Fj60 Cali smog legal vortec v8 swap fuel tank advice needed. (1 Viewer)

Joined
Nov 19, 2005
Messages
543
Location
Pasadena, CA
Hey all,

I had a shop do a cali legal swap on my fj60 and am having issues with the fuel tank. Could really use some collective mud help to get this thing back on the road as the shop took over 2 years to get it back.

it's got the carb referee sticker but have had some issues since i got it back a major one being the fuel tank leaks fuel when filled up.


Some context, it's an 83 fj60 with a 5.3 vortec running an external inline fuel pump.

I've pulled the tank and here's a wide picture
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issue # 1
The shop used some kind of epoxy to fab a plate for the fuel tank pressure sensor and the fuel level sensor, both needed for the evap system.
The epoxy has cracked and leaks when filled up. I'm not happy with this epoxy solution and was wondering how other cali smog legal swaps handled the fuel tank pressure sensor( black plug)and the fuel level sensor.( white plug)
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#2), the gm fuel level sender has been grafted onto the factory one. I believe the gm one needs to be setup like this so that the ecu knows when to and when not to run the evap system. the down side to this is that its hooked upto my speed hut gauges, but the signal is very inaccurate. it'll be full for most of the time then drop rapidly when its nearing an empty tank.
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Seems like some people use this unit
prd_346.jpg

, and it works great with the speed hut gauges,
i'd also like to use this unit to get a more accurate reading on my speed hut gauges but need to make sure the gm ecu is getting a right reading on the fuel levels for the evap system.

I was wondering if i could tap the gm fuel level sender wires into the tanks inc fuel sending unit and if i did would the gm ecu get an accurate reading? i'm not so tech saavy with ohms and resistance etc, but guess what i'm asking is, does the floatless fuel sending unit and the Gm system speak the same language?

Would love any other tips or advice, on the fuel tank setup for a cali smog legal swap.

lastly, the shop buggered the mating surface where the gasket for the fuel level sender sits on. this really pisses me off. i'm also thinking it's causing leaks, do you guys have any thoughts on how to repair this?
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hope this all makes sense and would really appreciate any input from anyone.

thanks again
Kevin
 
Joined
Jun 7, 2009
Messages
151
The stock fuel sender is not going to be compatible with the new-fangled sensors. It is basically a potentiometer that is designed to work with the fuel gauge.

It looks like those jokers took you to the laundry. The buggered mating surface can be helped with some stock gasket cork/rubber gasket material you can get from RockAuto for almost nothing - something like FEL-PRO 3026. - correction - your mating surface looks OK to me. That inside is not what seals.

What in the hell did they do with your stock sensor??
One possibility for that epoxy nightmare would be to silver solder something on there that would accept those sensors. A mating surface that you can actually seal and do R&R on.
You need to run separate wires for the fuel sender. What they did there just looks wrong. If it were me, I would incorporate a connection into the thing you solder on so you don't mess with your stock fuel sender.

The safest thing is to fill the tank up with water to make sure there is no possibility of explosion. Sucks to get it dry, but better than taking body parts off. Once you do that, just drain enough water to be able to solder the thing on.
 
Joined
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Messages
543
Location
Pasadena, CA
The stock fuel sender is not going to be compatible with the new-fangled sensors. It is basically a potentiometer that is designed to work with the fuel gauge.

It looks like those jokers took you to the laundry. The buggered mating surface can be helped with some stock gasket cork/rubber gasket material you can get from RockAuto for almost nothing - something like FEL-PRO 3026. - correction - your mating surface looks OK to me. That inside is not what seals.

What in the hell did they do with your stock sensor??
One possibility for that epoxy nightmare would be to silver solder something on there that would accept those sensors. A mating surface that you can actually seal and do R&R on.
You need to run separate wires for the fuel sender. What they did there just looks wrong. If it were me, I would incorporate a connection into the thing you solder on so you don't mess with your stock fuel sender.

