Merc 700 '78 starting

[dkhuntr]

I recently got a Merc 700. The guy i bought it from met me at the lake, he started it up after a couple seconds turning over the engine and we went for a ride. It idles great, accelerates great, reverse is good, etc. It looks to be well taken care of. A little dirt buildup around the bottom outside of the case, but the engine looks clean.
I go a week later to use the boat and find myself just turining over the engine. It has a high idle lever and a choke on the throttle. He told me to raise the high idle and press the choke to start. So i do this in any combination i can of raising it, lowering it, pressing the choke once, holding the choke, pressing the choke fast, etc. Finally after 10-15 minutes of trying i get the thing to start. As soon as the engine caught, it ran perfect, never sputtered once, no troubles.
We ran it for a little while and shut of off. Let it sit for a minute and tried to start it back up, fired up instantanously.
Let it sit overnight, started early the next morning after about a minute of turning over and various combinations of choke/high idle. Ran great, drove about 2 miles with no trouble. Shut it off and hunted for about 4 hours. Went to restart it and could not get it to start. I crakned for 20 minutes before getting towed in by my hunting buddy...(yay for the maiden trip).
So we get it home, i pulled off the cover, pulled the spark plugs (3 cylinder) and sprayed a little starting fluid behind them. I went to crank and it started again without a hitch, no hesitation, no sputter.

So whats the problem?
Initially I was thinking the choke is not engaging, and high throttle not working. But when the engine is running and i push high throttle that works, and if its idling and i push the clutch it bogs down for a second telling me its putting gas into the engine.
I cannot figure this out? I dont want to have to use starting fluid every time i want to drive it (especially when the fingers dont work at 0 degrees F on a nice duck hunting morning in Wisconsin.

edited- typed clutch instead of choke, oops

 

[CharlieB]

Re: Merc 700 '78 starting

The 'older' Merc really liked the choke. Full fast idle lever and choke it till it fires. Once stared they start fine the rest of the day, but tomorrow, full choke again.

We suspect it was the design of the crank seals, the fuel has to get into them, fully wetted in order to seal. They dry out over night so back to that choke again in the morning.

 

[dkhuntr]

Re: Merc 700 '78 starting

So when I am choking, do i just press the choke button it and hold it, or repeatedly press it? I am not sure exactly which method is right.

(and thanks, i will see if that fixes it the next couple of times i take it out)

 

[GA_Boater]

Re: Merc 700 '78 starting

For cold starts, I pump the bulb til hard, lift the warm-up lever about straight up, hold the choke button and crank. As soon as the motor starts to fire, I release the choke and it starts in about a second. Warm starts, I just crank her. If it doesn't start quickly I raise the warm-up some, about 2 o'clock, crank it. Sometimes hold the choke button down til it putts and release.

Every motor seems to start differently. You just have to find the sweet method for yours.

BTW - Clutch? You don't have one. And welcome to iboats, dkhuntr.

 

[schematic]

Re: Merc 700 '78 starting

I recently got a Merc 700. The guy i bought it from met me at the lake, he started it up after a couple seconds turning over the engine and we went for a ride. It idles great, accelerates great, reverse is good, etc. It looks to be well taken care of. A little dirt buildup around the bottom outside of the case, but the engine looks clean.
I go a week later to use the boat and find myself just turining over the engine. It has a high idle lever and a choke on the throttle. He told me to raise the high idle and press the choke to start. So i do this in any combination i can of raising it, lowering it, pressing the choke once, holding the choke, pressing the choke fast, etc. Finally after 10-15 minutes of trying i get the thing to start. As soon as the engine caught, it ran perfect, never sputtered once, no troubles.
We ran it for a little while and shut of off. Let it sit for a minute and tried to start it back up, fired up instantanously.
Let it sit overnight, started early the next morning after about a minute of turning over and various combinations of choke/high idle. Ran great, drove about 2 miles with no trouble. Shut it off and hunted for about 4 hours. Went to restart it and could not get it to start. I crakned for 20 minutes before getting towed in by my hunting buddy...(yay for the maiden trip).
So we get it home, i pulled off the cover, pulled the spark plugs (3 cylinder) and sprayed a little starting fluid behind them. I went to crank and it started again without a hitch, no hesitation, no sputter.

So whats the problem?
Initially I was thinking the choke is not engaging, and high throttle not working. But when the engine is running and i push high throttle that works, and if its idling and i push the clutch it bogs down for a second telling me its putting gas into the engine.
I cannot figure this out? I dont want to have to use starting fluid every time i want to drive it (especially when the fingers dont work at 0 degrees F on a nice duck hunting morning in Wisconsin.

edited- typed clutch instead of choke, oops

Check for spark next time it leaves you stranded.....

 

[dkhuntr]

Re: Merc 700 '78 starting

For cold starts, I pump the bulb til hard, lift the warm-up lever about straight up, hold the choke button and crank. As soon as the motor starts to fire, I release the choke and it starts in about a second. Warm starts, I just crank her. If it doesn't start quickly I raise the warm-up some, about 2 o'clock, crank it. Sometimes hold the choke button down til it putts and release.

Every motor seems to start differently. You just have to find the sweet method for yours.

BTW - Clutch? You don't have one. And welcome to iboats, dkhuntr.

Thanks! I edited that orig post to avoid any future user confusion. appreciate the advice!

 

[dkhuntr]

Re: Merc 700 '78 starting

Check for spark next time it leaves you stranded.....

how do i do that? sorry maybe thats a silly question, im not extremely mechanically inclined, although i have enjoyed learning.

 

[quicktach]

Re: Merc 700 '78 starting

Best not to use starting fluid on that motor!

 

[dkhuntr]

Re: Merc 700 '78 starting

What is the reason for not using starting fluid?

 

[GA_Boater]

Re: Merc 700 '78 starting

Washes the oil off the cylinders and the 2 stoke motor starts dry leading to broken rings and wear.

 

[dkhuntr]

Re: Merc 700 '78 starting

Alright, so I have tried giving it as much choke and high idle as I can, but the thing thing still doesnt want to start. As I have previously stated, once running the thing starts back up with no hesitation. Is the choke not working? (When I have a friend press the choke I can see the parts moving in the engine that would indicate (to me) that it should be working?
Another thought, When i squeeze the bulb it gets hard, but it leaks some gas around the seal. I am sure its a long shot but could that have anything to do with it? Should I replace the hose?
The spark plugs look brand new, but I guess it would make sense to replace those too.
Anyone have any other ideas before I spend $$$$ to have it checked out in a shop?

 

[CharlieB]

Re: Merc 700 '78 starting

Definitely change that leaking primer, hoses also if they are showing any signs of aging. Any fuel leak while under pressure will also allow air to suck in while the motor is running and the fuel pump pulls a vacuum on that hose. Since air is lighter than fuel, the fuel sucks a LOT of air in, so much that it cannot keep the carbs full at WOT. Cyl's will burn lean and melt a piston.

Cranking speed has an effect on starting, slow cranking takes a lot longer to start. Make sure all cable connections are clean, bright, and tight. Both ends, and the starter cable. Sand every one. Toss those wing-nuts that came with the battery and use stainless nuts and a wrench, not so tight as to tear the bolt out of the battery, but tight enough the cable cannot wiggle, any.

Disassemble the starter, lightly sand the commutator until it is clean and smooth. A drill press works great to turn it. Lightly lube the bushings.

Push and hold the Choke, you should see and hear the solenoid snap and the choke shutters move. Hold the Choke in as you hit the starter. Some motors the starter motor current draw is so great that if the choke isn't held first it may not pull in if the starter is turning first.