JSki

Ok, so after the 2nd time of running out of gas with showing 1/4 tank or more I think it's time to mess with the pump. How bad is the pump to do? Can you replace just the sending unit? Are these things known (like most other chevys) for fuel pump problems? And lastly, should I go Delco or other for the pump/sending unit?

0Paul Ruggeri

The fuel pump is easy to get to, its under the gas cap door. I think you have to buy the whole assembly to get the sender. You may be able to clean the contact area with some electrical cleaner.

JSki

These pumps have an actual float mechanism, correct? Or is this all done electronically in some other fashion? I'm assuming it would be the float/sending unit causing the problem seeing as how I run out of gas at half a tank, but I'm new to Vette's so my knowledge of applicable systems is next to nothing. Any education on this matter would be appreciated.

VetteMed

It's a float on a long arm that alters the resistance depending on the level of fuel in the tank.

JSki

How do I access it? My FSM is not within reach...

0Paul Ruggeri

Remove the gas cap door and the rubber piece and you will see plate that you unbolt to remove the pump.

Les 94 Comp Yellow

Just a suggestion, but I would have another gasket on hand to replace the old dried out rubber one that will be coming off with the unit. Any dealer can order it for about $6.00. That is what the local dealer charged me about 6 months ago. Plus a few dollars for postage.
If you unplug the electrical connection to the gauge ( you will see it when you remove the gas door and the rubber boot) turn on the key >don't try to start the car< the gauge should go to full on the dash if the sending unit is at fault. It reads full with no ground connected. If the gauge still reads something else, than the problem is elseware. Possibly in the dash cluster or in the wiring between the tank and the dash??? Good luck, it is not an uncommon problem.

airblaine

you have to buy the whole assy that will cost about 350.00. if you want i have a spare float with the metering device you can have for 10.00 plus shipping

rodj

Cheaper here
http://www.corvetterecycling.com/198...p/25027510.htm

Many have has success by cleaning up the contacts on the gauge sender unit, gets corrosion from moisture

rodj

http://forums.corvetteforum.com/c4-t...h-article.html

pcolt94

This link is excellent and better than my write up.


I did this sender repair the first week I got the car in OCT 03 as I ran out of gas on the way home from the shop I had just bought it from. I was not on the Forum as of yet but did eventually do a write up for the repair also.

In the “older” cars with analog gauges, if the sending unit opened up or had higher resistance it would make the gas gauge read a lower quantity of fuel. It works totally different in the vette as the sending unit feeds the CCM which then in turn drives the gauge on the dash.

The resistance actually operates in reverse to what use to be normal. A full tank in a vette represents a high resistance (about 115 ohms), and low fuel is low resistance (about 20 ohms).

The kicker here is if the sender resistance goes out of normal resistance range (which is usually higher), it does not show a full tank. Instead the circuitry in the CCM ceases to work properly and just displays what it feels like making the indication meaningless.

Most other sending unit that I have fixed only had one contact on the wiper of the wires to clean. But the vetts unit has that plus another set of contacts for the ground return. If either one develops a higher contact resistance the gauge becomes inaccurate and usually shows more gas than that you have.

I also have to do the procedure again as I can see that things have changed a bit and probably need a cleaning.

I also added a resistor across the sending unit to increase the accuracy of the fuel gauge. As you know after fill up you can drive over 100 miles and the gauge never moves, then drops like a rock an usually shows more fuel than what you have. Now my gauge drops as my fuel drops and is pretty accurate. If interested, here’s what I wrote.

http://forums.corvetteforum.com/c4-t...-and-more.html

runner140*

Racetronix has a complete kit (everything) for $99.00 with Walbro fuel pump.

josephf31

They still have the kit but the pricing is out of date (check with them to be sure) it's more like $199 now.

avgjoe

I had a similar problem and I took out the sending unit and cleaned the connections on the plugs and it works great now.

Ramrod92

Racetronix does not have the fuel level sending unit, thier kit comes the fuel pump and wireing harness ( I have one and I'm very pleased with it. ) For the fuel level sending unit I would also recommend Corvetterecycling. Here's the racetronic stuff.. and here's the sending unit from Corvetterecycling.. The pump mounts onto the sending unit.