Can I swap this...???

[N.E fjord-by-fjord 2fiddy]

I have a bad rear tank pickup unit from the crap rear tank of my '94... (right)

...and a functional sending unit from the rear tank of my '88 f150 gasser....

I asked in another thread about something else, but got a vague answer as to how I would go about making the gasser unit work in my diesel's tank... All it did was confuse me, really...

Also, the gasser's unit has a plug connector ON the unit... whereas the diesel's has 4 wires coming out, and a connector about a foot from the send/pickup unit... (2nd pic)
I know I would have to wire the old connector to the gasser's connector to make it work...

What I'm really wondering is the steps I would need to take to convert the gas sender to work for the IDI...

So can I even do this? Or should I just buy a new, appropriate rear pickup unit for the IDI, and just use the good TANK from the gasser...?

Opinions? Instructions? ....Insults? Whaddya got OB's?

You must be registered for see images attach

You must be registered for see images attach

 

[riotwarrior]

Sending unit on diesel is different than gas, IIRC.

Find a replacement diesel tank or pickup to make it the best transition

It can be made to work, it's just sorting out the wiring and such. removing pump and adding extended pickup tube in place of pump.

 

[N.E fjord-by-fjord 2fiddy]

I figured that might be the case. My DIY side always starts the project... But sometimes the wallet HAS to get involved.

Any reason the gasser's tank wouldn't work in the IDI? Seems the same as the crap tank i took out...

 

[ifrythings]

The parts truck I got has gasser tanks in it, including sending units and fill tubes, ran perfectly fine, I haven't pulled the sending unit so not sure what they did with the fuel pump.

The connector changed on the obs trucks to the remote plug, just look at your bad sending unit, you'll see one wire directly connected to the metal and the other will go to the sender, just match them up on the gasser unit and ignore the fuel pump.

 

[LCAM-01XA]

Also, the gasser's unit has a plug connector ON the unit... whereas the diesel's has 4 wires coming out, and a connector about a foot from the send/pickup unit...

That's not a gas vs. diesel thing it's a brick ('91-down) vs. OBS ('92-up) thing. OBS trucks also got braided flex fuel lines and stainless tubing, the entire sender/pickup unit is also stainless. I run a PSD unit in the front tank of my brick truck, like a moron I didn't grab the proper connector so I had to hardwire the new sender to the factory harness - works good except that if I ever have to drop the tank I'll have to pull the sender/pickup from it on the ground under the truck. I got a rear PSD sender/pickup unit ready to go in also, and I got the wiring manual for a brick truck - I can match the two tomorrow and tell you what to splice with what. Hope you can wait, brain is fried right now so chance of erroneous information is unacceptably high.

As for actually plumbing the gasser sender/pickup into the diesel, the lines should match up, 3/8" supply and 5/16" return. Then to bypass the pump it looks like all you'll need to do is run a piece of steel line in its place. Bend it down at the end and either reuse the diesel "shower head" or run a short hose to a brass T-ee fitting. I'll see if I can find my bronco sender/pickup (obviously gasser) and test that for you tomorrow also.

 

[N.E fjord-by-fjord 2fiddy]

I've got tube and a tee fitting ready to go for the gas unit... The old diesel sender was so corroded, i thought the 4 wire remote connector wire on the round mounting plate was just rusted on there.. (not knowing about the 92+/- part change)... I pried it off, only to realize that the remote connector was supposed to be a fixed piece.

So now the old unit has four empty holes in the top of the plate, and no wires for me to reference when splicing the remote connector wire onto the gasser sender....

So I guess at this stage, I just am trying to figure out what terminals on the gas sender to hook to what wires coming out of the remote connector...

I guess the silver lining is that now my gas sender will be '92+ compatible with that remote connector on it

I'll get pics up of the color wires coming out of the connector, and the gasser's terminals....

I wonder if a volt meter with the key in the on position would yield any pertinent information....? I really want to get this done today, as it is the first step in the reassembly process of my multi-fix project right now...

