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Topic: fuel guage problem,, i think (Read 1027 times) previous topic - next topic

fuel guage problem,, i think

While i was unemployed , i started up my garage for side cash and charged 15 an hour no matter what the job. 

I went out on a house call (30/hr) on a 99 mustang that would not start.  I spoon fed the info to the "mechanically inclined owner and he still did not try the things i said. 

the problem,- car cranks but wont start

findings
fuel guage says 1/4 tank
car is sitting at a 25deg angle nose slightly down.
spark is arriving at the plugs nice and bluish white in color

fuel presure tester says 0 psi
turn key on and i hear the pump and the relay

roll car down to a level area and it starts:D

Problem solved in about 12 minutes.

I noticed something and here is my question.  I noticed that his fuel guage said 1/4 tank but when i turned the key on,, it dropped to almost 1/16 of a tank.

i turn the key off and the needle goes up again.  Im like, wtf

Somehow i just happened to notice that the very same thing happens to my wifes bronco. 

Is something broken?  I turn the key on in the bronco and the fuel level drops a little.  I turn the key off and it rises.

is this normal or acceptable?

fuel guage problem,, i think

Reply #1
I would say it's normal. I think it even mentions that condition in the owner's manual somewhere
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

fuel guage problem,, i think

Reply #2
the technology behind the system must be different in the mustang and bronco vs my cougar.

on level ground my bronco does this.  The cougar does not do this at all.
When we turn out keys off, the gas needle transitions to the below "E" position.  On that one mustang and my bronco, the gas needle maintains a reading after the key is truned off.

fuel guage problem,, i think

Reply #3
Ours are the heated-bimetal type. No current, no heat, drop to zero.
Maybe the newer ones are the magnetic type, with a pair of "balanced" coils to position the needle?
Death awaits you all with nasty, big, pointy teeth.

1988 5.0 Bird, mostly stock, partly not, now gone to T-Bird heaven.
1990 Volvo 740GL. 114 tire-shredding horsies, baby!

fuel guage problem,, i think

Reply #4
Mine reads E all the time haha. Do parts stores sell sending units?
"Real cars dont power the front wheels, they lift them"
[SIGPIC][/SIGPIC]
1984 Mercury Cougar GS 5.0:cougarsmily: BBK Equal Length Shorties, BBK O/R X-Pipe, Magnaflow Magnapacks, Mustang GT Stainless Tailpipes, 18" Magnaflow Rolled Edge Tips. Turbo Coupe Hood, Mach 1 Chin Spoiler. 17"x9" Cobra R's, Falken Ziex 255/50s, and 245/45s.
1984 Ford Thunderbird 3.8L "Drag Queen"
2009 Dodge Ram 1500 Lone Star Edition 5.7L Hemi 400hp, lex DOD14M Magnaflow retro-fit ler kit

 

fuel guage problem,, i think

Reply #5
The fuel gage in my 91 Grand Marquis stays put with the ignition off.
The sending unit in the tank goes to an "anti-slosh module" which controls the gage. Don't know how the gage works but it is not spring loaded to return to Empty. It just stays where it is put.