First time boat owner, motor has a few issues, Please Help!

[joshackley]

First time boat owner, as the title says. Been around boats in and out, can operate them, but know next to nothing about maintenance, care, wiring, or the motor. I am having trouble locating the correct manuals. The motor is a 1991 Force 70 HP, model 708F91C. So if someone could direct me to the correct manuals I need for this motor, that would be a great help.

It has not been run since last summer, and I suspect was not winterized. Prior owners have replaced the built in fuel tank with a portable tank. The motor does start with a little bit of work, will idle, and will (with limited throttle) run in the water. The motor runs okay in neutral and in idle, although it doesn't seem to be running like I think it should. Forward and reverse gears work and are not hard changes. Prior owner says the carb and water pump were done last summer.

Issues I have with the boat.
1. The tach does not work.
2. Motor bogs down and starts to quickly die at somewhere between 1/2 and full throttle. If you quickly put it into neutral it will idle and will not die. If you do not, it will die.
3. Throttle in forward has to be pushed from vertical to almost horizontal before any increase in RPM's.

The prior owner gave me some gaskets for the carb. But I really have no idea where to start, what to do, how to do it, etc, so all help would be greatly appreciated. Also, I've read about flush valves, ear muffs, and using a trash can to test at home. Can someone provide some insight for this motor?

Thanks in advance. I hope I've provided enough information for you to help me.

 

[JB]

Re: First time boat owner, motor has a few issues, Please Help!

Hi, Josh.

Welcome to iboats.

Your story is too big. People won't read it. Make it short and to the point.

Check this out: http://forums.iboats.com/force-chrysler-outboards/how-get-best-results-your-question-250874.html

 

[pnwboat]

Re: First time boat owner, motor has a few issues, Please Help!

Sounds like you have a few issues here. Probably should start with the basics first. Like you mentioned, check compression, fuel pump diaphragm, etc. first. If you have any questions on those specific items, then we can address them one by one. Let us know and good luck!

 

[roscoe]

Re: First time boat owner, motor has a few issues, Please Help!

Welcome to iboats.

You want a manual by Clymer, or the factory tech manual from Mercury, which can be found on ebay.

The Clymer Force repair manual will cover 2 cycle motor general info, as well as troubleshooting and repairs.

Force Outboard Repair Manual 4-150 HP incl. L-Drives 1984-1999

Yes, first check for good spark, and compression.

Sounds like fuel pump is not keeping the carb bowl full.

Could be a weak fuel pump diaphragm, which is cheap and easy, and likely due for a change anyways.
Or the carb float is hanging up and not opening the needle valve.
Another possibility is that the fuel line is sucking in air.

THis link will be of help to you.

70 H.P. - Mercury, Mercruiser, Force, etc. Parts Lookup

1991 was an odd year for those motors. Many components were changed mid year, which is why there were so many models available.



The parts listing shows different carbs, fuel pumps, ignition systems, tilt n trim pumps, depending on the model.

THe tach signal comes from a gray wire coming out of the voltage rectifier.
It may continue on as gray, or may be purple, by the time it gets to the tach.


THere is no conventional choke on that motor.
It has an enrichment valve, or primer.
When you push in the key, it opens the valve and uses fuel pressure to dump fuel into the manifold behind the carb.
The valve is only open while the key is being held in.


Below is the starting procedure for that motor:



Open fuel tank vent

Check the kill switch, place in "run" position

Squeeze fuel primer bulb till firm.

Advance the throttle 3/4 way, 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.


Keep us posted on how you are getting along.

 

[joshackley]

Re: First time boat owner, motor has a few issues, Please Help!

Hi, Josh.

Welcome to iboats.

Your story is too big. People won't read it. Make it short and to the point.

Check this out: http://forums.iboats.com/force-chrysler-outboards/how-get-best-results-your-question-250874.html

Thank you for your welcome. After looking at many different forums, I liked the way that everyone here has been helpful instead of offering useless information (like your motor is junk, just trash it, etc.) I've shortened my post. Please let me know if I should condense it more.

