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Just starting???

Posted: Thu Aug 30, 2007 6:01 pm
by JimIsbell
I have read the manual pretty throughly but I may have missed the following answers that I think I need.

I am using the MS 1 version 2.2 with a GM TBI with 2@ 55 lb/hr injectors on a 229 cui GMC V-6 engine so have a low fuel flow requiremnet on only 115 HP. Thus, low PW requirement

1) The discussion about resistance of injectors and the need for resistors or a flyback board does not discuss what I think might be a good solution to the low impeadance injectors.

The injectors measure, with my meter, at 4.9 ohms which would require a 2.1 ohm resistor at 15 watts to protect against currents higher than 2 amps.

It would seem simpler to wire the two injectors in series since I am "batch firing" them anyway. Then they will be 9.8 ohms which would not require a resistor. Is there some reason this is not a good idea. The only drawback I can see is that the voltage across each would only be 7 Volts. BUT if I use a series resistor to do the job it will ALSO reduce the voltage, to 8 Volts, so there is little difference. Either I waste half the voltage on a resistor or on a second injector. Ok, there is a slight difference, 7 volts is not 8 volts.

2) I have a Holley fuel pump #12-920 to use with this GM TBI which, I understand has its own internal fuel pressure regulator. The paperwork with this fuel pump says I should have a low pressure filter in the input and a high pressure filter on the output. I am assuming that I can use a carburetor filter on the input but I am wondering if there is a specific high pressure filter I can use on the output? Is there a fuel filter integral to the GM TBI?

Posted: Thu Aug 30, 2007 6:23 pm
by JimIsbell
I hadnt thought of that. But you are absolutely right. What might work better is a capacitance in parallel with each injector to tune the frequency to prevent flyback altogether.