Possible pump issue, cold start and missing

[Greg5OH]

I had this problem last winter but it is getting worse this winter.
Engine is a 96 215 Ppump with 300k on it


Symptoms:
-Hard to start, as in coughs and sputters, rolls lots of white and blue smoke, starts on maybe 2 cyclinders,then the others come online after a few seconds of bucking, then rolls blue smoke until up to temp.
slight blue haze at idle.

-When warm and driving, sounds like a dead hole or fuel knock when loading in 4th gear over 2200 rpm

-When still cold and trying to go over 1600 rpm starts missing, popping shooting white and blue smoke out the exhaust

-Very quiet on cold start, can have a conversation right beside the engine

-Normal loud cummins clack when warm

-When warm runs quite nice, but still breaks up at about 2200 rpm when free revving. Fine below and above that rev range.


Thing that have been checked:
-Timing, set reset and rechecked, 17.5 degrees.
-Compression, cold engine, 400 psi dead on all 6 holes
-Injectors, 15 bar below spec (unknown miles) but all pop within 1 bar of each other and have good spray pattern. Tried a set of new injectors just in case, same issue
-20-25 psi fuel pressure at idle. New cummins lift pump, new torktek overflow valve


At this point I think I may have an injection pump issue. Before I take it off and just send it to a shop, I am trying to do as much diagnosis of it myself. Got an DV holder socket coming to inspect the gaskets and see if there is any damage.

Any other ideas?

[Mark Nixon]

Sounds like a worn injection pump, or possibly fuel supply (aeration) issues.

Mark.

[Greg5OH]

Thanks Mark.

Regarding aeration, I have the snubber type gauge ntop oif the filter housing, and the bastard still bounces around like crazy. Any other way to verify if there is air getting into the system?

Regarding worn injection pump, this is what I am afraid of but am accepting that is very well may be the issue. i just want to know what exactly internally to the pump woudl cause this. stuck rack, warped DV, scored plungers?
IF a plunger is scored, i assume it would not pump enough fuel in and it would end up pump in quite late, and only starts running good once it warms up and the piston expends in it?

[turbo2387]

run the truck out of a bucket to eliminate fuel system air leaks. years ago we had a 6.5 that ran as good as it could when it was warm but when the temps outside got below freezing it was always a PITA after lots of tinkering we found ice crystals in the fuel tank which were clogging the in tank fuel sock.

[Greg5OH]

Will give it a try. Put the inj back in, run a supply line from the bucket to the lift pump and dump the overflow back into it, prime it, start it, and then will let it sit overnight again to make sure its all stone cold.
tight fuel system will keep the fuel in the supply line (within the bucket) and prevent it from draining back into the bucket yes?


will try it out this weekend

[turbo2387]

correct. you might get a little drainage so it might take a few more cranks to start but that will eliminate all air leaks from the tank to the lift pump. all other leaks would be pressurized leaks you would see.

[Greg5OH]

alright, will report back here in a few days.

[turbo2387]

you can run the return line the way it is straight back to the tank just watch your fuel level in the bucket as it will all go back to the tank.

[Greg5OH]

Thinking about this some more while at work..if fuel supply pressure is good...that would eliminate air or strainer no?
I mean, easy enough to test but..just thinking

[jasonc]

Check your overflow valve, if the spring has broken it will cause a hard start.

[Greg5OH]

^ i wish thats what it was, put a new one in last year when these issues started originally, no help

Going to do the bypass tonight actually, get it all prepped, put the injectors back in and fire it up tomorrow morning see if anything changes

[56cummins]

Mine does the same thing if the grids are disconnected and i didn't plug it in, temps 20 deg and below.

[odieub]

Had simular issues with my old 95. Only showed its face in the cold for 2 or 3 years. Then started it back in the summer. Rigged up a fuel tank cap with regulated air. Didnt take just a few minutes @ a very low psi to find the hose on suction side from frame to motor was leaking. New line no more spitter sputter.

[Greg5OH]

so put the injectors in yesterday, and hooked the suction side up with about 4 feet of hose to a jerry can of diesel. Hand primed it, cracked injector lines, took longer than usual but got fuel out of them, tightened the injectors, the thing would not want to catch, just shaking sputtering, Then it look slike it ran out of fuel, cracked the lines at the IP, and got nothing coming out of them
I can build a few pounds of pressure witht he hand primer, and i can hear fuel returning to the fuel tank, verified the FSS is all the way up...stumped on this one now...
I know the pump was putting fuel out when i was doing my compression testing couple days ago..

[turbo2387]

so your lift pump is giving out? run a cheap electric special to prime the mechanical. see if the mechanical then gets a visible leak and if the engine fires right up

[Yotadzl]

A few other things to check:
-Make sure the idle RPM is at spec, which I believe is 870 RPM. If the idle is too low it will make it hard to start and start and die until its warm. If you give it a little throttle (just enough to move the pedal) it should start easier if the idle is too low.
-Make sure your timing is ok. Worn Plungers, which is likely at 300k, will effectively retard your timing. Bumping the timing to the top of spec or just over may help this issue, if not it may be time for a pump overhaul.
-As the others stated, verify your fuel pressure and quality. In my experience however the first two are more likely for your complaint on cold start.
-Make sure your grid heaters are working properly, pulling around 40 amps each when you turn the key on cold.

****EDIT: I missed that you had set/checked timing. If everything else is ok, I would say your pump is done. Very common for the plungers in those pumps to get "dusted" from poor quality fuel and fuel filters. There's no adjusting around it.

[Greg5OH]

-Dont think the lift pump is giving out. 1 year old genuine cummins, and it was squiring fuel out the filter housing when i was doing my compression check couple days ago.
-While my initial though for this whole fiasco are worn plungers, id expect fuel to still at least dribble out with no injection lines on the pump.
I think I am doing something stupid here, but..thinks appear to check out.
I will source a little electric pump and run it in front of the mech to see.

[jasonc]

I got a 12v up and running out of a wrecked truck that had been sitting for a long time by splicing into the line going into the fuel filter and using a boat primer bulb and 5gal fuel can. More for wanting to hear it run before I bought it. Worked fine though for a quick and easy cheap test.

[Greg5OH]

thinking out loud though, if i can build pressure using the hand primer on the pump and there is fuel in the filter...the IP should be able to take even what little there is and pump it out with no IP lines on it no?
Wondering if for some reaosn all of a sudden maybe the FSS is deactivating while cranking..will jump direct from battery tonight as well

[95cummins5.9]

Just zip tie the fss up temporarily. Verify fuel pressure.. seen lift pump less than a year old die, straight from Cummins