Page 1 of 3 123 LastLast
Results 1 to 10 of 25

Thread: Fuel Starving Problem

  1. #1
    Join Date
    Oct 2009
    Posts
    18

    Default Fuel Starving Problem

    Our diesel Scout with SD33T just started having intermittent fuel starvation problems. It runs great and then it acts like it is not getting fuel and sputters. If we pull over and let it idle a bit, the problem goes away. It seems to be kind of random. Its almost as if someone put a ping pong ball in the tank.

    The first thing I did was change out both fuel filters, bleed and then test drove. It ran great last night after the change. However, it acted up again on the way to and from work.

    My next thought is that there is something in the tank, or lines that is obstructing the flow of diesel. Maybe the body is crimping the fuel line. I doubt this but it will be easy enough to check. I guess I will have to pull the tank and clean it out. Then blow out the line from the engine compartment to the tank.

    Am I missing anything?

  2. #2
    Join Date
    Oct 2009
    Posts
    18

    Default

    After reading some other threads,maybe there is a fuel line problem between the tank and the first fuel filter. I did run a couple of tanks of B20, but that was a year ago and its run fine since on regular diesel. The problem is intermittent, meaning I can go WOT and it runs great for several minutes. But evenutally it acts like its not getting fuel, but returns to good again after stopping or slowing down. If it was a bad fuel line, wouldnt it have a problem all the time? I dont see why it would be intermittent unless there is something in the tank that plugs up the line and when the fuel demand decreases, the obstruction falls off. Does this sound reasonable?

  3. #3
    Join Date
    Jun 2009
    Location
    Hurlburt Field, FL
    Posts
    495

    Default

    Sounds like an interesting problem. Do you have a 19 or 33 gallon tank? If a 33, they're easy to check for dirt as they have a drain plug, and they're covered with sealant on the inside; very well designed. If a 19, you'll have to drop the tank and take off the sending unit/pickup. Don't think the 19's came sealed from the factory IIRC. Maybe the sending unit/pickup has something wrong with it? I don't remember if they have their own filters on them or not. Easy way to determine if it's the sending unit or tank would be to disconnect your fuel delivery line going into the injector pump and stick it in a gas can. The injector pump works off of suction, so you shouldn't have a problem getting fuel out of the can. Run the RPM's up for a while and see if it still chokes out on you.

    Otherwise, have you ever had a problem with your injector pump? There's a possibility it might be starting to go bad. If it's acting up after running for a while it might not be able to pull enough fuel from the tank to deliver to the injectors anymore, and lowering the RPM's would allow it to catch back up. An electric fuel pump won't hurt one bit if the tank turns out to not be a problem.

    If you suspect your fuel lines, it's a cheap fix to replace them entirely with rubber lines. I ran mine along the frame on the inside to keep them protected when I replaced my old plastic lines.

  4. #4
    Join Date
    Oct 2009
    Posts
    18

    Default

    So far I dont think I have a problem with the injector pump. However, I really dont know. The injectors are good and each cylinder is firing fine. I put new rings, pistons and a couple new liners in a few years ago. It does seem to blow more white/grey smoke on WOT then our other diesel which blows black smoke. This one will blow black when the truck isnt moving, but under load it blows greyish colored smoke. I wonder if the pump is getting weak. Im nearly positive that the tank and lines are fine. I just restored the truck and although I reused the fuel lines, I do know the tank was okay earlier. Im starting to think that the pump is wearing out. Although the intermittent problem is a mystery. So you think an exterior pump between the tank and filter would help? Maybe a local diesel mechanic can rebuild the injection pump if I remove it?
    Last edited by Jim; 10-31-2009 at 11:00 AM.

  5. #5
    Join Date
    Jun 2009
    Location
    Hurlburt Field, FL
    Posts
    495

    Default

    Yes, a local diesel mechanic can rebuild your pump if you remove it. When you replaced the pistons and liners, did you inspect your head? Were there any cracks in it? It's very common (and still within factory specs) for them to crack in between the valves. That might account for some of it. Also, check your head gasket. It might be blown out, and that would explain the irregular colored smoke.

  6. #6
    Join Date
    Oct 2009
    Posts
    18

    Default

    Okay, the problem isnt so random. I still need to run the vehicle with a spare 1 gallon tank in the engine compartment to rule out a problem in the lines or tank. It starts to stumble after a couple miles of highway driving. Then after letting off the throttle, it recovers. IT blows grey smoke when its not stumbling, and essentially no smoke when it is stumbling. IF there is no fuel restriction caused by tank or lines, Im leaning toward an injection pump starting to fail. Could be the cam lobes are wearing down and so the pump isnt as efficient as it could be.

    I had the head checked and new valves put in when I did the engine work. There is no loss of coolant so Im confident it isnt burning coolant. There is a small seepage leak at the head gasket, but I dont think this is the cause, since it has been like this for years.

    I will try to bypass the fuel tank sometime this weekend. IT still gets me to work no problem, so we might just run it this way until we can afford to have the pump rebuilt.

    BTW, if I remember correclty, to remove the injection pump, one needs a special tool (bolt) to press it out. Anyone know where I can buy or rent this tool?

  7. #7
    Join Date
    Jun 2009
    Location
    Hurlburt Field, FL
    Posts
    495

    Default

    Local mechanic should have the tool for removal, or at least know where to get one so you can use it. I'm concerned about the blowing smoke and head gasket leak though. My SD33T was completely rebuilt (sleeves, pistons, rings, etc) and doesn't blow any smoke at all now. The old head was cracked pretty badly though so it used to blow white-ish smoke all the time. Maybe I'm just being overly concerned with it though. It's possible that the smoke could be un-burnt fuel vapors.

  8. #8
    Join Date
    Oct 2009
    Posts
    18

    Default

    Yeah, Im getting concerned too. The draft tube is puffing out more smoke than I would like it too. I may not have done such a good job on the partial engine rebuild. I never looked at the head very closely, maybe it was cracked all along. I do know the PO really messed up the engine, it was pretty well fried when I got it. Ive never liked its performance, so maybe we will look for another SD33T to replace it. If I was rich, I would get one of those Jesco new SD33T's. I think their price was something like 7K

  9. #9
    Join Date
    Jun 2009
    Location
    Hurlburt Field, FL
    Posts
    495

    Default

    Lol. I know all about JESCO... they're expeeeeeeensive. Try this though... if your block is fine, and you're really serious about a full rebuild, check ebay for a full turbo rebuild kit (search nissan SD33). They come from Australia and cost about 1100 USD. That's what I did with mine; bought a new head from JESCO and a full rebuild kit from eBay and hired a mechanic buddy of mine to do all the work for me. It's not a power house by any means, but it gets the job done and it's finally starting to break in after 2500 miles (it's in the Scout I'm rebuilding right now).

    (btw, not sure if the first post will show up; I had a link for ebay in it)

  10. #10
    Join Date
    Oct 2009
    Posts
    18

    Default

    Thanks, that sounds like a good alternative.

    It turned out to be the fuel sock in the tank pick up. I removed it and added a see thru filter in the engine compartment. Its running good now.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •