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

Originally Posted by Scottydoggs

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.

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?

Originally Posted by Y2KGTP

Is there a trick to the full pump resistor, or simply check/replace it?

Found it, no go still won't start. I'll throw some gas in it tomorrow just to make sure.

Originally Posted by Scottydoggs

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.

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.

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

Originally Posted by Twizted 1

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

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.

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.

Originally Posted by Scottydoggs

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?

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