Hi,
I’m really hoping you guys can help me out as you have in the past.

92 Dually 350 – I turned the full power screw in a turn about 14 months ago. Loved it! Ok, but about 6 months ago it seemed to be leaking fuel in a drip----drip----drip sort of way from there. Well, I lived with it for a while because we were hauling butt all over and I never had time to try to figure out what to DO about this leak. Anyway, this brings us to the problem now. Day before yesterday, I pulled out the screw all the way and put a tiny layer of gasket maker on the little rubber ring, and then a little bit near the top of the threads where they enter the Injector Pump. Screwed it back in, waited 24 hours and then started…oops…it wouldn’t start…got frantic (“Oh no, I ruined my injector pump! Ahhhh!”) and pulled it out to clean it off…in doing so I realized I had not put the stupid little key tab thing in the the little groove and so it wasn’t seated and in correctly…duh…fixed that and put it back and viola! It started right up. So then we go to head into town and the minute my wife (who is driving) pushes the pedal, the thing cuts out and loses power and almost dies…she lets off, and it idles fine…she pushes and it loses power and almost dies…In PARK it will rev up fine, but seems to have little hitch right when START to put the pedal down…so we keep checking and it seems to go to about 10-15 before this becomes apparent, then it chokes, stutters, loses power and almost dies. I was really freaked. So I went in the house as it was getting dark and put on my thinking cap. I figured maybe I messed up and the full power screw wasn’t in enough, so it couldn’t get fuel enough. I also thought maybe air in the injectors and I could loosen them until it spit. Ok, long story short(er) I did that stuff, put the screw in further (to the little stop thing on the collar) and let any air out of the injectors. Then I went for a drive, and it still does the same thing. Possibly a bit less, but what I noticed is this: If I leave it idle, it’s fine. If I push it down say ½ inch to say 1¼ inches, it stutters dies out loses power and acts like ALMOST NO fuel is getting through, but if I push the pedal quickly past that to the 2 inch plus (I’m guessing on the actual distance here..but that was it felt) it revs up and I can drive it normally, and even took it for 5 miles at 70 miles an hour on the highway. When I got off, I let the pedal up, and it idled fine, but when I pushed it back down to go “city street speed” it chokes, stutters and cuts out and if I just keep it there it finally dies. Starts RIGHT back up, does speed fine, but low acceleration kills it.

Please, I’m a fulltime traveler and I’m in Bowie Arizona (it’s a VERY small town with not much in the way of services) at the RV park (we pull a 5th wheel), I’m self employed right now due to the economy, so a new IP is not happening right now. Is there anything you guys can offer as advice, or am I missing something, or is there some crucial adjustment that will fix this? Any ideas WHY it is happening? And supposing all goes well and there is a fix, how would you stop the leaky full power screw?

James, who is hoping you guys can come through for me yet again.

 

perhaps try your lift pump, it could be bad. another possibility could be that the fuel shut off solenoid has trash stuck in the seat and is thus reducing fuel flow. it can be easily removed to check. as for your fuel screw leaking, the best (rather the only) way to repair that leak is to simply replace the seal packing on it. using any kind of sealant is a bad idea , being that the injection system utilizes very small ports and orifices to deliver the fuel, any kind of particle no matter how small (including gasket makers) can cause malfunctions. some more information could be helpful if you were to let us know if the exhaust is smoking and of what color when the truck runs poorly.

 

I'll check tomorrow when it is light out. I mean this is a problem that would SEEM to be wholly related to the removal and replacement of the power screw. The truck drove quite well, I did my little attempt at sealing it, and now it does this. It is not an intermittent thing either. I mean, if I push the pedal to where you would to slowly accelerate to like 30-45 in the city, it refuses and just chugs and misses and stutters and mostly just feels like the engine shut off, with little bursts of "vroom" in between. But if you "punch it" (and not even to the floor, but just to pretty heavy acceleration), it runs like gangbusters, and it did 70+ with no problems.

