJ40s, the fuel cap generally only vents in to allow air to fill the tank as fuel is depleted.

However, as we drive vapor pressure builds in the tank due to warm fuel being returned via the fuel return line, fuel sloshing around, etc. This vapor exits the fuel tank through the EVAP system. The EVAP system on my 1974 FJ40 consists of a fuel separator, check valve, charcoal canister, and VSV.

From the top of the fuel tank, three lines lead to a fuel separator. The separator is just some plastic tubing behind the B-pillar. This lets any liquid fuel settle out. From there it goes through a one way check valve right behind the B-pillar and exits below the truck. The check valve allows the tank to slightly pressurize before opening. The purpose of the valve is to keep the vapor in the tank while parked so it does not smell of fuel every time you walk by. If you get a slight whoosh when fueling then this valve is working. If you tank is over pressurizing then something is plugged in the EVAP system.
The separator and check valve are circled below.

After the check valve, the vapor goes through the charcoal canister for cleaning. Then it goes to the VSV and back into the intake system.

Again, not sure about your specifics.