Trans Change, Now Fuel Gauge is funky

SPL Neon · Post by **SPL Neon** » Sat Oct 05, 2013 1:01 pm

Hey guys, just swapped in another atx trans into my 2000 winter car and now the Fuel gauge will go to E when accelerating, and will go to Full when the brakes are applied. Any idea which wire or Ground got messed up during this Process. I tried adding a ground from the Batt - to the strut tower, but that didn't help. The sh!tty ground from the Battery Tray to Starter bolt is broke, would this cause this problem? All other Motor to chassis grounds look good on the passenger side. Any help is appreciated
Oh, forgot that the speedo sensor got broke in the process so it isn't plugged in.

Post by **occasional demons** » Sat Oct 05, 2013 3:06 pm

Interesting.

The actual wire that goes from the FP module to the gauge doesn't even go into the engine bay area.

Should go from the cluster down the driverside foot area and to the rear of the car. Maybe check the ground for the FP module connector. Although the fuel pump may also have issues if the ground is faulty there.

Or there is a power issue with/within the cluster. Is there any damage to the VSS sensor plug? Possibly it is somehow affecting the cluster.

SPL Neon · Post by **SPL Neon** » Sat Oct 05, 2013 4:12 pm

The VSS plug is still fine, it is really baffeling me lol

NickKo · Post by **NickKo** » Sat Oct 05, 2013 5:29 pm

My guess is that these two issues, are dis-related, and happened at the same time, due to coincidence.

BUT as long as we are talking about grounds - Be sure to dismantle and clean the ground leads that attach near the driver's side headlamps, on the upper radiator core support.
Those 'ground' some of the drivers in the PCM, as well as other functions & accessories, and they are very important.

CAUTION / IMPORTANT:
Do NOT operate any accessories, while these grounds are disconnected - even with the key switched 'off' !!!

Clean the attachment points on the upper radiator core support, down to bare metal.
Wire brush / clean the wire lugs for these grounds, too.... As well as the attaching hardware or screws / bolts.

After putting these back together - I usually put a bit of PB Blaster on them, to slow down corrosion - AND slather on a generous coat of Vaseline, dielectric grease, or Mobil One grease afterwards - to keep corrosion away.

I wouldn't be surprised if cleaning these grounds, fixes the problem.
It might not, but since these grounds are so critical - and usually neglected - Cleaning them is a very good idea, and it's all the excuse you need.

- Nick

SPL Neon · Post by **SPL Neon** » Sat Oct 05, 2013 9:24 pm

That is funny, cause I was looking at those grounds thinking " I should really clen them up ". Ill do that in the morning and see how it goes. Thanks!

SPL Neon · Post by **SPL Neon** » Sun Oct 06, 2013 3:29 pm

cleaned up the ground above with the same results with the fuel gauge. its raining out so didnt want to lay in the driveway to check the ground strap that attaches to the FPR/Filter.

MichNeon · Post by **MichNeon** » Sun Oct 06, 2013 4:53 pm

There is a separate ground (circuit Z2) for the fuel level sending unit, it is G303, which terminates at the ground point on the left rear wheelhouse near the left taillight. That is what i'm seeing on the wiring diagram on TechConnect. The other ground (circuit Z1) is for the pump itself.

https://w05.dealerconnect.chrysler.com/ ... 011965.gif

SPL Neon · Post by **SPL Neon** » Thu Oct 10, 2013 11:45 am

Awesome, I will clean that ground and see if that works. I do know the Taillight seals Leak, so maybe some corrosion has occured! Thanks!

NickKo · Post by **NickKo** » Sat Oct 12, 2013 12:26 am

SPL Neon wrote:Awesome, I will clean that ground and see if that works. I do know the Taillight seals Leak, so maybe some corrosion has occured! Thanks!

I wouldn't be surprised if fixing this, cures the issue !!

Please keep us posted.

- Nick

SPL Neon · Post by **SPL Neon** » Sat Oct 12, 2013 1:54 pm

So I cleaned that ground, which looked ok, and the one wire ground on the Passenger side rear near the taillight and it was real rusty, then while I was at it, I cleaned all the other Chassis grounds I could find and the fuel guage seems a little better but it is still fluctuating a bit during acceleration and Braking. I'm starting to think its a problem in the tank, that just happen'd to happen during the trans change. Ill wait till the fuel pump fails before yanking it apart. I wish it had have been a Ground problem though. All is not lost though, at least I know the grounds are good on the car lol.

MichNeon · Post by **MichNeon** » Sat Oct 12, 2013 7:58 pm

The one thing that i'm thinking now is, have you ever noticed the movement before the work you just did?
If i understand correctly, the plastic tanks do not have any baffles in them. I really do not know yet, as i have not been in a plastic tank yet. I've been in the metal tank of my 95, it does not have any baffles. I've noticed any hard acceleration, braking, and cornering will make the gas move around, and cause the float to move, as well.
My R/T's gas gauge shows some movement under those conditions. It will even show when parked on an incline or hill. Where i park at my job, has a slight incline, the needle drops a little. When i pull out of the spot to level road, it moves back up. I'm wondering if what you're seeing is just normal, and you've never really noticed it before.
Also, it would be more noticeable if you're always running about around the 1/4 mark.

