More Fuel Problems @!#$@#%!!!

[Petri317]

A while back, I was having surging/rough-running problems, which were caused by a bad lift pump. In went a holley red, and all was great....Until yesterday, when rough running returned. All of the return lines are brand new, and everything else is 6 months old. I have verified a steady stream of fuel to the injectors (no air) but, 2 of the injectors (6 month old Delphis) on the passenger side have puddles with bubbling as the rpm increases at their base (not the return caps.) These injectors were installed with new copper rings and clean threads (the heads were rebuilt and spotless.) and were torqued to spec(and verified with two seperate torque wrenches, as I am **** about that stuff. Do you'all think the copper rings are bad? Or the threads? My game plan is to replace the two injectors in question. Any thoughts, comments, suggestions?
Thanks in advance,
Peter A.

 

[sle2115]

That would be where I would start. Should see some carbon in there if they are leaking I would guess as it seems to form pretty quickly.

 

[OkieGringo]

You might want to get ahold of a "injector seat cleaner". They are VERY expensive to buy, but someone might lend you one. It screws into the hole and the knives are rotated. OkieGringo

 

[RLDSL]

You might want to get ahold of a "injector seat cleaner". They are VERY expensive to buy, but someone might lend you one. It screws into the hole and the knives are rotated. OkieGringo

And if that is out of the budget range, a shotgun bore brush will do a half decent cleaning job with a bit of elbow grease

--------Robert

 

[Petri317]

Update: Haven't changed out injectors yet, but noticed no bubbles/fuel around any of the injectors. And I have isolated the miss in the engine. It now seems to only occur between Idle and 2500 RPM. Above that it runs smooth as it should, as well as deaccelerates smoothly upon lifting off the fuel pedal. Below 2500rpms and it cuts in and out, sometimes randomly, sometimes in a pattern. I'm at my wits end with this thing!!!!!!

 

[reklund]

If you've got fuel bubbling up around the threads of the injectors, I'd suspect bad injectors. A failed copper sealing ring will allow combustion pressure to escape through the injector bore...

I just had this problem on my truck, and the injector wasn't lapped properly during a rebuild, and the injector body itself was leaking. It was leaking between the upper and lower case halves of the injector, and bubbling up out of the threads. The threads aren't designed to hold any pressure or liquid back- they just hold the injector into its bore.

You might consider swapping the injectors around to see if the problem goes with the injector- if it stays in the original location, THEN suspect copper washer or injector bore seat sealing issues. IF it moves, then the problem is associated with the injector...

HTH,
Ryan

 

[Petri317]

Update: I swapped in three brand new injectors in (all the local parts place had to buy) the truck runs a little better, but still rough. I then proceeded to swap around the old injectors in order to weed out potential bad ones. I was unable to tell the difference except for one I had replaced with the new ones. Meanwhile, it still runs rough at idle, acceleration up to 2500rpm, and upon deacceleration. I am thinking I need to buy more new ones (to complete a set.) What ****** me off is the "old" set(Delphi's) is 8 month old and have only been run for 2 month (and they ran great til about 2 weeks ago.) I bought them from DIS in Texas, and I suspect it will be difficult to try and make them take them back, as they are under new ownership.

Any suggestions, similar experiences with this problem?

Thanks RLDS for the tip, the brushes came in handy and worked well!!! Thanks everybody else for the help!!
Peter A

 

[Diesel JD]

Hey you might want to have your timing checked and verify that it is within spec as retarded or advanced timing will cause poor idle, and less than optimum performance under acceleration. Its hard to set timing without tools and the spec is 8.6*BTDC@2000 RPM with the pulse method or 1.5*ATDC @ 1400with the luminosity method.

 

[Petri317]

I actually just had it timed by a diesel shop (with a meter) about a week before it started running bad.

 

[TLBREWER]

Peter

Not to doubt the quality of the diesel shop you used, but you made a very important statement. You just had it timed by a diesel shop about a week before it started running bad. This may be a coincidence. Or maybe not. Trying to find a diesel shop that actually knows anything about IDI's is getting increasingly harder to do. Not saying they did something wrong, but that may be where you need to start looking for the rough running. I've given up trying to find any shop that knows how to work on these. I've even had my local mechanic ask me questions about them because all they work on is powerstrokes and cummins'. Go figure.

Tom

 

[Petri317]

The pump is tight as can be(bolts are not loose), and in the same place as when they timed it. It ran beautifully after they did so. I just replaced 3 more of the injectors (for a total of 6!!!) and moved around all 8. No difference. Still a stumble & cutting in and out from idle to 2300 and back. I'm at my wits end and moneys end as well. I've thrown $300 into this POS just to fix this problem that won't go away, and appeared out of nowhere. Any other (possibly cheap) things this could be? Thanks again for all of your help guys!!

 

[Petri317]

Maybe it's the IP? How does one access the "screen" in the IP that could get clogged?

 

[dsblack]

Do not pull the inlet screen from the pump. That nut does more than hold that screen in.
Have you changed the filter since this happened? Maybe some real bad fuel??

 

[Petri317]

yes, I did change the filter, and added power service additive to the new filter and in both tanks.

 

[dsblack]

It sounds like it does this when in the driveway also? if so, have you tried running out of a jug of fuel, to eliminate a colapsing line, or fuel pickup issue? Just a couple ideas. this is strange.
Do not give up.