84 Corvette, fuel gauge

[Jerry H.]

When I thought I had gas because there was 2 lines showing on the gauge, it ran out of gas. I had no idea what was wrong
and started asking questions before, it came to me to put fuel in the car.
Ok, now just yesterday I ran out again, this time 4 lines left on the gauge. Is there a way to adjust the sending unit out of the tank
to match the gauge?? I mean 4 lines if you know the car is almost a 1/4 of a tank.

[Jim T.]

Re: 84 Corvette, fuel gauge

Jerry I do not know anything about adjusting the sending unit in the gas tank. Having no gas to the engine with two lines showing and then having 4 lines showing and running out of gas, if you filled it up, how many gallons did it take? The gas gauge in my 1996 is not working right. First noticed that on an almost 300 mile trip starting with a full tank that the gauge was not moving enough for the miles driven on the trip. On return fill up the gauge showed more gas in the tank than the amount of gas to fill the tank.
Second problem that appeared was taking the 96 on another trip. Do not drive this car daily, in fact it will set for months with the battery negative cable disconnected although the battery is checked and charged every 15-20 days. The second problem just recently appeared in DEC 2011. The gas gauge did not show any of the bars. About 30 miles of highway driving it started working and showed a full tank. Another 300 mile trip and it showed full to long and on fill up showing closer to 3/4 than 1/2 tank but only took almost 10 gallons of fuel. The fuel gauge bars worked on the return trip.
The 96 has not been driven since the DEC trip and battery again disconnected. Will see what happens next time I take it on the road.
One thing about 84-96 Corvettes, the fuel sending unit has easy access from the top of the tank. Replaced the electric fuel pump in my 1985 Corvette, the most difficult work was getting the fuel lines (supply& return) removed from the sending unit without damaging them. The dash fuel gauge in the 85 works with no problems since new.

[Ken A.]

Re: 84 Corvette, fuel gauge

It's either the sender or cluster that's the problem. I would replace the sender & pump unit. Don't forget to clean the tank.

[Peter M.]

Re: 84 Corvette, fuel gauge

I have a write-up on how to repair your in-tank sending unit on your early C4. The file is too big to add here so send me your email address and I'll send you the How To file.

While you are in the tank you should replace your intank fuel pump with a Walbro high performance pump for your MY. If you shop around you can get a Walbro for something in the $75 - $85 range.

http://www.frsport.com/Walbro-GSS341-255-Universal-High-Flow-In-Tank-Fuel-Pump-255-LPH_p_16850.html

[Ken A.]

Re: 84 Corvette, fuel gauge

I wouldn't waste the time on trying to repair an old style sender. Use the new ones that are ethanol compliant, as the ethanol is what's causing the failure. An 84 Corvette does not need a "high performance" fuel pump as the cross fire only needs 13-18 #'s of pressure.

[Peter M.]

Re: 84 Corvette, fuel gauge

Pat:

I have emailed the instructions to you. Let me know if I can be of further assistance.

[Peter M.]

Re: 84 Corvette, fuel gauge

I wouldn't waste the time on trying to repair an old style sender. Use the new ones that are ethanol compliant, as the ethanol is what's causing the failure. An 84 Corvette does not need a "high performance" fuel pump as the cross fire only needs 13-18 #'s of pressure.

Really ? A new sending unit is over $250 and the repair I am recommending has no cost. What's more, your comment that the current E10 and E15 fuels are the culprit is not correct. I have not heard of anyone having C4 sending unit failures due to E15 fuels. I think what you are talking about is the sulfur content which effects the sending units in C5 & C6 Vettes.

[Darrell S.]

Re: 84 Corvette, fuel gauge

I have had this problem with my 84. On my car the problem was with the sending unit not the fuel gauge.I tried cleaning the sending unit but the problem came back in a few weeks. The sure fix was replacing the sender/fuel pump assembly. I would try to avoid enthanol fuel. If you have to use enthanol fuel try not to use no more than 10% enthanol.

[Joe L.]

Re: 84 Corvette, fuel gauge

I have had this problem with my 84. On my car the problem was with the sending unit not the fuel gauge.I tried cleaning the sending unit but the problem came back in a few weeks. The sure fix was replacing the sender/fuel pump assembly. I would try to avoid enthanol fuel. If you have to use enthanol fuel try not to use no more than 10% enthanol.

Darrell-----


I believe that GM approved the use of fuel containing up to 10% ethanol for all of the C4 model years. However, it's possible that this did not include the early C4 years.

The vast majority of the fuel that does contain ethanol contains 10% or less ethanol. If there is any fuel out there that exceeds 10%, I'm not aware of where it's available. I think that any fuel with greater than 10% ethanol has to be prominently labeled at the pump as containing whatever the higher percentage is.

[Darrell S.]

Re: 84 Corvette, fuel gauge

Joe
You are right. I checked the owers manuel on my 84. GM said " Blends of unleaded gasoline (grain alcohol) sometimes know as gasohol are available in some areas. You may use these blends in your vehicle if they are no more than 10% enthanol with jeopardizing the new vehicle and emission warranties"

[Ken A.]

Re: 84 Corvette, fuel gauge

GM has changed their stance on ethanol and in late 2005 mandated all fuel senders, including service parts back to the 60's, use the new film resistor and improved float material and hoses that are resistant to alcohol. It's a PIA to keep changing and cleaning old fuel senders to save a few bucks. The old filters (socks) can dissolve with E85 and really gum up your fuel system.

[Bill H.]

Re: 84 Corvette, fuel gauge

Just a comment on ethanol, messing up the fuel system on older C4's? I guess it's possible.
However, I drive a 92 probably 4 days a week, - on 10% for last 6 years.

With the 84 running out of gas, I'd be more worried about the pump than the gauge.
I've seen the same problem on other C4's.
Some of the pumps look like this:

[Perry M.]

Re: 84 Corvette, fuel gauge

My 84 would not start a few years back. No fuel was getting to the injectors. I could hear the pump working but still no fuel. I changed the filter thinking it must be plugged solid. Finally, I removed the sending unit and found the 2'' piece of rubber hose that connected the pump to the hard line was completely deteriorated, which gummed up the unit. The gas was pumping but only back into the tank.
Last summer, I was cruising along and the car began to stutter. It was running out of gas. The gauge said I had 3/4 of a tank. I coasted to a gas station and topped it off. The car started. I left the station but it quit again, in the middle of traffic. I kept starting it and finnally got it off the road. I was accross the street from a NAPA store so off I went. I bought some cheap tools and removed the sending unit from the car right there on the shoulder of the road. At first it looked fine but after more observation I discovered a slit in the soft hose. The gas had again dissolved the hose to the point that the pump was able to rupture it. NAPA gave me a 2'' piece of hose and I was back on the road again. So don't tell me that ethonal treated gas, even only 10%, doesn't affect our cars.

[Jerry H.]

Re: 84 Corvette, fuel gauge

Thanks for all the help, I think I'll start with the sending unit. I just don't think it's the pump, it was replaced a couple of years ago.
All you guys are great, I now have a direction in which to go, thanks Again,,,,