You must be registered for see images attach

 

[N.E fjord-by-fjord 2fiddy]

So... It was easier than I thought it would be.....

I inspected the midship tank sender (they really should call it a "sucker" on a diesel... it's doesn't "send" anything...)
...all connections except the yellow wire for the tank reader end at the mounting plate (grounded)

So I:

1: Removed the sender from the gasser's 3/8" tube (detach 2 electrical conn., unbolt @ bottom, uncrimp top cinch, and remove black tube from metal tube)
2: Figured the distance from the center of the mounting hole for the sender tube to the bottom depression of the tank where the pickup tube would sit... (roughly 9" horizontal); also, if it makes it easier for anyone else, just figure that the bottom of your pickup tube should sit as close to the floater on the end of the arm for the level indicator when it's at the low end of it's range... It's meant to end up right next to wherever that fill tube is sitting when the fuel is used up, so you don't have to measure really, just get the tip of your tube to sit next to where the floater is when gravity doe it's thing...
3: Splice yellow>yellow, black>black, and just isolate the other wires, since they're doin' jack now...

Voila! A gas unit converted for diesel, with '92+ remote connector...

Took me about 10 minutes to figure out, and 30 min to do. (working on the ground with disorganized tools...)

Here's the pictures:

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

 

[N.E fjord-by-fjord 2fiddy]

Now a little rust removal and protective paint on the unit's top, and syphon out and let dry the gasser's tank... She'll be all set!

Thanks for the tips... As always, coming on here gave me confidence, and direction... and saved me some $$$.

 

[Knuckledragger]

You may want to examine the gasser tank before installing it. Most were galvanized inside and out for rust prevention, but diesel fuel reacts poorly with zinc, the primary ingredient in the galvanized coating.

 

[N.E fjord-by-fjord 2fiddy]

The outside of the gasser tank is showing some minor rust spots... would that be enough evidence to safely assume it's not galvanized?

...also, after I empty it, is there an easy way to test if the inside is galvanized?

 

[laserjock]

You may want to examine the gasser tank before installing it. Most were galvanized inside and out for rust prevention, but diesel fuel reacts poorly with zinc, the primary ingredient in the galvanized coating.

You know, I have heard that said several times but nobody has ever mentioned a reason for it. Just curious if you know why it should be a problem. The chemist in me says it's hydrocarbons mainly, why should it care what the tank is made out of so long as it doesn't disolve (incompatible plastics etc). If it was high in sulfur content I could possibly see an issue because zinc might be attacked by the sulfur causing sediment to form in the tank. Just curious.

 

[LCAM-01XA]

No idea how to check for galvanization, my tanks are aftermarket and use different coating and it works for both fuels.

The "sender" part of the thing is the rheostat the float arm is attached to, it's short for "fuel level sending unit". Many vehicles have the fuel level sending unit and the fuel pickup unit as two separate assemblies, since the advent of in-tank electric fuel pumps most manufacturers tend to combine these into one big assembly to make packaging easier and installation faster, but that's not always the case (Fox-body Mustangs for example). The "sender" name got adopted for the combination assembly, as it sends out both signal for fuel level to the gauge (via the rheostat) and fuel itself to the engine (via the e-pump).

And since I mentioned E-pumps, the one in question here is a low-pressure lift pump, its purpose is to move fuel from the tank and feed it into a frame-mounted high-pressure pump which gives the 40psi the gasser injectors need to work properly. There is a low-pressure pump in each tank, the switching of the tanks is handled by this odd-looking pressure-operated mechanical valve that also has a filter built in it, and only after that comes the high-pressure pump. So I'm wondering, couldn't we use this same setup in our IDS, minus the high-pressure pump of course - we get rid of the somewhat problematic tank selector valve, we gain all advantages of an e-pump setup, and now there are two e-pumps so should one fail there is always a backup at the ready in the other tank. That is of course assuming the pumps are diesel-compatible, which I wouldn't be surprised if they hold up fine...

 

[N.E fjord-by-fjord 2fiddy]

Thank you for correcting the noob on where the name sender comes from... (not sarcasm)
Now I can stop spouting off like a *******...

