1993 Force 70

brillfamily

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Joined
Sep 11, 2014
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3
I recently traded to get a 93 bayliner with a force 70 hanging off the back. Was told it ran but due to sitting for a while he assumed the carb would be clogged up. For the deal i was getting on it i figured i'll clean it out and give it a shot. The next weekend i got myself a barrel and ran it in the back yard. Fired right up, seemed kinda loud but being my first boat and outboard i just figured it was nature. Took it out on the lake the weekend after and seemed ok but didn't want to go anywhere, my father in law came out and was like well your prop should be like 3 times the size it is, thats why it doesn't want to go. Took it out a few times fishing after (since speed wouldn't be an issue). Last weekend i put a new prop on it, took it out to see how fast i could get her and when i opened up to full throttle she jumped and then bogged down. Any ideas on what it might be. I'm pretty good with cars so i'm assuming it's a fuel issue (same reason she is kinda hard to start without giving her a little gas at first) but being new to this type of motor just thought i'd get some field opinions. I'm gunna try and tinker with it this weekend in the barrel, finally found a new fuel filter for it so gunna try that to. Any other ideas would be great and maybe how to adjust the high end throttle since i have only found an idle adjust as of yet. Thank you Shawn
 
Last edited:

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
The 70's take on a wide selection of props from a tiny 10" up to around 12" depending on the pitch. The higher the pitch the smaller is the diameter of the prop. For example a 15" pitch can come as small as 10.25" depending on the manufacturer while the 10" pitch can be as large as 12". If the new prop is within this range, maybe you need to do some checking on the following:

- using an inline spark tester check for sparks on each cylinder
- Check compression and all should be within 10% of each other with a range in the 90's up to about 150 PSI
- Check the position of the carb throttle at WOT, it should be at full horizontal, no more , no less. There is a "link and synch" sticky thread on top of this forum. Do that and you should have the carb and control in synch properly.
- Verify timing using a timing light (inductive ones used in auto shops) with static timing procedures. There is a video on this also on top of the forum

After all of the above, install a clear fuel filter between the fuel pump outlet and the carb inlet. Do a test run again. The clear fuel filter should stay at least 3/4 full at all times. if it doesn't, then you have fuel delivery problem (leaky fuel hoses, restricted pick up tube or tank vent, faulty fuel pump, faulty check valves on primer bulb, etc.). If it does, then you have misfiring, carburetion problem or reed problem.
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,657
Welcome to iboats.

Assuming the engine is a 1993 model as well?

Mercury Force serial number ranges 1991 - 1999

OE000001 - OE065371 1991-1993

OE065372 - OE093699 1994

OE093700 - OE138599 1995

OE138600 - OE202999 1996

OE203000 - OE287999 1997

OE288000 - OE344999 1998

OE345000 - OE369299 1999


As far as being hard starting, needing extra gas to start, this is normal.

Follow this starting procedure.



There is no conventional choke on that motor.
There is a fuel enrichment valve, that releases fuel directly into the intake manifold.

Open fuel tank vent

Check the kill switch, place in "run" position

Squeeze fuel primer bulb till firm.

Advance the throttle 3/4 way or more, without putting it in gear. -- This is done by either pushing a button in the center of the controls, or pulling the shift handle toward the driver, or raising the fast idle lever, all depending on what control unit you have.

Turn the key to the on/run position.

Activate the choke (fuel enrichment valve) by pushing in on the key. The valve is only open while the key is being pushed in.

Turn the key to start while continuing to hold the key in.

Release the key and choke when it starts.

3-5 seconds of "choke", is usually enough.

Be ready to pull the throttle back toward the idle/neutral position, when the engine starts and the revs increase.

Continue to pull the throttle back as the engine warms up.

You should not have to use the choke much, if at all, once the engine has warmed up.

Engine should start within 10 seconds of turning the key.
 

brillfamily

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Joined
Sep 11, 2014
Messages
3
Thank you guys for the quick responses. The motor is also a 93 and it is nice to know that having to open the throttle up to start smooth is normal. When i first got it the motor was half messed with. Like somebody thought they could do something, got half through it and realized they had no idea or just left it. The plugs weren't installed, but were just laying in there. So i put them in, they looked brand new. I rehooked up the wires in the order that they seemed to reach in length. Put a timing light on each and like i said it fired right up and seemed ok. So i'm assuming the wire order is correct. I plan to barrel run it this weekend so i'll post some pictures of it and the things i do and the reactions i get from the motor.
 

brillfamily

Recruit
Joined
Sep 11, 2014
Messages
3
Ohhh and the prop. The one that is on there now is 11 1/4 inch at 13 pitch. The one that was on there was 10 3/8th inch at a 15 pitch but it was down to nubs (so only messured about 5 inch), like they had ran it in a rock bed
 
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