fuel gauge/fill issue?
12-18-2018, 09:45 PM
#1
Instructor
Thread Starter
fuel gauge/fill issue?
The last two times I have filled my 2002 C4 Cab the pump nozzle has clicked off and I have topped it a bit and then gone on my merry way, only to notice the gauge is registering 3/4 full. I talked to my mechanic who indicated (in his opinion ) that this is not a typical problem. I also had one fill up where it just kept clicking off and I eventually went to another station thinking it was the pumps problem, now I am thinking different? Next time I fill up I will take it down to almost empty and measure the fill. I just wanted to see if you guys have experienced a similar issue?
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Ratchet1025 (01-10-2020)
12-18-2018, 10:39 PM
#3
Rennlist Member
This happens to me from time to time. I believe its related to the strange shape of the fuel tank (it is kind of like a U shaped around the front differential on the C4 and C4S).
12-18-2018, 10:51 PM
#4
Rennlist Member
Make sure you don't leave your engine running while filling up. I read that can cause similar issues.
12-19-2018, 12:18 AM
#5
Rennlist Member
My '99 never shows "Full" either. Not the end of the world for me, just odd. I am not going to lose sleep over my misreading 
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Ratchet1025 (01-10-2020)
12-19-2018, 04:48 AM
#6
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My 99 has never showed a full tank. Always about 3/4 full. I have had the car the last 7 years and done 50,000 miles in it with no major problems.
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Ratchet1025 (01-10-2020)
12-19-2018, 08:57 AM
#7
I always fuel my 996 using the lowest/slowest notch on the nozzle handle, stop filling on the first click, and never top off the tank. Fuel gauge shows "full" ten out of ten times with this process. /X3
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12-19-2018, 09:08 AM
#8
Rennlist Member
2003 C4S checking in. Many times mine will click that it's done but only be 3/4 full. I can usually pull the nozzle out slightly or just adjust it a bit and finish it up.
12-19-2018, 06:19 PM
#9
Drifting
My 99 does it as well. And my low fuel light comes on at just under the 1/4 mark. #annoying
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Ratchet1025 (01-10-2020)
12-19-2018, 08:31 PM
#10
Mine shows full. I did learn on my first fill up to NOT top it off as gas spewed everywhere pretty much as I started slowly pumping after the first shutoff. I have to fiddle with my G35 to get it full after the first shutoff.
12-20-2018, 08:40 AM
#11
Rennlist Member
Mine has never showed full, always 7/8ths and even when driving with the light on for a long time, I still cannot get more than 15 gallons in the tank.
The reason is because the gauge requires calibration due to how it works: it guesses at how much fuel is in the tank due to the tank’s irregular shape. The calibration procedure is non-trivial. One way to fix it didn’t work for me: fill the car all the way up (one-click refill), disconnect the battery for 15 mins, reconnect.
The reason is because the gauge requires calibration due to how it works: it guesses at how much fuel is in the tank due to the tank’s irregular shape. The calibration procedure is non-trivial. One way to fix it didn’t work for me: fill the car all the way up (one-click refill), disconnect the battery for 15 mins, reconnect.
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Ratchet1025 (01-10-2020)
12-21-2018, 06:49 AM
#13
Rennlist Member
2004 C4S I have had the same partial fill issue. Found a trick that works every time but it’s tedious: push in the gas nozzle and hold the handle UP so the tip of the nozzle touches DOWN in the filler neck. When it finally clicks, it’s always full. Going for one more “click” to top it off results in an embarrassing spill (“doot-de-doo, don’t mind me while I stand here and hold this while gas drips out under my car...”)
I used to drive old Mercedes diesels and always had to be careful about foaming while filling. Seems like a similar effect in my C4S. My theory is that holding the tip of the gas nozzle against the filler pipe makes for a nice smooth flow so no bubbles or foam. Could be wrong but the mental model works for me every time.
I used to drive old Mercedes diesels and always had to be careful about foaming while filling. Seems like a similar effect in my C4S. My theory is that holding the tip of the gas nozzle against the filler pipe makes for a nice smooth flow so no bubbles or foam. Could be wrong but the mental model works for me every time.
12-21-2018, 08:44 AM
#14
Rennlist Member
^^ There are two separate issues.
One is the gauge that’s wrong. In this case, the tank is full, but the gauge shows 7/8ths. The second is the issue you are describing, which is the inability to fill the tank completely from the nozzle.
I’m sure some people might confuse the two, especially newbies because there’s no easy way to figure it out.
One is the gauge that’s wrong. In this case, the tank is full, but the gauge shows 7/8ths. The second is the issue you are describing, which is the inability to fill the tank completely from the nozzle.
I’m sure some people might confuse the two, especially newbies because there’s no easy way to figure it out.
