Getting rid of dual tanks.

[ShortWide]

I would like to eliminate one of my tanks in a 1985. What side of the frame do the fuel lines go to the fuel pump. I also what to just have 1 line without a return and vapor. Would like to keep the driver side, any issues i don't know of? Thanks MB

 

[towjoe]

Just take tank off. Or tape fuel door shut. I have several trucks with a missing tank. 81 up feed off drivers side and 73-80 feed off passenger side in default mode.

On another question does anyone know trick to get dual tanks to run and feed together. I had a 78 c30 that ran off both tanks all the time and it was great. Gil just one up and it would even out to half in each one and fed off both

 

[cooter55]

I would like to eliminate one of my tanks in a 1985. What side of the frame do the fuel lines go to the fuel pump. I also what to just have 1 line without a return and vapor. Would like to keep the driver side, any issues i don't know of? Thanks MB

My question would be...Why?
Unless you're going to a rear center-mounted tank, having the two tanks means twice the range.
Some things to consider ... If your fuel pump is set up with a return, why mess with it?
You vent to a charcoal canister and unless you really like the smell of gas in the morning...let it do it's job. Fuel vapors are going to have to go somewhere. It definitely doesn't hurt performance.

Final thing to consider is if you ever go fuel injected you most likely will need the return line.

 

[NOPHO84K30]

I took both out and had one made holds 48 gal. In the bed behind my in bed tool box mines a k30 so no vapor lines just vents on each tank then a feed line. It had a return line but my pump dosent have a outlet for return. Going to cut the floor out and lower Iit for new seats. Maybe do some frame sliders for the rocks.

 

[Ark6]

Just take tank off. Or tape fuel door shut. I have several trucks with a missing tank. 81 up feed off drivers side and 73-80 feed off passenger side in default mode.

On another question does anyone know trick to get dual tanks to run and feed together. I had a 78 c30 that ran off both tanks all the time and it was great. Gil just one up and it would even out to half in each one and fed off both

I've got the diesel version, only my RH tank works (well, other one might work but I've never tried, I'm sure it's full of gelled crap that will make my life miserable) I'd like the extra range from the secondary, but was thinking of making it basically a transfer tank after I get it cleaned out (wiring seems like a mess, last owner wasn't electrically inclined) just putting a pump in it to transfer over to RH (master, or at least I think it is) tank.

Looking for someone to tell me this is a bad idea and why (or that the wiring is easy... either way, I mostly just worry about getting air in the line at the transfer switch, or something going wrong.

thoughts?

Thanks!

 

[chengny]

Actually the wiring is real simple.

There are only 3 wires that make up the entire harness (from tank select switch to the transfer valve) for a diesel with dual tanks.

One is a common sensing lead (PNK) that goes from the transfer valve straight to the fuel gauge. It is switched between the two tank senders along with the transfer valve - whenever it is shuttled.

Other than the fuel tank sensing lead, there are just two more wires (LT/GRN & DK/GRN) that run from the select switch to the transfer valve.

When the dash mounted select switch is moved from left to right (or right to left), the polarity in these two wires is reversed. Depending on switch position, the valve motor rotates CW or CCW. That action realigns the internal plumbing to the desired tank and also shifts the fuel gauge sensing leg to the active tank.

Other than a hot wire and ground connected to the select switch - that's pretty much it for the electrical system.

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If you want to isolate the production (LH) tank, do something like this:

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but on the other side:

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[bucket]

I've got the diesel version, only my RH tank works (well, other one might work but I've never tried, I'm sure it's full of gelled crap that will make my life miserable) I'd like the extra range from the secondary, but was thinking of making it basically a transfer tank after I get it cleaned out (wiring seems like a mess, last owner wasn't electrically inclined) just putting a pump in it to transfer over to RH (master, or at least I think it is) tank.

Looking for someone to tell me this is a bad idea and why (or that the wiring is easy... either way, I mostly just worry about getting air in the line at the transfer switch, or something going wrong.

thoughts?

Thanks!

I personally would go to the trouble of making the tank work like original, especially if everything is still there. But it's not a bad idea, just don't forget about turning on the switch and overfilling the other tank as you drive down the road.

 

[Ark6]

Thanks!

I may just drop the tank and clear it out then, still wonder about the air in fuel issue (the one thing I dearly despise about my diesels, ruined a starter on it once) may give it a try though, it would be nice to have twice the range, especially here in AZ, fuel prices vary wildly with no logic I can see.

 

[Ark6]

oh, love the quote btw. good song.

 

[chengny]

I've got the diesel version, only my RH tank works (well, other one might work but I've never tried, I'm sure it's full of gelled crap that will make my life miserable)


I'm sure it is too, and you're in Arizona.

With shipboard applications, the problem is way more prevalent and has far greater implications. Due to the high humidity associated with marine atmospheric conditions, bacterial contamination of stored diesel fuel supplies is a constant and serious concern. Samples are drawn from every tank on a weekly basis, tested for the presence of bacteria and treated with additives if required.

A bacterial bloom capable of shutting down a diesel engine (due to fouled filters/restricted fuel pump lines) can develop overnight. If a bloom occurs in the storage tanks or fuel supply lines associated with a critical piece of equipment (an emergency generator for example), when the time comes for that engine to be operated, it won't be available - at least not for long.

If the bloom is serious, fuel flow will be inadequate. The engine might run okay at idle. But, when any considerable load is applied, it will bog down. Even a dual/switchable fuel filter setup won't solve the problem. The operator won't be able to change elements fast enough to maintain a constant flow of fuel. The engine has to be shut down and the fuel system will need to be cleaned.


Anyway, just some info from the 1986 GM Light Truck Service Manual regarding bacterial contamination/leak testing of diesel fuel tanks and supply lines:

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