Lift pump?

[Waterloo]

(01-27-2019 )Konstantin Wrote:  

(01-27-2019 )Waterloo Wrote:  Check the filters for a proper seal? Could just be a pinched o ring in the Davco if you have one or the main filter is not seated properly, bad gasket. That is where I would start. Especially if it just happened after swapping out the filters.

Thanks, I checked filters before , was ok. I would start by checking from lift pump and on. maybe will find something

More than likely the pump, they do not last forever... I replaced mine at 800,000, just to be on the safe side.

[Signature620]

While the lift pump is running, grab the bottom of it and try to move it back and forth. If the sound of it changes then it is likely sucking air because they come loose from the top plate over time. If that's the case and it's done a lot of miles then it's probably worth just changing.

If you change it, use some ordinary 6 point m8x1.25 bolts instead of reusing those allen type bolts - The next guy will thank you.

[Evotrucker]

We have the same Volvo! so my issue started just like yours.... turned out the gear pump was going out. After replacing the gear pump i noticed that i wasn't priming the system enough to get all the air out when i was changing out the fuel filters.... so now i do 5 or 6 primes just to make sure all air is out and then i check if their are big bubbles coming out of the IFSM with a compucheck.

[Konstantin]

(01-27-2019 )Evotrucker Wrote:  We have the same Volvo! so my issue started just like yours.... turned out the gear pump was going out. After replacing the gear pump i noticed that i wasn't priming the system enough to get all the air out when i was changing out the fuel filters.... so now i do 5 or 6 primes just to make sure all air is out and then i check if their are big bubbles coming out of the IFSM with a compucheck.

what port on a pump you use to check for bubbles? i see there is 3 of them. could i buy this fitting in any store or it is from cummins only? thank you

[snailexpress]

(01-27-2019 )Konstantin Wrote:  

(01-27-2019 )Evotrucker Wrote:  We have the same Volvo! so my issue started just like yours.... turned out the gear pump was going out. After replacing the gear pump i noticed that i wasn't priming the system enough to get all the air out when i was changing out the fuel filters.... so now i do 5 or 6 primes just to make sure all air is out and then i check if their are big bubbles coming out of the IFSM with a compucheck.

what port on a pump you use to check for bubbles? i see there is 3 of them. could i buy this fitting in any store or it is from cummins only? thank you

There is good video on Youtube part1 and part2 to understand 871 fuel system.
Compucheck connector with clear tube you can buy from cummins or online. If fuel line is empty after night it definitely not air tight. Could be filter housing cracked, fuel line connections not tight, pickup tube cracked(if it's not Volvo), water separator.
Refer to quickserve how to diagnose fuel system.
https://www.youtube.com/watch?v=HvvFElrc5ak

[Waterloo]

The fitting you are looking for looks like this... But, It will be brass.



You can get a female end to hook up test equipment at FleetPride or a Parker Exotic store. You can order on line, but you need to know the size. Best way, is to remove and take with you. Or, go to your local dealership and find out what size their mechanics use... If they even know what it is for. Good luck.

Hope this helps.

[Konstantin]

Yesterday I put ignition ON , I hear noise from lift pump working and i pressed with a nail on Compucheck fitting in top right corner of fuel pump. I was expecting some fuel to leak out, but nothing happened. Now i am sure the lift pump is defective. Is it possible to prime the engine with broken fuel pump? the engine is not starting now.

[Rawze]

(01-29-2019 )Konstantin Wrote:  Yesterday I put ignition ON , I hear noise from lift pump working and i pressed with a nail on Compucheck fitting in top right corner of fuel pump. I was expecting some fuel to leak out, but nothing happened. Now i am sure the lift pump is defective. Is it possible to prime the engine with broken fuel pump? the engine is not starting now.

CM871 engine ...

when my lift pump is running, truck not started yet, and I press in on that compucheck fitting at the top right of the gear pump, fuel comes blasting out at me with a high force, and gets all over everything.

Just stating this for reference.

Also, if someone monitors the fuel pressure in insite while cranking, it has to be more than 50 psi or the truck will not start. As a reference, most trucks will show 70-100+ psi when cranking and everything is ok.

[Konstantin]

(01-29-2019 )Rawze Wrote:  

(01-29-2019 )Konstantin Wrote:  Yesterday I put ignition ON , I hear noise from lift pump working and i pressed with a nail on Compucheck fitting in top right corner of fuel pump. I was expecting some fuel to leak out, but nothing happened. Now i am sure the lift pump is defective. Is it possible to prime the engine with broken fuel pump? the engine is not starting now.

CM871 engine ...

when my lift pump is running, truck not started yet, and I press in on that compucheck fitting at the top right of the gear pump, fuel comes blasting out at me with a high force, and gets all over everything.

Just stating this for reference.

Also, if someone monitors the fuel pressure in insite while cranking, it has to be more than 50 psi or the truck will not start. As a reference, most trucks will show 70-100+ psi when cranking and everything is ok.

Thank you for your help! Somebody told me that I have to crank engine and press another Compucheck fitting at end of the pump and let air out. That is how I started truck today. But it was a mess of diesel leaking all over. When I have time I will replace lift pump for sure.