My 73 Series 3 Project

[ninescorpions]

The new tank was a tighter fit than the old one, but we got it in there. I found out the hard way that whomever had the tank out before (fixing a leak) did not put it back in with the right bolts and rubber washers. Anyways, we are fixing all of that in one swing.

[lumpydog]

Awesome work! That Land Rover won the lottery when you took it over. Keep the updates coming.

[ninescorpions]

Awesome work! That Land Rover won the lottery when you took it over. Keep the updates coming.

Thanks man. I will plumb up the tank either tomorrow or Monday. I need to marry that with motor mount replacement so I can start the beast!

[ninescorpions]

So got some good news today, followed by some not so good news and them some more not so good news.

The new tank sealant finally cured, so we plumbed up the tank and put fuel in it today. It has a new tank, new sender, tube sock, gaskets, etc. After sitting a month with her pants down, she fired right up with little effort (good news). Getting clean fuel out of the tank (as you would expect). However the fuel gauge is now about half of what it should read or somewhere in there. I put in about 5 gallons and I show 1/8 of a tank. In reality, I should be just under a half tank or at least 3/8. (bad news). I have read about multiple possible causes for this.

1. New sending unit and original fuel gauge are not compatible (gonna double checking my packaging, but what I am pretty sure I got was PLE494 which should be compatible. It is the only proline one for the S3.
2. Incorrect wiring of low fuel vs gauge. According to what I have read, T = gauge and W = warning light. That is how I have it wired. I have run a wire for low fuel, but not finished the wiring on the engine bay side for that yet. So no issue here that I can see.
3. Improper voltage at fuel gauge potentially due to voltage regulator. I have a hard time with this one since it was working before the swap
4. Defective sending unit

Any other potentials? One experiment I want to run is to compare impedance of the current sending unit (as it sits) vs my original sending unit. I was reading (in various threads) the resistance swing is somewhere around the 240 Ohm to 24 Ohm range (full to empty). I think this can help me narrow down if the sending unit seems to be working properly and that the issue is downstream.

Other bad news is that my LF hub gets hots after a 10 mile drive or so. Looks like works needs to be done there. (other bad news)

[lumpydog]

Try grounding the sender first. A new tank has fresh paint all around and is fairly well insulated from the chassis. The sender needs a good ground - this is usually established via the mounting screws to the tank, which is grounded via the tank's mounting hardware. Doesn't always work. Run a wire directly from one of the sender mounting screws to a bare metal contact on the chassis and see if that changes things.

Early lesson in Series ownership: Where electrical is concerned - it's all about the ground. Tip: make sure your battery ground to the chassis is clean and rust free. A little 600 sand paper on all contact points ensures the battery ground is clean and that's a good start. Don't allow paint between the ground contact and the chassis. Paint is an insulator.

On my truck I run a ground wire from the sender to the chassis. Ring terminal at both ends. Screwed into the chassis. Super accurate sender.

[ninescorpions]

Try grounding the sender first. A new tank has fresh paint all around and is fairly well isolated from the chassis. The sender needs a good ground - this is usually established via the mounting screws to the tank, which is grounded via the tank's mounting hardware. Doesn't always work. Run a wire directly from one of the sender mounting screws to a bare metal contact on the chassis and see if that changes things.

Early lesson in Series ownership: Where electrical is concerned - it's all about the ground. Tip: make sure your battery ground to the chassis is clean and rust free. A little 600 sand paper on all contact points ensures the battery ground is clean and that's a good start. Don't allow paint between the ground contact and the chassis. Paint is an isolator.

On my truck I run a ground wire from the sender to the chassis. Ring terminal at both ends. Screwed into the chassis. Super accurate sender.

Excellent points. I did ponder the grounding (closed circuit) that the sender in the tank is utilizing, but didn't spend any time on it. I am surprised that the design would not come with a wire connection specifically for ground, but then again the alternator is designed in a similar way. I still have the passenger seat out...so that is a quick go-do kinda thing. I realized how little is between you and the road when I took off today for a test drive and some dust was coming up from around the gas tank and I realized that I could look down at the road...lol.

