HOHN

I've suspected that my gauge has been off for a while. So I did an experiment, and started carrying 5 gallons of diesel in the bed, just in case.

Last week I needed it in busy traffic. I was expecting to fill up soon, and that it would show my needle was off. But I HAD NO IDEA it was *that* much off!! I had 555 miles (all in town) on the tank, so I knew it was getting pretty low.

How is this relevant to products and accessories?

DO NOT OVERDOSE WITH FUEL ADDITIVES. As I add more fuel with no additive, my needle is become more accurate. So there was no permanent damage done.

Do not overdose your additives. Here, the law of diminishing returns applies quickly. IOW, that first ounce of additive does a lot more than does the second, and so on. Eventually, there's no real benefit to adding 15oz over 6oz.

I'll update this as I get more miles on the truck and dilute the additive in the tank.

Mike D

That why I stopped using "that" additive, it messed with my gauge. I'll stick with PS as I've never noticed any difference in my gauge reading.

infidel

Few years back there was a poll on TDR that revealed that people who used Marvel Mystery Oil had many more tank sender failures than folks who used other additives...

duallydave

wasnt there also a recall on some senders?i had a 94 that the sender faliled and it was replaced free because it was a recall,it was way past waranty,

DeanM

I recently took my tank and sensor out of my truck. I was suprised to find some plastic mesh caught up in the fuel sensor float. No wonder the gauge was reading incorrectly. I think the mesh was from around the sending unit but I am not sure.

So you might take your sender out to invesitgate. Or not

Dean

Ph4tty

Which additive? MMO?

Mike D

FP60 or something I can't remember.

P.J

What was that other additive you were using? A number and letter combination? SP something or other? I rememer looking it us last year in gallons because you were having such good success with it.



Interesting. I would bet alot of guys would say More is Better when it comes to additives (within reason of course!)

HOHN

The fuel additive in question is Fuel Power, aka FP60. It's made by www.lubecontrol.com

I feel it is a superior fuel additive in terms of burn cleanliness and lubricity. I like it a lot. Even accounting for the gauge goofiness, I had notiveable MPG improvement-- about 1mpg overall.


I'm quite confident that the reason I had this issue was due to "overdosing". I didn't want to carry around the container in the truck anymore, so I emptied over a quart and a half into the tank (which already had some in it).

As a result, I had probably 4x the amount of additive that they recommend in my tank. This additive DOES leave an oily film on the fuel system in an effort to enhance durability and lubricity.

I believe it's this film that goofed up the sender accuracy on my truck, and in this particular case, I think it was the overdosing. I noticed earlier on that the "richer" I ran the ratio of additive, the more my gauge was off.

Oddly enough, after filling up with no additive (34.9 gallons in my dry 35 gallon tank), the needle moved off of full earlier than at other times.

When overdosed, the needle would be parked on pegged full for well over 120 miles-- in some cases 150+ miles before it would move off pegged full.

With the dilution of the fillup, the needle is moving off pegged full at around 80miles.

I'm going to continue to run without additive of any kind for a little while. I'm out of FP60, so I'll have to go without it for a while.



In the end, I do NOT think my sender failed; rather it was fooled because an excessive overdose of additive interfered with normal operation.

On the other hand, the senders on these things aren't exactly works of engineering art


Final advice: trip odo is your friend. Set it EVERY fillup and use it.