how to test an isuzu c190-c240 diesel engine's governor and fuel control system

the isuzu C series of diesel engines is one of the most reliable classes of  diesel engines

to date, even from the 1970's this 2 litre OHV diesel engine has proven itself

for eons of work here in the Philippines. now I have posted a process on how to

test an Isuzu C engine's pneumatic governor system for air leaks for our visitors who

have problems with this class of engine which includes the following:

 1. engine is dying when the accelerator is  relieved

 2. Abnormal Idling

 3. unsustainable idling

the C190, C221 and early variants of the C240 uses a Diesel kiki(Zexel) inline

injection pump and the pneumatic governor system is designated as "RBD" to regualte

the injection pump's fuel delivery. there are 2 hoses, "suction" which is connected

to the most end part of the governor, and the "discharge" which located just behind

the last connector of the injection pump.

what to do:

first disconnect the suction hose as illustrated above, and leave

the discharge hose.

next push the idling control lever (you will see a lever below)

forward,

then press your thumb into the suction opening, and let go

of the idling control lever and observe if  the idling control

lever moves backward. if it moves instantly, you have a broken control

diaphragm, if it moves slowly or not rapidly, you may need to re-tighten

the 4 bolts that hold the diaphragm chamber or you may have to check

your diaphragm again for possible micro-punctures.

if there is a problem with your diaphragm its advisable to buy a new one

instead of installing the old one back or find a surplus replacement.

remember, pneumatic governor diaphragms

tend to lose elasticity when they age or experience rough  usage,

better yet buy a new one!