Got my car running today. Unfortunately the gas guage is broken and is showing a full tank. i have looked around and i was wondering if you guys thought Techron would work? oh and also my rpm tach is not working either, it sits past 6g and thats if im cruisin. anyone got info on that? thanks

 

I read one artical on Techron fuel additivel and it reported good results as compaired to other fuel additives, try searching on it....

I tried it a few times and I can't really say it worked.. maybe some.. maybe I just didn't use it long enough. I have had better results using Seafoarm as a cleaner of carbon and cleaner.

 

I recon the degree of improvement a cleaner (Techron or whatever) provides depends on what condition the engine (injectors) were in to begin with. I suppose that's why we see the huge improvement numbers in the adds of various products - assuming they dummied up a really nasty (read: dirty/carboned up) engine to do the "before and after" test on. If you don't have much crud to speak of, then could cleaning a "clean" engine do much? No harm in trying (I guess), but I wouldn't be disappointed if there wasn't any change.

Just my 2¢

P.

 

It is the reason I try to run Chevron only. Not sure what Techron would have to do with your problems though.

 

I agree with Aminnich, it sounds like your gas guage problem is an electrical thing...I don't know what Techron would do to solve that problem. As far as the tach goes, we all know that's broken because an L98 won't rev that high!!! Sounds like you've got some electrical demons that need to be worked out, try using the search function or buy yourself a good repair manual. Good luck, keep us posted.

 

I have never had any problem with the fuel gauge on my C4, but I did on my C5. I am not sure if the C4 is prone to this issue or not, I have not heard of it. The problem was fouled fuel sensors in the tank and Techron was known to be helpful in cleaning them. This is very common problem with C5s.

Here was my story. I found out (too late) that fuel from less than top brands (cheap gas) often contained excess sulfur that could build up and eventually foul fuel sensors. My fuel gauge stopped working when I had about 40K miles on the car. The C5 has saddle tanks and 2 sensors. My gas gauge typically functioned until I was down to about ½ empty, and then dropped to “E.” I consulted the C5 technical section of the forum and found a lot of guys experiencing the same problem. The advice I received was to run a couple of tanks of Chevron Gasoline through the car, and see if it helped. The Techron in the gasoline would (supposedly) help to clean the sensors. It did not work at first. I then tried adding Techron to my gasoline, with mild improvement. Finally I used some stuff called “Seafoam” and it did seem to work around town. Unfortunately, when I drove the car on a trip of over 100 miles or so, the gauge would quit on me and go to empty. That was as good as it got for me. From that point until I traded the C5 in, I would just set the trip meter and fill up every 300 miles or so. Since it costs around 1500 to get those sensors replaced in a C5, I chose to live with it.

Some of the guys over there on the C5 forum had more success with Techron, I guess mine was just too far gone. Like I said, this may not have anything to do with C4s though.

 

One thing that you can do for the gas gauge is remove the fuel pump from the gas tank and clean the sending unit. It removes easily through the fuel filler door. Remove the fuel filler door, then remove the screws around the fuel fill spout and the entire unit will lift out of the tank. The sending unit may be stuck. Just a thought.

The tach problem is not unusual on the 1990, mine registers the same way. You will have to remove the entire instrument panel and send it of to be recalibrated - about $185. Do a search of "tach filter" and you will find a few threads on this. By the way, I replaced my Tach Filter a couple months ago and it didn't help at all.

There are a few issues with the 1990, but they are all pretty minor. Now get ready for the VATS issue. Lots of Fun.

 

Both Chevron and Texaco contain Techron as their fuel additive. As long as you use either one consistently, you should not need to add a bottle of the Techron from a parts store.

Check the wires around the distributor to see if the tach wire has become disconnected.

The FSM has trouble shooting procedures for the fuel level gauge. Could be the sending unit in the tank is shot or the display is bad.

 

i will start using the chevron gas and see if that works out. my next thing will be the techron or maybe the sea foam. i will post later if i get any results. thanks guys!

 

I've had the gas gauge issue with my 85. I bought a spare sending unit to replace the one in the car just in case I couldn't get it to work. But I added 2 bottles of Techron and its made a difference. When I first got the car, the gauge worked, then I changed gas stations and that's when the problems with it started. I definitely agree that some brand gas contains more sulfur than others because the same problem started happening in my Cadillac. I'll be going back to other station to keep the problem under control, its worth the extra 5 cents a gallon.

 

make sure you use the Techron CONCENTRATE the 20 gal size is $10.88 at wal mart AA ad Auto Zone-not the regular Techron-you can tell the difference by the price
I like to use Chevron, boosted by Techron Concentrate a few times a year-very happy with the results

 

yep....the concentrate works best