TowRig.com - Diesel Discussion and Tow Tech

hey guys, my 98' 12v is acting up. been doing it on & off or about 7-12 months.when i start the truck up after it sits all night, it'll idle fine for around 3-5 seconds and then will start to try and die. It'll sputter and spit and sometimes it will die, but sometimes it'll clear up and be fine.once its fine in won't happen again all day.When it does die i have to crank it for a few secs to get it started but it'll start and run perfect. it doesn't do it all the time just now and then.i was told it could be the lift pump, or a hole in a fuel line.i think but i'm not sure, it seems to happen when fuel is below 1/4 tank.Any suggestions?

I'd be cautious of the fuel guage, you might be actually on empty and not at 1/4 tank.

it could be. i have'nt thought of that.

You are getting drain back caused by either a bad check valve ( I am not sure if these trucks have check valves or not), you are getting air in the lines somewhere, or possibly a pump going bad.

I've seen it happen on different equipment before. You've got to figure out why you are losing fuel prime.

i'm not sure, but is an overflow valve the same as what your talking about?

First - fuel filter? Changed it?

Next, mileage? how about fuel quality? might bejunk in the tank clogging the pickup.

Next, injection lines. Check them to insure they are tight.

Check thelines from thetank to the injectors. You need to look for small amounts of fuel indicating a small leak.

Finally, check fuel pressure. Its rare, but maybe you have lift pump going south.

Oh, yeah, sending units can be common. I know of a few customers that read over 1/4 tank and run out. . . .

i'll check it all out. thanks guys!

You have a fuel drain back issue on the suction side of the lift pump. It is probably the fuel supply and return lines. They are rubber lines (make sure you use Diesel rated hose) that go from the frame rail to the metal lines at the engine. What happens is the fuel lines will have small cracks on the inside layer of the liner. When they crack they don't leak fuel but they will leak air. When they leak air you get what your discribing.

The other possibility is the fuel heater is leaking air at the electircal connector. Just bypass the fuel heater. I live in MN where we see temperatures in the -20 and colder range. I don't have one, and I know lots of trucks that don't around here.

I don't remember the sizes at the moment. I believe the big line is 3/8th's. Again, make sure it's Diesel rated hose.