87 C4 Vette - Improper Fuel Reading

[DarbyOhara]

Hi guys & gals!

I am a new owner of a 87 C4 Coupe and it is my restoration project. Although I only had it a few days and just got it MD inspected, I have an issue I need guidance or help with...

The previous owner told me to be careful with the gas gauge reading because it is not accurate. As you know the 87 had the digital gauge. When I purchased it, it was showing a half a tank. I have been crusing and zipping around since I purchased it and today it is still showing a half a tank (it should have moved by now). The previous owner said he ran out of gas and the reading had 2 or 3 bars, so something is wrong. All the other digital gauges in the cluster seem to be working ok, so I don't think it is the digital cluster, but that is an unqualified opinion. The previous owner also noted that the "Unleaded Fuel" light below the gauge is lit and he claims it should go out after you start the vette. I don't know. The mechanic that inspected it refuses to troubleshoot or help much and said it might be the bulb-level thingy in the gas tank... and he claims he isn't sure they even make replacements. He doesn't seem to be much help.

Can anyone give me some ideas, pointers, help or direction? It would be really appreciated. Remember I am a newbie Vette owner and very immature mechanic (although I am in my mid 50's, so not a youngin'). My last alternative is to travel a good 40 miles away to the Chevy dealer and see if they can help. I am hoping either myself or someone local can fix this. Or is there possibly an alternative for the 87 C4 to install a normal reading gas gauge as a backup? Sending a stick down the gas filler hole isn't an option... lol. Please, anyone? Thank you in advance... ~ Ed

 

[DarbyOhara]

I am wondering if possibly this might be the cure? Fuel tank gauge, sending unit?

1985-1987 Corvette Sending Unit, fuel tank gauge with pump @ Davies Corvette Parts

Although it isn't a cheap fix.. it would be an expensive replacement if that wasn't the cause and would be deeply disappointing.

 

[Schrade]

What other people SAY means NOTHING. NOTHING! Show me PAPER, with names on it, and words, etc., ...

Do you have FSM yet? You can get it on eBay for cheap. That is the START! (unless you just want a vette to drive, hammer down, and tune doesn't matter, which is the case all too often) ....................

 

[vetteoz]

the gas gauge reading because it is not accurate. .
Can anyone give me some ideas, pointers, help or direction?

Fuel Gauge Sending Unit Repair Tech Article. - Corvette Forum

The mechanic claims he isn't sure they even make replacements. .

$200
listed for later models but works the same

1989 - 1996 C4 Corvette Fuel Tank Sending Unit - NOS

 

[jmhorn52]

My 96 doesnt read right either, its not accurate when its at a 1/2 it closer to 1/4 tank, i just adjust when i fill the tank knowing its not accurate, cheaper than trying to fix

 

[DarbyOhara]

What other people SAY means NOTHING. NOTHING! Show me PAPER, with names on it, and words, etc., ...Do you have FSM yet? You can get it on eBay for cheap. That is the START! (unless you just want a vette to drive, hammer down, and tune doesn't matter, which is the case all too often) ....................

I honestly don't understand your reply and I don't know what a FSM is. What other purpose do people buy a classic vette for? To drive. Some hammer down I suppose. Not sure if you are having a bad day with this reply or you're being a jerk. Either one, you didn't upset me, if that was your goal. Have wonderful day.

 

[DarbyOhara]

My 96 doesnt read right either, its not accurate when its at a 1/2 it closer to 1/4 tank, i just adjust when i fill the tank knowing its not accurate, cheaper than trying to fix

I am not too comfortable with that process. I need mine fixed and rather not poke around with faulty fuel reading.

I been researching and I found a thread regarding someone else having erradic fuel reading and it sounded possibly like my situation (sat long period of time). Which they claim possibly that gunk buildup is possible and to try a fuel cleaner made by Chevron. I don't have the link to the thread or do I remember the name of the fuel cleaner, but it sells at Texaco stations. We have one close here and I am gonna try that first on my next stop for gas. I am hopeful that is all it needs. My next step is to try the more expensive route that vetteoz suggests above regarding the fuel gauge sending unit. I'll be glad to fork out $200 for a new sending unit IF it fixes it. I'll be rather disappointed if spending that doesn't fix it.