Sounds like you have a few issues here. Probably should start with the basics first. Like you mentioned, check compression, fuel pump diaphragm, etc. first. If you have any questions on those specific items, then we can address them one by one. Let us know and good luck!

I've never checked compression or have the tools to do it. What do I need? I have seen a couple different threads here and there on how to do it, so I think I can follow them if I have the proper tools.

To be honest, I'm not sure what the fuel pump looks like. I would assume that it would be the unit connected to the incoming fuel line. I'm not sure where to find parts either. I'll try calling some dealers around this area. There is a pretty big network of dealers since I'm so close to the Gulf, and there are many rivers and lakes.

I assume I need to start with the compression check first, then check the fuel diaphragm. I'd also like to replace the spark plugs, but I'm not sure what plugs I need.

 

[joshackley]

Re: First time boat owner, motor has a few issues, Please Help!

Welcome to iboats.

You want a manual by Clymer, or the factory tech manual from Mercury, which can be found on ebay.

The Clymer Force repair manual will cover 2 cycle motor general info, as well as troubleshooting and repairs.

Force Outboard Repair Manual 4-150 HP incl. L-Drives 1984-1999

Yes, first check for good spark, and compression.

Sounds like fuel pump is not keeping the carb bowl full.

Could be a weak fuel pump diaphragm, which is cheap and easy, and likely due for a change anyways.
Or the carb float is hanging up and not opening the needle valve.
Another possibility is that the fuel line is sucking in air.

THis link will be of help to you.

70 H.P. - Mercury, Mercruiser, Force, etc. Parts Lookup

1991 was an odd year for those motors. Many components were changed mid year, which is why there were so many models available.



The parts listing shows different carbs, fuel pumps, ignition systems, tilt n trim pumps, depending on the model.

THe tach signal comes from a gray wire coming out of the voltage rectifier.
It may continue on as gray, or may be purple, by the time it gets to the tach.


THere is no conventional choke on that motor.
It has an enrichment valve, or primer.
When you push in the key, it opens the valve and uses fuel pressure to dump fuel into the manifold behind the carb.
The valve is only open while the key is being held in.


Below is the starting procedure for that motor:



Open fuel tank vent

Check the kill switch, place in "run" position

Squeeze fuel primer bulb till firm.

Advance the throttle 3/4 way, 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.


Keep us posted on how you are getting along.

Which is better to have, they Clymer, or factory tech manual? I?m thinking it wouldn?t be a bad idea to go ahead and purchase both of them. I found this factory manual on ebay:
Manual on Ebay

Is this the right manual? There are a couple different versions. Some say 1991, 1991-1995 and 1991J-1995.

Will check for compression as soon as I figure out what I need to buy/borrow. Will purchase tomorrow when I get off if I figure it out by then.

How do I check spark?

I?m also going to empty existing fuel tank, and put new clean mix in. What oil do I need to mix with the gas, and what octane rating do I need to use?

Will start looking for right fuel pump diaphragm. Not going to hurt to get a new one anyway.

I have some gaskets the previous owner gave me for the carb, still in sealed plastic.

I will also check the hoses to make sure all the fittings from the portable gas tank to the motor are tight.

I don?t know what the voltage rectifier looks like, to try to find the gray wire for the tach.

There is some kind of button at the base of the throttle lever, I was thinking that this was what allowed you to throttle up without engaging a gear. Pretty simple control unit, has the kill switch, ignition switch, a little tab that you can turn, trim up/down, gear lock (on the handle, press to be able to put into gear), and the button at the base of the throttle lever.

Can I start it using this procedure in my backyard with a hose connected to the flush valve? Or am I better off getting a big trash can and filling it with water or trying to find a pair of those muff things?

