Losing Patience with Force by Mercury 75 HP

Joined
Apr 17, 2016
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I purchased a 1996 Bayliner 1600 with a 75 HP Mercury Force. The first time I took the boat out it would not even get on plane. We changed the spark plugs. Replaced plug wires and cleaned the carb and checked reeds. Also found the throttle cables were not allowing it to go WOT. Adjusted the cables took out for another outing. Tach did not. This time every time you put in gear it died. Could not get it to idle. Mercury dealer recommended me replacing fuel pump. Also said I needed a regulator rectifer for tach. Replaced Fuel Pump & Regulator Rectifer. Also went ahead and replaced external fuel lines and priming bulb. The engine started and idled in neutral. It also stopped dying when put into gear.The tach worked fine. This past Monday I took it out and it did ok. I thought my problems were over so I brought my wife and daughter yesterday. Boat started fine and idled fine. Going up the lake the tach dropped to 0 and stopped working. We went into a no wake zone to fish. After we ate lunch and fished we came out of the no wake zone at idle. I then increased the throttle and it immediately stumbled and died. It started right back up. I tried again and it died. After 5-6 times of that it began not wanting to start. If I put in N it would rev up fine. I went back and felt that priming bulb it was soft. I pumped it up and it started again. I ended up having my wife to keep pumping the priming bulb to keep it running. The boat would not run more than 12 MPH and would not plane. We made it back to the marina safelly thank goodness! Any ideas? I cant keep dumping hundreds of dollars in this engine if its not going to run correctly.
 
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jerryjerry05

Supreme Mariner
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May 7, 2008
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You sure the pump was installed right?
​The wife trick usually means the pump is faulty????



First do a compression and spark test. Post results.



Then check the fuel pump.

A bent plastic washer in the pump can do that.

When you post.
Don't run all your sentences in one long line.
Break it down.

It's really hard to read and follow what you said.
 
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Joined
Apr 17, 2016
Messages
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Jerry,

You must be reading on I-Phone. Sorry I'm using a lap top I was
just typing till the line was full.

I'm not a mechanic myself. I'm trying to get some information to point the dealer in the right direction.
I live in a small town in WV I'm limited on Marine Mechanics.
I had a relationship with this dealer from previous boats.
I have never had any trouble with their work.
Nobody in the shop really seemed that thrilled to work on a Force engine.
Also it doesnt seem like they know
alot about the Force engines.
When I called them on Saturday to tell them what happened
the service manager said
"You see why we tried to sell you a used Johnson for your boat"

15 yr Mercury certified technician installed the fuel pump.
I assume he knew what he was doing.
They had to order a new pump from Mercury they didnt have one on the shelf.

Dealer did compression check on the boat in March.
All 3 cylinders were over 130
They said that was acceptable for its age. Is that true?

I suppose its possible to have dropped a cylinder since then but I have ran the boat less
than 5 hours since the test.

Is it true that the wrong fuel mixture can cause this condition? It still has gas in it from
the previous owner.

Could it be old gas causing this problem?
 
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flyingscott

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Apr 8, 2014
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Try a different tank with fresh gas if that doesn't fix it. TAKE it back to dealer /mechanic who fixed it if it was recent they should warranty their work and parts.
 

Jiggz

Captain
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Oct 23, 2009
Messages
3,817
Since pumping the priming bulb makes the motor go for at least 12 MPH, this is because pumping the priming bulb will not provide the needed amount of fuel to go faster. Do the following first. Even a non mechanic should be able to do this. Install a clear fuel filter between the fuel pump outlet and the carbs inlet. You can get one from big box stores for less than $5 and even comes with hose clamps. Fram G2 will suffice for this job. This is more of a troubleshooting tool than filtering fuel. Try to position the filter in a semi-vertical position with the inlet side lower than the outlet side.

Ran the boat on muffs on the driveway with cooling water provided. Watch the clear fuel filter to make sure it should stay at least half full. Also watch for bubbles. If you see bubbles you have air leak upstream of the fuel filter. Rev the motor a little bit slowly and smoothly to about 2K and you should see increase in the fuel delivery. If not either there is an obstruction at the suction hose or the fuel pump is not working properly.

To check for obstructions, the best tool is to get an external portable tank, fresh fuel oil mix and use a new fuel hose with new primer bulb. (Note, if you want to conserve on $$$, you can also just use the existing fuel hoses and priming bulb with the external tank with fresh fuel oil mix. However, this lengthens the troubleshooting required to isolate the problem.) If fuel delivery improves, try running the boat at the lake (with the portable tank and new hoses) and see if that solves all the fuel delivery problem. If the problem persists, then the fuel pump is the source of the problem.

If it works, while still at the lake, switch the new hoses and primer bulb with old one that connects to the in-tank. Meaning you will now use the new hoses and priming bulb with the old in-tank. If problem ceases, then you know the problem is the fuel hoses and/or the priming bulb. If problem persists, then you know the problem is in the in-tank either with a clogged pick up tube or sour fuel.

If you were able to resolve the problem from the preceding, the new external tank can be used as a spare fuel tank. I always have one to make sure if I ran out of gas out there I can at least get back home. To ensure the spare fuel doesn't sour, you want to use it once a month and replaced. Or use some fuel stabilizer and replace it once a season.

As for not being a mechanic, with this forum, technology and patience you will become one unless you have a lot of $$$ to throw away to a mechanic.
 
