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Fuel consumption

pete31

pete31

Regular Contributor
gentlemen
Bought a 34 santego last summer with a pair of 7.4 mercs in it..approx 1100hrs on each, both are hard to start..lots of cranking and pumping, and in my opinion drink fuel, almost double the consumption of my old Trojan, she had a pair of 318's in her.I have already changed the plugs (right heat range ), wires,caps and rotors..cleaned the rust out of the distributors, checked the ignition timing ( both base and full advance) and that the chokes pull off ( they do) only thing left to check is the carbs.. Quadrajets on there now, was thinking of swapping them for a pair of 1410 Edelbrocks..any ideas??
pete
 
On my old boat, the carbs were empty every time I left her for more than a week. The result was a lot of cranking, cranking, cranking before the carbs filled enough to get her running. (Mechanical fuel pumps.)

Got sick of that crap so I eventually converted both motors to electric pumps with a by-pass switch to TEMPORARILY override the oil pressure safety switch. Then I ran the pumps for 15 seconds or so to fill the carbs, pumped the gas a few times, and away we go!

Jeff
 
Ayuh,..... The Quadra-jets might be worn out, but yer also feedin' a Much larger motor,.....

Personally, I Love the Edlebrock AFB clone carbs,.... easy to tune, 'n easy to rebuild,....

Jeff also brings up a Great point, a leaky carb will do that, primin' 'em at start up shortens the crank time,....

To test for it, go to the boat, pull the flame arrester, 'n actuate the throttles to see if gas is present, 'n bein' pumped into the intake,....
 
2x on the electric fuel pumps.

Pull those Qjets and Freshen them up. DO NOT SEND THEM OUT FOR A REBUILD!!!!!!

If they are original to your engines, they are set up for your engines.

I bet your boat is burning more than fifty gallons an hour at WOT!
 
thanks for the replys...already checked that there is fuel in the carbs before start up, good idea about the electric pumps, and I seldom run it at wot for that very reason, most of my cruising is done at around 1200 rpm.. what I have noticed is a slick behind each exhaust, even after the engines have warmed up...thought it might be unburnt fuel. While its tough to get them going Friday night , they run ok, its the same procedure the next morning..more pumping and cranking..the old Trojan after the intial weekend start up would kick off just touching the keys, thats what makes me think the carbs are toast, they are 25 yrs old after all, and finding a good carb shop around here is like finding hens teeth
 
Those big blocks in a 34 Santego will burn a lot of fuel. About 30 gallons/hr at 3100-3200 rpm and over 50 gph at 4400 rpm. Nothing you can do will change that. If the carb is dry overnight you probably have leaking well plugs in the bottom of the carb. Not difficult to fix if you are mechanically inclined (heck you tube). I used JB Weld. I also changed from thermal to electric chokes and removed the fast idle cam on the carbs. This allows the choke to close as the engine cools and reduces fuel evaporation. Even after a week of sitting the engine both start after 3-5 cranking revolutions and not touching the throttles. Almost fuel injection. Plus the electric chokes open quickly helping reduce fuel consumption during warm up.
 
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