A few questions... If I drain the fuel filter bowl or housing and leave the drain open and then turn the key on, shouldn't fuel be pumped back into the bowl and start coming out of the drain again? When I turn the key on it seems that nothing is happening. No noise no fuel flow, nothing. When I switch tanks I can hear the switch working. Does the truck have to be running before fuel will be pumped back into the bowl?

My truck, a 97 HD, started running terribly rough and quit yesterday, and my first thought is fuel problem. Is there a pump in each tank? The truck will not start, but it does seem to hit now and then like it wants to. I plan on searching through some threads later today to educate myself, but thought I would throw a few questions out there. See if anyone could share some info on what the problem might be. Thanks. Josh

 

Josh, our truck don't have pumps in the tanks. The only pump we have is mechanical and runs off the cam shaft so the engine has to be running. It is located in front of the fuel filter way down in the valley.

On the rough running first check the valve cover electrical connections. There are two per valve cover. Look for burnt or melted plugs where they connect to the valve cover. That is a good place to start. Here is a picture what one looks like. The two outer pins are glow plugs, the next two inner pins are injector connections and the center pin is injector ground.

 

Thanks, that makes sense. I started it that morning and it ran a little rough, which is not normal... then cleared right up. went down the road about two miles, started running rough and in no time it was knocking loud and had no power. I pulled over and shut it down. Has not started back. I will check the injector connections. Had a guy stop and say he had a truck like mine and told me that it had electric fuel pumps in the tanks. I didn't know enough to question it. Had already drained the bowl and looked in there, just messing with stuff... Also unplugged and plugged some stuff back in and changed the CPS. I unplugged the ICP tried to start it, then plugged it back in. That's about all I knew to do so called a friend to tow me home.


Josh

 

what you describe sounds just like what happened when my fuel pump went. you should get a fuel pressure gauge and connect it to the test port on the side of the fuel filter. see what you get while cranking. you could also use a tire pressure gauge but I don't recommend it. something about the right tool for the job making things easier...

 

Thanks, I will check the fuel pressure also. Back when I first bought the truck I did check it with a tire pressure gauge just to see about where it was. Seems like it was about 60 psi.

 

I do have one melted connector but it looks like it is just effecting the outside pin, which would be the glow plug. I just plugged that back in then checked the fuel pressure. I was getting about 5 lbs on the gauge and when I noticed that it was just spewing air I cranked the engine over multiple times (after charging my batteries all night). After about 15 times and pumping the pedal (not sure if that is necessary) the truck started up and ran just fine. I then checked the fuel pressure and it was pulsing up to about 70 lbs. The truck does have a BB in the fpr.

Really makes me wonder if the truck wasn't just starved for fuel. The tank was down by the red mark, but I have run it lower than that several times. May have a fuel pick up issue as I've read the rubber deal gets brittle and won't suck up the fuel. I generally put about 26 gallons in it when both tanks show down near the red line, even though according to specs it will hold close to 40.. so I know I'm not getting to low in the tanks. I'll be looking into all that at some point.

Does anyone know if I can just splice in a new valve cover plug or do you have to buy the harness? Whats the easiest way to deal with that? I know its a bad connection because I felt of the plugs after I started it up and the bad plug was extremely hot to the touch and the others weren't. I appreciate the suggestions. Josh

 

Josh, they do make splice kits however I've never had to do it .. yet. I will let someone more knowledgeable inform you what/where kit to purchase. Sounds like you had air in the fuel filter. Was the filter canister empty when you started cranking? Inside the filter canister on the drivers side (up top) there is a small round hole. Inside that hole there is a screen. The purpose of the hole/screen combination is to vent trapped air back to the fuel tank. If that screen becomes clogged up with debris then trapped air has a hard time venting resulting in poor performance. You can take a q-tip with the cotton removed on one end and gently scrap the screen to remove any debris buildup.

 

Thanks Jim, it would be a good idea to check that... I took the thing off and cleaned it good about a year ago, but it may need it again. I know when I left that morning that there was fuel in the canister, cause I opened up the drain while the truck was running and it really poured out the end of the hose, in other words there was some pressure on the system. This was after the truck ran rough for a minute.

About 2 miles up the road it died so I opened up the drain again and there didn't seem to be much come out. That's when I open it up and turned on the key to see if it would fill up, not knowing the truck had to be running. I cranked on it off and on till my battery was low, and the canister may not have ever really filled back up, even though I could see some fuel in there when I opened it. Later on I put a couple gallons of diesel in the front tank, and cranked on it some more, then opened the canister, it was so full it seeped out when I opened it. After a few more cranks the truck started... this was when I was trying to check the pressure. I'm just going to run the truck for now and not run it below a quarter and see if it happens again.

If it did run out of diesel then there is about 5 gallons in that front tank I'm not able to use. Oh, and I had it on the front tank because I had already run the rear tank to the red line. Even though there should be a few more gallons in there I never switched it back to there because the front tank showed more.

Josh

 

Same thing happened to my truck. Before spending any money, fill up the tank to half or better and prime the fuel. If your truck runs great (it probably will) your pickup tube is broken at about the quarter tank mark. Your new empty is a 1/4 tank until you fix it. Be careful, my front tank went, and two tanks later my back tank went. Both run great to a 1/4 tank. Each puck up is about $18. Hope this helps. By the way, I replaced my CPS, ICP, IPR, and fuel pump before I figured this out. Good luck!