I installed a new battery ground line to chassis...actually that was the first thing I did to this beast.

[SafeAirOne]

If you have the sender wired backwards (ground where power should be, power where ground should be), you'll get wonky readings. Mine always showed a half a tank when actually full with the wiring reversed.

[lumpydog]

If you have the sender wired backwards (ground where power should be, power where ground should be), you'll get wonky readings. Mine always showed a half a tank when actually full with the wiring reversed.

Some of the petrol senders (Late 2a and 3s) have only a single terminal and use the tank itself as a ground - I was referring to this setup in my post!

[SafeAirOne]

Some of the petrol senders (Late 2a and 3s) have only a single terminal and use the tank itself as a ground - I was referring to this setup in my post!

My SIII tank is one of the cam-locking sender-type tanks and has (or used to have, anyway) a ground tab on the top surface of the sender.

[2roverlabs]

Let me know if you solve the problem and how. I just posted a similar problem - installed new tank (multiple coats of rust protection applied to the outside of the tank - insulator?) and new ProLine sender. Sender barely registers....

[2roverlabs]

ProLine sender I installed was moving slowly and registered only a fraction of the fuel in the tank. I took Lumpydog's advice and ran a ground from the fixing bolt on the sender to the chassis. The sender/fuel gauge now responds quickly but now registers that the tank is full when it only has 5 gallons...Thoughts?

[SafeAirOne]

ProLine sender I installed was moving slowly and registered only a fraction of the fuel in the tank. I took Lumpydog's advice and ran a ground from the fixing bolt on the sender to the chassis. The sender/fuel gauge now responds quickly but now registers that the tank is full when it only has 5 gallons...Thoughts?

Did it perform correctly before you installed it in the tank?

[lumpydog]

Did it perform correctly before you installed it in the tank?

I just replied to the other thread with a similar thought...

It's worth noting that my first challenge/problem with my (then-new-to-me) Series 2a was the fuel sender. Mark (SafeAir) helped me fix it (and many other issues since then as well!)

[ninescorpions]

Sorry guys for being so slow...got caught up in other projects. Anyhow, before I parked the LR for a while...I ran a wire directly from the top of the sender (all metal) by using a ring connector on one of the sender screws...and then I ran that wire directly to the battery negative terminal. It made no change whatsoever...I am still getting very low reading and slow to respond. In theory...negative batt and chassis are the same and I already replaced the negative battery wire to chassis. But just for S&G's, I will run one now directly to chassis. If that does not work, I intend to drain the tank...pull the new sender and then attach the float to my old sender and run it up the flag pole.

Looks like I am going to need to replace the front wheel bearings...so I need to get past the fuel so I can tackle that. On my last test drive (about 10 miles), I found some good and some bad stuff:

Good:
-With the new alternator and wiring, my signal lights now flash faster. Sweet! Actually, (as you would expect) all lights are brighter
-Much smoother idle with new motor mounts
-I now have two side mirrors thanks to Ike...but still not enough miles to trust them. I guess since I drive slow...you always feel like you are getting run over from traffic behind.
-My dog loves getting in the back...but bounces around like a pinball which I find entertaining.

Bad:
-Tranny wants to pop out of 2nd great under deceleration (high or low range). I also seem to have a leak around the rear seal of the tranny. From what I was reading, both of these may be linked to the rear nut coming loose.
-Front hubs are getting hot...went back to the shop notes and they put in new seals, but not new bearings. I am about 90% sure they are in need of replacement. Hopefully the races are not loose on the hub...I do not want to replace the hubs.


I feel I am close to actually being able to drive this thing with some confidence.

[ninescorpions]

Did it perform correctly before you installed it in the tank?

Mine did