Lift pump?

[Konstantin]

Hi guys, maybe somebody will point me in a right direction. It is volvo with iSX Cm870 . Recently I changed fuel filters at a truckstop and after they couldn't start the truck. Later I noticed that one guy took some kind of a round tool put some diesel in it and connected it to the fuel pump. After that the truck start. Mechanic told me that my lift pump is probably no good. Right now i need to turn the key and wait for like 5-10 seconds and engine will start, if I try to start without waiting it might no start no matter how long you crank. I connected insite and ignition ON I have fuel pressure 0. When cranking fuel pressure is more than 100 psi. When running Idle it is around 250. And also I noticed that when i do not wait 5-10 seconds and start to crank right away my fuel pressure is 2-3 psi even if i crank for more than 20 seconds. Is it lift pump or something else? Also i have a wet spot near one of solenoids. Thanks, Konstantin

[tree98]

The lift pump your talking about is more of a priming pump. If you turn the key to the ON position without starting it, you should hear it buzzing for about a minute or a little more. If you don't hear it, that doesn't mean the pump is bad.it could be the hot wire going to the pump.If the pump is bad its possible for it take out the gear pump with it, but if it still runs ok I would assume the gear pump is ok. Take a look at the terminals on your starter, if they look corroded and green I would bet on it being the power wire to the pump. By the way, the buzzing is loud enough that you'll hear it with no problem even without lifting the hood.

[Konstantin]

(01-27-2019 )tree98 Wrote:  The lift pump your talking about is more of a priming pump. If you turn the key to the ON position without starting it, you should hear it buzzing for about a minute or a little more. If you don't hear it, that doesn't mean the pump is bad.it could be the hot wire going to the pump.If the pump is bad its possible for it take out the gear pump with it, but if it still runs ok I would assume the gear pump is ok. Take a look at the terminals on your starter, if they look corroded and green I would bet on it being the power wire to the pump. By the way, the buzzing is loud enough that you'll hear it with no problem even without lifting the hood.

I can hear that pump is working for 2 minutes ignition ON. Also i checked voltage seems to be good.

[Moose]

It will run and still not make pressure. It should only run for 30 secs key on engine off. You need to check the PSI at the compuchecks to see if it's doing what it's supposed to.

[Rawze]

(01-27-2019 )Moose Wrote:  It will run and still not make pressure. It should only run for 30 secs key on engine off. You need to check the PSI at the compuchecks to see if it's doing what it's supposed to.

Just for reference, a CM870 and Cm871 engine, it should run for 2 minutes (not 30 seconds) when the ignition key is turned on.

[Rawze]

(01-27-2019 )Konstantin Wrote:  Hi guys, maybe somebody will point me in a right direction. It is volvo with iSX Cm870 . Recently I changed fuel filters at a truckstop and after they couldn't start the truck. Later I noticed that one guy took some kind of a round tool put some diesel in it and connected it to the fuel pump. After that the truck start. Mechanic told me that my lift pump is probably no good. Right now i need to turn the key and wait for like 5-10 seconds and engine will start, if I try to start without waiting it might no start no matter how long you crank. I connected insite and ignition ON I have fuel pressure 0. When cranking fuel pressure is more than 100 psi. When running Idle it is around 250. And also I noticed that when i do not wait 5-10 seconds and start to crank right away my fuel pressure is 2-3 psi even if i crank for more than 20 seconds. Is it lift pump or something else? Also i have a wet spot near one of solenoids. Thanks, Konstantin

Maybe sucking air when it first starts?

Also some engines, there is a screen filter inside the inlet pipe of the lift pump. Maybe it is clogged up?


The pressures you describe while engine is running seem slightly low but not abnormal to me.

Maybe post a link to a youtube/sound video of it? to capture the sound of the lift pump after turning the key on? - If it sounds bad, it could be an indication of it sucking air or it failing.

[Moose]

(01-27-2019 )Rawze Wrote:  

(01-27-2019 )Moose Wrote:  It will run and still not make pressure. It should only run for 30 secs key on engine off. You need to check the PSI at the compuchecks to see if it's doing what it's supposed to.

Just for reference, a CM870 and Cm871 engine, it should run for 2 minutes (not 30 seconds) when the ignition key is turned on.

I stand corrected

[Waterloo]

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.

[Konstantin]

(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