NickKo · Post by **NickKo** » Sun Oct 13, 2013 9:20 am

MichNeon wrote: If i understand correctly, the plastic tanks do not have any baffles in them. I really do not know yet, as i have not been in a plastic tank yet. I've been in the metal tank of my 95, it does not have any baffles. I've noticed any hard acceleration, braking, and cornering will make the gas move around, and cause the float to move, as well.
My R/T's gas gauge shows some movement under those conditions. It will even show when parked on an incline or hill. Where i park at my job, has a slight incline, the needle drops a little. When i pull out of the spot to level road, it moves back up. I'm wondering if what you're seeing is just normal, and you've never really noticed it before.
Also, it would be more noticeable if you're always running about around the 1/4 mark.

MichNeon is correct ..... There are no baffles whatsoever in a plastic tank.

Also, if you are one of those folks who drive around on a 1/4 tank ( I know a few), yes, that will aggravate the 'fuel sloshing'.

SPL Neon wrote:So I cleaned that ground, which looked ok, and the one
wire ground on the Passenger side rear near the taillight and it was real rusty, then while I was at it, I cleaned all the other Chassis grounds I could find and the fuel guage seems a little better but it is still fluctuating a bit during acceleration and Braking. I'm starting to think its a problem in the tank, that just happen'd to happen during the trans change. Ill wait till the fuel pump fails before yanking it apart. I wish it had have been a Ground problem though. All is not lost though, at least I know the grounds are good on the car lol.

It sounds like the gauge has 'improved' somewhat ??

If so, it sounds like you are on the right track.

You might want to try re-cleaning the trunk ground..... Get it down to bare metal, and wire brush the heck out of the wire lug and clean (or replace) the attaching screw / bolt, too.
A Dremel Tool, would work great for this.

- Nick

SPL Neon · Post by **SPL Neon** » Sun Oct 13, 2013 5:25 pm

It does it with 3/4 tank or 1/4 tank lol, it didn't have this much movement before. The Trunk grounds are down to bare metal too, I am also wondering if there could be sludge or varnish on the level sensor as this car sat for a year with 3/4 tank before I bought it. I drove it for a month before swapping the trans, so I would have thought any sludge would have shown up right away?! I threw in some Fuel system cleaner just in case it is sludge on the level sender.

NickKo wrote:
MichNeon wrote: If i understand correctly, the plastic tanks do not have any baffles in them. I really do not know yet, as i have not been in a plastic tank yet. I've been in the metal tank of my 95, it does not have any baffles. I've noticed any hard acceleration, braking, and cornering will make the gas move around, and cause the float to move, as well.
My R/T's gas gauge shows some movement under those conditions. It will even show when parked on an incline or hill. Where i park at my job, has a slight incline, the needle drops a little. When i pull out of the spot to level road, it moves back up. I'm wondering if what you're seeing is just normal, and you've never really noticed it before.
Also, it would be more noticeable if you're always running about around the 1/4 mark.
MichNeon is correct ..... There are no baffles whatsoever in a plastic tank.

Also, if you are one of those folks who drive around on a 1/4 tank ( I know a few), yes, that will aggravate the 'fuel sloshing'.

SPL Neon wrote:So I cleaned that ground, which looked ok, and the one
wire ground on the Passenger side rear near the taillight and it was real rusty, then while I was at it, I cleaned all the other Chassis grounds I could find and the fuel guage seems a little better but it is still fluctuating a bit during acceleration and Braking. I'm starting to think its a problem in the tank, that just happen'd to happen during the trans change. Ill wait till the fuel pump fails before yanking it apart. I wish it had have been a Ground problem though. All is not lost though, at least I know the grounds are good on the car lol.
It sounds like the gauge has 'improved' somewhat ??
If so, it sounds like you are on the right track.

You might want to try re-cleaning the trunk ground..... Get it down to bare metal, and wire brush the heck out of the wire lug and clean (or replace) the attaching screw / bolt, too.
A Dremel Tool, would work great for this.

- Nick

MichNeon · Post by **MichNeon** » Sun Oct 13, 2013 5:55 pm

Thank you, Nickko for the info.

SPL, that would be a good theory. When i put a new pump/sender assembly in my 95, at first the gas gauge was acting strange, then after a few tanks, it started acting normal. I think that if there is something on the resistor surface, it can cause the sender to be erratic. With mine, it was because it was new, and needed to break in a little.

SPL Neon · Post by **SPL Neon** » Sat Oct 19, 2013 8:56 pm

Ok, Im driving this car now for a while, as my wife has been using it I Noticed on Some FM radio channels, a crackle that is RPM dependand no I know there is a module on the back of the head to suppress this ignition interference, would any of that cause electrical problems for the fuel gauge?

MichNeon · Post by **MichNeon** » Sat Oct 19, 2013 10:34 pm

SPL, that is a good question. I don't know enough about rfi to be able to answer your question with confidence. However, rfi is known to cause problems in wiring, which is why the spark plug wires are designed to suppress rfi.
I don't think that the rfi could corrupt the signal from the fuel level sender, since the wiring harness that carries that particular wire does not travel anywhere close to the head. According to the wiring diagram i just looked at, the fuel level sending unit sends the info directly to the instrument cluster.

SPL Neon · Post by **SPL Neon** » Sat Oct 19, 2013 10:41 pm

yeah, it has got me baffled; im not sure what else to try other than dropping the tank. now that i am driving the car, im not too concerned about the gauge fluxuation tho lol.

SPL Neon · Post by **SPL Neon** » Mon Oct 21, 2013 5:24 pm

So I re-cleaned the Batt to Starter Bolt - connection and I also cleaned the Ignition/Radio Interference Module (the spade and female were green on this, so its good and clean now) Have not road tested yet tho lol

SPL Neon · Post by **SPL Neon** » Wed Oct 23, 2013 11:57 am

No dice. Filled the car yesterday and it doesnt read quite full, so it has got to be in the tank.