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jerryjerry05

Supreme Mariner
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May 7, 2008
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Old gas??
​When Ethanol first came out I found problems with hoses and seals in the connectors.
Now I'm finding water from the Ethanol is getting worse.
I've found that the fuel left in the hose/ squeezie deteriorates fast.

Maybe unhook the fuel line connector and try pumping some fuel into a glass jar.
Let it set for 10min and see what develops??

Compression: you motor should have the same compression as when it was new.
My motors both 88/85hp both have 145-150# on all 6 cyl.

The "acceptable for it's age" isn't right.
It shows it wasn't done right or done with a cheap or faulty gauge.

If it really is 130 on all 3 I'd say the good thing is the results are all the same or real close.
Usually anymore than 5# difference could mean a problem might develop?

The v-6 motors usually have lower comp.
The smaller 2/3/4 cyl need a higher reading.

I'd do another test.
 

lmuss53

Lieutenant Junior Grade
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Sep 9, 2008
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130 PSI is fine on that motor, 145 is better but 130 is fine. Get rid of that gas. Syphon it out and run it in a lawn mower. I would bet fresh gas is going to fix this problem.

I am cleaning the carb on one of these 70 hp 3 cylinder Force motors right now. I can find nothing wrong with anything in this fuel system, so I will insist that the owner take it to the lake with my 6 gallon tank, hose and fresh fuel for a lake test when I am done. If it runs well, which I'm confident it will. I will tell him to pump out his onboard tank and run that gas through a lawn mower. BTW, the first thing I did with this motor was a compresssion test, 125 psi in all three tubes, just fine by me.
 

jerryjerry05

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If the comp readings are all the same then it's good.
​The compression on that motor should be 145-150#.
That just shows the gauge isn't reading right if it reads 25# less.
Or the test wasn't done right?

The "acceptable for it's age" is BS.
 
Joined
Apr 17, 2016
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My Force Saga continues! After my last post my mechanic said I had a bad Coil.
I went ahead and replaced all 3 with brand new Mercury coils
​I purchased a new 6 gallon external fuel tank. I also purchased a new Mercury priming bulb and hose.
I installed the in-line fuel filter as was recommended. There are bubbles gathering in the fuel filter.
The new external fuel tank did originally on Wednesday made the boat run a top speed of 22 MPH. In May the boat was running 32 MPH.
Today the boat was back to running 12 MPH. I work for a Cat dealer. The guys pumped my internal tank and I added fuel additive and fresh fuel.
Is it possible to buy a new carb? Are there any Force mechanics that live near WV? I'm becoming very desperate to get this boat fixed. I cant use it, I cant sell it, I cant trade it and I haven't found anyone who can fix it.
 

flyingscott

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Apr 8, 2014
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Do a cylinder drop test get it idling and pull each spark plug off 1 at a time see if the idle changes. Use a plastic pliers or very thick glove when you pull the plugs off they will get you. Your motor sounds like it is on 2 cylinders or less. Get back with the results.
 

lmuss53

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There is a fuel reburn, recirculating circuit on these motors that the covers come loose on. Instead of going into the cylinder the fuel charge bleeds off under the cover into the atmosphere. It will usually make a mess under the hood, like a leak or bad float. You may find a stray bolt floating around and the motor is a lot noisier than it had been, the one that most often comes loose is the top one behind the CDI box.

If it is loose the gasket will be shot, you'll need to get a new one and rettighten the bolts, check all the other ones too. DO NOT overtighten these bolts, they break easily, or break the tabs on the cover off. I forget the torque setting, but before I had a small torque wrench, I'd put some blue lok-tite on them and make them real snug.

Your motor is behaving like one I saw last week with the top cover loose.
 
Joined
Apr 17, 2016
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Jerry, I have been reading some old forums looking for information.

You posted this "If you get no response from the air screws, it could be the motors sucking air someplace around the intake
.Does it spit back out the front of the carbs or leak fuel?Yes? The reeds might be bad??"

​I ran with cover off and the carb is spitting gas out the front. Does that mean I need reeds?

.
 

Nordin

Commander
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Jun 12, 2010
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Yes it sounds like you have broken reeds.
Common on these "late" engines.
 

jerryjerry05

Supreme Mariner
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Possible, remove the carbs and look inside.
​With a flash lite and tiny,tiny mirror.
Look at the reeds.
They can have a small gap.010 but no more.
Any obvious crack or missing pieces means a replacement is in order.
I might have some you can have. (i'll need to look)Just pay postage
 
Joined
Apr 17, 2016
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Well Folks need more advice. Took boat to Mercury dealer. The tech called and he said that the engine has water in it. I suppose he means the cylinder walls? Is there any fix for this? Should I get a rebuilt power head?
 

Nordin

Commander
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Jun 12, 2010
Messages
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Well if there is a crack from waterjacket to the cylinder yes you need a "new" engine block. That is the best way to go.

I have had a same problem with a Chrysler 75Hp that I left for rebore and they notice a small small crack from waterjacket to cylinder.
In this case the crack was high up in the cylinder just about 1/2 in from the head. It was easy to reach it and to treat and process the crack.

As my father worked with heavy loaders, forklifters and trucks he told me about a chemical metal brand called Belzona.
The use this for repairing diesel engines from block cracks etc.
Brands such as Scania and Volvo recommended this chemical metal compound.

I took a chance and repaired the crack with this, was very patient and cleaned up and sanded the crack and surface before I applied Belzona compound.

The engine is still runing.

This is just an suggestion and it is up to you to make the decision. It may work or not.
 
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