need help on 5.7 mercruiser please

[patrickwebb]

Hi all. I just bought a 96 celebrity with a 5.7 lx mercruiser. The boat is a 96 and it has 140 hours on it (so you know it has been sitting for most of its life.) Heres the deal. I take the boat out the first time and runs good untill about 2600 rpms then it will bog down but not stall. I thought it was bad gas. So i changed the water seperating fuel filter and drained all the gas incase there was water in it. After putting 15 gallons I started the boat and ran it for a few minutes in the driveway before I went to the local lake. The boat runs fine out of the water, I can even rev it as high as it will take. It will not bog at all on land only under load. I noticed the starboard side riser was hotter than the port side. I changed the thermostat and still its the same problem with the heat of the one side riser. So now I have two problems that could possibly be tied to one problem (hopefully)--"THE CARBURETOR" I noticed when I was out yesterday after the fuel change my boat ran worse....only 1,000 rpm's I put the throttle half way. looked down the 4bl carb and seen that only one barrell was getting fuel. So out comes the carb and a rebuild for today. But my question to you all is....Do you think that my carb running only off one side would make the riser get hotter than the other...I mean gas cools right? Hopefully this is my problem. and thanks in advance for you help.

 

[Bt Doctur]

Re: need help on 5.7 mercruiser please

HI REVS are detrimental to longevity especially out of the water. Suggest you replace the impeller at this time.
After purchase describe what items you checked, serviced, examined, fluids/oils checked/ changed,etc. The "it sat for a long time and i just took it out" dosent "hold water". If fuel drelivery is ok, then a carb rebuild after sitting all these years is a wise choice.

 

[patrickwebb]

Re: need help on 5.7 mercruiser please

replaced-fuel & filter

doing a carb rebuild at this current time.

i will change the impellar after i get it running right.

Note****the power steering does not seem to be working. do you think the impellar could have broke off and up in the power steering cooler, thats why my power steering isnt working.--or a deverter valve?

what eles would make this thing not want to get up in RPM's but not stall.

Also why would it heat up on one side of the motor both in the water and out. lake/muffs.

It runs cool on both sides untill you get it to about 1800 RPM'S. then the starboard side will get hot. you can lower the rpm's back down to 750 and it cools back down.

i have took off the riser and inspected it. and replaced the gasket.

I have changed the thermostat and made sure there was no blockage.

I have pulled off the water hose that goes to the manifold/riser and it flows just like the other side, just hotter.

gauge reads no hotter than 170---never. but the water coming out of the bell housing is hot.

come to think about it.....i didnt see much water coming out of the lower unit. do you think this could be the problem?

fuel pressure seems to be ok....i poped off the center wire of the distributer while i put the gas line from the filter that runs into nthe carb in a clear bottle within a few seconds the bottle was almost filled.----full throttle--

The boat seem to run better yesterday before i changed the fuel filter & gas, I sprayed the carb down while it was running with some carb and choke cleaner but it sounds like to me that i stirred up more dirt that clogged the jets in this carb.--whats you opinion?

 

[patrickwebb]

Re: need help on 5.7 mercruiser please

what brings attention to my question already mentioned above.....Would the carb make the engine side heat up because "gas cools" or that side of the motor is working harder so its hotter because of that reason.

 

[patrickwebb]

Re: need help on 5.7 mercruiser please

anyone?

 

[Bondo]

Re: need help on 5.7 mercruiser please

what brings attention to my question already mentioned above.....Would the carb make the engine side heat up because "gas cools" or that side of the motor is working harder so its hotter because of that reason.

Nope....

Risers, Rarely run exactly the same Temp.... It's probably a Non-Issue...

 

[patrickwebb]

Re: need help on 5.7 mercruiser please

even if one side is really cool and the other you can barely touch

 

[Bt Doctur]

Re: need help on 5.7 mercruiser please

1996 w/ 150hrs Let`s see??? 13 year old motor.
Most likely atleast drained and winterized properly because it runs and no complaints of water leaks or water in the oil.The question was it filled or left dry all thise years. Cast iron tend to erode and scale away regardless.Mosy likely cause for a hi speed overheat are clogged risers. You also said you would change the impeller AFTER it was running right. THATS A BIG MISTAKE.
How do we know it`s not a water supply/flow problem?
Cooling: check impeller and risers
Fuel system: tank inspected for water, lines, filters, fuel delivery
Engine: rebuild carb, compression, leakdown, full tune up, timing and ign system check