Main/Aux Gas Tanks switch working? diagnosis (1 Viewer)

[Kschep]

other thank running the rig and waiting to see if it goes down ... how would I assess whether or not my toggle switch (Front/Rear) is actually toggling btw tanks...trying to assess whether or not my AUX tank is being utilized at all...I parked on a little incline and wow gas started leaking out of that rear tank fast...the seal is not great obviously but I thought it the gas was being used from back there now I dont think so....

 

[Living in the Past]

Since a auxiliary tank was never offered by Toyota hard to say what you have. All the cruisers I've bought over the years use a manual valve. Toggle switch sounds like a electric valve. Does you fuel gauge work? Do you know if you have a sending unit for the gauge in both tanks or just the front. If both the gauge should probably read different when switched. If just the front then switched to the back it should not change. If it doesn't work than your going to have physically check the levels. Since all my Land Cruisers are not daily drivers I have no use for a second tank and have removed most with only one non operating cruiser still having a second tank. I see no reason to carry around thirty five gallons of gas when it would probably go bad before using it. When I actually used an auxiliary tank I would run the back tank out that didn't have a sending unit then switch to the front tank I made sure the gauge work well enough to not run out of gas.

 

[peesalot]

Best and fastest way is to take apart the valve , determine which tank is connected/active and mark switch accordingly so you know in future which tank your on, then hit the switch and verify the valve actually switched ? use a spare piece of fuel hose and blow thru it. verify that when you hit the switch the air comes out other hole. sometimes the valves click but the piston inside doesnt seal off completely therby not isolating the suction to 1 tank.
Assuming you have an otherwise stock fuel system ?
There is another possiblity that the switch is a transfer pump that simply loads the rear tank into the stock.
Fuel level, install a gauge, or it may be a transfer pump set up which wouldnt need an additional gauge.

 

[Downey]

I can get it sorted out for you, but I need more info.
1. What is your fuel pump situation?, how many, where?
2. Does your rear tank have a sending unit?, if so stock or aftermarket?
3. What year model is your rig, and are you using the stock dashboard fuel gauge?
4. Is your rear tank plumbing tied into the evapo canister system?

 

[Solace in Solitude]

From what little we know right now, before going to a lot of trouble, I’d simply crimp/pinch the soft line that feeds from the main tank. A clamp, with plastic jaws works well for this... or a pair of vice grips, with a cloth, to protect the line.

Then, switch to main and run the truck for about 5 minutes. It should die by then, if main is really aux.

Then, switch to aux and run the truck for about 5 minutes. It should die by then, if aux is really main.
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How do you switch tanks, is it a DPDT toggle, an electric switching valve (like a Pollak), or, merely a ball valve?

 

[John McVicker]

^^^
This will work.

 

[Mark Jennings]

Need a picture! In the mean time I have a story to tell. I had just finished a 2 year restoration that included an aux tank with a brandy new electric tank valve. Same issue as yours...park with the truck nose up hill, gas filled the aux tank and overflowed....park with truck nose down hill, gas filed the main tank and overflowed.....and both tanks ran out of gas at the same time. Ask me how I figured that one out......LOL

Couldn't believe my brandy new valve leaked, took me several months of siphoning gas to keep it from running all over my shiny new paint. Finally spent the $30 to buy a new new valve and guess what...I can park on a hill without overfilling the other tank and..... I run out of gas one tank at a time.

When I took the old/new valve apart, internal sealing o-ring was broken causing the valve to leak. But it was a new valve....how could that be....it’s actually a pretty cheaply made unit...so I bought 2 more....and keep them around for the next unexpected gas transfer catastrophe...LOL

When you buy yourself a new one to replace the leaker, find the cheapest source, Amazon, etc...and by 2.

 

[bikersmurf]

Pollak seem to be the most common electric valves.

For reliability I purchased a brass manual valve from the local Marine Shop. It is simple and reliable... with little to fail.

 

[Downey]

There have been more reports here on Mud lately about defective electric switching valves, Pollack being the most popular that most guys would have, I suspect a bad batch, or them switching to cheaper construction of late ???. I sell all the brass manual switching valves I can find at swap meets/estate sales, but the problem with them is they have to be mounted near the drivers seat/reach, which means all the fuel lines have to come to the manual switching valve before entering pump up to engine, which means electric pump is not mounted as close to tanks as it should be since electric pumps are pushers, not suckers. I know, some guys are running the stock engine driven full pump with a dual tank arrangement, but that sure seems like it could create some starvation issues ???.

