TOPIC: HELP ME before I light this boat on fire (Merc500)

OK, same as before, I have checked the timing, checked the compression, replaced the fuel pump and almost the entire fuel system, taken the carbs apart and cleaned them, checked everything I could think of, still I get the same result:

Throttle up, rpms jump from lets say 1000 to 2500... slowly build over a period of 70 seconds to 1 minute and then climb higher, probably and 4k

boat is 14 and with me in it will only do 23mph

could it be the reed valves? are they inside the block? I didn't see anything when I took the carbs off and the only diagram I can find on-line says they are part of the crank assembly? I'm ready to light this thing on fire!

Also does anyone in WNY know of a good repair shop? I'm about to give up here!

if it was reeds it would spray a fine mist out the carbs.

at idle? when running or even during startup?

whats the color of the plugs after running it...plugs usually tell a story...post some pics of them immediately after it acts up

plugs look good, brown tops no signs of issues.. I can get pics tmw

Hi,
It would be helpful to know what year Merc you have. Ignitions vary and that may be the real issue. Poor running/eratic problems like this are from one of three general causes: fuel, ignition or mechanical. Each can be gone through methodically in the most to least likely.
Mechanical: Compression
Crank end seals
crankcase split seam seal
reeds

Fuel: Bad Gas and or water in fuel
Tank vent closed
faulty bulb
decayed/crimped fuel line
fuel line quick connects faulty
dirty clogged fuel pickup

carbs: dirty gummed or varnished carbs
stuck or sunk or misadjusted floats
decayed or dirty needle and seat
decayed fuel lines
idle mixture way off

fuel pump: stuck valves
bad diaphram
weak pressure pulses due to vacuuum leaks

Ignition: depends on which you have on your motor.
Regardless of ignition type check the wiring
harness, as a lot of these are junk on older
Mercs and can cause issues
so now depending on ignition:
points
trigger
switchbox
coil (s)
cap, center contact, rotor
wires
plugs
total timing and initial timing and
timing pick-up.



So most of these things can be isolated and checked to eliminate leaving the more difficult checking. You've been throught he carbs and pump has this problem been created by the work you've done or are you trying to fix an initial problem? That would help to know too.
Randy

This may be far fetched but what is the pitch of your propeller?

bingo may be trying to swing too big of a blade but I think it is a low chance but you never know. Tim Calmes may be your best choice for a fairly local guru

Not so far fetched, an overpropped 50 with poor setup would take off just like that. 4000 is way too low.

In Z's post below this one,which this is just a continuation of, he says the prop has a 10" pitch. I wonder if it is marked correctly.Take it to a prop shop and they can put it in a jig and verify. How did it run before you kissed the bottom.How did it run last year when you bought it? Don't light up the boat as it is the motor,maybe, that is giving you the hard time. As mentioned Tim at Silver Lake is the guru and there is a show there a week from Saturday,make a day of it.

Prop is 10.75 by 10 pitch OEM

Motor is 1964 Mercury 500

fuel system is all new, pump replaced

compression was all ~130 to ~140

gas was replaced, twice

ignition: all i did here was clean the points and check (visually) spark by holding the plugs to the motor

timing I checked by verifying that the two pulleys aligned when the motor was at TDC

prop is OEM has the part number from 64 still on it, no question that it is 10.75 by 10

OLD thread: fiberglassics.com/glassic-forums/home/mercury-outpost/mercury-500

Anyone have Tim's contact info?

assuming the carbs were infact rebuilt correctly, my 2 cents is on the mag

Zwarbyt wrote:

Anyone have Tim's contact info?

Nicklecityclassics.com under the icon Paradise Boat Works

I've read all of the original postings on this and all of these as well.
Randy layed out all the possibilities pretty well, but I'm gonna guess that either one carburetor still isn't providing a fuel supply, or the crankshaft seal closest to whichever cylinder isn't working is gunnysack, or a reed valve is broken, but not spitting fuel out the related carburetor. (rare, but possible and was the cause of a similar problem I had with a 500 a few years ago - but it requires a total engine teardown to see - let alone fix - so let's try and totally eliminate all external potential causes first.
That old school magneto usually either works or it doesn't work & it sounds like it is working since the thing will idle.
The 500 can be very deceptive in its ability to maintain a decent idle even though one cylinder isn't performing, but will not accelerate and will not reach max RPMs as described in your posts.

