Threaded Mode | Linear Mode

shawn21998 · 10-25-2023, **(Subject: Peterbilt 386 starts and dies immediately )**

(10-24-2023 )Bengy88 Wrote: I just pm’d you my number. I can send you a schematic and if you want I’ll remote in and monitor a few things and give my opinion if you want

Yes that would be great. Thank you!

shawn21998 · 10-25-2023, **(Subject: Peterbilt 386 starts and dies immediately )**

(10-24-2023 )Rawze Wrote: cranking up and then stumbling out sounds more like a fuel issue to me... but one never knows when they are just guessing at it on a forum...

fuel pump acting up or going out?. - Has anyone bothered to pull the fuel pump head off and inspected the plungers, rollers, cam, etc?.

Performed a plunger test to ensure they are not sinking ... and Also pulled them put and flipped them upside down to see if they go into the holes upside down, to ensure they are not not flared out slightly at the tops, causing sticking when operating?.

Initially I was thinking fuel issue but the batteries were at 8v so I installed new batteries and still got low voltage code as only active code. Someone replaced the solenoid on the back of the pump so I checked wiring from that to ECM and insured resistance is within specifications. I am open to ideas but not sure how to perform plunger test. The way the truck fires right up initially is what lead me to believe its a voltage issue at ECM. Truck acts like you just turn the key off after it fires up. Is there any fuel pressures I should monitor before pulling the head off the pump?

shawn21998 · 10-25-2023, **(Subject: Peterbilt 386 starts and dies immediately )**

(10-25-2023 )shawn21998 Wrote:
(10-24-2023 )Rawze Wrote: cranking up and then stumbling out sounds more like a fuel issue to me... but one never knows when they are just guessing at it on a forum...

fuel pump acting up or going out?. - Has anyone bothered to pull the fuel pump head off and inspected the plungers, rollers, cam, etc?.

Performed a plunger test to ensure they are not sinking ... and Also pulled them put and flipped them upside down to see if they go into the holes upside down, to ensure they are not not flared out slightly at the tops, causing sticking when operating?.

Initially I was thinking fuel issue but the batteries were at 8v so I installed new batteries and still got low voltage code as only active code. Someone replaced the solenoid on the back of the pump so I checked wiring from that to ECM and insured resistance is within specifications. I am open to ideas but not sure how to perform plunger test. The way the truck fires right up initially is what lead me to believe its a voltage issue at ECM. Truck acts like you just turn the key off after it fires up. Is there any fuel pressures I should monitor before pulling the head off the pump?

I have the head of the pump off. Performed all inspection procedures outlined in the cummins service manual. Insured plungers extended with shop air, inspected springs and retainers and removed. Performed plunger test and insured they are not flared out. Rollers, tappets, and camshaft all look great.

shawn21998 · 10-27-2023, **(Subject: Peterbilt 386 starts and dies immediately )**

UPDATE:Not sure if anyone cares but I thought I'd give an update. After testing and inspecting I have found the fuel shutoff solenoid is only getting 9v at connector, when measured with good ground voltage is 12v. Removed ECM engine harness connector and insured wiring is under 1 ohm for connector. Seems like ECM has short on ground circuit and is causing voltage drop. Im trying a test ECM and will update accordingly. Thank everyone for your suggestions.

Rawze · 10-27-2023, **(Subject: Peterbilt 386 starts and dies immediately )**

(10-27-2023 )shawn21998 Wrote: UPDATE:Not sure if anyone cares but I thought I'd give an update. After testing and inspecting I have found the fuel shutoff solenoid is only getting 9v at connector, when measured with good ground voltage is 12v. Removed ECM engine harness connector and insured wiring is under 1 ohm for connector. Seems like ECM has short on ground circuit and is causing voltage drop. Im trying a test ECM and will update accordingly. Thank everyone for your suggestions.

My fuel shutoff solenoid on my CM871 went bad years ago. I removed its guts to get the engine running again, and off the side of the roads.. and have not bothered to fix it for about 300,000 miles now...lol. - Engine starts and stops just fine without it.

shawn21998 · 11-16-2023, **(Subject: Peterbilt 386 starts and dies immediately )**

(10-27-2023 )Rawze Wrote:
(10-27-2023 )shawn21998 Wrote: UPDATE:Not sure if anyone cares but I thought I'd give an update. After testing and inspecting I have found the fuel shutoff solenoid is only getting 9v at connector, when measured with good ground voltage is 12v. Removed ECM engine harness connector and insured wiring is under 1 ohm for connector. Seems like ECM has short on ground circuit and is causing voltage drop. Im trying a test ECM and will update accordingly. Thank everyone for your suggestions.

My fuel shutoff solenoid on my CM871 went bad years ago. I removed its guts to get the engine running again, and off the side of the roads.. and have not bothered to fix it for about 300,000 miles now...lol. - Engine starts and stops just fine without it.

I got the new ECM and unfortunately the truck still has the same issue. Still trying to figure it out... The only active code is SPN 168 FMI 1 SAE- Battery potential (Voltage) Data valid but below normal operational range - Most severe level. From component #128. I can't find any info on that code or what component 128 is.

Rawze · 11-16-2023, **(Subject: Peterbilt 386 starts and dies immediately )**

(11-16-2023 )shawn21998 Wrote: ...
I got the new ECM and unfortunately the truck still has the same issue. Still trying to figure it out... The only active code is SPN 168 FMI 1 SAE- Battery potential (Voltage) Data valid but below normal operational range - Most severe level. From component #128. I can't find any info on that code or what component 128 is.

What is the fuel pressure and oil showing while cranking?... and after, as it dies?.

What is the ecm voltage while cranking?>,.. and after, when it dies?.

Also, what does the Insite software show for active and inactive faults instead of some after-garbage SPN-type code reader?.

Bengy88 · 11-16-2023, **(Subject: Peterbilt 386 starts and dies immediately )**

Component 128 is referring to mid128. That’s just identifying the engine ecm. I got your text but I’ve had a lot going on and forgot to get back with you. I’ll get on that lol

shawn21998 · 11-17-2023, **(Subject: Peterbilt 386 starts and dies immediately )**

(11-16-2023 )Rawze Wrote:
(11-16-2023 )shawn21998 Wrote: ...
I got the new ECM and unfortunately the truck still has the same issue. Still trying to figure it out... The only active code is SPN 168 FMI 1 SAE- Battery potential (Voltage) Data valid but below normal operational range - Most severe level. From component #128. I can't find any info on that code or what component 128 is.

What is the fuel pressure and oil showing while cranking?... and after, as it dies?.

What is the ecm voltage while cranking?>,.. and after, when it dies?.

Also, what does the Insite software show for active and inactive faults instead of some after-garbage SPN-type code reader?.

Fuel pressure while cranking 6300psi, up to 7400psi when it runs then drops out to around 2000psi after it dies. Oil pressure is 2psi while cranking then 10.5psi when it fires. ECM voltage while cranking drops to 8.5 from battery voltage while key switch voltage stays at 11 at ECM. Jumps up to 11 when it starts then dies. Component #128 voltage drops to 8.5 as well. There is no active or inactive codes on Insite. Jpro is showing low voltage codes from EC-60 ABS and component #128. Using jpro while monitoring voltages it shows the component #128 being CECU3.