 

[bikersmurf]

There have been more reports here on Mud lately about defective electric switching valves, Pollack being the most popular that most guys would have, I suspect a bad batch, or them switching to cheaper construction of late ???. I sell all the brass manual switching valves I can find at swap meets/estate sales, but the problem with them is they have to be mounted near the drivers seat/reach, which means all the fuel lines have to come to the manual switching valve before entering pump up to engine, which means electric pump is not mounted as close to tanks as it should be since electric pumps are pushers, not suckers. I know, some guys are running the stock engine driven full pump with a dual tank arrangement, but that sure seems like it could create some starvation issues ???.

I’ve not had any issues with starvation with my Carter P4070 electric pump. The pump is still very close to the tank, and unless I ran two pumps, it’d be difficult to have the pump closer to the auxiliary tank.

 

[Mark Jennings]

There have been more reports here on Mud lately about defective electric switching valves, Pollack being the most popular that most guys would have, I suspect a bad batch, or them switching to cheaper construction of late ???. I sell all the brass manual switching valves I can find at swap meets/estate sales, but the problem with them is they have to be mounted near the drivers seat/reach, which means all the fuel lines have to come to the manual switching valve before entering pump up to engine, which means electric pump is not mounted as close to tanks as it should be since electric pumps are pushers, not suckers. I know, some guys are running the stock engine driven full pump with a dual tank arrangement, but that sure seems like it could create some starvation issues ???.

Yep, I use a Pollok fuel 3 way solenoid, and yep they are cheap.....and yep, they do fail regularly. However, every motorhome supplier and most Autozones/O’rielies/Napa’s carry them and they are pretty inexpensive from Amozon. So when you replace yours, buy 2 and keep one in the glovebox....just in case.

 

[Downey]

Pollacks is what every motor home and dual tank truck used for most of my 75 years on earth, never an issue ever- - -and now ???

 

[bikersmurf]

Yep, I use a Pollok fuel 3 way solenoid, and yep they are cheap.....and yep, they do fail regularly. However, every motorhome supplier and most Autozones/O’rielies/Napa’s carry them and they are pretty inexpensive from Amozon. So when you replace yours, buy 2 and keep one in the glovebox....just in case.

be careful of what you’re getting off Amazon, sometimes they may be cheap knockoffs. As with any online seller

 

[Mark Jennings]

Yep, I use a Pollok fuel 3 way solenoid, and yep they are cheap.....and yep, they do fail regularly. However, every motorhome supplier and most Autozones/O’rielies/Napa’s carry them and they are pretty inexpensive from Amozon. So when you replace yours, buy 2 and keep one in the glovebox....just in case.

My Bad.....sorry mine is not a Pollak...mine a Single Wire Standard Motor Products....and yep, they are cheap.

 

[Downey]

^^^^^ And if I remember correctly, I think I use to buy Pollacks from Standard Motor Parts.

 

[SteveH]

I was one of the ones with the leaky 6 way Pollack valve (in fairness, it died of old age) that I replaced with two 3-way valves, one of which leaked. They would alternately leak air and fuel (depending on the day) and the endless driveability problems led to me fuel inject my FJ40. The aux tank is sitting in my barn and I just fill up the FJ40 more often.

The way I found the air leak was that I put a clear plastic fuel filter between the switching valve and the electric EFI pump, and I was seeing a great deal of air in the filter, which was causing the pump to cavitate and the EFI to hiccup and randomly die. When I gleefully ripped out ALL the valves and plumbed directly to my FJ40 tank, I finally had a reliable setup.

Jim Downey is right - those valves used to be bulletproof and brass switching valves are usually parts-swap antiques and must be mounted within reach of the driver to be practical. I would use an aux tank as a 'refill tank' for my main tank, and plumb it that way.

 

[Downey]

SteveH, if you want to re-install the rear tank with a brass manual switching valve I have one right now that I picked up at the last swap meet, haven't put it into my ebay store yet, so your's for what I paid, lemme know.

 

[SteveH]

Thanks - I'm enjoying the simplicity of single-tank plumbing right now, but I will keep it in mind.

 

[SteveH]

@Downey - Jim - This is the box from the Pollack valve I bought in 1990. Sad/odd that I still have it

 

[4idaho]

I can get it sorted out for you, but I need more info.
1. What is your fuel pump situation?, how many, where?
2. Does your rear tank have a sending unit?, if so stock or aftermarket?
3. What year model is your rig, and are you using the stock dashboard fuel gauge?
4. Is your rear tank plumbing tied into the evapo canister system?

I have similar issues with my setup. Answers to your questions:
1. one electric fuel pump, along frame rail.
2. Rear tank has an aftermarket sending unit.
3. 78 FJ40 with aftermarket gauges, Dakota digital.
4. Rear tank is not tied into the evapo canister system.