Okay, I admit to being brand new to diesels but I'm trying to learn as much as I can.

Dodge, Ford and GM have all had their problems with fuel injection systems in their diesels. I can't remember any big problems with their gas engine fuel injection systems or, for that matter, anyone else's gas fuel injection systems.

Why is the diesel fuel injection systems so hinky compared to the gas systems?

 

In short it is because it is injected at much higher pressures directly into the combustion chambers.

Gas is injected at (relatively) low pressures upstream of the chambers... Somewhere... Not positive on that location...

 

yes-- the technology of diesel injection is LIGHT YEARS more sophisticated than most gas setups.

Gas-- 45-70psi
diesel-- 28000psi

Gas-- port injected
diesel-- cylinder injected (much harsher environment)

gas-- air throttled
diesel-- FUEL governed

 

I know the first MPFI on the corvette in the early 80's had a major problem. The engines were completely wore out with cams wiping in about 25-30,000 miles. The problem was in the location and angel of the fuel injector spray. Originally it was directed towards the intake runner and didn't atomize but ran into the cyl as a liquid. That washed the cyls down and when the mixture burned, the flame front went from extremely lean to extremely rich, all in one combustion cycle. This caused it to produce black smoke at 14.7:1 A/F and heavy carbon which washed down the cyls and got in the oil. The carbon is hard and like a lapping compound and raw gas dilutes the oil and ultimately the enging wore out prematurely. It took redesigning the intake manifold to correct the problem. Then they had to replace all the engines.
Gas engines are able to use a lot of sensors to monitor the engine to maintain 14.7 to 13.5 A/F while the driver pushes the gofaster pedal to give it more air and the computer calculates the fuel rate to maintain A/F and advance the spark according to map. Diesels take in as much air as it can and controls power output by changing the quantity of fuel injected.It runs at infinite A/F's. The early electronic diesels had transient control problems. meaning, changing loads and speeds smoothly. It took a long time to get the buggs out of the systems. I think they did a pretty good job of it after they figured it out. Now they are trying to engineer a service life into the engines, but that is another story that is on my sour list. Hope I helped you out.

 

Hey Hohn, I knew gas was low pressure, but not that low.

Gotta learn something new every day I guess

 

I would rather drive my 23+ MPG cummins then the 4MPG chevy 7.4 vortec gas hog