turning down diesel injection pump?

mmidlam · Mar 26, 2009

I have a 1992 ford diesel pickup and 1968 deutz tractor. Most of the info I have read is about turning fuel up.
If I wanted to turn down the pump in order to use less fuel, the engine might start a little harder. Also may have may have to add some intake restriction. Might have too much air flow for the amount of fuel. I understand some diesels had a butterfly in the intake that moved with fuel lever.
So turning pump down is really not that doable, right?

Bob · Mar 26, 2009

The injection pump will only deliver the fuel needed to maintain engine RPM's under a given load.

So if you are not running it "balls to the wall" all the time, the IP is NOT up against the "smoke screw" anyway, so turning it down a bit won't have ANY effect on economy.

Are you lugging the tractor at all times or just putzing around with it? If you're not lugging it all the time an fuel screw adjustment won't make a whit of difference with fuel economy.

Of course, with the pickup, your FOOT is the determining factor with economy, and just training that body part not to mash the pedal the the floor at every opportunity will allow it to get max economy with NO troublesome adjustments to the machinery.

JDemaris · Mar 26, 2009

The Ford has a mechanical rotary Standyne/Roosmaster pump. Yes, you can turn down fairly easy with a 5/32" or 4 mm Allen wrench. If you turn too low, yes it will start hard.

And also yes, several diesels with air-governors have butterly valves in the air intake. Several Fordsons, some British-Indian International Harvesters, etc. Several of my IH B-275 diesels have butterly valves.

buickanddeere · Mar 26, 2009

A partly loaded diesel burns more galons per HP per HP per hour. Than the same diesel running at full rated power.

guido · Mar 26, 2009

Hello mmidlam,
Turning the pump down, fuel or RPM'S will do nothing to reduce fuel consumption.
Having the engine at the right rpm for the load will insure proper fuel burning. Diesel engines have a lot air intake capability, and the extra air is used for evacuating any remaining unburned particles in the combustion chamber.
This is done in the exhaust stroke, to insure a clean mixture for the next combustion cycle.
This happens when both valves, intake and exhaust, are open at the same time during the exhaust stroke. So you should would not restrict the intake system .
Startability,if that is your goal/problem, is usually related to worn components. One of many reasons for hard cold starts are the injectors, their spray pattern changes with mileage and spray tips dribble, rather than atomize fuel. This makes the engine hard to start when cold, and also it will have white exhaust smoke at stat-up.
Guido.

Bob M · Mar 26, 2009

Turning a diesel pump down affects ONLY the maximum power that can be produced by the engine. At less than wide open throttle it affects nothing - including fuel economy.

On your truck you can accomplish the same thing as "turning down the pump" simply by sticking a piece of wood under the accelerator pedal so it can't go all the way to the floor.

And turning the pump down on your tractor will simply cause it to lug more under load and feel generally sluggish. It won't help fuel economy a bit. It may also make it more difficult to start as others point out.

Also forget about restricting the inlet air. This simply makes the engine work harder and smoke more - and increases fuel consumption. (It's the same as running a diesel with a very dirty air cleaner...)

JDemaris · Mar 26, 2009

Not entirely true. You take that Ford/IH diesel and turn the head screw in too far (which lengthens the strokes of the plungers), and it will smoke every time he hits the pedal hard, while climbing hills, etc. That because the metering valve can swing full open on demand of the governor to full throttle position, even though the accelerator is only part way down. Not a big difference for a flat-land highway cruiser, but can make some different in the hills or around-town driving.

Tramway Guy · Mar 26, 2009

The diesels with butterflys in the intake system used them in conjunction with a pneumatic governor. They did not have centrifugal governors like modern diesels. Mercedes used these on their cars till about 1978.

turning down diesel injection pump?

mmidlam

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