140 merc problem

[jamdown]

can anyone help me with this problem, I took my boat out for the first time in july after the winter. I gave the boat a service changed the oil & filter changed the plug & water seperator the gas tank was 3/4 full I put in gas staberlizer and topped with more gas, put the boat in the water.
the engine is a MERCRUISER 140 3.OL I/O the boat ran good all day, on the way home i was running about 17mph for about 1/2 hr then the motor just died on me and would not start I think the freeze plug blew out on me because my temp needle went to cold on me and the bilge was full of water,
sea tow brought us back to the dock.
now checking the engine i notice there is no gas pumping from the pump on the block the pump was put in a year ago and the boat was not in the water 6 time last year. i removed the pump but it look good. WHAT SHOULD I LOOK OUT FOR NOW. THANX

 

[thrasher]

Re: 140 merc problem

Is it a mechanical pump or an electrical pump?

 

[jamdown]

Re: 140 merc problem

it a mechanical pump

 

[Haut Medoc]

Re: 140 merc problem

Start the engine on muffs & see where it is leaking....
You will need to do a fuel pressure & vacuum test to isolate your problem....
I suspect a clogged pick up in the tank....​

 

[thrasher]

Re: 140 merc problem

So there are only 2 reasons that the pump wont pump.
1) there inlet is blocked so gas cannot reach the pump
2) the pump is broken/worn out

Mechanical pumps are quite reliable, how old is the engine and pump?
the first thing I would do is put a small pipe on the inlet to the gas pump with a small container to hold some White spirit (safer than gas and won't harm anything). Hold the container with the wite spirit slightly above the pump and use the starter motor to turn over the engine. You should see the white spirit come out the outlet of the pump in pulses. If the white spirit just dribbles out of the pump, then the pump is your problem. If it comes out in strong pulses, then the pump is good and your problem is with the gas supply. Gas and white spirit are all highly flamable so use extreme caution when doing this test and try not to squirt gas or white spirit all over the boat.

Assuming the pump works, you will need to look at the gas tank and the feed from the tank to the pump. You might have an inline filter, so check that. The easiest thing is to see if you can blow back down the fuel line from the pump into the tank. Depending on how full the tank is, it can be difficult to blow back. Can you get easy access to the tank?

Gary

 

[jimmytee]

Re: 140 merc problem

I just had a similar trouble with the same engine. Check the anti-siphon valve on the fuel tank. Should be where the fuel line leaves the tank to go to the pump.

 

[jimmytee]

Re: 140 merc problem

one more thing, Thrasher said to blow air back into the tank. You should NOT be able to do this if you have an anti-siphon valve installed. And I believe that valve is a USCG requirement.

 

[jamdown]

Re: 140 merc problem

Hey GUYS thank for the Input but still no go.
I by pass the in board tank with a new 6 gal external tank and installed a new fuel pump and still the gas does not go to the carberator checked the fuel line from the fuel pump to the carb, it was clean disconnect the fuel line from the carb and tried to turn the engine over, to see if gas is going to the carb, NO GO N/G connect the fuel line back to the carberator put gas in the carb she turns over and run untill the gas is gone from the carb..

 

[Don S]

Re: 140 merc problem

Well, if a new pump won't pump from a new tank. Time to check the cam lobe for the pump, or you missed the lobe with the new pump (not sure that's possible, BUT)

 

[jamdown]

Re: 140 merc problem

Don S.
if the cam is worn do you have to take the engine out to replace the cam

 

[thunderroad]

Re: 140 merc problem

just asking...but suppose his cam lobe is worn to the point of not running the mechanical pump...is there a safe place where he could put an electric pump and just block the hole where the mechanical pump was mounted?...instead of having to disassemble the engine and replace the cam.

If this is a stupid idea just tell me to sit down and shut up.

 

[capthook]

Re: 140 merc problem

just asking...but suppose his cam lobe is worn to the point of not running the mechanical pump...is there a safe place where he could put an electric pump and just block the hole where the mechanical pump was mounted?...instead of having to disassemble the engine and replace the cam.

If this is a stupid idea just tell me to sit down and shut up.

They do make covers to block off the mechanical pump. But if the cam lobes are worn for the pump, what do you think the rest of the lobes are going to look like as well. If he is looking for a quick fix then that would be an option. But beings how one thing goes wrong there are sure to be others that follow ie: Poor engine performance. Follow Don S signiture there is a whole hell of a lot of truth to it belive me.

 

[thunderroad]

Re: 140 merc problem

I understand and totally agree with what you're saying, but he mentioned that the boat ran fine before the pump quit. From my own perspective, I'd have to try something like the electric pump if the engine seemed to be ok otherwise. I've seen automotive cams where one lobe might be worn perfectly round and the others hardly worn at all. Weird things happen with moving parts.

 

[mkpj1]

Re: 140 merc problem

Wait a Minute!

I'm missing some dots here? You said there was water in the bilge? Blew a freeze plug you said? Where is that water coming from? Sounds catastrophic to me? Pull your plugs and give us some compression numbers. Hows your oil?easy stuff first!

Ken