Photomania

It's possible that water is in the gas tank of my 1990. The engine is stalling out at traffic lights and occasionally tries to cut off while cruising done the interstate highway. It might go 30 miles with no problem. I installed a new fuel filter because I thought trash might be in the tank, but that didn't help.

Now, I'm considering the possibility of rain or condensation in the tank. Three days ago it was 75 degrees F outside. Today, it was snowing. Someone told me I should keep the tank full as much as possible to prevent condensation.

I just bought a bottle of Valvoline Water Remover and a bottle of Peak Gas Line Anitfreeze. Someone with a Chevy sedan suggested I use an STP product to remove water from the tank.

Will any of these products damage fuel injectors? I'd appreciate any input before I dump one of these products into the gas tank. I've got to do something. The car left me stranded a couple of nights ago. -- Eric

jsup

How much water are we talking? You're not going to get a gallon of water out with Dry Gas.. Dry gas is basically alchol that mixes with the water and breaks it up so the water can pass through the fuel system.

A bigger problem is ICE in the fuel system at those temps.

Clean the drain around the gas cap.

65Z01

I believe that if you check the contents of those additives you will find they all contain alcohol in some form and should not damage the fuel system if used as directed.

VenkmanP

What was the condition of the previous filter, and what is the condition of the new one after driving a few days? Just replacing the filter wouldn't get debris out of the tank.

What about your diagnosis of it being the TPS? You said you ordered one. Did you replace it and did that help?

It sounds like you are throwing $ at the problem instead of diagnosing it.

Photomania

Thanks for the tips. I read on the label that Valvoline Water Remover has only isopropyl alcohol in it. I'll try that. I'm hoping any water that might be in the tank is only a small amount, perhaps from the gas station's tank or from condensation from the wide range of temperatures we've had in Virginial lately. It was 75 several days ago and now it's below 20 F.

I checked the old fuel filter, and to be honest, the openings looked clean. Maybe I should take a hack saw and cut it open.

I ordered a new throttle position sensor, and it hasn't arrived yet. If the Valvoline product solves the problem, I'll cancel the order.

I don't have a hand-held diagnostic computer. Is this a common item to have among Corvette owners? Where's the best place to buy hand-held diagnostic tools--Ecklers? I'm sort of new at this. Just bought the car in March of '04.

I've replaced the basic things: water pumps, thermostats, shocks, plugs, drum and disc brakes and wheel cylinders throughout my adult life. Thanks for all of your advice. -- Eric

runner140*

Get a couple quarts out and see if there is any water in the gas. Water doesn't mix with gas and it you syphon some gas out and fill a two quart see thru container, you will be able to determain if there is water in your tank. You might have an other problem and not gas related. In answer to your question, DryGas is fine to try if you do have water in the gas.

comp

sraft

If you have a lot of water (more than a few ounces) I think that you would have worse problems than you describe. The water is heavier than the gasoline and will sink down to the lowest point in the tank. This is where the fuel pickup is located - any substantial quantity of water would get quickly make it's way to the injectors.

If your tank is near empty, getting all the gas out is not hard. You can remove the gas door and expose the top of the tank. Remove the bolts and a few electrical connectors and the sending unit/pump comes right out. You can then syphon the rest of the gas out (or even reach in and scoop it out with a cup).

If you find water, I recommend that you also disconnect the fuel lines and fuel rail and blow them out with compressed air. After you're positive that all the water is gone, install a new filter. Keep you fingers crossed that the injectors haven't rusted or are clogged with rust from the fuel line.

VenkmanP

I wasn't referring to a computer.

I meant:

- before you change the fuel filter due to garbage in the tank, determine if there is actually garbage in the tank.

- before you put water-remover in the tank, determine if there is actually water in the tank.

- before you order a replacement TPS , determine if the current one is actually faulty.

- i.e. diagnose = determine what the problem is before you go "fixing" things.

jackdaroofer

[QUOTE=Photomania]Thanks for the tips. I read on the label that Valvoline Water Remover has only isopropyl alcohol in it. I'll try that. I'm hoping any water that might be in the tank is only a small amount, perhaps from the gas station's tank or from condensation from the wide range of temperatures we've had in Virginial lately. It was 75 several days ago and now it's below 20 F.

ISNIP

You can go to the drugstore and get 93% isoprpyl alchohol for a lot less than branded dry gas products which are generally only 70% isopropyl.

70% means it is already 30% water when you pour it in the tank!

93% means it is only 7 % water and it will absorb a lot more water for the buck!

seeya

Photomania

You guys are sharp. You ought to be getting paid for giving out all of this helpful info.

I tightened the throttle position sensor and added Valvoline Water Remover. Then, I drove the car 60 miles while running errands and it ran absolutely flawlessly. Not one stall or hesitation. I also filled the tank with Amoco premium just before returning home.

I'll drive this '90 Corvette again tomorrow and see how it does.