The safest thing is to fill the tank up with water to make sure there is no possibility of explosion. Sucks to get it dry, but better than taking body parts off. Once you do that, just drain enough water to be able to solder the thing on.


Here is a thread by @orangefj45 , that shows what and why they did what they did to the fuel sending unit.


Normally there is nothing there, it's just a blank spot, so there isn't a stock sensor there.
 
Joined
Jun 7, 2009
Messages
151
So they cut a hole in your tank to put a connector and wires on. I feel the same way about that as the idiots that thank beating the hell out of the hub is how you get the cone washers off.

Does nobody have a conversion from the stock linear fuel sender to the GM unit? Then the whole thing just goes up front. Also, that evap sensor could have been TEEd into the lines coming off the side of the tank - no reason to screw up the integrity of the tank. You can get to those lines, If I remember correctly by taking the passenger side cover off in the back. There are 4 or 5 lines that go up.

Failing a converter, the link you sent seems like a very nice solution. Now that I think about it, there might be a real easy way to convert the 12V signal off the tank to the one GM needs. I PMed the guy to get some more info.
BTW was it a commercial outfit that did the conversion? If so, you should let other forum viewers be aware of these guys.

FuelTank.png
 
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Messages
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Thanks for your help, the tank pressure sensor teed off the side hoses going to the vapor seperator is a great idea , I'll see if I can find some kind of converter as well thanks for the help
 
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If you are going to change to a different sender one thing to note is that the LS series senders are usually 40-250ohm, but in some later year vortecs (2004+?) they switched to 250-40ohm, so before purchasing a new sender do a bit of research and figure out which one you need. I have seen some threads on other forums where people have converted a 0-90 to work. Also make sure to double check the new sender length vs the length you can actually fit into the tank.

The mating surface of the sender looks ok, as long as the bent lip area isn't interfering with the seal or pressing up on the sender it should be fine, maybe just clean the surfaces up and inspect the seal and if needed replace it.

The black fuel pressure sensor could be tapped into one of the lines going to the tank off the side, I believe there is a V8 swap thread that someone shows which line they used for this.

However I think the bigger issue is you now have two holes in the tank that you need to seal. Depending on the spacing of those two holes you may just want to switch to a using an in-tank fuel pump in that location using a tanks inc or similar retrofit kit, where either the mounting ring is welded in and you use a foam or cork gasket or some other kits use a no weld ring with a compression foam to make the seal. Many of the V8 swaps I have seen on here use the tanks inc kit, I used a FiTech/Hyperfuelsystems retrofit that uses the no weld method and initially had to battle some small leaks when full due to a torn o-ring, so I would probably recommend the weld-in ring with the normal seals like the tanks inc style if you can do so.

Obviously any sort of welding make sure the tank has properly been cleaned and dried before hand...

If you don't want to switch to an in-tank at that location, maybe consider the same idea of relocating the sensor and the fuel level connector to a plate that is bolted in with a good gasket in between instead of using the epoxy.

Regardless if you switch to intank or keep the pressure sensor and the fuel level connector there, if you haven't done so already I highly recommend adding an access door to the floor so you can access that area without dropping the tank if you don't already have one.
 
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Thanks for your insight @MrFitzie , need to learn how to use my multimeter to check ohm. I've also considered using fj 62 tank or the LRA long range tank, but worried about passing smog here in Cali

I'm a little paranoid of welding on the tank so would prob take it to a shop.. unfortunately the way they drilled the two holes, it's right up on the edge preventing me from using the tanks Inc no weld method..
 

