Cold Starting A Mark 78E

Mercury Outboard  general discussion

Cold Starting A Mark 78E

Postby dannynagasaki » Thu Aug 22, 2019 1:11 am

Hello everyone, I hope the boating has been great this summer..

Once warm, my Mark 78 starts instantaneously, it doesn't even turn over...bang it's running in a split second and will idle/run very slowly. Cold starting is more involved. Just wondered if any of you seasoned DR runners have any advice for cold starting. I'm finding that I have a very slim window of throttle movement to engage the starter motor, it won't even turn over unless it is exactly in the correct leverage spot. I thought I should have more movement or range at low idle in order to activate the starter motor. Is this the nature of the beast?

I make sure the fuel bulb is good and hard before I choke it and attempt to start it. Sometimes the motor will groan like some Merc starter motors will rather than turn over. In the mean time, I'm drifting away from the dock, nothing happens quickly when I'm attempting to start a cold motor without a cold start lever, it could actually take a few minutes till it's running. I'm trying to speed up the process, any thoughts??
55' Mark 25, 55' Mark 55E, 58' Mark 10, 58' Mark 35, 58' Mark 78E (2) 62' Merc 60, 62' Merc 450, 67' Humber Jewel, 74' Grew SS140, Oak Ridges, ON (winter), Wahsoune Island, Georgian Bay, ON (summer) Canada
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Re: Cold Starting A Mark 78E

Postby 58woody » Thu Aug 22, 2019 1:42 am

I just rebuilt a guys electrics for his DR and set it up.
It fires right up as it should in reverse and forward.

What state is your distributor, rotor, wires, points etc.
If you don’t have strong electrics that could be your issue especially when cold.
Mark 6, 1956 Mark 55 & 55E, 1959 Mark 55A, 1958 Mark 58, 1960 Merc 300, 1961 Merc 500, 1961 Merc 700, 1964 Merc 1000 Bradford, Ontario, Canada

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Re: Cold Starting A Mark 78E

Postby dave bernard » Thu Aug 22, 2019 2:06 am

check your chokes . why don't you start it at the dock to warm up the shut it down and push it out and start and go.
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Re: Cold Starting A Mark 78E

Postby dannynagasaki » Thu Aug 22, 2019 3:34 am

The distributor has been rebuilt, rotor OK, copper wires heavier than the norm, new points and plugs. The starter has been rebuilt at the shop but seems lazy, it does groan rather than crank once in 4 attempts if you know hat I mean by that. I've heard that condition from other Merc starters years ago and don't know what causes it.

Dave the boat has an odd shape with sponsons at the rear that almost come flush with the surface of the water which makes it a bit of a challenge to rope it tight to the side of the dock, would be easier with a more vertical freeboard. Perhaps extending it on a  line off the end might work till warmed up, just curious to hear what others here do and wonder what a new owner did back in the day when they were new. Again, motor runs like a top and starts easily when warm..
55' Mark 25, 55' Mark 55E, 58' Mark 10, 58' Mark 35, 58' Mark 78E (2) 62' Merc 60, 62' Merc 450, 67' Humber Jewel, 74' Grew SS140, Oak Ridges, ON (winter), Wahsoune Island, Georgian Bay, ON (summer) Canada
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Re: Cold Starting A Mark 78E

Postby dave bernard » Thu Aug 22, 2019 4:41 am

A good starter is the real key to those starting I have a few good ones.
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Re: Cold Starting A Mark 78E

Postby 58woody » Thu Aug 22, 2019 12:30 pm

dave bernard wrote:A good starter is the real key to those starting I have a few good ones.


I agree!
Mark 6, 1956 Mark 55 & 55E, 1959 Mark 55A, 1958 Mark 58, 1960 Merc 300, 1961 Merc 500, 1961 Merc 700, 1964 Merc 1000 Bradford, Ontario, Canada

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Re: Cold Starting A Mark 78E

Postby mercaholic » Thu Aug 22, 2019 1:14 pm

The DR's have the old style auto ignition systems so you do need a battery with good amps.  A lot of juice is used during the cranking procedure drawing away from the ignition system.

Secondly check that the choke plates are fully seated when you activate them.  Even slightly left open, they can delay the firing up of a cold engine.  This is very common on the in-line fours so I assume the same pertains to the DR.

One test you can try is to pull the motor over by hand when cold.  If it fires right up, the chokes are probably working as they should.

I miss my Mk78.... :roll:
Mississauga , ONT
Canada
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Re: Cold Starting A Mark 78E

Postby Jeff Register » Thu Aug 22, 2019 3:02 pm

Danny,
They are correct! Try this: put a volt meter on the coils resistors & check voltage drop while engaging the starter motor. I kind of lean toward a bad spot on the armature or shorted fields. Had a 51 Chevy, 6 volt that I found out the fields were insulated with paper. Well the paper went away & I had very little magnetic energy to spin the starter & was like a dead short leaving no current for one coil. Replacement fields fixed it, Guessing on yours. Bad bushings?  Anyone use a growler anymore to check the armature?
I too have a DR starter extra. My health says I'll never use it. You know they are heavy & shipping is expensive from Arizona. Let me know.
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Re: Cold Starting A Mark 78E

Postby dannynagasaki » Thu Aug 22, 2019 3:14 pm

All great points, thank you..I took 3 starter motors to a starter rebuild shop and asked him to service the best one. He claimed to have used parts from all three to build one good one and was happy with the results. It does work well and strongly when it engages but doesn't always crank every single time. I have two more starters that can be tested if the problem persists, It's not really a problem it's just not perfect.

