Two lift pumps in series?

[svein]

Ive been seeing even lower fuel pressures after I installed my new walbro frb-5 pumps. @Hink mentioned that he is running two lift pumps in series in his wvo system. I am contemplating plumbing one of my acdelco ep1000 pumps in after the walbro and the first fuel filter, so it´s closer to the fuel filter manager and gives a bit more push. Would this be a stupid idea? Could it put an extra strain on the walbros, or would it help them push more?

 

[svein]

I couldn't resist, so I went out and tried plumbing it in. At idle, it would be stable at 13ish psi, and during driving it would be between 9 and 13. When I let go of the pedal, I could sometimes see it peak at 14. The walbro stayed dead steady at 4,8psi. That seems like pretty good readings to me?

 

[red]

As a general rule with all diesel engines whether performance build or stock, 1psi or higher of fuel pressure at the injection/high pressure pump inlet when at maximum load is all that's needed. Means when the engine is operating at maximum torque (need a load to do it) and there is still 1psi of fuel pressure at the injection/high pressure pump inlet, then the system is doing all that it needs. Any extra fuel pressure above that is just excess.

 

[svein]

It seems to be many schools of what is the best pressure at IP.

I´ve always been happy with a stock setup as far as what the car could do for me, so I don´t really want to alter it. But I would like to maintain a positive pressure at the IP at all times to be gently with it. Especially since I am experimenting with WVO.

I´m going to do some more modifications to the system tomorrow, to see which results I get with the fittings I got with the FTB kit I ordered. I´m thinking I´ll bypass the original fuel filter manager to see what pressures I can achieve then - with only the Walbros.

 

[red]

Agreed, the only way to really know if your current lift pump design is adequate or overkill is by testing at max load with the gauge plumbed in by the injection pump inlet.

 

[Hink]

Ive been seeing even lower fuel pressures after I installed my new walbro frb-5 pumps. @Hink mentioned that he is running two lift pumps in series in his wvo system. I am contemplating plumbing one of my acdelco ep1000 pumps in after the walbro and the first fuel filter, so it´s closer to the fuel filter manager and gives a bit more push. Would this be a stupid idea? Could it put an extra strain on the walbros, or would it help them push more?

Yes, I have a Walbro 5 in the stock position running diesel and then a stock style pump kicks in to help when on wvo but I'm afraid that I couldn't tell you the pressure. I have not had any issues when under heavy load though so I haven't been concerned with it.

 

[svein]

Thanks Hink, it is indeed very helpful to know that others are using this solution!

At the moment I am running with the walbro only, and I guess some testing back and forth is in order before I settle on a solution.

My fuel pressure readings are very bouncy - which I believe is due to my digital sensors which are updating 10 times per second, so they probably read both the high spikes and the lows from the lift pump. The software guy who sold me the measurement computer has promised to customize the readings for me with less updates and more average readings, so I´m excited to see what I will read when the pressure can be measured a bit more steady. Ultimately, as long as the fuel delivery is adequate and the car actually can run on wvo I am happy, even if the fuel pressure isn´t up to max potensial.

I had a little project yesterday evening putting back the fuel filter manager post FTB mod. I managed to fit my temp/pressure gauge probe thingie under the intake between the FFM and the IP, so from now on, I will have readings from just before IP!

First time taking the upper intake off - not as scary as I had thought. The job would probably have been easier if I took the lower half off as well..


It started as a bright and nice afternoon, but ended as a cold and dark evening. At least the car runs again!

 

[NVW]

Thanks Hink, it is indeed very helpful to know that others are using this solution!

At the moment I am running with the walbro only, and I guess some testing back and forth is in order before I settle on a solution.

My fuel pressure readings are very bouncy - which I believe is due to my digital sensors which are updating 10 times per second, so they probably read both the high spikes and the lows from the lift pump. The software guy who sold me the measurement computer has promised to customize the readings for me with less updates and more average readings, so I´m excited to see what I will read when the pressure can be measured a bit more steady. Ultimately, as long as the fuel delivery is adequate and the car actually can run on wvo I am happy, even if the fuel pressure isn´t up to max potensial.

I had a little project yesterday evening putting back the fuel filter manager post FTB mod. I managed to fit my temp/pressure gauge probe thingie under the intake between the FFM and the IP, so from now on, I will have readings from just before IP!

First time taking the upper intake off - not as scary as I had thought. The job would probably have been easier if I took the lower half off as well..
View attachment 56251View attachment 56252

It started as a bright and nice afternoon, but ended as a cold and dark evening. At least the car runs again!
View attachment 56250

I love my heated shop, and the lift sorry, it took a long time to get.

 

[ak diesel driver]

X2 Leo

 

[svein]

@NVW , I bet you do!! One day...I dream. And I´m not complaining - I get to borrow a shop with a lift all the time, but sometimes it´s easier and quicker to put on the thermal suit and go out there!