Also, I just learned tonight from the Haynes C4 repair book how to connect a wire to the diagnostic module under dash to get trouble codes. The Haynes book lists all of the code numbers and a description of each. Apparently, the ECM stores the codes until the battery is disconnected.

Maybe I didn't need to install a new fuel filter. But at least it's done. The one I replaced looked like it had lots of mileage on it. I didn't mind replacing it. It was 70 degrees outside. I can add that to my list of accomplishments.

Thanks for your help. -- Eric

MikeC4

Eric - got your PM tonight, but I'll go ahead and stay with your thread here. If your problem is cured after running the dry gas, that is great! If problem persists, pulling the codes from the ECM is great start. Heck, pull the codes reagardless!! You may also want to check coil connections, and make sure they are sound. Also check the coil wire to make sure it is not shorting out. I have a '95 with the Opti setup, but your '90 has different ignition system. Maybe someone else from the Forum could chime in here regarding how '90 ignition system works, and if it has any shortcomings. When you get the error codes, post them, and the ECM experts here can help you out.

Photomania

I connected a small wire to terminals A and B in the diagnostic center under the dash and then turned the key in the ignition. I was hoping to see a code, but all I got was the flashing "Service Engine Soon" light for a dozen or so times. I'm hoping the wire was ample in size.

I disconnected the battery when I replaced the fuel filter. The car tried to stall out the next day, but I rev the engine carefully at a traffic light and kept it from quitting. During those time, the "Service Engine Soon" light came on for 15 to 20 seconds at at time, maybe 30 or 40. Maybe that wasn't enough time to record a code.

Best of all, the car has functioned perfectly for two consecutive days and for nearly 120 miles. Apparently the problem was solved by: A) Tightening the barely loose TPS or B) Pouring a bottle of Valvoline Water Remover into the tank. It was 10 degrees last night here in Virginia, and I'm keeping the tank full.

Is it possible the 1990 Corvette or C4 in general is more prone than other vehicles to producing condensation in the gas tank?

John Robinson

If you don't want to use dry gas you could put a quart of Jack Daniels in tank but then car might not steer in a straight line

MikeC4

Eric, the above procedure you did was correct. Flashing SES light has to be read like morris code. If you see the SES blinking, your wire size is fine!! Please read the following carefully for determining your error code(s) from the flashing SES light after shorting term A and B:

"To recover the codes, it is necessary that you short pins "A" and "B" together using a small section of electrical wire. Alternatively, you can cut up a paper clip and fashion it into a shorting device. Regardless of your method, you will want to utilize something that will reliably make contact with the two pins but will not damage the connector or the pins. With the ignition turned Off, short pins "A" and "B" on the ALDL using your previously prepared pin shorting device. Turn on the ignition but “ Do Not Start the Automobile. ” Within a few seconds, your “Check Engine” light (early C4s) or "SYS" light (later C4s) will flash a code of 12. There will be a single flash followed by two flashes and this will repeat three times: Flash (pause) Flash Flash (long pause), Flash (pause) Flash Flash (long pause), Flash (pause) Flash Flash (long pause). Code 12 is a delimiter or marker code to show where the error code string begins and ends. After the three code 12 flashes, you will either get an error code (or codes) or you will get another string of code 12 flashes if there are no trouble codes stored. All codes are repeated three times with a long pause between each code group so (for instance) you could recover a string like this: 12, 12, 12, 36, 36, 36, 44, 44, 44, 12, 12, 12. In this example, your OBD has stored error codes indicating that the Mass Air Flow burn off circuit has exceed the Hi/Lo limits (Code 36) and that the Exhaust is to lean (Code 44). Whether or not this means that the sensor is bad or that the parameter it measures has truly been exceeded is yet to be determined however, you do know that the PROM based limits for these two sensors have been exceeded. If the "Check Engine / System" light is on when the engine is running (during normal, driving operation in other words), the condition(s) are currently present; if the light is not on during normal operation, the limits were exceeded at some point in time and the event was recorded in memory but the reading has since returned to the normal operating range. Once you have determine the error code situation, you can set about troubleshooting the problem or you can take your vehicle to a Corvette repair shop, tell the technician what you have found in the OBD system and perhaps somewhat shorten the repair time. Remember to remove the shorting device from the connector after you have read the codes."

Photomania

Thanks, Mike, for the advice. Your explanation is better and more thorough than what I found in the Haynes C4 repair book. I drove the 1990 for nearly 120 miles Monday and Tuesday and the engine ran perfectly. That says a lot about a car that's 15 years old and has nearly 90,000 miles. I wanted to drive it today, but it snowed like crazy in Virginia, and I wasn't about to endanger my car. So, I drove my pickup truck instead and watched as a car slid in the snow on a four-lane divided highway, crossed the median, spun around in front of me and fishtailed back across the median and back into his original lane. I'm glad I wasn't driving my Corvette. -- Eric