Joshua

 

[roscoe]

Re: First time boat owner, motor has a few issues, Please Help!

That appears to be the correct factory manual.
It should cover all 1991 models. Really good price too.

Factory manual is more technical, and helpful. But it assumes you know the basics.

The Clymer manual explains things for the first timer. More step by step, and explains how everything works.
Yes, good to have both.

Compression check just requires a compression gauge. A $25-$30 gauge will work, no need to spend $100 on one.

You remove all the plugs and ground them so as not to damage the ignition system.
Or you can just flip the kill switch on the controls.

Push the throttle to full to open the carb.
Screw the gauge into the head.
Crank it over 4 times, record reading, go to the next hole.

If all is good, you should get 130-140# readings on that motor.
ANything over 115 is good.
Over 100 is still acceptable.

Spark:
Remove one plug at a time and use an inline spark checker.
Or hold the plug with an insulating pliers, about 1/2" from the head, and have someone crank the engine a few times, look for a bright blue spark.

Fuel:
Any octane rating is good.
Manual says 87 or higher.
Use ethanol free if possible.

Oil:
tcw3 rated oil.
(for two cycle water cooled engines.)
Any one you like, petrol based, synthetic blend, full synthetic, as long as it says tcw3 rated on the label.

50:1 ratio.
You mix 2.6 ounces of oil per gallon of gas.
or 16 ounces per 6 gallons of gas.
Don't add extra.

Also check all fuel lines connected to the carb.
These will sometimes suck air.


Follow the links on this page:

70 H.P. - Mercury, Mercruiser, Force, etc. Parts Lookup


Those are the Factory parts diagrams, and will familiarize you with the parts in question.

Fuel pump is where the fuel line from the tank is connected.
According to the diagrams, your model will have the older 2 stage pump, kind of oval.
THe newer Mercury pump is about 2.5" square.

Voltage rectifier will be a 1.5" square block, 4 wires connected, 2 yellow, 1 red, 1 gray.

Flush valve fitting - NO.
That can be used to flush the salt out of the engine, but not while it is running.

You need to have water going through the water pump while the engine is running, or you will burn up the water pump impeller.

The water pumps on these motors don't prime very well, so you would be better off using a barrel or tank.
And the water muffs don't fit the lower unit very well. Yeah, use a barrel, tub, or cattle tank.


Later.

 

[jerryjerry05]

Re: First time boat owner, motor has a few issues, Please Help!

That's the manual! The clymer is ok too.
It has a bunch of different motors and is a good general book.
The 70 is a simple motor.One carb and easy to work on.
The carb: setting the air screw, one turn out for inital setting.
Then after it's running then fine tuning is suggested.
The fuel: clean tank,add a 8oz of oil then 3 gal of gas.
That will start the mixing off right.
If you just dump all the oil in it can get up in the pickup tube and not run right.
Putting in gas first, possibly the only thing picked up is straight gas and damage can be done.
I put in 1 pint and 6 gal then as I add more I increase the amounts.
The poor idle:could be low compression,the choke/enricher diaphram bad,weak spark?
DEEP is a barrel.Needs to be 5 inches over the cavitation plate.

Most auto parts stores or chains will loan a comp tester,But your gonna need on so get one,a good one.
Cheap tools get cheap results.
The comp should /could,would? The results will vary from tester to tester and mechanic to mechanic.
What your looking for is the results to be even,within 5 # of each other.
My guage, akit from MAC tools.$100 I know it's right.A cheapo might not give the best results.
Spark testers,again buy good ones.The 3-4$ ones work great in dark garage or at nite.

 

[JB]

Re: First time boat owner, motor has a few issues, Please Help!

Thank you for your welcome. After looking at many different forums, I liked the way that everyone here has been helpful instead of offering useless information (like your motor is junk, just trash it, etc.) I've shortened my post. Please let me know if I should condense it more.

Much better, Josh. You are now getting excellent, helpful responses.

