LANE A START UP QUESTION
in 912iS Technical Questions
8 years ago
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by Rob Seaton » 8 years ago
The fuel pressure is controlled by the mechanical regulator so it has not relationship to just Lane A.
Lane A controls half the injectors and half the spark plugs. So you have a plugged injector or a ignition issue.
-Start the engine on Lane B
-Note the EGT numbers
-Turn on Lane A
-Turn off Lane B
-Look at the EGT's the bad cylinder will have a dropping value. That is the cylinder with the injector or ignition problem.
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by Bill Hertzel » 8 years ago
This is the new engine, what's the probability that the injector is broken?...
When I wrote that the Injector may be "Broken" I meant to say that it not Operating as Intended in the general sense, not necessarily specifically meaning that it is defective.
The Low fuel pressure and the Lane "A" problems are likely separate problems with a common root cause.
Both problems could be caused by debris in the Fuel system.
If the input to a fuel injector were blocked and the regulator was unable to close completely, that would explain both problems.
As Rob explained when the engine starts missing, the problem will show up as an EGT change.
If you get the engine running smoothly, the fuel pressure problem may still exist. Don't ignore it!
It is highly unlikely you have two problems at the same time unless they both have a common cause.
Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.
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by JUSTIN » 8 years ago
Why is it that when I turn on LANE A the engine have obvious shake and RPM decrease?15031336911.png (You do not have access to download this file.)
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by Bill Hertzel » 8 years ago
I would guess that you have 2 fuel injectors both operated by Lane A, CYL#1and CYL#4 with reduced flow.
The RPMs Drop, The MAP Increases, The EGTS Drop, The Fuel increases.
The ECM sees the cold EGTs and the MAP increase, the dropping RPMs and starts to add fuel to compensate.
It thinks that it is increasing the fuel flow, but does not know the bigger squirts are not actually happening.
The Reported Fuel flow is what the ECM "Thinks" it is delivering, Not a true measurement of the actual flow.
Lane A operates 4 of the injectors.
Lane B operates the other 4.
Operating only lane B removes the 2 bad injectors from the Loop. Good!
When you add Lane A to the Mix the engine runs on 2 cylinders but only on every other cycle. Bad!
When you remove Lane B from the Mix and operate Lane A ONLY, the engine runs on only the 2 good cylinders. Worse!
Is operating on Lane A ONLY, worse than operating on BOTH A+B?
The Rough running along with the Fuel pressure issue both indicate a fuel flow problem.
Contamination is the most probable culprit.
It is time to remove the fuel injectors and the fuel regulator and give the fuel lines a good flushing and the parts a good inspection and cleaning.
Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.
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