Cummins 1.5l 3 cyl; as found on 2011 Branson 3120


New User
Hi. Can anyone give an idea of what the optimum Lift Pump pressure should be on these engines? If a range (e.g. 2-5 psi) how might the lower pressure show itself while in operation?
On this same tractor (2011 Branson 3120), would also like to know what the 'Output' pressure of the Injector Pump is supposed to be. (Injector Pump is 'VE' type manufactured under license by Zexel. There's also the name 'Doowan' or 'Doohan' on the pump tag.)

Thanks in advance. Tech data seems extremely hard to come by for this tractor . . .
The INJECTORS control the fuel pressure, the VE rotary
pump has to pressurize, time, and meter fuel through the
injectors. DO NOT dead head a pressure gauge on ANY
injection pump outlet! Thats NOT how that pump is ever
Appreciate the reply, Diesel Tech.
So how does one know if 'LIFT' Pump pressure is at the lower range of its output; or what it's even supposed to be (I can find nothing on-line or on youtube so far - hence the question.)
Btw, I have put a guage on my LIFT Pump (it's reading ~ 3 psi) though I don't know how that compares to the mfg's spec for this engine. (I have not tried putting a guage on the Injector Pump.)
So if the "injectors control pressure . . ." then as long as the injectors are "spraying", it's obvious that pressure(s) within the Injector Pump are therefore above minimal, but is it possible to know if these VA type Injector Pumps are worn or wearing (still good enough to operate the injectors but may be on its "last leg"), without pulling it from the engine & testing on a bench? Thanks again.
Engine is a good test bench too, IF one knows what to look
for. On any rotary injection pump, if engine has trouble
starting when hot, thats a sign the hydraulic head is worn and
needs replaced. Fuel is bypassing internally the fuel that
SHOULD go to the injectors. Most VA/VE pumps use a 3-5
PSI feed pump, and some dont even use one.
Mine starts easily hot or cold (though sometimes if the ambient temp is below 40 F, it might take a little longer.

I'm trying to get smarter on these diesels & their injection systems. Recently bought one of those injector testers though haven't had a chance to test mine yet. At least I can see if they are all popping about the same pressure.

Thanks for the good info/advice. Cheers.
Not disagreeing, but mine is not working as well as it used to. It currently has 1655 hrs on it but the RPM's currently won't go above 2k (thus cannot get into optimal PTO range); it has started to puff black smoke when I blip the throttle (not that big a deal); and (worse) it threatened to "run away" twice (even though it is not turbocharged) when I had a load in the bucket. I've cleaned the fuel system using Seafoam and the technique they advise on youtube, so thought I should try to gather some performance specs on the 2 pumps so that I might then be able to see if they are working to the level that they should. Unfortunately, finding this data is about like finding what the next winning Lotto numbers will be. Thanks for your reply.

I did manage to confirm that the Lift pump for this engine should be putting out 3-5 psi. (Still have to wonder, since I don't know what it put out when new, if it is on its "last leg", and what exactly will happen (i.e. will the injector pump just be unable to reach sufficient pressure to fire the injectors) if the Lift pump falls below 3 psi output pressure.)
Just trying to learn here. Thanks.
The VE pump can run under a slight vacuum, but it's not good for them.
If your lift pump is working, the VE is getting enough fuel.
Too much supply pressure can push the seal out of the front of the VE and load up the crank case.

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