 

[joshackley]

Re: First time boat owner, motor has a few issues, Please Help!

Ordered both manuals this morning. A couple more questions. Also, want to change the oil, this is done on the lower unit only? What oil do i use for this? I know some of these questions will be answered when i get the manuals, but they may not be here for 1-2 weeks. Going order diaphragm and a few other gaskets for the fuel assembly.

Kill switch. I don't think this is a toggle like switch so much on my control unit, but a little button that is pushed out by a plastic piece on a curly elastic piece attached to my key, right? So if i do not put the plastic piece in, that is the same as switching it off?

What spark plugs do i need? Will Oreillys carry them?

Do i need some kind of compound on any of these gaskets, diaphragm, bolts, etc.?

 

[Frank Acampora]

Re: First time boat owner, motor has a few issues, Please Help!

Yes, that is the kill switch and the curly thing is the lanyard. You put the clip onto the kill switch and this pulls out the button. If you want (its a good practice anyway) you attach the lanyard to you. If for some reason you go overboard while running, the engine stops.

Because of the design of the throttle linkage, it is common for the control handle to move quite a bit before the engine starts to rev. This allows shifting into gear before the engine speeds up. However, If the throttle cam is not correctly set, this movement can be excessive..

As with all Force engines, when at idle, the throttle advance cam should contact the carb roller somewhere close to the scribed line on the cam. Again, the important setting is: With the throttle at wide open, the butterfly inside the carb should be horizontal or nearly so.

 

[joshackley]

Re: First time boat owner, motor has a few issues, Please Help!

I just want to say a huge thank you to all of you for your help and suggestions. Without your guidance i would be at a complete loss and end up taking it to have someone service it, instead of being able to learn about it and be able to work on it myself, which i prefer. So thank you all very much! I am extremely grateful.

Thought so about the kill switch, but wanted to make sure I was on the same page.

Is the throttle cam difficult to adjust? I'll have to pull up a diagram to see what you are talking about with the cam contacting the carb roller. I know that when i put it into reverse, it doesn't take much movement before the RPMs start increasing.

Ill add checking the butterfly inside the carb to my list of things to check. I'm at work, and it's been raining all morning, so not sure yet if they are going to send me home for the day. if not, I'll probably have some time this evening to check a few things.

Found a local dealer who carries parts for my motor, including the diaphragm,stock. Going to try to get there today and pick it up. Anything else i might need to go ahead and get while I'm there?

Found this: http://www.harborfreight.com/compression-test-kit-66216.html. This is what i need to do the compression test correct?

 

[roscoe]

Re: First time boat owner, motor has a few issues, Please Help!

DO NOT remove the gear shift pivot screw from the lower unit. If you do not know which screw that is, don't remove any. Wait for the manual to arrive. Remove the wrong screw and you are screwed.



Yes, when plastic clip is removed, and the button retracts, the kill switch is activated, grounding out the ignition.

 

[joshackley]

Re: First time boat owner, motor has a few issues, Please Help!

Thanks for the advice. I'll wait for the manual.

Going to get most of the stuff i need in about an hour and a half, especially the diaphragm, fuel filter, and spark plugs.

Do i need some kind of compound when i replace the diaphragm? Like a sealant or silicon?

Got the diaphragm, fuel filter and spark plugs, as well as spark tester, compression tester, and a 55 gallon drum that I'm going to have to cut the lid off. About to eat dinner, then to get fresh gas, and out back to do some tests. Will post my results as soon as i have them.

 

[roscoe]

Re: First time boat owner, motor has a few issues, Please Help!

Thanks for the advice. I'll wait for the manual.

Going to get most of the stuff i need in about an hour and a half, especially the diaphragm, fuel filter, and spark plugs.

Do i need some kind of compound when i replace the diaphragm? Like a sealant or silicon?

No, goes together with no sealants.

 

[joshackley]

Re: First time boat owner, motor has a few issues, Please Help!