Just yesterday I finally received my Clymer shop manual for my year vette and hope to learn more thngs... but my understanding is that the sending unit and fuel pump is right under the fuel cap area for the 1987 and hopefully is an easy access to change or diagnose. Maybe a few bangs on the elements might do the trick. lol. You know, the old classic fix... duct tape and a hammer! lol. ok.. don't run out of gas!

 

[jmhorn52]

I think you are referring to Techron as the cleaner, It started with Chevron then with texaco. It was supposed to be good.

 

[vetteoz]

My next step is to try the more expensive route that vetteoz suggests above regarding the fuel gauge sending unit.
I'll be glad to fork out $200 for a new sending unit IF it fixes it. I'll be rather disappointed if spending that doesn't fix it.!

The 1st link I posted for you above , details the very simple to do , removal of the tank unit and cleaning of the variable resistor
that is the most common cause of irrtatic fuel level readings

 

[Schrade]

What I was trying to say DO, is that you can't trust what other people SAY; only what they SHOW you.

FSM is Factory Shop Manual. You HAVE to have it for diagnostic work.

 

[DarbyOhara]

What I was trying to say DO, is that you can't trust what other people SAY; only what they SHOW you.

FSM is Factory Shop Manual. You HAVE to have it for diagnostic work.

Ok... I do have a shop manual, but I am not sure who you are referring to for trust. Appears rather harsh to think that of everyone, but I assume you are referring to the mechanic that done my inpsection and told me that he wasn't sure parts are still made for this 1987. Anyway, I've already done plenty of research before I heard his baloney and just moved on and didn't think it literally. But he was referring to the bubble thingy inside the gas tank. Everyone else points to the sending unit. Oh well...

I haven't found the Techron locally yet... still searching. Our Texaco here is mostly a convenience store and don't appear to carry too many auto parts and such; just lots of beer. I may have to order it online. I did try another fuel cleaner that was in a clear tall skinny bottle (found in k-mart). Don't remember the name, but I thought it couldn't hurt to try. So I applied it with about $20 of hi-grade fuel. So I been watching the gauge (and I also have the (miles to go) turned on... Unlike my newer vehicles, I get a low fuel reading when it is first started and cold. As the engine warms up... the fuel gauge reading rises to what I noted when I shut it off the prior day. Not sure this is natural... but I am trying to track the readings. I also placed a new empty 2 gallon fuel container in the back in case I do run out of gas... lol. I'll try these easy fixes and hopefully it eventually resolves it... if not, then the next step is the fuel sending unit. Thanks everyone.

 

[vigman]

This might be of help

Fuel Gauge Sending Unit Repair Tech Article. - Corvette Forum

 

[Schrade]

Mechanics ARE the worst - they'll tell you that you have a DTC 'x', and say, "I can replace 'x' sensor, and that will PROBABLY fix the problem.

"Well, how 'bout, showing me the multimeter test showing good power TO the sensor, and a good ground FROM the sensor, that leads you to 'probably' think the sensor needs replacing"??? Then you drive away cold motor, Open Loop, and guess what? No SES light...

I should have made clear not to include you in the 'just have a vette, hammer down, and to hell with the tune' type of vette owners. There IS a lot of those types. And I usually welcome new members - check my posts

Probably forget about the 'snake oil in a can' fix. It's possible, but highly unlikely.

And welcome onto the boards there........

 

[DarbyOhara]

Mechanics ARE the worst - they'll tell you that you have a DTC 'x', and say, "I can replace 'x' sensor, and that will PROBABLY fix the problem.

"Well, how 'bout, showing me the multimeter test showing good power TO the sensor, and a good ground FROM the sensor, that leads you to 'probably' think the sensor needs replacing"??? Then you drive away cold motor, Open Loop, and guess what? No SES light...

I should have made clear not to include you in the 'just have a vette, hammer down, and to hell with the tune' type of vette owners. There IS a lot of those types. And I usually welcome new members - check my posts

Probably forget about the 'snake oil in a can' fix. It's possible, but highly unlikely.

