Cm870 lift pump or gear pump?

[Evotrucker]

Hey guys! Hope is well with everyone and happy holidays!

This past Saturday I was working in and around the truck. I changed the fuel filter and water separated filter. The truck turned on and ran fine, after a hour or so I go to turn the truck, I don’t hear the gear pump working. So I try to turn it on anyways and nothing doesn’t wanna turn on. I try again but don’t hear the gear pump running....

Could this be the same issue I had when I just got the truck? The last couple of weeks I’ve noticed the gear pump making some weird noises but I didn’t notice it not working properly... I guess it gave out...

This is a cm870 in a Volvo, I was also told their is a fuse for the gear pump and ecm... can someone mark where on the harness they could be? I couldn’t find them....

[Rawze]

the gear pump is mechanical and is driven by the injector cam.


The ELECTRIC LIFT PUMP however is electrical and is used to prime the engine during the first 2 minutes of the key-on cycle. It will not operate unless the key has been off for more than 30 seconds + during only the first 2 minutes after the key is turned back on.


--- As the electric lift pump goes bad, it very often takes the gear pump with it. there is usually some delay of a few weeks to months before this happens, as the metal fragments form the lift pump eat away at the gear pump. Usually what happens is that the main shaft in the mechanically driven gear pump snaps, leaving you on the side of the road and cursing for days trying to find out why your engine will not start but for a few moments then quits.

[Evotrucker]

So I was getting ready to take of the gear pump, I was told to find that fuse and check it.

So i manage to find it and it actually was burned out. I replace turn the key over and I 4got I disconnected the line that goes to the gear pump. Bunch of fuel dumps out and I turn it of connect it back it’s now making this horrible noise like from a scary movie.

https://youtu.be/4eGAD84BJrM

Here is a video of the gear pump making that sound and some pictures of the fuse

[Evotrucker]

(12-26-2018 )Rawze Wrote:  the gear pump is mechanical and is driven by the injector cam.


The ELECTRIC LIFT PUMP however is electrical and is used to prime the engine during the first 2 minutes of the key-on cycle. It will not operate unless the key has been off for more than 30 seconds + during only the first 2 minutes after the key is turned back on.


--- As the electric lift pump goes bad, it very often takes the gear pump with it. there is usually some delay of a few weeks to months before this happens, as the metal fragments form the lift pump eat away at the gear pump. Usually what happens is that the main shaft in the mechanically driven gear pump snaps, leaving you on the side of the road and cursing for days trying to find out why your engine will not start but for a few moments then quits.

So would you recommend I replace the used gear pump I put on and replace the fuel lift pump since idk how old it is???

[Rawze]

(12-26-2018 )Evotrucker Wrote:  So I was getting ready to take of the gear pump, I was told to find that fuse and check it.

So i manage to find it and it actually was burned out. I replace turn the key over and I 4got I disconnected the line that goes to the gear pump. Bunch of fuel dumps out and I turn it of connect it back it’s now making this horrible noise like from a scary movie.

https://youtu.be/4eGAD84BJrM

Here is a video of the gear pump making that sound and some pictures of the fuse

In the video, your pointing to a line going into the back of the GEAR PUMP....

THAT IS NOT THE ELECTRIC LIFT PUMP!!!!!! --- THE PUMP YOUR POINTING TO IS MECHANICALLY DRIVEN BY THE INJECTOR CAM WHEN THE ENGINE IS RUNNING and is not electrical at all.

THERE ARE 2 PUMPS --- THE GEAR PUMP and THE ELECTRIC LIFT PUMP.

The fuse you found and the horrible sound you hear is for the electric lift pump and not the gear pump. The electric lift pump is located to the right of the fuel filter on the CM870/CM871.

[Evotrucker]

(12-26-2018 )Rawze Wrote:  In the video, your pointing to a line going into the back of the GEAR PUMP....

THAT IS NOT THE ELECTRIC LIFT PUMP!!!!!! --- THE PUMP YOUR POINTING TO IS MECHANICALLY DRIVEN BY THE INJECTOR CAM WHEN THE ENGINE IS RUNNING and is not electrical at all.

THERE ARE 2 PUMPS --- THE GEAR PUMP and THE ELECTRIC LIFT PUMP.

The fuse you found and the horrible sound you hear is for the electric lift pump and not the gear pump. The electric lift pump is located to the right of the fuel filter on the CM870/CM871.

Okay so i was planning on getting both the gear pump and the lift pump but only put on the lift pump to see if that fixes the issue.

Thanks rawze!