Battery and coils are new and powerful and plates on all three carbs activate and seat properly when choked. I believe that you miss yours John, the motor runs so slowly without a miss and since I changed to a 19 pitch from 21 the hole shots are much stronger. It doesn't seem to lose much on the top end either. I also have a 15 and 17 to try at some point just for reference. An amazing motor!
55' Mark 25, 55' Mark 55E, 58' Mark 10, 58' Mark 35, 58' Mark 78E (2) 62' Merc 60, 62' Merc 450, 67' Humber Jewel, 74' Grew SS140, Oak Ridges, ON (winter), Wahsoune Island, Georgian Bay, ON (summer) Canada
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Re: Cold Starting A Mark 78E

Postby ctpdsr » Thu Aug 22, 2019 3:38 pm

When you squeeze the bulb, do you actually see fuel enter the carbs? You may need to do more. Also, check the float heights  - they may be set a touch low. I always recommend upgrading to solid brass seats available from Mercury vs. the old neoprene inserts.

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Re: Cold Starting A Mark 78E

Postby EdMc » Thu Aug 22, 2019 8:40 pm

The typical drill for cold-starting old Mercs is to squeeze the primer bulb until it's hard, then give it a few more squeezes.  This should overpower the float needle and "prime" the carbs.

Then, full choke, fast idle (in your case, as much throttle as you can get before the safety switch kicks in), full choke until she kicks, then as necessary until she runs smoothly.

Years ago I had a 700E Dockbuster on a small runabout.  I set up the distributor so the points dwell was perfect.  Got the idle mixture just right,  Cold or hot, she'd start right up with turn of the key.  I only paid $25 for the motor, and it was well-spent!  We skied a whole summer on the cheap with that rig.

If the idle mixture needles are a bit on the lean side, that'll make it hard to start.  The thing to do is get it tweaked in the water, warmed-up and in gear.  Do one carb at a time;  adjust the idle needle to find the extreme lean (clockwise) and extreme rich (CCW) idle.  It's nice to lean 'em out so they run nice 'n clean, but when you do that it's too lean for cold starts.  

The thing to do is set the needle maybe 1/8 turn lean (CW) from the extreme rich position. After getting all (3) carbs adjusted, do a hole shot and if it takes off cleanly, all's good.  If it bogs, you're too lean.  Move each idle adjust screw another 1/8 turn lean and repeat.  

Hopefully all the tips in this thread will get 'er running sweet for ya.  HTH & G'luck........ed
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Re: Cold Starting A Mark 78E

Postby dannynagasaki » Fri Aug 23, 2019 1:14 am

Thanks Chuck and Ed...Yes with all of that I can tinker till the cows come home, great food for thought. Many great suggestions and Ed we can all appreciate your summer time 700E story!  :arrow:
55' Mark 25, 55' Mark 55E, 58' Mark 10, 58' Mark 35, 58' Mark 78E (2) 62' Merc 60, 62' Merc 450, 67' Humber Jewel, 74' Grew SS140, Oak Ridges, ON (winter), Wahsoune Island, Georgian Bay, ON (summer) Canada
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Re: Cold Starting A Mark 78E

Postby Alex from GA » Fri Aug 23, 2019 9:17 pm

On my '74 850 without a choke I squeezed the bulb until hard then 3 more hard squeezes, set the idle up and turned the key.  In 50* or 90* it started immediately.  I did this for 10 years several times a week.
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Re: Cold Starting A Mark 78E

Postby EdMc » Fri Aug 23, 2019 9:58 pm

dannynagasaki wrote:Thanks Chuck and Ed...Yes with all of that I can tinker till the cows come home, great food for thought. Many great suggestions and Ed we can all appreciate your summer time 700E story!  :arrow:


Yeah, those were the days, when we could go boating very cheaply.  I had the 700E on a 13-1/2' Sea King runabout and it would do a solid 35mph and deep-water-start a slalom skier like Gangbusters.

I still recall the time when my good skiing buddy wanted to do a step-start on one ski, from the beach.  There were a bunch of guys at the launch laughing at our old rig.  Well, he took a lot of coils of ski rope, yelled "Hit It!", I hit the key and we launched like a rocket ship.  

I think all their mouths were agape when he flew off the beach and later on he said, "I had too many coils, it took off so fast my head was swimming".  Those guys never laughed at us again!    8-)
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Re: Cold Starting A Mark 78E

Postby dannynagasaki » Mon Aug 26, 2019 4:13 pm

Hey Ed, I know your 700E would have been running at absolute peak performance and as for the guys at the launch, welcome to an intro of "THE TOWER OF POWER"  [drinkingbeer.gif]
55' Mark 25, 55' Mark 55E, 58' Mark 10, 58' Mark 35, 58' Mark 78E (2) 62' Merc 60, 62' Merc 450, 67' Humber Jewel, 74' Grew SS140, Oak Ridges, ON (winter), Wahsoune Island, Georgian Bay, ON (summer) Canada
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Re: Cold Starting A Mark 78E

Postby EdMc » Tue Aug 27, 2019 2:01 am

dannynagasaki wrote:Hey Ed, I know your 700E would have been running at absolute peak performance and as for the guys at the launch, welcome to an intro of "THE TOWER OF POWER"  [drinkingbeer.gif]



[drinkingbeer.gif]  [drinkingbeer.gif]  icon_thumbup.gif  [wrench.gif]  :arrow:
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