is the "fuel filter" dash light usually accurate?

[GREASE FIRE]

my fuel filter has less than 1000 miles on it and the other day just as i was getting on the highway the "fuel filter" light came on the dash. Truck was running fine and the light would sometimes go off and then come back on.
Then, after the truck was warmed up, i hit the switch on the dash the draws fuel from the wvo tank in the bed, which has a heated fuel pick up and heat exchanger a few inches from the fuel filter, and the light immediately went off.
i switched back and forth a few times and it would eventually come back on with diesel but when i switched back to wvo it would go off right away.
there must be a pressure sensor in there that "works" because it is sensitive enough to register changes in fuel pressure - but is it really accurate enough to tell me when the fuel filter will actually clog and stall the engine?
i only drove about 20 miles on wvo that day but the light did not come on at all, and even after switching back to diesel before shut down it did not come on.
i keep extra filters on board of course but i am just wondering whether i should really take this seriously enough to change filters now. BTW i have PLENTY of diesel anti-gel in the tank so i am sure that is not the problem (probably at least 3X as much as is needed).
any comments appreciated!
thanks,
Paul

 

[Agnem]

You need to fill out your signiture, as we don't know what truck you have, but judging by your description, I'd say it is 7.3 powered. If you have fuel with water in it, it won't matter how old your filter is, it will need to be drained if so equipped.

 

[icanfixall]

Yes they are but.. Running the differant fuels maybe you should install a pressure gauge so you know better whats going on. The filter lite is telling you that you have lost the fuel pressure and are now pulling a vacuum on the fuel system. The injection pump does have a small draw pump in it but thats really not going to get much fuel. When some members have lost their mechanical lift pumps they can run the motor but it has now power because it can't draw enough fuel to make the power.

 

[Dsl_Dog_Treat]

If you're running a stock lift pump, it's prolly starting to fail as mentioned.

Not sure if it's coincidence or not but it seems that lift pump failures seem to be higher for those running WVO concoctions.

 

[subway]

yea filter light on the 7.3 just measures if there is vacume on the system. could be a pump loosing it or a restriction somewhere including the filter itself. it dousent actaully read pressure before and ofter the filter by itself to prove it is just the filter though, just a vacume in general.

 

[GREASE FIRE]

thanks for the replies.
it is a 7.3 and the "water in fuel" light is NOT coming on - only the "fuel filter".

so the sensor is at the outlet of the filter, right?
i have thought about installing a fuel pressure gauge but i would think the best place would be before the filter - that way when the filter is getting clogged i would see an increase in pressure and i would have plenty of warning before the truck stalls out. Does anyone else set it up that way?
thanks,
Paul

 

[subway]

yea it is actually a small canister near the outlet. i cant say for sure on the pressure gage location but i was planning on putting mine on the outlet of the filter so i know i have enough pressure. i will let others chime in on this one

 

[Exekiel69]

You want the fuel gauge after the filter so when the filter is ready to go You will know. Yes the filter light is relatively accurate, once it's ON You may have about 1 mile to go is it doesn't go off.

 

[93turbo_animal]

yeah they will let you know when its getting close to the end and since its going out when you switch to your heated wvo tank more then likely your filter is plugged up with solid wvo and the hot oil is disolving it and letting it flow and when you switch back to the diesel its cold and making it set up plugging your filter. All this is assuming of course you are having cold weather. I had the same problem so I installed a glow plug in the fuel filter to heat the diesel and let it clean it out

 

[darwin]

It depends. Are you running WVO through the stock filter? what is your WVO set up valves etc. ? Information like this could help.

 

[subway]

You want the fuel gauge after the filter so when the filter is ready to go You will know. Yes the filter light is relatively accurate, once it's ON You may have about 1 mile to go is it doesn't go off.

yea sometimes mine gives me that much time running a mix of something, other times when running diesel i have gone 75 highway miles before i could change the filter and it was ok.

 

[gonecrazyi]

Mine never through the light until I was running a 50/50 mix and it got down into the 30's and 40's. Who would of guessed Florida would go from 90 to 35 in a couple of hours.

What a mess that was, plugged my filter, killed the fuel pump and plugged my lines. It took a full weekend to get it all cleaned out.

I had to drive home with the ip pulling fuel, couldnt get over 1200 rpm and 25 mph, like driving in low gear.

But with a new filter and fuel pump, it was like driving a completely new motor! And up until the cold weather I had been running mixes up to 80% for well over a year without any problems. Gall Darnit it shouldnt get that cold in Florida anyway!

 

[Hallworth]

Haha I'll trade you. you can come live in Canada and I'll move down to Florida. It was 5 degrees fahrenheit this morning. Lol Its hasn't been that warm in the morning in three weeks.

 

[Exekiel69]

yea sometimes mine gives me that much time running a mix of something, other times when running diesel i have gone 75 highway miles before i could change the filter and it was ok.

It's funny, when mine did this the light worked as a gauge it could be dim and slowly brighten up until really bright and hen die.

 

[tractorman86]

It's funny, when mine did this the light worked as a gauge it could be dim and slowly brighten up until really bright and hen die.

mine too, when it flickers i start working on getting a new filter when it comes on dimm i had better get one on it soon, if it is bright i am screwed. but the filter that plugs on me is the 2micron i have on my framerail before the e-pump.