Since you can get away with the following test without causing ill effects like it would in later solid state ignitions, I would pull off one sparkplug wire and plug it onto a spare sparkplug so it will lay down in the pan okay while you run the boat. Leave the regular sparkplug in the cylinder & make sure any spilled fuel mix is wiped up before doing this one.

Anyway,...
Do this with #1 and then start the motor and go for a short ride to see if the Merc acts the same or differently.
If it is obviously running poorly with this cylinder not getting spark you might skip the short boat ride and go straight to #2 cylinder.
At least try this with all (4) cylinders to see if it makes an obvious difference with each cylinder or if perhaps you find one cylinder that doesn't have as noticeable of an effect on the performance as the other three.
If you discover one cylinder doesn't make as much of a difference as the other three - try holding the sparkplug wire almost on the sparkplug, but so that the spark has to arc farther and see if that cylinder tries to kick in, etc.
Then report your findings.
Thom

tim's the man in perry,n.y.....silver lake. paradise boat works.

recheck the points set at .010 give or take .001.= .009-.011
that will do it if it is sey wrong.JAT.

Timing & sync? Lining the pulleys up isn't setting the max advance or pickup timing.

Timing & sync? Lining the pulleys up isn't setting the max advance or pickup timing.

I second this.

I also think you should do what Doc says in his test.

I wish I was there to help, probably could get it figured out for you fairly quick.

Keep trying.
Conrad

I am in the check timing camp too. This describes what might happen with incorrect timing, particularly where you have done the points where exact setting effects timing. Also your timing pick-up needs to be checked. You need a piston depth gauge or dial indicator to do it along with a voltmeter or buzz box to indicate when points break.
Randy

I dont have a timing gun, I put a call into Tim to see if he can take a look hes only 50 minutes from me...

I'd think that would take a 10 in pitch ok. A timing gun isn't that much at sears. I would always just run them out of gas and jump the starter relay and check the timing at full speed forward. If I remember right it should be somewhere around 20 degrees btdc = or -.

When in doubt. Get with Tim. He will get you up and running.

For with the Lord Tim there shall be light at the end of your long black tunnel of despair. Hold back the torch of despair!

Try to see if tim can squeeze me in, heard he is fully booked...

Zwarbyt wrote:

Try to see if tim can squeeze me in, heard he is fully booked...

Tim IS THE MAN!!!!!!!!!!!!

He said he could spare an hour to take a look, his shop has SO many mercs you wouldn't believe it!
We eliminated the prop as a problem and he advised it was likely dwell or points

Took it back home with NEW points condenser and water pump (all of which he had in stock)

Took it apart today and he was correct, points were off mark and gap, re assembled and she now does 32 with me in it! So happy!!

I highly reccomend his services on ANY merc!!!

ALLRIGHTEEEEE Zmannnn No burning required just ONE of the Zen masters magic fingers as I include Thom [and a couple others that reply on here],just a few thousand miles out of the way for us East coasters...

you have been blessed by the Merc Gods

i told you to check the point gap !

i told you to check the point gap !

we all did .........Im glad its sorted

I would bet a adult beverage that TC took more than a hour,not on the job but jabber jawing and showing you his shop, more like 2+ hours......Zwarbyt wrote:

Zwarbyt wrote:

Try to see if tim can squeeze me in, heard he is fully booked...

Tim IS THE MAN!!!!!!!!!!!!

He said he could spare an hour to take a look, his shop has SO many mercs you wouldn't believe it!

He did take a while to show me the shop! And although people suggested the points I had never seen any before and he walked me through all the procedures and gave me the specs as well, he really helped a noob out!

Tim is the man. I went down there last weekend to get some merc controls(and drop of my Mark 55 starter) and spent two walking around with him talking and checking things out. He even sold me a much better wrap than I had for a grand total of 6 dollars.

Just imagine that he also has a huge other warehouse full of stuff that he hasn't had the time to move over there yet.

And he is retiring next summer from is other distraction job to be our full time Merc Man

If you chat with him ask him how he likes the rare 65 Glastron Thunderjet that Tim(me) handed to him last week

Tim

Tim's the man. Checked out his new place when I brought the 650 in for some lower unit work this year. He's booked solid - and that's a good thing.

Hey Guys;
Thanks for all the kind words. Really appreciate it. Not sure it's all true, I'm just a guy trying to do things right.
Tim