Older Cummins 8.3 Fuel Feed Linkage at Startup

[DonBaja]

During a period wherein my starter was going bad, I got in the habit of pumping the fuel foot pedal at start up. It felt like I was doing some good. Lately I realized that the fuel foot feed is not operable for a period of time after the engine fires, presumably to make sure the air pressure gets a chance to build up.

Do I understand this correctly, that pumping the fuel pedal to start is of no consequence?

[wolfe10]

Many mechanical engines had air throttles-- easy to tell. Under the throttle, is there an air line, mechanical cable or electric wire? Newer electronic engines generally have electric throttles (basically the throttle is a rheostat).

You can also look in the engine compartment. Does the linkage from the injection pump go to a device supplied with air or electrical wire, or does the mechanical cable go forward?

[DonBaja]

Brett, does this mean that due to the distance from the driver to the engine on a DP that no mechanical linkage exists and the mechanism is air driven?

[Tom_Barb]

DonBaja wrote:
During a period wherein my starter was going bad, I got in the habit of pumping the fuel foot pedal at start up. It felt like I was doing some good. Lately I realized that the fuel foot feed is not operable for a period of time after the engine fires, presumably to make sure the air pressure gets a chance to build up.

Do I understand this correctly, that pumping the fuel pedal to start is of no consequence?

Correct If that engine isa diesel. the old gas engines have a accelerator pump, that will deliver fuel into the manifold, the newer ones with FI will not.

pumping the throttle really does no good in the late model engines. all it does is deliver a signal to the computer.

[wolfe10]

Certainly true if you have an air throttle-- no air pressure, no throttle.

I am not aware of any diesel engine with a recommendation to pump the throttle at start up.