Fuel Starving Problem

[Jim]

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?

[Jim]

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?

[lindstromjd]

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.

[Jim]

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?

[lindstromjd]

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.

[Jim]

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?

[lindstromjd]

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.

[Jim]

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 :eek:

[lindstromjd]

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)

[Jim]

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.

[lindstromjd]

Hah... so I hit it on the first reply. At least it was something simple. That's good to know. Never any fun chasing gremlins and spending a ton of money trying to figure them out though...

[unloala09]

Can anyone help me explain the newest mood swing my car has taken on...

So after the whole gas in the eye escapade, skibby took me to work the next morning and he went to start up the Z when he got back to my house and it fired right up. Since then its died 3 other places, It runs perfectly fine when It does run. after you start it, drive around and park it, it wont start again. until it sits for at least an hour. Until yesterday morning when It wouldnt start at all. I changed the fpr and got a new filter in there and then it was trying to turn over and every once in a while would run on a few cycles but couldnt sustain an idle. This morning I finally got it running where it will start up consistantly but its got a little knock and I cant tell if its burning oil or a little bit of coolant. its not huge... yet... as in if the head gasket just took a crap, it literally JUST took one and hasnt been driven on. Im about to check valve clearances because Ive always had one that rattles loose every 6 months and its been about that long... but Im afraid its going to go back to not starting... Ive gone through all the fuel injection and it makes no sense why it would be starving it fuel... the ignition is fine, the fuel... should be fine, and air is fine... the basics are all there. The weirdest part is before when it was an intermitent problem, when it ran it ran PERFECT, never died or had trouble while running.

Anyone up for wrenching at my place? or if you have any suggestions Im all ears.

call me as Ill be outside wrenching. 805 895 8462 I live in Beaverton/Aloha.

if some of the smog crap is acting up... would it have an affect like this on it? since Im not in CA anymore Im sure all that stuff can go

[skslave]

I am also having the same problem, I am dropping the tank at school today to check for any clogs and I was wondering if there was a small filter anywhere in the lines that could also be clogged?

Thanks,
Michael

[lindstromjd]

I am also having the same problem, I am dropping the tank at school today to check for any clogs and I was wondering if there was a small filter anywhere in the lines that could also be clogged?

Thanks,
Michael

There's two filters in the fuel line... one right after the fuel pump (the easy one to see and replace) and there's a "fuel sock" type filter on the pick-up inside the tank.

[skslave]

Hey, I'm looking for a fuelpump rebuild kit for my SD33T but I can't find one at any of my local part stores. Does anyone have a website/company with a part number for the fuel pump rebuild kit for this beast?

[lindstromjd]

Officially, there is no fuel pump on the SD33 engine. The injection pump takes the place of it by creating suction on the fuel line, drawing fuel from the tank. If you're not getting enough fuel to your engine, I'd suggest installing an electric pump to help it out. Otherwise, if you need to rebuild the injection pump, a local diesel shop should be able to help you out. Have you tried JESCO in California? They have a lot of parts for the diesels, but they're really proud of their parts, too.

[Archie N. Carroll]

I am new to the in's and out's of the truck world but i would like to say thanks to all as i have used your info, i promise i will have some input to the forum soon just need learn a lil more and ill soon be member of the month :)

[chris olson]

I was on here years ago but I guess my registration was lost in the shuffle......
The Sd33t has a small very fine wire mesh INSIDE the banjo fitting to the fuel lift pump (on the side of your injection pump)
Take it out and you will no doubt be shocked by the debris you will find there..

[Allan E.]

The stock injector pump for the scout diesel is the same Bosch pump used on a zillion mercedes diesels with 5 cylinder engines. It's kind of pricey, but it's a common pump.

[skslave]

Officially, there is no fuel pump on the SD33 engine. The injection pump takes the place of it by creating suction on the fuel line, drawing fuel from the tank. If you're not getting enough fuel to your engine, I'd suggest installing an electric pump to help it out. Otherwise, if you need to rebuild the injection pump, a local diesel shop should be able to help you out. Have you tried JESCO in California? They have a lot of parts for the diesels, but they're really proud of their parts, too.

Okay, so I'm going to try out the electric fuel pump idea, but had a few questions. How much psi should I am for when looking for an electirc fuel pump and where would it be okay to instal it, right before or after the cartridge filter or does it not really matter?

Edit: So I got a 4-7 PSI electric fuel pump and put it right before the manuel pump. When it is on I can crack one of the lines on the canister filter and no fuel will come out, but when it is off and I manuel pump it fuel will come out. Also I can get the engine running but just bearly with teh electric filter off and again when I turn it on while I had it running it will cut off. The flow of the pump is facing the right way. I also cracked the water filter and all that came out was diesel fuel. The only thing I haven't checked is the micro inline filter I've read about in this thread, I just don't know the exact location of it if anyone could help me out there?

[roberthope6]

skslave - any luck with this problem? I've been having similar issues with my truck. Would love to hear if you've made progress.

[timscout1]

After reading all 3 pages I am still wondering if you have checked all your rubber fuel lines? they may have a crack that opens a bit and lets the pump suck air. It may or may not leak fuel out but should be damp. It coukd also be a crack or rubbed spot on the steel or nylon line. When you work on the truck it can shift position and seal for a bit.

[Cummins Travelall]

Jim, try checking for an air getting into the line and causing the injection pump losing pressure. Or you can try running an inline secondary fuel pump

[robcday]

I have a an SD-33T and have just posted a thread concerning engine hesitation, loss of power, and abnormal black exhaust at high altitude in the Rocky mountains. (9,000+ feet) I had the fuel injectors pop tested and they spray fine and the fuel and air filters have been replaced too. Do you have any insight into this? Do you think I should take this fine wire mesh out and clean it? Is it easy for a less-than-amateur mechanic like me to do?