And welcome onto the boards there........

Appreciate the replies and feedback, but honestly... have you read back through your posts here? Do try to place yourself in the readers shoes.. not your own. You seem very angry and I am not sure what to make of your ramblings. I am in my mid-fifties and don't need anyone virtually scolding me, or lecturing me about mechanics and life. I am new to the classic Corvette ownership and will try to suck in as much information as I can... but I am not stupid. Enough of this... have a nice day!

 

[Mac]

Appreciate the replies and feedback, but honestly... have you read back through your posts here? Do try to place yourself in the readers shoes.. not your own. You seem very angry and I am not sure what to make of your ramblings. I am in my mid-fifties and don't need anyone virtually scolding me, or lecturing me about mechanics and life. I am new to the classic Corvette ownership and will try to suck in as much information as I can... but I am not stupid. Enough of this... have a nice day!

Hi DarbyOhara,

Welcome aboard. I'm glad you are speaking up rather than just signing off.

Posting comments is not an exact science and text messages are easily misinterpreted since there is no real way to communicate the 'rest of the message' (ie: humour, irony, sarcasm, etc) so sometimes folks come across as being grumpy when they are posting or they sound as though they're lecturing. Sometimes they ARE angry and that is where the moderators and administrators end up having to intercede.

The vast majority of folks on the CAC are friendly and helpful with a wealth of knowledge and experience. I hope you find us helpful!!

-Mac

 

[larry bud]

Hi guys & gals!

Can anyone give me some ideas, pointers, help or direction? It would be really appreciated. Remember I am a newbie Vette owner and very immature mechanic (although I am in my mid 50's, so not a youngin'). My last alternative is to travel a good 40 miles away to the Chevy dealer and see if they can help. I am hoping either myself or someone local can fix this. Or is there possibly an alternative for the 87 C4 to install a normal reading gas gauge as a backup? Sending a stick down the gas filler hole isn't an option... lol. Please, anyone? Thank you in advance... ~ Ed

Here's how I would start since it's an easy check, and that is to pull the fuel pump and sender out of the tank (it's all one unit). Open the fuel door, take the cap off, take the rubber gasket/cover off, and remove the 6 or 8 bolts and pull out the assembly.

The way the fuel level works is that there's a float on an arm. The arm is attached to a potentiometer, and the dash reads the value of the pot and displays the level. If the float is damaged or broken or the arm isn't moving freely (maybe someone bent it when replacing a fuel pump) it might not be sending the right value back.

 

[mlm0]

I had the exact same problem, and did the fix that is posted. I'm not that great at fixing things. but removing the sending unit and the cleaning were every easy. I think you will enjoy doing the procedure and the results good luck Mike

 

[navy2kcoupe]

Hey Darby! Welcome to the world of Corvettes, and the Corvette Action Center. The FSM that was mentioned
is the Factory Service Manual, and is specific to your year (or years) of Corvette, whereas the Clymer's or Hayne's
manuals are much more generic. The FSM's give you MUCH more in the way of information and troubleshooting
help than ANY of the other manuals, and as such, cost more. You can probably find a set on ebay for less than
a new set would cost. I've got a set for my 2000, and they are worth their weight in gold! If you DO try the Techron
additive, just understand that it might take 2 or 3 bottles to clear it up depending on how bad it is. As for the
unleaded fuel light.........I've got no clue about that, and one of the C4 guys will have to chime in about it. That's
the type of info found in the FSM, but not in the more generic manuals. Good luck getting it straightened out! Keep
plugging and you'll eventually get there.
Andy

 

[mlm0]

got my FSM off ebay for 50.00 could not do without it

 

[DarbyOhara]

Thanks everyone for the help and comments. I will tackle the fuel sender issue soon. I am in the middle of retoring my front carpets.. so everything is torn apart... seats.. console, etc. Once I get the new front carpets in and stuff back together, I will certainly try just pulling it out and checking that. It's just so freakin hot and humid to do much at a time in a hot sweaty garage.