What would you do?

[eightpointup]

1982 mercury 50 hp 4 cylinder

History is I bought it and was told the first time to start it each year he used starting fluid. I tried it (I now know its a bad idea). It started but I couldn't get it to idle. I could give it about 3/4 throttle in neutral and it would run but would die it when I tried cutting the throttle back. I tried it again the next day and started a small fire due to the starting fluid. I melted the choke linkage the plastic on one choke shaft. I removed the carbs ordered the parts after a ton of searching. I did not order kits to rebuild yet due to money.

Actual Question Before installing the carbs is there anything I can due to them as far as adjustments or cleaning without rebuild kits to have a better chance at the operating correctly?

Thank you

 

[saumon]

Re: What would you do?

BEFORE throwing any money in parts, DO a compression test, it's mandatory!

If the engine has been run on starting fluid and only run on 3/4 throttle, chances are there are some internal damages.

On any engine of unknown history, the more efficient approach was to check, IN THAT ORDER, for:

1- good, even compression on all cylinders (over 100 psi and within 10%)
2- strong (blue, crisp) spark at all cylinders (jump at least a 7/16 gap)
3- fuel system checkup (from the tank pickup up to the carbs with everything between, including the fuel lines, the primer bulb and the fuel pump)

Trying to adjust timing, changing fuel lines, cleaning & adjusting carbs or throwing costly electronics on an engine with a bad, scuffed cylinder is a waste of time and money, as you'll never be able to get it running right...

 

[eightpointup]

Re: What would you do?

saumon Thanks for the reply. Unfortunately #1 and #2 I can't check at the moment. I have the motor partially apart so I could remove the carbs.

#1 on hold but I do have a compression gauge
#2 on hold but how should I go about checking for the crisp blue spark that jumps 7/16 gap?

#3
I am waiting on a choke shaft then I will put it back together. The lower carb had a busted spring on the choke relief I replaced it and took it a part and cleaned it. I cleaned the upper carb as well. Both carbs were really clean with only a few bits of dirt in the screens. Floats looked set right and I adjusted the idle mixture screws to 1 1/2 turns out. The tank is plastic, clean with new gas mixed 50:1. Bulbs pumps up, stays hard while disconnected from motor. No leaks. Connected gas flows to carbs. I am not sure how to check the fuel pumps with them being in the carb ?

 

[saumon]

Re: What would you do?

but how should I go about checking for the crisp blue spark that jumps 7/16 gap?

With a spark gap tester. 10$ at any auto parts store.

http://www.pelicanparts.com/catalog/images/tools2003/THE-404.jpg

I am not sure how to check the fuel pumps with them being in the carb ?

You have to do these steps in that order. If compression check ok and engine still run like crap, then proceed to the electrical parts. If, again, everything is fine, then clean the carbs and service the fuel pump diaphragm and check all the lines.

As for the pump itself, you have to open it and look to see if the diaphragm is punctured but, anyway, it is cheap enough to don't botter with this and replace it.

 

[eightpointup]

Re: What would you do?

Thank you again. I bought a spark gap tester at Autozone today.

I replaced 1 fuel pump diaphragm today, the old one didn't have a tear in it but was stretched not real pliable. Local shop had to order the second one might not have it until Monday.

 

[Crazyman1225]

Re: What would you do?

just a suggestion for you. instead of using starting fluid, which as you know is a very hot burning liquid. try using a spray can of carb cleaner, it burns but isn't nowhere near as hot as starting fluid.

 

[j_martin]

Re: What would you do?

just a suggestion for you. instead of using starting fluid, which as you know is a very hot burning liquid. try using a spray can of carb cleaner, it burns but isn't nowhere near as hot as starting fluid.

Do not spray anything in that engine that does not have the proper lubricant in it. Neither carb spray nor starting fluid have any lubricant in them. In addition, both of them burn so fast that if there is enough in a cylinder to fire, it will cause pressures to go way over reasonable (that's the knock you hear) and cause damage to the engine. If you must spray fuel into the engine for testing, use 2 cycle fuel. (gasoline and TCW=3 oil mix)

BTW, I've found over the years that using a little of my chain saw fuel to start an old carbureted automobile engine that's been sitting is way more effective than starting fluid. I think the main thing is that it oils up the cylinder walls and valves, increasing compression rather than washing all the lube off and killing compression.

With this history, odds are real good that internal damage is done to the engine, and any "tune up" things you do can't possibly make it right. Compression readings are the first data needed to make a reasonable decision on the next step.

hope it helps
John

 

[Nickledimed]

Re: What would you do?

Confirmed, DO NOT SPRAY STARING FLUID OR CARB CLEANER INTO THE CARB.
I use a spray bottle with 50:1 gas/oil mix.
Tts also a good way to tell if your running lean.

 

[eightpointup]

Re: What would you do?

Saumon I found this on compression checking

. Fully charge battery.
2. Start engine and warm her up.
3. Remove all spark plugs and disconnect fuel line.
4. Rig a jumper to engage starter solenoid without turning ignition on. Pull the emergency kill switch on rope start engines.
5. Screw guage into #1.
6. Turn engine over until reading on guage stops increasing or 5 times, whichever is more.
7. Repeat #5&#6 for all cylinders.

Without being able to warm it up first should I wet the cylinders with something? I have no idea how to Rig a jumper to engage starter solenoid without turning ignition on.

