Merc 500 Revival

[spamn]

Re: Merc 500 Revival

Guessing the carbs need new gaskets (built in fuel pump). When I try to prime the bulb I notice that once the bowls fill, fuel leaks our the carbs and the bulb won't stay stiff. Easy fix.

Big problem now.. Engine runs fine at idle. I let it warm up. Make sure the choke is off. Put it in gear and... nothing. I barely go anywhere. The engine still runs but I have no power. I can put around at an idle pace with the throttle all of the way forward.

When I try to put it in reverse I get a grinding sound and no reverse. I immediately put it back in neutral to not grind anything up.

Ideas?

 

[spamn]

Re: Merc 500 Revival

Any ideas, guys? Haven't had time to do anything yet, but also still confused.

 

[spamn]

Re: Merc 500 Revival

Still no luck. I replaced all carb gaskets and the fuel lines. Bulb seems to stay firm now but still no power and doesn't like to run without choke.

I'm thinking (mostly hoping) that I need a tune up. Carbs adjusted and controls/timing adjusted. Lync and sync I believe.

Any ideas?

 

[merc850]

Re: Merc 500 Revival


Are these the controls you have? If so the inner one is shift the outer is throttle. I don't know if they will work on your motor, you need the single lever Mercontrol.

 

[chum1]

Re: Merc 500 Revival

Looks like your on the right track, compression is good, fuel system gone through, make sure all plugs are firing at idle and under load, try priming bulb with engine running to see if its starving for fuel, link and sync for sure, since you already went through the carbs it could be a timeing issue which can be checked with just the starter, if thats not it i would start investigating the spark system, you will have a great engine when its running right.

 

[spamn]

Re: Merc 500 Revival

My controls looks like these

Gear selector/throttle and fast idle lever.

I start it in neutral with the idle lever in the middle (both levers pointing towards the sky) correct?

 

[spamn]

Re: Merc 500 Revival

Looks like your on the right track, compression is good, fuel system gone through, make sure all plugs are firing at idle and under load, try priming bulb with engine running to see if its starving for fuel, link and sync for sure, since you already went through the carbs it could be a timeing issue which can be checked with just the starter, if thats not it i would start investigating the spark system, you will have a great engine when its running right.

Sounds like a lot of good advice. Too much for me to take in at once though.

1.) How do I check to make sure all plugs are firing?
2.)Have tried priming while running and it seems to help - why?
3.)Link and sync sounds way too complicated for me as I have no idea about TDC and all that jazz. Hoping to narrow it down to that and pay to have that done. Will probably have to sell a kidney to afford that though.
4.) What do you mean about timing checked with starter?

Sorry about all the questions but you had a lot of good advice at once. Just want to clarify a few things.

 

[spamn]

Re: Merc 500 Revival

Tinkered with the engine last night and have the fuel system completely fixed. Zero leaks.

Took the boat out this morning and she cranked on the first try. Took the choke off right away and she stayed running..

Put her in gear and got idle speed even at WOT. No power and a lot of smoke. Not getting more than a dribble from the telltale either. Turned her off and waited an hour or so and then fired her up again. Bulb was still firm and she fired on the first try. Still no power in gear.

I brought her home and took off the lower unit to see if my new impeller was shot or something since I am not getting a stream from the telltale.

Impeller and all water pump gaskets look fine. Even double checked to make sure the little gasket dealy where the water tube connected to the water pump was in there. All seems well in the lower, yet no stream from the engine.

 

[spamn]

Re: Merc 500 Revival

Edit

 

[spamn]

Re: Merc 500 Revival

I was looking at my rectifier to try to see how I would wire a tach up and noticed the two wires from the stator were missing insulation and pretty frayed. I patched them up and wrapped them in electrical tape. Looks like they were rubbing against the ground wire that attaches to the top starter mount. Not sure if that was happening or even could be a problem.... With the lower unit back on, telltale unclogged, and the wires patched up I took her out to the river real quick. Dropper her in and she fired right up. Let her warm for a minute with the fast idle and then put her in gear. She was SCOOTING across the river. This is my first time seeing her in action and it was great. Ran like a champ. Now for some minor things I noticed...

Lastly, my electric choke still won't work. When I first got the engine, the plunger was missing. I replaced that but the choke button on the controls won't activate it. I tested the solenoid by placing a wire from the postitive of the starter solenoid to the choke soldenoid and the plunger shot up like it should. Assuming there is a disconnect in the wiring from the button to the solenoid somewhere. Also, when I use the manual choke, the plunger likes to get stuck in the solenoid so when I push the manual choke down, it doesn' actually unchoke

Sorry for the long update. I'm pretty excited that I found this engine laying on it's side with years of non use and now it's rocking and rolling. I will still get a link and sync of some sort to get her properly tuned up.

 

[spamn]

Re: Merc 500 Revival

Another update.

I fixed the choke and all is well with that. Even when warm, she doesn't like to start without the choke though. As soon as she fires up, I take the choke off and all is well with the idle.

She was doing great the other day, but I took her out again today and at WOT or close to, she was cutting out. When I primed the bulb it helped. I'm thinking that my fuel leak may have disappeared. Does this sound like a logical guess? When I prime the bulb, the upper carb leaks from the "economizer jet". I don't recall it doing that before.

Upon disassembly of the upper carb I found the float stuck closed. It seems to be catching on the "7211A 1
fuel bowl baffle" that has a hook that sits where the bowl gasket is. The baffle is not bent. Wondering if somehow my float got bend out of whack?

I'll try to take a look at everything this weekend hopefully.

 

[spamn]

Re: Merc 500 Revival

For anyone following this, I found my float to be out of specs. I opened the manual and both carbs and bent the floats back to the proper measurements. All is well and the engine is running as it did 33 years ago new.

The Merc 500 is one fine engine.