Bulletin Today, April 2, 1982
by Roberto C. Bernardo
Under normal conditions, diesel engines are low on fuel consumption. This advantage is being magnified more by the prevailing cheaper cost of fuel. As commonly noted, it gives more kilometers per cheaper liter of diesel fuel.
However, this advantage could very well be upset by mal-conditioning in three areas namely; fuel system, engine proper (otherwise termed as “low compression pressure”), the drive line of the vehicle.
Among the three enumerated areas, malfunction in the fuel system is the most common point where the problem of high fuel consumption is often traced - particularly on the injection nozzles or bad spray formation or on the too low setting of its injection pressure. It could also be due to unequal or excessive injection quantities or improper injection timing.
Unequal or excessive injection quantities could be an indication of a damaged plunger and barrel, broken plunger spring, and malfunctioning in the delivery valves.
Improper injection timing could be worn down or loose tappet rollers or bolts, possibly worn out coupling.
Bad spray performance could be mean burnt needle of nozzles or broken nozzles spring clogging of carbon on the nozzle hole.
Too low setting of injection pressure may be a case of loose nozzle adjusting screw.
As you would note, high fuel consumption could be an indication of a serious problem in the injection equipment.
The proper repair or service venue in this case is a qualified diesel fuel injection repair or service shop.
Black Exhaust Smoke. This is another indication of fuel injection equipment problem.
Black exhaust smoke could mean incomplete combustion of fuel engine cylinders and could be due to any of the following: Uneven distribution of fuel on the cylinders (some may be receiving more fuel than the others or all cylinders are receiving too much fuel). Or there is no sufficient intake of the air, poor spray formation of injection nozzles, etc.
Again, the proper service venue is the same as that of high fuel consumption.
Warning: In both cases, some of the parts may have to be replaced. Be sure to insist that only the original parts must be used as replacement, not inferior replacement parts or imitations. These don't normally last very long, much less give back the original engine performance.
This warning is being given due to the proliferation of imitation fuel injection parts in the market today.
Samples of imitation and inferior replacement parts have sent to Diesel Kiki Co., Ltd. in Japan and it was found that these imitation and inferior replacement parts are indeed of inferior quality.