Can't seem to find the thread that talked about this. The last couple of mornings have had all kinds of trouble getting started. Losing prime. Has been intermittent over the last couple of months . . .and this morning I was below half tank. Have replaced the lines all the way back to the tank and new overflow valve about 4 months ago, so I think leaking lines are out as a possibility.

I filled up and will try again tomorrow morning to see if I have any problems. If not, then probably pick up tube? It seems that there was a fix for this without having to replace the whole module? Can someone help me out with what that might be or the thread that talked about it.

Also, would a hole in the tube cause idle speed to drop? This morning it was under the 750 line and after fill up it was back about 850 where it normally is.

Thanks!

 

Maybe this is what you were looking for https://www.dieseltruckresource.com/...d.php?t=112472

 

Thanks Bill for the reply. I was thinking someone had put rubber lines suitable for submersing in diesel fuel over the pick up tube? I just couldn't remember the rating for the hose and what size/how much? Maybe I'm imagining.

Does this sound like a reasonable diagnosis though?

 

Hole in the pickup tube is somewhat common pre '97 due to the sharp self tapping screws used to put the module together rubbing on the tubing.
Happened to me and I had the half tank blues. Drove around never letting the tank go below half for almost a year before figuring it out.
Other points I've run across that cause a problem with low tank levels or parking on an incline are a bad check valve in the lift pump or a leak in the steel tubing on top of the bell housing (which you've eliminated) Other common leaks such as at the fuel heater or return line usually cause problems no matter what the tank level is at.
I usually run down supply system leaks with compressed air to the tank but unfortunately this doesn't work with a leak in the tank. You'll have to drop the tank or tilt the bed (preferred) to get the module out.

 

Pretty sure I confirmed it this morning. Went out and started right up. Unly stumbled a bit when I free revved it but that was at 2800+RPM, so I guess I would expect it then.

Guess it's check out the tank now. Thanks for the help!

 

Well, we got the tank down and the module out yesterday. (Bed has way more bolts to take out cuz of the gooseneck plate, and a transmission jack worked real good for lowering it down). Cleaned it all up and pressure checked all the lines, no leaks. So I guess now I just wait for it to get down under half again and see if I still have problems? If so, lift pump? We tried to pressurize the tank to check for any leaks, but everything kept coming right back out the little vent on the top. Plugged it and couldn't find any other leaks. Starts and runs fine now.