1965 kiekhaefer mercury 500 50 hp no power at full throttle

[cotterj]

I need some help troubleshooting my outboard which has no power from 3/4 throttle to full throttle. It will run but it sounds bogged down. It starts and idles well with the only exception being when its cold. Its take a minute or two of warming to get it to want to idle OK. The boat was put into storage about 3 years ago and was pulled out of storage this year.

Here is what I have done thus far:
- Checked for spark on all 4 plugs. All looks good.
- I do not have a compression guage, but you can feel a good amount of compression when pull starting it.
- Replaced battery
- Replaced gas twice and used a marine gas treatment
- Replaced fuel line and primer bulb
- Checked the fuel tank pickup filter
- Replaced starter and starter solenoid
- Sprayed carb cleaner in both carbs at full throttle - no improvement
- Checked tell-tale hole and water is pouring out

The only thing that I have done that shows a noticeable improvement is when going full throttle if you pump the primer bulb the motor starts to pick up speed and power but only for a second or two. The engine is not burning a lot of gas either. Can anyone help point me in the right direction on what to focus on next? It seems like a fuel issue to me.

 

[JB]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

Hello, cotterj. :welcome:

"Parts replacement is the most used, most expensive and least effective troubleshooting method known to man." JB.

The part where you say you pumped the primer bulb indicates fuel supply is inadequate for WOT. That could be insufficient vacuum/pressure to the fuel pump, failing fuel pump, air leaks, insufficient venting of the tank.

 

[cotterj]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

Thanks for the info JB.

I will say the fuel line and primer bulb were dry rotted when I took it out of storage. I'll double check all my connections on the new line. I'm assuming the tank has a good vacuum because when I have it closed all the way and no fuel line hooked up it will start to send gas out the gas connector on the tank. What kind of venting do I need on the gas tank? It will run great on muffs.

What recommend ways are there to test for air leaks in the gas line? How about any tests to see if my fuel pump is the problem? Does this sound like a bad stator? I have read quite a bit that that is a possible issue for my scenario.

I should add that I replaced the starter and solenoid because they were broke physically. I didn't replace them due to my power problem.

 

[matt167]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

You may have a weak fuel pump. and a 500 only has one pump ( I think ) so it would be more pronounced.. Just rebuild the pump. The kit is about $7 and you know it has been sitting for at least 3 years

 

[cotterj]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

$7? Thats not bad at all. I assume I can purchase a new kit over an OEM original from eBay or something?

 

[matt167]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

Not sure the Mercury/ Quicksilver kit is still available, but Sierra aftermarket is. It should be 18-7804 which is about $4 here at Iboats. http://www.iboats.com/Fuel-Pump-Kit-Sierra/dm/view_id.174937?cm_mmc=Google_Main-_-Mall+Product+Listings%3AGoogle-_-+%3AMall+Product+Listings%3AGoogle-_-Sierra&kw={keyword}&gclid=CKeJ__u_tbkCFcie4Aod9iIAeA

Check your S/N against the chart. http://www.iboats.com/Mercury-Fuel-Pump-Kits/dm/*******.822393842--session_id.656593149--view_id.271585

 

[cotterj]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

Is it obvious to see if its bad if I take it apart first? My serial number does match up with those ranges on the fuel pump page.

 

[matt167]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

diaphram may be dry or stiff

 

[Chinewalker]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

FYI - spraying carb cleaner into the carb throat while running does NOTHING for the carb, but will do a nice job of cleaning residual oil off the motor's internal parts - NOT a good thing. The ONLY way to properly clean a carburetor is to remove it, disassemble it and thoroughly clean all passageways.

 

[cotterj]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

OK thanks for that info. I won't do that anymore. I plan to do that after taking a look at the fuel pump.

 

[cotterj]

Re: 1965 kiekhaefer mercury 500 50 hp no power at full throttle

I took the motor apart this weekend to see what the deal might be. The diaphragm doesn't appear to be dry or stiff. The was some dirt in the carb bowls which i dumped out. I didn't take the carbs apart any further yet. I did find one tube that was plugged. Its on the same side as the tell-tale hole but its more towards the front on the engine. Is this an air intake or exhaust? Could this be a possible reason for my issues?