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Re: Prime fuel resetting

Andy Drummond

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Hi Simon

This is very important to my car and me. I have sent a lot of time and energy looking for solutions etc. So please respect my request for a software change.

It is all about the resetting of the Prime fuel control.

Now the prime fuel works excellent, the engine fires and ramps sharply on the very first ignition spark. (It skips crank enrichment completely). From starter engaged to engine running is 0.4 to 0.7 seconds (depends on the engine static start position). A beautiful thing.

I am running a electric water pump. Requirement is to run the water pump for some time after the engine is stopped (ecu must remain powered up). To date my wiring/setup works excellent.

So my problem comes when I stall the engine and must restart as quickly as possible. Example sitting in the middle of racetrack corner, this can be life changing experience and not recommended. Painting the picture, the Driver needs clean underpants, battery is half flat, the prime fuel is NOT reset so the engine must crank & crank to start.

Need a solution that the prime fuel is reset, other than powering down the ecu.

Example, add new prime fuel control mode that uses combination of Ignition Switch digital input and the Start Position digital input.

Please let me know comments, so we can progress to a solution.


Andy Drummond.

My setup;

G4 extreme red.

Individual injectors and coils, trigger 1 crank 60 minus 2, trigger 2 camshaft.

Prime mode “Start positionâ€

Isolator switch for ecu power

Driver ignition switch for injector, coil power etc

Driver push button starter switch, starter controlled by the ecu.

Electric water pump, controlled by ecu

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There are other ways around this too - a check valve on your fuel pump will probably hold enough pressure in the fuel rail to allow the engine to fire before the fuel pump has kicked in. Alternatively you could add a jumper that energises the FP relay when the starter button is pushed...

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Ah yes, I should have paid closer attention to the original post.  I had jumped to the conclusion that he was talking about the fuel pump prime so sorry to confuse matters.  I have never needed much crank enrichment with most of the engines I have tuned.

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