Low fuel indicator light *&#!!! + fuel sock info (1 Viewer)

[spartan]

A while back low fuel indicator light came on and stayed on. Gauge worked fine, but low fuel indicator light was on from full to empty and everywhere in between.

So I check around and some knowledgeable folks tell me it's a bad sensor in the tank. Of course this tiny little sensor is part of the entire fuel float level / gauge sending unit. So I figure OK - I'll replace it and that PM fuel sock item that I've been reading so much about.

Couple of hundred bucks later I get all the new parts from Cdan for the job and dig in. Pull the seats, the carpet and do a nice clean job getting everything out and back in - except the fuel sock - more on that in a moment. New fuel tank gauge sending unit, electrical connection screws, banjo fitting gaskets, fuel pump housing cover gasket. Button it all up and sure enough the low fuel indicator light is off and the gauge is working.

One week later the low fuel indicator light came back on full time and has stayed that way since. Anybody else have this experience or any ideas?

And then there's the infamous fuel sock. The part that I got didn't fit. It wouldn't go on no matter how hard I tried. The fitting was too large for the inside diameter of the opening on the new sock. No way was it going on. Too small. The old one was clean as a whistle other than some discoloration so it went back on and I threw the new POS away.

FYI I triple checked the fuel sock part number before and after the fact just for the record. Moral of that story on the fuel sock is - I wouldn't worry about it unless it's screwed up. It's a lot of work to get at just to have to throw the new one away.

 

[Ebag333]

You'd have to check the EWD to be sure, but I'd suspect that the light comes on when grounded. So I would guess that something is shorting to ground, which causes the light to come on.

 

[spartan]

Thanks for the response. MMMM - it's early. Whats' the EWD please? :0

 

[dannyp]

Electrical wiring diagram.

 

[Schwein]

the electrical wiring diagram

 

[spartan]

Thanks folks. Will dig it up.

 

[maronism]

I've been fighting the same gremlin. Changed out the float with a new sensor, and no change. Been trying to track down the short or fault otherwise.

 

[JohnR]

There are only 3 connectors between the fuel tank and the ecu. The one at the fuel tank directly, b01 (iirc) underneath the rear driver's side door (by the rear tire), then driver's side kick panel (ID2) , then instrument cluster. It's the RED wire. I literally just did all this today for the fuel sender. I traced it from b01 (rear tire) then to the fuel tank, opened the tank and pulled the pump/sender assembly. Opened up the little box that holds the fuel sender wire-round resistor / potentiometer. My gauge was always at E, with 16megaohm resistance. Ha. It must have sat for a while, I sprayed it down with carb cleaner and moved it back and forth a good 20 times, then tested it. Worked like a champ. I also 'tweaked' the sender to read E later (closer to the truth). The low-fuel sensor seems to just be a capacitor using the fuel as a dielectric.

A very handy habbit I picked up long ago makes me put dielectric grease in every connector I touch!

 

[jonheld]

And then there's the infamous fuel sock. The part that I got didn't fit. It wouldn't go on no matter how hard I tried. The fitting was too large for the inside diameter of the opening on the new sock. No way was it going on. Too small. The old one was clean as a whistle other than some discoloration so it went back on and I threw the new POS away.

FYI I triple checked the fuel sock part number before and after the fact just for the record. Moral of that story on the fuel sock is - I wouldn't worry about it unless it's screwed up. It's a lot of work to get at just to have to throw the new one away.

FWIW you're not the first one to change out the pre-filter on the pump. It has been done countless times by countless others without issue. I suspect either the wrong parts were shipped or the PO replaced the fuel pump with a non-OEM unit.
The pre-filter is easy to change and is a 100K mile maintenace item. It shouldn't be overlooked.

You also could have reached out to Dan and I'm certain he would have taken the parts back as a return. Throwing new parts away because you couldn't get them to work sounds a bit silly to me.

 

[JohnR]

I may add, I've used seafoam recently, and added 1/2 bottle to maybe 15 gallons of gas. The fuel sock was brand spanking new looking. I don't know if the seafoam did it, or the PO had the tank / sock serviced in the past. But the tank was sparkling!

 

[Ebag333]

I also 'tweaked' the sender to read E later (closer to the truth).

FYI the fuel sensor is calibrated to trigger when 5 gallons (exactly) are left. If you 'tweaked' it (why the quotes? is it a euphemism for something?), then it will read closer to true empty, but it's no longer calibrated (unless you drained the tank, then slowly filled to see how much fuel is in there when it comes on).

 

[JohnR]

Not the low-fuel light, the actual sender. I've read on here they are set very high from the factory, meaning it shows empty before the light comes on. I lowered the float, so that the light will turn on, when it reads E. There is a seperate sensor for the low-fuel lamp, than the rheostat gauge.

 

[bdac]

I lowered the float, so that the light will turn on, when it reads E. There is a seperate sensor for the low-fuel lamp, than the rheostat gauge.

How did you adjust the float? My gas gauge is on E and only filled up 16.1 gallons today. I'm fairly certain that my float is sitting too high. When the gauge reads half tank I only fill up 7 gallons of fuel.

 

[pnolanIH8MUD]

So my mechanic replaced the Low Fuel Sending Unit. The Sending unit was NOT malfunctioning but we replaced it for good measure. Well, the Low Fuel Sending Light is still on. We checked and found that the Base Plate for the sending unit appears to have continuity from each of the posts to ground. Yes, some sort of short. Anyone know if this is normal or how this base plate could be shorting?? At this point, I don't know what to try.

 

[spartan]

Just noticed this thread again.

Jonheld - I ordered the parts from Cdan. He triple checked the part number. Right part number - did not fit. Measured with calipers and fittings didn't match. Filter id opening .043" too small or so to go on the male fitting. Talked to Cdan and he didn't have any ideas. Would have cost more to send it back than the filter. Trash.

I've been working on motorcycles, cars and trucks for over 40 years. The filter did not fit.

I'll send you an auto trader if you want....LOL

 

[pnolanIH8MUD]

Light is still on. We replaced the sending unit twice and still no luck. It appears the fuel tank cover is grounding somehow but HOW? What could possibly begin to short on the fuel tank cover? We checked the wires and connectors. Is there anything to physically "wear" to cause a short?

 

[CycloSteve]

One of the wires from the plug at the fuel tank cover goes to one of the bolts holding down the cover itself IIRC. This would be the grounding point, and if that wire, or that connector was broken you could have an intermittent grounding issue. Check the ground at the plug going back into the harness and gauges, and check the ground/continuity you get between the plug on the tank side and that bolt.

The only short that I can think of would be between the wire from the low-fuel sender to the chassis/tank cover as it passes through the cover itself. What sort of condition are the pass-throughs? Cracked, split, or otherwise compromised?



Steve

 

[spartan]

Mine is still on - I've basically given up on this one. An electrical guru could maybe figure it out, but that I'm not. Maybe it will burn out soon. LOL