So in your idea, you're basically just replacing everything before the mechanical lift/electric pump by the filter head with a gasser setup? (except that 40psi pump...)

Sorry if i'm not getting it... I'm assuming if the mechanical valve you're talking about is pressure operated, that it's the tank pumps that are controlling the switchover... Is that how the gas delivery system works? Did you literally just say that and I repeated it? Jeez... I'm way too tired.

The reason I'm trying to understand, (and if I DO understand correctly, why i seem so interested...) is because I think it's my tank selector valve that's been giving me air issues. I've just about replaced everything else! That, coupled with the fact that I have a dual tank gas donor truck that I'll be scrapping soon.... Makes me VERY curious about the whole theory...

The questions the skeptic in me instantly asks are:

If this setup WOULD work, why didn't they just use it for all their trucks... gas and diesel alike?
Wouldn't that have saved Ford a LOT of money, just having one setup for everything?

To me, it seems like if they were willing to spend all that $$$ to develop diesel and gas specific systems, there HAS to be some reason the idea wouldn't work... (cue disclaimer: "I AM NO EXPERT") Not trying to rain on the parade. If anything I wan't it to be true.

Could fuel viscosity/lubricity have something to do with that pressure valve maybe not operating the same with diesel, you think?

Now i feel like i'm WAY outta my league in this conversation.
Talk amongst yourselves...

 

[N.E fjord-by-fjord 2fiddy]

Just found this regarding the galvanization/diesel issue:

http://www.bigmacktrucks.com/index.php?/topic/10996-galvanized-steel-tank/

POST #5...
POST #15...

It's enough of a testimonial/reason for me not to be trying that galvanized tank... Not if it's gonna mess up my injection system...

 

[LCAM-01XA]

So in your idea, you're basically just replacing everything before the mechanical lift/electric pump by the filter head with a gasser setup? (except that 40psi pump...)

Yes, and then bypass the mechanical pump on the engine and run a hose from the line on the frame up straight to the filter head.

Sorry if i'm not getting it... I'm assuming if the mechanical valve you're talking about is pressure operated, that it's the tank pumps that are controlling the switchover... Is that how the gas delivery system works? Did you literally just say that and I repeated it? Jeez... I'm way too tired.

Yes, the way I understand is it's exactly how it works. Besides, you have two pair of fuel lines coming in and one pair coming out, and there are no electrical connections on the unit - switchover gotta be mechanical via pressure, no other way to do it.

If this setup WOULD work, why didn't they just use it for all their trucks... gas and diesel alike?
Wouldn't that have saved Ford a LOT of money, just having one setup for everything?

To me, it seems like if they were willing to spend all that $$$ to develop diesel and gas specific systems, there HAS to be some reason the idea wouldn't work... (cue disclaimer: "I AM NO EXPERT") Not trying to rain on the parade. If anything I wan't it to be true.

Actually no, it would have cost them lots of money - a diesel has nothing but simple lines, one electric switchover valve, and the $20 Carter pump on the engine. The gasser has the same lines, mechanical switchover valve (not cheap either), but now two pumps in the tanks, along with their wiring. Later gassers did away with the switchover valve altogether, I think they have some valves built in their sender units and the fuel flow takes path of least resistance in the return line (pump no run -> valve closed -> fuel goes thru line with tank with pump running and valve open). I can tell you tho that if you disconnect the lines on one of those newer ones and drop a tank, if you try to drive the truck off the remaining tank it will suck fuel from it but it will return it thru the now-open return line of the removed tank, and dump it on the ground. Plug the line tho and she will return fuel back to the tank it came from.

Could fuel viscosity/lubricity have something to do with that pressure valve maybe not operating the same with diesel, you think?

Doubt it, from what I've seen diesel is quite as liquid (and thus ready to leak in your face) as gasoline is. May be the rubber the switchover valve seals are made of is degradable by diesel in the long run. Or maybe it works just fine and they simply went with the cheaper setup.