 

[saumon]

Re: What would you do?

Saumon I found this on compression checking

. Fully charge battery.
2. Start engine and warm her up.
3. Remove all spark plugs and disconnect fuel line.
4. Rig a jumper to engage starter solenoid without turning ignition on. Pull the emergency kill switch on rope start engines.
5. Screw guage into #1.
6. Turn engine over until reading on guage stops increasing or 5 times, whichever is more.
7. Repeat #5 for all cylinders.

Without being able to warm it up first should I wet the cylinders with something? I have no idea how to Rig a jumper to engage starter solenoid without turning ignition on.

You don't have to jump the starter solenoid. Simply flip the kill swith, it will disable the ignition, then you can use your remote starting swith as usual, the only side effect being that you'll have to walk back and forth from the remote control to the engine to have a peek at the readings and reset the compression tester.

Cold test is ok if you can't start it. If you get a slightly low reading on one hole, you could wet that cylinder with 2-strokes oil to see if there's an improvement. If you're lucky, it could be an indication of a stuck ring.

You haven't mentionned it but you could also open the throttle via the idle lever on the remote.

 

[eightpointup]

Re: What would you do?

Compression is 100-105 on all cylinders dry with throttle closed
All passed the spark test.

I hook the fuel line up and starting pumping but the bulb did not seem to pump up. I think it was leaking from a fuel line going to the carbs but that was using a flashlight. Dark has come and tomorrow is another day.

Any tips or advice on going thru my fuel system checks appreciated

Thank you,
Ron

 

[saumon]

Re: What would you do?

Any tips or advice on going thru my fuel system checks appreciated

Yeah, you did it right. Comp and spark test ok so you now proceed to the fuel system.

I've found that the more efficient approach was to split the fuel ?path? in half. Get or borrow a known good portable tank with fuel line, primer bulb and connector and hook it onto your engine. If it now works, you'll know that the problem is somewhere in your tank pickup/line/primer/connector. If not, then it's likely on the engine side (fuel pump, carbs, hoses). An easy test for the fuel pump is to squeeze the primer bulb when the engine start to bogs down. If it pickup speed, then the fuel pump diaphragm is shot.

 

[eightpointup]

Re: What would you do?

I'm going nuts !!! Ok I took the inlet covers pulled the hoses thru and replaced zip ties at each hose connection. Tried putting the inlet covers back on but the lower one would not seat correctly. So I pulled the carbs again and fixed the problem. We now have no fuel leak.

But while doing this a wire to the stator came loose from a butt connector someone had put in. I started looking and found another wire (appears to be tan or dirty white) that had two butt connectors in it and these connections were close to breaking (appears to be going to trigger). After a trip to the napa store I put new connectors on along with a little extra wire.

Then I put everything back together and hit the key but it wouldn't even act like it wanted to start. I connected the spark gap connector and I now have no spark Everything is hooked up and the kill switch is flipped to run. The only wires I disconnected were going to the solenoid could I have connected these backwards? Attaching photo of the way is connected.

What should I check?

 

[grandpaclint]

Re: What would you do?

just a suggestion for you. instead of using starting fluid, which as you know is a very hot burning liquid. try using a spray can of carb cleaner, it burns but isn't nowhere near as hot as starting fluid.

i second that,,,i have seen ether blow a hole in the top of a piston
not good.
good ol carb cleaner

GOF here

 

[milehighboater]

Re: What would you do?

At least you know when the spark problem started, I would take a moment and come back to the motor with a lot of light. If there were two loose wires backing out of the connector there is a good chance there are a few more. Look around and make sure nothing else had come apart or is loose, also make sure there are no blown fuses. If the wires came apart during testing they may have grounded out and blown a fuse.

 

[eightpointup]

Re: What would you do?

I was hoping someone had an order I should check things out in and what voltages I should find where. I will be back at it tomorrow.

 

[saumon]

Re: What would you do?

Chasing electrical problems can litteraly drive you nuts, as they can be intermitents; some acting only when the engine warm up and the temperature rise.

If the insulation on the wires is cracked, you'll have to replace them.

And you'll definately need an OEM Service manual to diagnose the problem.

 

[eightpointup]

Re: What would you do?

Sounds like my chances of selling this thing and breaking even are dwindling

 

[Gomer50]

Re: What would you do?

Just my 2 Cents,
If you have compression and you have spark there is hope.That being said the question is and will be is this going to be worth your time on the water and in your driveway. Electrical components are not cheap and some are hard to find.On a Motor that is 30 years old the wiring can be brittle cracked and will cause a headache chasing it down.A manual is a must.I have a 72 80 hp merc. that has caused me grief from day one and has been an educational challenge.Investment wise I spent more dollars on components than I will ever be able to get my money back should I sell.Oh and on another note My Wife thinks boats are a waste of money and take up space and attention,and causes friction BEWARE LOL....Good Luck and decide wisely..

 

[eightpointup]

Re: What would you do?

I have $600 in it. I bought it to change out my 25hp with the 50hp. The boat runs 18-19 mph with 25 so i figured I could deal with the boat as long as it went faster. Then another opportunity came so I bought a stratus 256v.

Now I need to sell the merc 50hp with or without old 14' bass boat and trailer. I also need to sell the 15'6" Aluminum deep v with 1992 Johnson 25hp to pay back some money I borrowed to get the stratus.