MANUCHAO

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I've also considered using fj 62 tank or the LRA long range tank, but worried about passing smog here in Cali
Initially I used the 62 tank with intank fuel pump.... it works....
Smog guy would never know the difference....
with a custom tank... who knows.. is a hit and miss these days....
Using epoxy on your fuel tank is a bad bad idea... it eventually breaks down and ends up restricting fuel flow & pressure...
If a gasket is what you need use Nitrile rubber, also known Buna-N (plenty on Amz)
Ideally you want to mimic the GM set up...including the complete fuel pump module...it can easily be modded to fit the low profile of the OEM fuel tank...and it already comes with a fuel lever sender if ever want to upgrade your gauges..
This way no need to alter any of the wiring from whomever did your harness.
If you need to weld on that top part of the tank you might want to consider welding-in a Fuel Pump Module Mounting Ring.
I havent seen these on mild steel.. only SS and Alum, but would make the R&R so much easier.....
Good luck and we need to see pics of the engine bay... cause they never get old.....!!!!
 

87CRUSR

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Whichever route you take the fuel tank must not be compromised so invest $ where needed to avoid unwanted outcomes.
There is (was) a shop in San Bernardino that does fab work on fuel tanks and builds custom LR tanks as well.
 
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Here’s how I did mine. I drilled a hole in the plate and fitted a machined bushing (my son has a lathe). It’s held on with a circlip underneath, and is sealed with JB weld. I don’t have a pic of the GM sender, but it fits right into the bushing.

IMG_1626.jpg
IMG_1627.jpg
 
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Since the folks that did the conversion were able to pass CA emissions, they seemed to know what they were doing? What’s your gut feeling? Good intentions, bad execution? Maybe give them a chance to make it right. Redoing the plate and sealing it properly to the tank wouldn’t be that difficult IMHO.
 
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Initially I used the 62 tank with intank fuel pump.... it works....
Smog guy would never know the difference....
with a custom tank... who knows.. is a hit and miss these days....
Using epoxy on your fuel tank is a bad bad idea... it eventually breaks down and ends up restricting fuel flow & pressure...
If a gasket is what you need use Nitrile rubber, also known Buna-N (plenty on Amz)
Ideally you want to mimic the GM set up...including the complete fuel pump module...it can easily be modded to fit the low profile of the OEM fuel tank...and it already comes with a fuel lever sender if ever want to upgrade your gauges..
This way no need to alter any of the wiring from whomever did your harness.
If you need to weld on that top part of the tank you might want to consider welding-in a Fuel Pump Module Mounting Ring.
I havent seen these on mild steel.. only SS and Alum, but would make the R&R so much easier.....
Good luck and we need to see pics of the engine bay... cause they never get old.....!!!!

Hey Manu, thanks for chiming in, have read through your thread forward and backwards.

you said you initially went witht he 62 tank, did you change it to something else? i know you did the 80 frame swap, did you use an 80 tank as well?

thanks for the tips on the buna/nitrile im gonna definitely look into just using the gm assembly in the tank. probably take it somewhere to help fab up the welding/mounting.

i'll post a pic of the engine soon!
 
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Whichever route you take the fuel tank must not be compromised so invest $ where needed to avoid unwanted outcomes.
There is (was) a shop in San Bernardino that does fab work on fuel tanks and builds custom LR tanks as well.
whole heartedly agree, i've had the tank leak on me 2 times already, worst feeling seeing fuel pouring out of your truck with loved ones on board. felt very irresponsible and dangerous.
 
Joined
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Messages
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Since the folks that did the conversion were able to pass CA emissions, they seemed to know what they were doing? What’s your gut feeling? Good intentions, bad execution? Maybe give them a chance to make it right. Redoing the plate and sealing it properly to the tank wouldn’t be that difficult IMHO.

Good intentions, bad executions sums it up. Got the truck back initially, and was out at toquerville falls , and the power steering hose blew and had to do a trail fix getting covered in PS fluid, another time, i had fuel pouring out of the evap due to bad routing of the vapor separator, towed the truck out to them to fix it, second time i was out on a multi day trip in anzaborrego desert and found myself with fuel pouring out of my gas tank with my fiance on board. that really pissed me off. this is in addition to other safety issues i found on the build.

I rather fix it myself. my standard of work and attention to detail is much higher than the shops and I'm likely going to and have already redone a lot of stuff.
 

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