Didn't get to the tests. By the time I had a chance to get out there, it was too late to crank it. I'm sure the neighbors would not appreciate me cranking the motor at 10pm, haha. Replaced the diaphragm. Definitely needed to be replaced. Couple of rips, a few holes, had a little difficulty getting it to sit right with the spring pushing against it, but got it seated properly and reinstalled. Shot the parts with a little carb cleaner to clean them up, including the little screen filter. Checked the fuel hoses from the tank to the fuel pump, good. Also checked the hoses in/out/around the carb, good. Butterfly in the carb goes horizontal when the throttle is wide open, in both reverse and forward. The mark on the cam lines up as far as I can see in idle. Adjust the screw with the spring on the carb, which I am pretty sure is the idle screw. Screwed it in until it was snug, but not too tight, and backed it off one full turn. Pulled all the spark plugs, shot a little carb cleaner in the hole, on the plugs, and in the plug wires. Have spark plugs to replace them with already, as they are cracked, pieces of ceramic broken off. Cut the top off of my 55 gallon barrel, got it under the motor, and full of water. Should have plenty of coverage.

I plan on spraying the rest of my carb cleaner, it's Quicksilver Power Tune I believe, into the engine tomorrow while it's running. From what I understand, there's a little plastic screw on top of the carb, and I spray into that? I understand from other research that this can cause the spark plugs to foul if there's excessive build up. So I'm going to wait until I'm done with that to put the new plugs in. While the plugs are out, I'll go ahead and do the compression test. After the compression test, I'll install the spark plugs, and do the spark test. I also have an inline fuel filter to replace. Found the tachometer wire, it's grey from the rectifier until it hits some terminal, then goes to purple in a bundle of wires that runs to the console. Not a priority until I get the motor running better. Will fix it before I take it out to the river so that I have some numbers to report back with.

Included are pictures of the old diaphragm.

 

[jerryjerry05]

Re: First time boat owner, motor has a few issues, Please Help!

A little bit of duct tape and you've got a good spare
Do the comp test before you Powertune.
Power Tune. Motor warm,spray in till it starts smoking GOOD.
Spray it into the mouth of the carb.
You might have to raise the rpms.
Shut it down and remove the plugs.Spray in the plug holes.
Let it set overnight or even a couple of days.
Power tune is a carbon remover.

 

[foodfisher]

Re: First time boat owner, motor has a few issues, Please Help!

The internal fuel tank may have leaks, being the reason for the portable one. Caution is advised and the old smell test. Smell fumes, don't ignite.

 

[joshackley]

Re: First time boat owner, motor has a few issues, Please Help!

Compression came out at 90/95, 100, 100 from top to bottom. Can't get it started today, ran the battery down. Headed to get a battery charger. Fresh gas/oil, new spark plugs, new diaphragm. Haven't done the spark test yet, can't get the tester to stay in the spark plug wire.

 

[joshackley]

Re: First time boat owner, motor has a few issues, Please Help!

Got back, charged the battery up to 95%, primed it real good, and finally got it started. Took it a litte bit, but got running pretty good, sounds good and smooth idling, figured out hit to throttle up in neutral, revs up good. After she warmed up, started right back up in seconds, no hesitation. Sprayed the bottle of power tune in mouth of carb, filled the neighborhood with smoke, haha. Let it run at idle for about 30 minutes, she's still smoking a bit, but not excessively. Noticed oil in the barrel I've got her in after i shut her off. Is this normal? Heading to the river in a little while to see what happens on the water.

Pulled the panels where the switches are for the bilge, nav/anchor lights, and horn as well as the panel that houses the tach and fuel gauge. Tach had two wires plugged into a light bulb, and a hose that runs out of the transom and connects to a plastic piece on the edge of the bottom. Tested the lights in gauges by unplugging leads and touching to battery. Nothing works, although i was testing with motor off.