Oh and would either of those allow the condition where it will accelerate fine under heavy acceleration? Lift pump was replced about 8-10 months ago.

Will check the smoke tomorrow morning and report back here. Also, where exactly is the fuel shutoff solenoid, is there a diagram or pic some where? Could my little surgery have clogged it?

Thanks so much for helping.

James

 

as for the lift pump, I carry one spare in the toolbox at all times along with a spare belt, and I have had a bad one straight from the box. the shut off solenoid is located next to the fuel screw and has the main 12 volt power wire going to it, center/top portion of the pump right in front of where the injection lines go in. I do agree with you from a mechanics view, that the last thing to be worked on before a problem started is usually the first place to start looking for the culprit. the only other thing I can think of possibly causing this type of problem with your truck is some sort of failure with the governor or the pump itself, but as I was always told..... start with the simple stuff first.

Are you sure that you have the screw back to where it was when you originally removed it? Are there any air restriction to the turbo, does it spin freely. Is a air pipe disconnected?
These are just a couple of more things to consider.

 

Hope you didn't get thread sealant floating around inside your pump. Just a we dab of it in the wrong place and you will be walking.

 

Ok, so, new observations and stuff:

1. My smoke is and always has been dark gray-ish. It isn't smoking really more or less than ever before, and overall this truck isn't a big smoker. Part of that might be that I haven't put gauges in yet, so I ONLY turned up the full power as a mod so far. So, thus no real smoke other than when I start there is often on big puff of black. Then a real light barely visible grayish.

2. The fuel pump prime lever has NO resistance when I pump it. I am pretty sure this one never really has. But on the fuel pump question...What doesn't make sense for the fuel pump to be out to me, is that the truck will always accelerate just fine if you actually give a good amount of fuel. Know what I mean? Wouldn't a lift pump that dies allow for start and idle (generally) but as soon as load gets put on, it won't actually MOVE the truck? Cuz like I said, right now, if I go out and nurse it to a 45+ zone, and then punch it up to 45+ it runs like a champ and can do 70+ no problem. In fact once yer past that first inch or so of accelerator, it even cruises at 50-75 just fine.

3. I loosened the power screw to check it, and it got worse, I mean even if I mashed the accelerator, it would go vrrrrrooOOOMM-------vrrrrooOOOM-----vrrrooOOOM--etc. almost like a metronome like 2 second accelerate-1.5 no accelerate on and off. So, I turned in the power screw a teensy bit further than I had it before (it's by the jam nut thingy tho, so not much further) and it got better, but it still will die out if I hole the accelerator at like 1 inch down, and stutters and hitches even on a steady acceleration, but if I push it quickly past and byond 2 inches, it revs mostly like normal.

I hope you guys understand why this has me so stumped. I mean, if it was just a matter of idle works acceleration or putting it under load doesn't, I'd jump to the normal Fuel Filter, then fuel pump route. Or even that I clogged the IP, but even the IP...would it act like this if it was clogged? I mean would be able to go 70, but not 25? I'm racking my brain here. I will check the fuel shutoff solenoid tomorrow morning, since I have all day to work on it tomrrow.

Again you guys, thanks for the awesome brain power and keep up the wonderful ideas.

James

 

It really sounds like what they do when the throttle lever is clocked too loose. Did you mess with the throttle lever at all?

 

Not sure. In other words, not on purpose. At our last stop one of the two springs on the throttle linkage stuff was busted (but still there) so I rebent the end and re-hooked it. I did notice today that the little thing on the side of the IP (that faces you) that ius under the throttle linkages and springs and stuff, that turns with like springy pressure (I'll take a pic tomorrow I promise) has NOTHING going to it...it looks like it should have something attached, but doesn't. Is that the throttle lever? I'm pretty darn handy mechanically, but my knowledge of the names of parts and terms for them is not so great. Anyway, lemme see if I can get a pic and post it....

