axcelr8

We were out cruising in my '90, and I admittedly was letting the tank get low. I still had three bars showing, though. The car began to miss big time. We hit a gas station and filled it up, and it has bee fine since. It was a very hot day and the car always runs hot anyway, of course.

So, the first question is, how does your car act when it is running out of gas?

Second question...do you trust your digital readouts? I already suspect that my sending unit may have some "dead" spots between full and 1/2. Has anyone had sediment/contamination, or vapor lock problems on a low tank? Should I run a fuel system cleaner through? (Safe for injectors or "snake oil"?). Will pulling the whole pump/filter/sender assembly tell me anything?

Thanks in advance for your feedback!

Dan

scorp508

Mine personally is super accurate the lower it gets. But I may just have a freak....

...when I get down to about 1-2 bars left and 25 miles on the range gauge, I know that I can NOT floor it, or the car will bog from starvation.

axcelr8

Scorpee, that sounds like what mine was doing, all right. Not happy 'bout that guage, though. Thanx for the info.

87SAM

I've ran mine down till the GET GAS QUICK IDIOT light has come on and has run fine for normal driving. Never put my foot in it at the point though.

scorp508

When does yours come on? Mine typically is somewhere between the (Avg. MPG * 2) and 50 miles.

87SAM

Mine shows about the same. I know I had to drive ~15 miles after it came on which is a little before the second to last bar goes out.

Vic'89

Anytime a get to about 2/3 bars on the fuel gauge the car will not run right if I give it alot of gas.

It picks up air in the tank when it gets that low. If you feather the gas you can still go about 20 miles.

Vic

SLEV89

Scorp, your's works? that IS freaky!

pretty common problem with vette (GM) gauge.

my gauge has been reading high for a while. recently, it read full scale constantly so i decided to finally tackle the level sensor. very easy job.

there is a really simple resistance slider (potentiometer) attached to a pivoting float/arm. REALLY simple.
on mine the copper 'rivet' that slides across the resistive element had a bad (high resistance) contact with the little tab that it is mounted on. i had to 're-squash' the rivet to make it tighter in its mooring.
and, whalla, she back in action.
should read 90 ohms in full position, and near zero at empty (measure between Purple wire and Black wire). the connector is behind the rubber 'boot' at the gas filler spout - you can test your sensor there easily.
make sure you disconnect the connector from the vehicle harness so that you don't damage the electronic dash with the ohmmeter!

the gauge/pump assembly slips out from the top, at the fuel filler nozzle.


you may get away with the same kinda procedure.

paul

TAC

If I get down to 1/4 tank and take a corner hard she will buck like crazy. I learned to never let it get down to 1/4 in town traffic. I hate that feeling.

GlobalGreg

My LT1 does the EXACT same thing. It didn't used to do it when I first got her last June.

Black85L98

85 is perfect 93 runs out of gas at 1/4 freinds 89 runs out at just under 1/2. Yes we both have run out of gas, just once though.

RU4L98

Yes my 89 C4 w/digital dash and my 89 Iroc w/analog gauges both do, you wanna know why. It's called fuel slosh, our cars are capable of generation high lateral G-forces. This force not only tries to push you up from out of your seat, but also causes the fuel to slosh away from the pick up tube in the tank. It sometimes takes up to a minute before the sucked up air makes it to the Injectors, which makes you forget about that last fast corner/take off you did. Then you're thinking; what the hell is wrong with this P.O.S. car NOW! The solution is, when driving aggressively don't allow the gas tank to get lower than 2/3 empty. This is one of the reasons why RaceCars use fuel cells.

black85

My car gets starved for gas if I really floor it when it is much below a half tank. For this reason I always thought it read high, but it only takes 12 gallons to fill so I guess the gauge isn't too far off.

Juliet

My warning light comes on with 2 bars to go. I've had the readout as low as 7 miles to empty. It only took 17.9 gallons of gas to fill up, so I figure I can run below 0. I wonder what the dash says then?

One of the issues with the fuel pump can be operating temperature. I don't know if this applies to C4s though, but I thought I'd throw the ideas out anyways incase someone can tell me if they apply or not. Generally speaking the in-tank fuel pumps use the gas in the tank to cool the pump. As the gas level goes down there is less to draw away the fuel pump heat and the gas heats up. In carbureatered cars this can lead to vapor lock, which in C4s I'd imagine the sensors / injectors / whatevers (I haven't a clue how they really work yet) would try to address. It's possible (I had a car where this was a PITA to finally diagnose) that the fuel pump is overheating when it gets low on gas. The other possibility is that the pickup has been bumped out of position. One of my other cars had a problem where the 'sock' on the end of the pickup was bumped and not allowing fuel to flow in. The other possibility is crud in the tank. Often it will float on top. When the level gets low you start sucking in the crud. (Been there done that too).

SLEV89

Sarkee,
yep. tank removal is not necessary.
this is a stand up job:

remove Flip-Lid Bodypanel
remove rubber boot from filler neck
disconnect electrical connector
disconnect three hoses
remove 9 bolts
wiggle wiggle...
up 'n out



p

[This message has been edited by SLEV89 (edited 07-17-2001).]

jaa1992

My 88 with the digi-dash seems to be real accurate, even down to the average MPG! Beleive it or not?!?

I've had it down to the "Reserve" indicator and with normal driving on the Interstate there were no problems. It scared me so I don't let it get below 1/4 now.

The reserve light came on with about 50 miles left on the range indicator. It took 19.2 gallons when I filled it up with 20 miles showing on the range.

I guess I have an exceptional experience, but with the responses in this thread I think If it starts to act up I could fix it.

The forum does it again!!

dppeaden

I well let you know from first hand experience, When it goes 00 you are out of gas. Yes it does start acting up near empty, sputters, like dad fuel , its called fuel starvation.

glock19

My LT1 does the same thing

Frizlefrak

Wow....deja vu. Today I had about 3 or 4 bars left on the gas gauge, and I did a quick U-Turn, and the car sputtered and acted like it was gonna die. It creeped along at about 5-6 MPH as I freaked out and looked for a place to pull off. After about 5 seconds, it took off just fine with no further symptoms. I filled it, everything seems OK.

To answer your question about trusting the digital readouts.....not any more

Aggravated4life

Seems all C4's are affected one way or another with/by low fuel.
However, I never let my gas tank drop down less then a 1/4 of a tank..youll heat your fuel pump up this way..
Your fuel pump stays "cool" by the gasoline surrounding it..when it gets low it runs hotter..
So keep your tanks filled or get gas asap before its less then a 1/4 to a half a tank left.

Doing this has really helped my cars since the 80's...Ive never needed a fuel pump due to failure on my part since then.