Fuel pump

[thumbburn]

Boat quit last weekend out on the lake..... Thank god for kickers..... Got back home and no fuel to the motor..... Disconnected the inlet line from pump and can suck gas out of the tank..So figured a bad fuel pump.... Ended up buying one and put it on and still no fuel getting to engine.... Friend told me to crank motor and see if the cam is moving...... The cam is not moving.... So now I am stuck....it's a 1986 mercruiser 3.0 liter engine....... If this helps...when it quit it was no warning at all..... Just bam .. Any thoughts on the cam not moving? Not the biggest gear head here.... Lol...... It's a mechanical fuel pump also.... Thanks

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[fisherdude]

the cam (arm) to the pump must be under the fuel pump drive for it to work . check for bad fuel line, crack lines will suck air not fuel . also check to see if water separator is full of water or grim

[Xxx]

OOPS!!!

Edited June 5, 2016 by pap

[chinook35]

If the cam is not rotating  You broke a timing chain or gear . break out your wallet I am not sure if the 3.0L is an interference motor or not I will check my manual and find out . If it IS  You bent valves when the cam stopped rotating . Not a good scenario in ant case 

[Xxx]

If the cam is not rotating  You broke a timing chain or gear . break out your wallet I am not sure if the 3.0L is an interference motor or not I will check my manual and find out . If it IS  You bent valves when the cam stopped rotating . Not a good scenario in ant case

[/quote

Well that would explain the instant shut down.

[chinook35]

Well here's the good news. 3.0 l is not an interference engine. Valves should be ok. Also , thee is no timing chain. Gear to gear and they are phenolic (plastic) get a shop manual and if you have any mechanical skills you should be able to do the repairs yourself. Check on line for parts. Much cheaper

[thumbburn]

Well my buddy the mechanic came over to look at it and the cam is moving......... But still can't get fuel to the carb..... There is some fuel in the pump but not enough to do anything..... He mentioned it could be vapor locked.... ?

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[Xxx]

If the motor is cold I very highly doubl it's vaperlocked!!

[thumbburn]

Is it possible to get a pressure gauge and see what the pressure is when cranking the motor over.... And if the pressure is inconsistent could it mean I am sucking a bit of air and need to check the fuel line?... I can get fuel from the line that goes into the inlet buy sucking on the line from the tank.... And it doesn't take much effort to get the fuel.... I thought I ruled that out because I got fuel that way

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[chinook35]

Yes  there are several brands of fuel pump pressure testers . You might want to check with auto zone or advance ,they have loaner tools available . Not sure about pressure testers . Did you replace your pump with a marine or automotive pump ?  The marine pump has a vent that goes to the carb  automotive vents to atmosphere ( can you say BOOM if vapors collect in engine compartment) . You may be right about a cracked fuel line to tank . If your fuel line is leaking ,you won't have much or any pressure at the pump . 

Edited June 5, 2016 by chinook35

[Xxx]

The info I provided is inaccurate according to a very well known boat mechanic. Sorry for any inconveniences, sometimes the web isn't always correct as we found out right here!! PAP!!!

[thumbburn]

It's weird how I can suck the fuel line to the carb and get fuel but can't get fuel past the pump to the carb..... Gonna go to parts store and see about a pressure tester.... Yes I replaced with the same marine fuel pump.... Someone told me the cam lobe could be wore out..... I might consider a electric pump and try it and if it works then send the other pump back.....

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[lakebound88]

Rule out fuel pressure first, ensure nothing has built a nest or plugged up the vent line to tank via applying a minimal air pressure to tank via fill cap. If pressure begins to build. Any, 2psi, stop. Your vent could be plugged, if so, clean the line. If these get plugged although you're sucking some, it may not be enough under proper cranking speed, and the rest would be vapor lock.. you won't be able to suck fuel past the pump pending where the piston is on the travel(assuming mechanical). If the lobes were worn on the cam, I would be concerned for the rest of the cam..

Rule out one thing first.

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[jimski2]

Electric pumps are dangerous on a boat.

[rolmops]

Start with the cheap stuff. Check the fuel filters. One in the pump and one at the entrance to the carb. Next check the mechanical arm that goes from the pump to the cam. Also replace your fuel lines and check the air inlet and the fuel pickup on your tank. Put some reverse direction air pressure on the line that goes to the fuel tank. It may blow some gunk out of the fuel pickup back into the tank.

Edited June 6, 2016 by rolmops

[thumbburn]

Well my friend that works on boats came over.... Cam was moving.... Love was good .... Took pump off with inlet and outlet hooked up and pumped it manually like 40 times..... Tons of fuel...... Put back together and all is good... Motor fired right up..... Must be the new pump took a lot more than I thought it would to prime.... Thanks for any and all responses.... Good fishing to all...

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[chinook35]

[emoji106]

[Xxx]

Thanks thumb burn, for that piece of info about priming the fuel pump. My daughters are riding my ass about going tubing, well my 93-3.0 wouln't start used a lower unit oil pump filled a quart oil can with gas pumped till it got hard to pump. Hooked the fuel lines back up, VA!VA!VAVOOOOOM she fired right up, idles like a kitten. If I had not read your post I would have put a new pump on, I filled it from the tank connection up to the carb. I've never had one not pick the fuel up. But the his motor hasn't run in 3-5 years. Last year my uncle said if I tow the boat home I can have it, well I just got the paperwork done now she's mine, and she runs. THanks for the POST. !!!! PAP!!!