Re: 1985 75HP O.B. --> Bad Fuel Pump??
Fred, you got tired of working on the 'ZuZu and playing with the boat instead??
<br /><br />If I recall your motor should have one fuel pump with a metal-mesh screen inside. You can take the outer filter cap off and blow the metal screen out with air. This'll also allow you to check for debris in the filter. If you don't have this style of pump, you may have the other type which has an external inline fuel filter. The diff should be quite obvious.<br /><br />It's possible you could have a 'sticking' float needle. It might be best to tear into the carbs and renew the carb fuel inlet needle, and seat. You can get 'carb packing' kits for the commonly needed gaskets etc when you tear into it. Sierra Marine or the Merc dlr would have what you need.<br /><br />You can find parts diagrams and pricing online at
www.mercurypartsexpress.com or at
www.dougrussell.com<br /><br />You can find cheap Sierra Marine parts online here:<br /><br />
http://www.boatfix.com/searchsierra.asp <br /><br />BTW at either the Doug Russell or Mercury sites, it'll be handy to have the model # ser # of the motor. You should find this on a metal or foil nameplate affixed to one side of the main transom clamp assy.<br /><br />Another thought, your motor has a solenoid-operated choke with linkage to both carbs; this linkage operates bellcranks on the carb which are not moving a butterfly but opening an enrichment circuit. I suppose if one of the 'choke' (enrichment) passages were plugged, it'd be very cranky at first start.<br /><br />Another thing to think about is that most Merc's like the bulb pumped up REAL hard, then you pump the bulb a bit more. And the choke assy only works as long as you hold down the choke button (or push in the key, depending on how your choke works). <br /><br />So, a good starting routine is to pump the bulb hard, run the fast idle lever up a reasonable amount, hold the choke in and crank until it hits.<br /><br />Keep choke on it and adjust the fast idle accordingly until the motor slows down a bit, indicating it doesn't want/need full choke.<br /><br />Your carbs have adjustable idle mixture needles, so you might try to richen them up a bit (CCW turn), and tweak in on the water, once warmed up and idling in fwd gear.<br /><br />Most Mercs including your 75 like to run on the rich side and tend to get a bit cranky when leaned out for extremely smooth running.<br /><br />Your motor doesn't have a thermostat, so will not get nice and toasty warm for that silky-smooth idle like your Trooper
but when adjusted properly they're not too bad. <br /><br />Anyway, you'll probably want to tear into the carbs for a cursory inspection. Worst part of the whole job is likely getting all the stuff out of the way so you can get at the carbs!<br /><br />HTH..............ed
