Logo
FULL SITE MENU

b84 MC 470 Fuel Pump

A

a1nowell

Contributing Member
"Well I took this old TriToon

"Well I took this old TriToon out for a a sea trial yesterday after replacing the new upper O/D. The old boat performed great for about 45 minutes then just died, and would not restart. After alot of checking I determined my fuel pump went bad. I am sure it is the original. I am considering replacing it with an electric pump. I read the Robert A Fierro discussion of 4/21. Would the same style of pump work on my old 470?

Bt Doctur would you wire it the same way as you suggested in the 4/21 discussion?"
 
"You might check your anti-sip

"You might check your anti-siphon valves in your fuel line. Also there is a one way rubber flap on the little filter (mercruiser oem) in the 2 bbl mercarb inlet that can get stuck closed with crud. I've had both of those get stuck on me and left me without power. I got rid of all the anti-siphon and one way valves and installed a water/fuel seperator and haven't had any trouble since.

I don't think a mechanical pump would just die instantly, there would be other tell tale signs like hard starting, missing, etc. Also there should be a safety hose attached to the pump that goes to the carb. If gas is filling this up then your pump is bad.

The best thing to do is first make sure it's a fuel issue. Then work your way back from the carb until you find fuel. If you're getting fuel to the carb then it could be the carb such as plugged filter or jet. If you're not then don't assume it's the pump and keep going to the inline filter, anti-siphon valve, fuel pick-up inside the tank. Good luck."
 
"PugentSounder,

I disconect

"PugentSounder,

I disconected the fuel line at my inline filter and cranked the motor, no suction from the fuel pump."
 
"If there is a clog anywhere a

"If there is a clog anywhere after that you won't get any suction prior to it. Try taking out the carb inlet filter and try again.

Just trying to save you some bucks if it's not the pump by using process of elimination. I've always hated spending money and time on replacing parts to find out that wasn't the problem. But if it does happen to be the pump and you switch over to electric, please put up a detailed 'How To' on here. If mine ever goes I would probably switch over to electric as well."
 
"Just out of curiosity how lon

"Just out of curiosity how long has your boat been sitting since the last time you had it running?

What wears out in a mech pump is the rubber diaphram inside the pump. When it is breached you should find fuel in that bypass tube that goes to the carb. If the motor has been sitting a long time, rubber tends to get dry and brittle. As soon as you hit the ignition it tears the diaphram. That's why they say the worst thing for a boat or car is to let them sit for a long time."
 
"This old boat, JC TriToon, ha

"This old boat, JC TriToon, had been setting in a cow pasture for 5 years prior to last April, '08, when I bought it. I got the engine started in May of '08. Then I started a redeck/rebuild that has taken up until now to finish. I have had a variety of problems in the process the last of which was the gears going out in the uper O/D. New upper O/D installed last week. Sea trial yesterday.

I'll check all the lines for blockage."
 
"Re:"I got rid of all the

"Re:"I got rid of all the anti-siphon and one way valves ...."

They are required safety items. If not present and you have a "happening", your insurance won't pay."
 
The nipple on the fuel pump fo

The nipple on the fuel pump for the safety hose that goes to the carb can clog w/varnish and the leaking diaphragm won't send fuel thru the hose.
 
"what Guy is saying is the &#3

"what Guy is saying is the "vent hose" is just that , a vent.If plugged it won`t allow the diaphram to operate properly. The "vent hose" does not send fuel to the carb UNLESS the diaphram has ruptured"
 
""They are required safety

""They are required safety items. If not present and you have a "happening", your insurance won't pay."

Explain how these valves are a "safety" item please. My VP didn't have one of them and it was newer than my MCM470 by four years."
 
"Should you rupture a fuel fee

"Should you rupture a fuel feed line,the gas wont simply spill out.The fuel pump diaphram vent is a vent to allow the diaphram to go up and down, Should it rupture any fuel going past the diaphran is returned to the carb thru this hose rather that pumping raw fuel directly into your bilge and giving you a entry into the "Darwin Hall of Fame""
 
Back
Top