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Full guage shows full when it's 1/8th tank - car won't start?

Y

Y2KGTP

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PROBLEM FIXED = BAD PCM

2000 GTP

Went to go start my car today, and it would crank, but not start. Typically it starts in just a bump of the key. I noticed the gas gauge read full, yet the digital display showed 0 mi left.

Car was low on gas (1/4-1/8 left) a week or so ago, so not sure why it would show full?

Wondering if I had a gas theft or evaporation somehow? Thinking of filling up a 5 gal with 93 and seeing if that is the problem.
 
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they this for the no start.

E3CCEAD.jpg



has the car been sitting a while? the gas lever may be stuck, or the sender on the pump took a dump, its fixable for about 20 bucks or so.
 
Scottydoggs said:
has the car been sitting a while? the gas lever may be stuck, or the sender on the pump took a dump, its fixable for about 20 bucks or so.
Click to expand...

I try to drive it once a week or so, it started fine just last week. I thought it was very strange that both the fuel guage jumped to full as well as the no start condition happened a the same time.

Is there a trick to the full pump resistor, or simply check/replace it?
 
if doing the bent tab on the relay works its the resistor, its in the fender by the battery.

if it dont work, test the valve on the fuel rail for fuel pressure. key set to run. if nothing comes out the pump is bad.

put a rag over the valve then push the pin in with a screw driver, fuel should spray out with some force, watch your eyes.

id check the fuse boxes also for a bad fuse.
 
oh, and then theres the bang on the gas tank bottom trick if theres no pressure. sometimes a little beating makes it work again for a while. if it does fire up the pump is bad.

also check for spark. you can take the plug wire off the coil, prop it a inch over the terminal crank the engine, a spark should jump to the wire.
 


Scottydoggs said:
oh, and then theres the bang on the gas tank bottom trick if theres no pressure. sometimes a little beating makes it work again for a while. if it does fire up the pump is bad.

also check for spark. you can take the plug wire off the coil, prop it a inch over the terminal crank the engine, a spark should jump to the wire.
Click to expand...

Thanks, I'll dig threw this in the AM as it's getting dark out shortly.
 
Fuel relay tab did not help so put it back. Got Spark. When I check the pressure valve I only get a tiny blip of gas onto a rag.

If I crank it for a few seconds, then stop and check the valve, no gas comes out.

I am trying to figure out what would cause the gas guage pegged at full as well as the low fuel pressure?

EDIT
As the sender is part of the fuel pump assembly?
 
Next day or so I will pull out the back seat and check for power to the pump, else I am thinking it just went bad.
 
the trap door for the fuel pump is in the trunk.

sounds like the pump took a crap on ya. you try pounding on the bottom of the tank with your palm? you hear it prime? as you turn the key to run listen in the trunk or open the back seat to hear better for a buzz, it only lasts up to 5 seconds after you turn the key to run.
 
Why would you pull the back seat out?
Just pull the trunk carpet up and take the inspection plate off.
When you turn the key to the on position can you hear the pump run?
Also, hold your hand on the relay pictured above and have a friend turn the key to the on position and see if the relay clicks.

Sent from Not so smart smartphone
 


Twizted 1 said:
Why would you pull the back seat out?
Just pull the trunk carpet up and take the inspection plate off.
When you turn the key to the on position can you hear the pump run?
Also, hold your hand on the relay pictured above and have a friend turn the key to the on position and see if the relay clicks.

Sent from Not so smart smartphone
Click to expand...

I have a 2-12 sub box back there, I mounted it so it just clears the pump access a while back.
 
Car actually started today as normal, so I was pretty sure it's the pump going bad as it sat for a couple weeks. Swapped in a new Airtex unit, and good to go.

Was nice just to have to access via the ski pass threw to get to the pump. That retaining ring was a PITA on the other hand to get back on.
 
And....I am back to the initial problem. Fuel Guage pegged at 100%, and no start....just cranks.

EDIT:

Add that voltage seems to be around 1.70v at the (Sender wiring), bumps to 1.8v when cranking......
 
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Well, got a bit further. The below is for the upgraded harness that came with my pump.

Black/white = Sender Ground
Purple = Sender Signal
Black = Pump Ground
Gray = Pump Power

When I have a meter on the pump wiring, turning the ignition on gives me about 9v to the pump for a second or so to prime. Cranking shows zero voltage.

Now it has as same symptoms as before I replaced the pump (gas gauge pegged 100% - crank no start)

Just before I replaced the pump, for giggles I tried to start the car, and it did. I replaced the pump regardless as could have been bad, and the wife reported the car was surging a bit when she last drove it.

I tried the resistor bypass on the replay (resistor was replaced a few years back), as well swapped both relays around, and 15A fuse is good.

I am getting power to prime the pump, but no voltage when cranking.
 
One thing I thought was interesting, is that I only saw 9v at the pump when priming with the key on.

Should this be 12v?

Hopefully will test the pump relays later today, but I don't see how this would effect the fuel gauge pegged at 100%. For almost 2 weeks it ran just fine on the new pump (gas gauge worked as well), then poof, back to the original issue.
 


Both relays 'click' when I jumper them on my bench.

Wonder if it's worth just pulling the negative from the battery for a few hours? I don't see how the fuel gauge and the no voltage to the pump problems happen at the same time.
 
Got my Bluetooth OBD2 adapter, so figured I would see if any stored codes, nope.

Tried to start, and it fired right up, as well as the Fuel gauge was back working correctly as well. Extremely frustrating.

I really don't want to drive it as no idea when it will act up again.
 
starting to sound like a crank sensor. they like to work when they see fit when they go bad.

it ever just stall for reason driving down the road in the past? and then fire right back up?
 
Scottydoggs said:
starting to sound like a crank sensor. they like to work when they see fit when they go bad.

it ever just stall for reason driving down the road in the past? and then fire right back up?
Click to expand...

I replaced that a few years ago when I had the wandering Speedo.
 
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