Cm870 running like it out of fuel???

[Chamberpains]

Did you use an inline sight glass at the IFSM to check for air in the system? Cracked pick up tube in the tanks will cause this. Does the problem go away on a full tank?

[Rawze]

(06-11-2021 )Rtrucking Wrote:  ...
change out the gear pump and it ran great for two days
...
then It started to do it again
...

(05-27-2021 )marek4792 Wrote:  ... Early Cm870 ifsms had a filter screen in the intake port before the electric lift pump
...

did you follow up with checking what 'marek4792' said for a possible intake screen problem?
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anybody check to see if you have a cracked pick-up tube inside a fuel tank?

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Is the ECM more than 8+ years old?

[Rtrucking]

It doesn't have a intake screen on it and the pick up tube is new, not getting any air in the system from the tank to the ifsm at all, the ECM is the original one I believe from 06 but I don't have any records from the previous owner and Pete doesn't have any records on the truck at all

[Rawze]

(06-12-2021 )Rtrucking Wrote:  It doesn't have a intake screen on it and the pick up tube is new, not getting any air in the system from the tank to the ifsm at all, the ECM is the original one I believe from 06 but I don't have any records from the previous owner and Pete doesn't have any records on the truck at all

You say it ran great for a few days then did it again. This is either that you touched on the problem that was is causing it mechanically... or that it may be electronic, and had sat for several days.. then the heat cycles got to it again.

(if you suspect the ecm) ...
If the ecm is from 2006 then it would not be a bad investment to replace it at this point if it is suspect. Most engine ecm's are only rated for 8 years and at 15+ years old, it has lived more than a full life it at this point.

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Also, has anyone done some data monitoring on the engine while its acting up? - Is it going into a derate?. Is the fuel pressure dropping off?. etc.
ref: http://rawze.com/forums/showthread.php?t...3#pid58693

[Rtrucking]

Ok so I know it's been a bit but I'm going to give a update on the truck, just replaced the ECM this last weekend and had running rough program it, his program is great and it ran good for the little test I did BUT now it's doing the same damn thing it did before but even worst now I can't drive it more then 30ish minutes and I have to pull over just like it running out of fuel I'm at a lost and look for ideas on what I need to do next, fuel pressure will be 280ish then drop to 210 and falling to 110ish then I stop and shut off the engine and check things out and can't find anything wrong then it starts running better then does it all over again.

[W9L]

Had a very similar problem with a cm2350. Found one tank vent questionable. Also had a blubbering idle that would make you wonder if a valve wasn't seating properly or spring broke. 8 yrs old so I changed out all fuel lines, vents, and new return splitter. Truck has never ran smoother or quieter at any speed. Been getting a fuel restriction code and I guess, a derate that would cut it to 40mph. Pull over, shut it off, wait a couple minutes, fire up and go on for a while. Always happened during high fuel demand.

[Rawze]

(06-28-2021 )Rtrucking Wrote:  Ok so I know it's been a bit but I'm going to give a update on the truck, just replaced the ECM this last weekend and had running rough program it, his program is great and it ran good for the little test I did BUT now it's doing the same damn thing it did before but even worst now I can't drive it more then 30ish minutes and I have to pull over just like it running out of fuel I'm at a lost and look for ideas on what I need to do next, fuel pressure will be 280ish then drop to 210 and falling to 110ish then I stop and shut off the engine and check things out and can't find anything wrong then it starts running better then does it all over again.

almost sounds like a tank not venting.

[Chamberpains]

Loosen you tank caps enough to let them vent and see if the problem goes away. Be sure you don't lose the cap going down the road. Tie a big ol tee-shirt or something around the cap so it can't back all the way off and fall off.

[DVT873]

Ran into this on a while back ISC CM554. Looking at an ESN I have for an ISX 870 I see a very similar looking lift/transfer pump.
  Pump with Screen.pdf (Size: 290.6 KB / Downloads: 198). You have to dismantle the pump to see the screen. On the ISC this pump runs for 12 to 15 seconds at startup to move fuel from the tank to the engine then shuts off. Another pump downstream then gets restricted by the crap on the screen. That in turn starved the CAPS pump and killed it. The CAPS pumps did not like being starved for fuel. We used this gauge to see what was happening. Have to get on the right port on top. Simpler to just take the pump apart. Ours was in a pusher motor home under the bed and a real PIA to get at. The test port was easily reached so we started there. had about 12 Hg of restriction once engine was running.

Looking in Quickserve on the ESN I have 79189652 I see some variations of this but they all involve little screens.

At some point Cummins also ran fuel thru a plate the ECM was mounted to. For ECM cooling. Never saw it myself but have heard of those plugging up also. Restriction test is useful if you figure out the right test point.