"FUEL FILTER" light ? - Diesel Forum

Phillipmc1268 · 10-12-2006, 06:22 PM

Guys, I'm on the road and the FUEL FILTER light in the lower right hand corner of the dash comes on whenever I'm pulling my trailer or running hard. Under light throttle, it stays off. I changed the filter and the light still keeps coming on. What triggers this light? The engine is running fine under heavy loads and freeway speeds. BTW, this isn't my water in fuel light.

Thanks!

Phillip

waterdude · 10-12-2006, 07:46 PM

Try draining some fuel out of the bottom drain. My fuel filter was doing the same thing that your's was doing, only under hard throttle. I drained it a few times over 6 months and then actually replaced the filter again and found sandy grit in the bottom drain, now the light has not returned. Never had this issue until I started burning biodiesel.

Good luck,

Hugh

DSBlack · 10-12-2006, 08:23 PM

If I remember right, this is due to a vacuum on the outlet side of the filter telling you of a clogged filter typically. Also could be a bad lift pump. Something that is stopping the fuel from getting through the filter as fast as the IP is using it.
I would change the filter again. and see if that helps.

cdnsarguy · 10-12-2006, 10:50 PM

Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when cranking. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of engine cranking, route fuel to a suitable container with a hose.

If there is a problem with the lift pump and you are changing it, ensure the new pump comes with instructions as to correct installation procedure if it is the newer model pump with the almost straight arm.

Greenie · 10-13-2006, 04:41 PM

The filter could be partially plugged. When more fuel is burned (acceleration, hills, or pulling a trailer) the restricted filter will trigger the dash light.

Phillipmc1268 · 10-13-2006, 06:55 PM

Okay, thanks for the replies. I'm starting to have an intermittent hard to start due to air in the fuel now. Sometimes it fires right off as usual, sometimes it fires off, runs rough and dies. Then I have to bleed air from the schrader valve.

I've never replaced the lift pump, therefore it's probably a good idea. Could you explain the statement about the correct instructions for the newer model pump with the straight arm? I'll probably buy a Master #60278 from AutoZone.

cdnsarguy · 10-13-2006, 06:57 PM

Call it what you will Master or Carter.........

This info pertains to Carter #M60278 pump or new long arm style.

WARNING

This fuel pump must be installed only at the low position of actuator cam.

If the pump is installed at any other position than low cam, the pump will be ruined, the engine will stall and damage may result.

Incorrect installation will loosen the pivot pin and allows the pin and lever to come out of the pump and drop into the oil pan. This can occur immediately or after several hundred miles. This type of failure is not covered by warranty.

To ensure that the cam is at low position, it is necessary to use a mirror and a remote starter switch. Observe the cam through the mounting port and bump the engine around until a one (1) inch wide machine surface is observed. This is low position of the cam. Now complete normal fuel pump installation.

9502CA
1991

Phillipmc1268 · 10-14-2006, 08:05 PM

New fuel pump installed, thanks for the tip on the camshaft position. I put a photo of the camshaft eccentric in my album in case anyone wants to know what the 1" machined surface looks like. It was harder to take the photo than to install the pump.

http://photos.thedieselstop.com/show...hp?photo=30430

I test drove the truck and had no problems, but didn't go so far as to hook up the trailer and give it a real workout. We'll see how it goes next week. Thanks again.

Phillip

Phillipmc1268 · 11-06-2006, 02:59 PM

I finally had the chance to put a heavy load on the truck since I changed the lift pump. I hauled 2 cords of seasoned oak on a 7x20 3 axle trailer Saturday. The filter light stays off and the engine does fine. There is one other thing the lift pump cured. On cold starts the engine used to start then run rough, as if it had an air leak, for a few seconds. Now it's smooth.