Stingray698 Posted February 11, 2012 Share Posted February 11, 2012 I have a 1988 R model R688ST with a 350 4 valve with jakes , complaint low power , and hard starting , i replaced fuel filters still wouldnt start , then ran hose to bucket right from fuel filter got it to start ran ok, then ran new suction line to tank and started truck - ran ok , checked fuel pressure it is 45 at idle and after shutting it off it maintains between 10-15 i looked through a mack tune up book it is from 1985 and every engine and configuration has a different fuel psi it seems like the happy median is 17-31 i also pulled overflow flow valve off pump everthing seems ok , i think im going to check overhead tommorow in the meantime , i know it doesnt effect fuel situation but probably should be checked/set , any ideas or comments would be appreciated , also does anyone know what the fuel pressure should be ?? Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/23184-1988-r-model-fuel-psi/ Share on other sites More sharing options...
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