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Removing corrosion on a fuel level sender
My VDO fuel level sensors are over 10 years old and have only had fuel inside the tank for 18 mo. Both senders matched the 10 Ohm full and 70 Ohm empty until 9 mo. ago. Then the Left tank sender in my CH 650B started raising the resistance. The resistance reading has been going up steadily over 9 mo. and would only read full on the gauge when it was less than half.
The reading last week was 220 Ohms FULL and 1,000 Ohms empty and it continued to increase. I verified a good ground to the sensor and tank. I suspected this was due to corrosion on the VDO sensing strip. Replacing the level sensor seemed like an ugly job.
An internet search found this was a common problem with cars that had been stored, especially Corvettes. Many recommended using a fuel system cleaner that might remove the corrosion. Chevron Techron fuel system cleaner had a good success rate. I added the recommended 1 oz./ gal to my Left wing tank. After 4 days at 35 - 40 F, The corrosion has been removed and the original OHM readings are restored!
I was getting ready to replace the Left level sensor with SW, but now it looks like the solution to the suspected sulfur corrosion has been fixed for now.
Good Luck! Larry Zepp, Zenith Zodiac 650B, N22LZ
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Replies to This Discussion
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Permalink Reply by John Austin on
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Great tip!
The VDO senders rub on wire wrapped around a flat surface and are exposed and subject to corrosion. If anyone does have to eventually replace them, I also highly recommend the Stewart Warner senders instead - they have a thick film encasing the resistance strip and are much less susceptible to corrosion, deposits, etc.
John
N750A
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Permalink Reply by Larry Zepp on
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Hi John,
Thankyou, I have read your threads on fuel sender woes and replacement with SW. I was ready to pull the trigger on this, but this fuel system cleaner delayed my installation of SW into my Zodiac 650B. As you have noted, SW has an excellent history with RV homebuilts.
When I read your posts, I coated the outside of the installed VDO senders with Proseal to maybe buy me more time before I have to replace. When I need to replace with SW, which sender do I need for the Left tank on a Zodiac - Right hand or Left hand?
Best Regards, Larry Zepp N22LZ
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Good question! I was totally mystified by the "left" and "right" designations as I couldn't see any difference in the senders. However, I "think" (and someone correct me if I'm wrong!) I've figured it out. Looking on the SW website, it says "left" means the float swings out to the left relative to an "index hole" at 12 o'clock position and obviously "right" is the opposite. I "think" this is only actually important in situations such as top-mounting the sender with a fixed orientation of the holes in the tanjk so that it has to protrude to the left or right for clearance from a tank wall (and keep the resistance range correct) versus mounting them on a vertical surface so that the float and arm move up and down vertically??? I "think" either left or right senders would work as we can orient the float arm any way we want (there's no fixed holes in the tank to mount to and no sidewall clearance issues) - just be sure the up-down resistance range is correct for full and empty! Clear as mud, correct? LOL!
John
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