Testing fuel sending unit on Duel tank?

[crabtruck]

I don't know what would be safe to call a comparable truck.
Which places don't list your truck ?
Makes a difference which smog rules and whether "robust" fuel system.
Some are using fuel tank pressure sensor and some are not.

I had thought the other relay was in the right IP fuse box
but it may actually be stuck to the side of the frame near second tank.
Follow the wires from second tank and see what you see.
You would be in the neighborhood checking for good connections anyways.

[Mrcrowley]

Originally Posted by crabtruck

I don't know what would be safe to call a comparable truck.
Which places don't list your truck ?
Makes a difference which smog rules and whether "robust" fuel system.
Some are using fuel tank pressure sensor and some are not.

I had thought the other relay was in the right IP fuse box
but it may actually be stuck to the side of the frame near second tank.
Follow the wires from second tank and see what you see.
You would be in the neighborhood checking for good connections anyways.

Well Like pep boys, advanced auto parts,VIP they list Chevy Silverado,3500,4x4 hd but not 1 ton,Duelly with 8.1 litre gas. Which means not sure if they are the same under the hood.As far as the other relay Ill look at that today I bet it is corroded or damaged if it is exposed to road salt and what not being on the outside.

[Mrcrowley]

Hey crab truck any idea how much fuel the primary tank would hold I am as of now just toping it off every few days but I need to drive it about 150 miles north not sure how much fuel the primary tank holds?

[crabtruck]

Check your glove box for an RPO code K53 (Robust Fuel), parts are different.
Did you get error codes pulled ?
No idea on tank size but should be able to find online/dealer.

Here's another hint how important they can be, could save big $$.
Even though officiallly a slightly different truck,
seems close enough to pay attention.
Problem shows up under other ways but I don't see the TSBs.

[Mrcrowley]

Originally Posted by crabtruck

Check your glove box for an RPO code K53 (Robust Fuel), parts are different.
Did you get error codes pulled ?
No idea on tank size but should be able to find online/dealer.

Here's another hint how important they can be, could save big $$.
Even though officiallly a slightly different truck,
seems close enough to pay attention.
Problem shows up under other ways but I don't see the TSBs.

No codes showed up and the Unit is a tcu unit said it on top ,Going to double check for second relay under hood then on the c chassis frame. Ill follow the wire's and then call the dealer about the tank capacity

[crabtruck]

Odd no code, maybe as simple as a bad ground.

[Mrcrowley]

Originally Posted by crabtruck

Odd no code, maybe as simple as a bad ground.

I also looked up enhanced code nothing Ill work on it this weekend . I am good at troubleshooting ...

[Mrcrowley]

Originally Posted by Mrcrowley

I also looked up enhanced code nothing Ill work on it this weekend . I am good at troubleshooting ...

Ok crabtruck I was looking for the other relay and I followed the wire bundle back to the fuse box under hood the only relay I found besides one in junction box was this one in picture.This was on the outside of junction box/fuse box.Other wise I do not know where the relay is all wires go towards the junction box .All the other wires do not have a relay on them only one does. It is in junction box labeled f/Pump. Ohh and I unplugged plug to secondary fuel tank and checked all the wires for power one had like 2.14 volts on it that was it I ground the meter to the frame .

[leolkfrm]

did you know a mac, or snap on scanner can read the sending units?

[Mrcrowley]

Originally Posted by leolkfrm

did you know a mac, or snap on scanner can read the sending units?

That would be great but it would cost as much to get a fuel sending unit as it would to buy one and I don't know anyone who has one besides repair garage. It would be great though.