Fuel Filter light on

[Ironman03R]

Ok guys I need to think this out, I've been having problems pulling WMO up to the fuel filter. Sometimes it works fine, sometimes it wont pump. I run straight oil in the rear tank filtered to 5 microns. I start and stop on Diesel. If I change the fuel filter it helps most times, but sometimes the light comes right back on. I've been changing filters about every 2-3weeks.
Added 5 gal diesel to dilute rear tank, Slightly better but still turning on light.
Drained water-NO change
Changed Filter- Came back on
I swapped lift pumps-NO change
Installed Holley lift pump- Light still comes on but goes back out quicker and dont try to die out when its on.
Today the light came on and it almost died, had to switch tanks. Stopped and got something to eat, ran on the rear tank on the way home, light only came on under acceleration.
If I switch back to Diesel its fine so that makes me think that its a problem with the rear tank. I know some of you guys are runnin straight oil with no problems, why am I having problems?

 

[subway]

no i am having similar issues with my bed tank. it brings up the light sometimes, i let it alone and it can go away. my next step is to heat the filter itself to thin the oil up. mine mostly does it when i am running the RPM's up like getting on the highway or a long hill. i am fairly sure my carter fuel pump is not keeping up. i actually dumped my airtex pump from a-zone and it helped a good bit but its still falling short.

this is running 100 BTW, when i switch back to a mix it goes away.

 

[Exekiel69]

I would think the oil is too heavy or the pump is not strong enough. You could use a fuel line heater on the tank to pick up the oil and a heat exchanger on the engine compartment. This is oil not diesel so being heavier it will take more time or pressure to move through the lines and filters. You may want to not only heat it but also thin it with some diesel, You are already saving money with the oil don't waste it on filters. Hope this helps.

 

[Ironman03R]

I am thinking about ways to heat it for winter, also thiniking about running a bigger fuel line to the filter. Another suggestion made was that the stock filter wont flow enough and to get a filter that has a higher flow rating.

 

[BigRigTech]

Just a thought but is there any noticable difference in the way the engine runs when this happens? I had this happen to me once when running almost straight WMO but it made no difference in the way the engine ran...If I took my foot out of it then the light went off....The truck was running fine when it happened.

 

[Ironman03R]

Yeah it tries to die out and surges like it aint getting fuel.

 

[subway]

well i found my main problem to be the relay not staying on and letting the pump fall behind. looking forward i want to heat the line from the tank on and up the fuel line size to help avoid this especially when the cold weather comes.
it dousent sound like it really is your filter though, i am also thinking of adding a fuel pressure gage to make sure pressure is getting to the filter that way i can narrow it down with the filter light easily between being the pump or filter.

 

[Ironman03R]

I changed out another filter because the light was coming on with diesel too, I fould that in the bottem of the seperator there was a really heavy black layer of deposits. It still comes on with the rear tank but only under a hard load. Maybe that batch of oil had something mixed in with it???
I'll check it out more in the coming weeks.