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zyNoT · 05-30-2018, **(Subject: Intermittent CM2250 stalling only at idle )**

Hey everyone, I have a CM2250 and it appears to randomly stall at idle.
One of the times it stalled out I was monitoring some parameters in Calterm.
Fuel commanded was @ 750 bar while actual dropped below 500 bar and it stalled.

Fuel gear pump is new within a year, I’ve changed all fuel filters and separator. Fuel lines are also new and were replaced at the same time as the fuel gear pump.
Pressurized the fuel system and did not seek any leaks. The engine also seems louder right after it’s started back up after a stall. So far every time it’s stalled the truck was on a hill, tanks were at half full or higher, and A/C was on. Sometimes it will start right up after a stall and only one other time it was a little bit harder to crank.

When truck is off I haven’t seen a drop in rail pressure it seems to maintain. I’m at a loss, any help is appreciated.

jimeneztrans84 · 05-30-2018, **(Subject: Intermittent CM2250 stalling only at idle )**

When my truck was stalling and loosing hp it was getting air from pick up tubes in both tanks. Pickup tubes were cracked.

zyNoT · 05-30-2018, **(Subject: Intermittent CM2250 stalling only at idle )**

I forgot to mention when it commands more fueling I get a ticking or knocking noise.

05-30-2018, **(Subject: Intermittent CM2250 stalling only at idle )**

your probably not maintaining rail pressure. I would run a low side sight glass and check for bubbles, the fuel water separators leak alot. if not could be a pump actuator getting lazy or a lift pump cutting out/getting old aswell.

zyNoT · 05-30-2018, **(Subject: Intermittent CM2250 stalling only at idle )**

(05-30-2018 )Unilevers Wrote: your probably not maintaining rail pressure. I would run a low side sight glass and check for bubbles, the fuel water separators leak alot. if not could be a pump actuator getting lazy or a lift pump cutting out/getting old aswell.

I can now confirm it’s when the truck is going up a hill. It will stall out, lose power etc. however for the most part while driving it maintains rail presssure. Even when going up a hill the pump maintains pressure unless you come to a stop then it stalls. It’s a Paccar water separator btw. Rail pressure seems to hold when truck is off. I wanted to test lift pump by turning key but when I checked actual rail pressure was at 10.2K psi hours after engine was shut off.

Rawze · 05-30-2018, **(Subject: Intermittent CM2250 stalling only at idle )**

(05-30-2018 )zyNoT Wrote:
(05-30-2018 )Unilevers Wrote: your probably not maintaining rail pressure. I would run a low side sight glass and check for bubbles, the fuel water separators leak alot. if not could be a pump actuator getting lazy or a lift pump cutting out/getting old aswell.

I can now confirm it’s when the truck is going up a hill. It will stall out, lose power etc. however for the most part while driving it maintains rail presssure. Even when going up a hill the pump maintains pressure unless you come to a stop then it stalls. It’s a Paccar water separator btw. Rail pressure seems to hold when truck is off. I wanted to test lift pump by turning key but when I checked actual rail pressure was at 10.2K psi hours after engine was shut off.

Just letting you know that air in a high pressure fuel system is like razor-blades. it iwll eventually cause some serious damage.

zyNoT · 05-30-2018, **(Subject: Intermittent CM2250 stalling only at idle )**

(05-30-2018 )Rawze Wrote:
(05-30-2018 )zyNoT Wrote:
(05-30-2018 )Unilevers Wrote: your probably not maintaining rail pressure. I would run a low side sight glass and check for bubbles, the fuel water separators leak alot. if not could be a pump actuator getting lazy or a lift pump cutting out/getting old aswell.

I can now confirm it’s when the truck is going up a hill. It will stall out, lose power etc. however for the most part while driving it maintains rail presssure. Even when going up a hill the pump maintains pressure unless you come to a stop then it stalls. It’s a Paccar water separator btw. Rail pressure seems to hold when truck is off. I wanted to test lift pump by turning key but when I checked actual rail pressure was at 10.2K psi hours after engine was shut off.

Just letting you know that air in a high pressure fuel system is like razor-blades. it iwll eventually cause some serious damage.

Trying to do all I can but the tools I have are limited and I’m better with a computer than I am with a wrench. Not much else I can do, I’ve looked at everything and I see no problems. It just randomly stalls. I’m thinking cracked pickup tube but I have no way to check it while it’s on the road.

Mr Hagg · 05-30-2018, **(Subject: Intermittent CM2250 stalling only at idle )**

Do you have any codes. Most of the time air in fuel will give you a code of some sort. Interesting how pulling its ok but only when you stop up hill does it do it. Almost like only when at idle like maybe the gear pump is failing to maintain pressure. When they did the new fuel pump did that pump get replaced too? SOmetime they only put the high pressure pump on and not the gear pump on the end of the high pressure pump. EVEN at 500 bar it should run no problems we see many trucks around that at idle. Im thinkinking more along the lines of cam or crank sensor. Id recorded all info on insight and get it to do it. Save it and you can send it to either me, Rawze or Unilever's and we can look at it to see whats dropping out.

Chamberpains · 05-30-2018, **(Subject: Intermittent CM2250 stalling only at idle )**

You can check for suction air leaks/cracked pickup tubes on the road or any time by disconnecting the suction fuel line anywhere and rig in a hose with a union and clamps and stick it straight in the tank fill hole. Secure it and put a cloth over the hole to keep fuel from sloshing out. Then test drive. Problem gone... Then you know you have problem on the suction side.

Of course if you have a fuel line sight glass that would take the test drive part out and i usually use a 5 gallon can of diesel and run my hose to that.