Oh yeah, I also unhooked the big air cleaner hose from the box for a sec and tried acceleration with it off and there was no discernable difference...so it isn't a clogged air filter...hehehe...off to try and take a pic..

James

 

Ok, the yellow line is the spriung I re-bent and fixed and the red circle is the thing that has NOTHING hooked to it and moves around with a springy motion.

Does any of that help?

 

Yellow thingy holds the tv cable forward (also known as a kickdown cable), the red thingy is the manual shut off lever. I does not have anything connected to it. If its running and you push the lever back it will kill the engine.

 

The green is your shut off solenoid, mine has 2 wires going to it, it would appear you only have one. Maybe check the wiring on it?? My frinds truck had a loose connector, and it would close at odd rpms and then come back on. The blue is the fuel inlet, looks like it has a kink in it, maybe its restricting fuel??? I would think the higher the load the worse it would get, not have bad mid range and do good up high.

 

I'll check it, though nothing on there (the tube) has changed or been touched since before my little escapade.

I can't find anything in search on "Clocking the fuel lever"...help?

I just can't understand, even with everything I've read about these IPs, how or why it would have a missing, stuttering, chattery, almost dies, and sometimes does LIGHT accel and Mid accel, but it sounds Beautiful at idle and runs great on the highway. Gaaahh! Soon boys, I will be insane!!! hehehe.

My wife was like "We could almost continue our travels, except we have to get off and get fuel and stuff"...which is exactly it...the red lights and the stop and go and the slow city stuff is all that is the problem.

James

 

I don't think either of the things I pointed out could cause this, I am at a loss. Fuel lever is the mechanism that the throttle linkage connects to. Internally it pulls on the governor spring. It has a splined shaft. If you take the pump top off and index or clock it wrong when reinstalling it will make it run wierd. If you have not taken it off, its not the problem. Some have had an issue where they took the fuel screw out and put it back in and it actually broke the little lever inside that the fuel screw pushes on. Not sure what symptoms that creates though.

 

So...today, I didn't have much I was able to do with it, so I just tinkered a little, and so far that hasn't done anything. I just cleaned the solenoid wires, made sure they connect ok (it seems like the ONE wire, if disconnected, makes NO difference...is there a fuse I should be looking at?), and cracked the injectors again to make sure. They seem to have real nice pressure and spit nice and hard when cracked, at least at idle.

Then I started experimenting with the pedal again. It seems that about 15% to 25% down and the car will literally drop from a nice highish idle (remember I have the fuel screw pretty far in) smoothly down to a low idle and a lower idle and then it dies...real smooth like....26%-35% (maybe even less of a range and it hitches and stutters and kinda goes from accelerate to dying and back in a real spastic sort of way. 36%-80% (maybe even 100%) and it accelerates fine with maybe a few little glitches here and there, but mostly it's fine and drivable in that range.

So could that be a lift pump or bad fuel filter? Bad fuel? Would a lttle piece of gasket seal floating around in there show up with these symptoms? I am so freakin perplexed and lost and I so don't want to have to a diesel mechnaic for this, since I see it costing me like 3 BILLION dollars to trace down. Sigh.

Ok, so my main question, other than those up there if anyone wants to give em a try, is this...I was thinking about what y'all say on here about starting simple. If it is Bad Fuel, or if it's a clog, wouldn't I be best off to throw some injector cleaner/Diesel conditioner stuff in the tank? Is that a good place to start? And what do you guys think..is Diesel clean the best, or do you think something else is more heavy-duty and will scour those clogs and make that fuel at least push through? I have an AutoZone at my disposal if i make the 22 mile trek to town. I don't wanna waste it.

Also, is there an easy way to test the LP?

Thanks in advance,
James

 

James, it really sounds like the throttle lever is clocked a spline too loose, but you didn't mess with that.

I'm going to go with sootforbrains and say that you might have hurt the governor lever, although I can't see how that could have happened unless you really cranked the fuel screw in tight.

I think the pump top's gotta come off.