Stumped on this problem!!!!

[onemeanfisher]

ok, I am stressing a little. I have a 84 Bayliner Capri with a 85 Force Outboard we have had the boat about two years. It runs allright but lately we have had problems starting it, it normally starts up good initially then once we run it awhile it takes a while to start again.But after about 10 minutes or so cranks right up.

I thought it might be a cracked hose so I replaced all hoses( gas & Vacumm) same thing kept happening. So we got a bright idea to take it to a boat mechanic and get all 3 carbs re-built, we spent 200 bucks ( along with a new stainless steel prop repair and a transom saver built) The short of it we spent 600 bucks for all that.

Well as you can imagine we are excited to get it to the water a test it, new prop, carb re-build it's gonna run great. we get to the water and it starts fine but when put it in gear and you give it the gas it dies!!! runs fine in idle and you can even reave it up in neutral and it runs fine but once it goes into gear it dies.

Well I took it back to the mechanic to fix it AGAIN. He comes back and tells me it looks like your motor is blown because the cylinders will not hold pressure. Now my first question is Does a cylinder hold pressure or once the cylinder dropped down or fires doesn't the pressure subside??? It shouldn't hold steady pressure right???

Well I tested it myself with a compression gauge( didn't have the capability to see if it help pressure or not!!!) The top cylinder hits about 120, the middle cylinder about 129 and the bottom cylinder about 119, 120. Is there a problem with the 10 pounds difference on the middle one???

Here is what I have been told, 10 pounds makes a BIG difference and it's probably a fuel or spark issue and has nothing to do with a motor blown, mechanic just doesn't want to deal with it and telling me it's blown it saves him the head-ache. Is this motor done?? Or should I take it to someone to re-build the carbs again?? Or just trash it and find another motor??? Thank you for your help I am at a crossroads.

 

[tater76]

Re: Stumped on this problem!!!!

Sounds fishy to me, 120psi will run your 2 stroke motor. Sounds like you have carb idle adjustment issues not a bad powerhead. I have run 120psi for 3 seasons on my 38 year old motor with no issues, so.....?

 

[ljc1957]

Re: Stumped on this problem!!!!

Fuel pump?

 

[Frank Acampora]

Re: Stumped on this problem!!!!

Referring to cylinders not holding pressure, the mechanic probably did a leak-down test which is different than compression testing. The cylindes are tested one at a time by pumping air into them and measuring how long it takes to lose a certain amount of pressure. EH! Yeah, it can be useful but in your case, I think not. With 119, 120, and 129, all cylinders are withing 10% and the engine should be fine. Your engine is not "blown"

You MAY be having a vapor-lock type situation where the latent heat of the engine when shut down evaporated the fuel in the carb bowls. In order to hot start, you need to crank the engine a while.

However, if it starts well after cooling, that sounds like electrical, where either a coil or the stator is heating up and losing efficiency on hot restart.

DO NOT discount sparkplugs. Force engines use a surface gap plug and they do tend to foul easily--even new ones. Many starting problems with Force engines are directly related to plugs. Both hard starting and stalling when put into gear. SO FIRST put in new plugs Champion L20V or NGK BUHW and see if that helps the problem. If she still stalls, then check idle speed and set it to 700-750 in forward gear in the water. Too low an idle will always result in stalling.

Check the sticky FAQs and the thread synchronizing carbs and timing--there is a good possibility that you mechanic set the carbs wrong and that will lead to major engine damage.

Do the work yourself. It is easy, will save you money, and you know it was done correctly. ---Ahh--Don't return to that mechanic.

 

[SwampThing]

Re: Stumped on this problem!!!!

Check the tank vent and the pick up tube in the tank for partial clogs / restrictions. Checked the fuel pump diaphragm & screen lately? For the $5 it cost it should just about be yearly preseason maintenance to replace it. If you put it in gear and hit the throttle fast can you keep it running?

Frustrating, yes. But your motor isn't "blown". I'm thinking your problem isn't anything major,baring any fuel related issues, 20 minutes with a volt/ohm meter will probably have it solved.

Do you really think the parts changer did a "leak down test"?

 

[SwampThing]

Re: Stumped on this problem!!!!

runs fine in idle and you can even reave it up in neutral and it runs fine but once it goes into gear it dies..

Every time I had this condition it turned out to be coil with a bad secondary (plug) wire.

 

[onemeanfisher]

Re: Stumped on this problem!!!!

Thank you so much for the advice. I'm going to test the cylinder pressure again this time using 10 cranks per cylinder. Before I let it spin til it got up to at least 120. Probably stay the same reading but I know the 3rd cylinder I had to crank it a while to get 119. So I'll get a more accurate & fair reading per Cylinder. I'll post results, I bought over the week-end another 85 force in Houston. That was 145 per cylinder but I need to mount it and change the lower units out( it didn't come with one),That is lots of work for one guy. So I want to be absolutely sure the one on the boat is beyond repair cause it runs and may just need some minor tweaking needed.

 

[SwampThing]

Re: Stumped on this problem!!!!

Cranking until you get the desired reading is useless and defeats the purpose. Somewhere there should be a spec for 1 crank and 5 crank. At least that was the way the auto companies used to do it. If you crank until you get the reading you want you have no base spec to determine if you have a deviation from that spec and thus a problem.

The compression test results from your original post are now void and should be discarded. If you would have provided this information in your OP people's prognosis might have been different.

 

[tater76]

Re: Stumped on this problem!!!!

Swamp thing is right, you need to crank the engine with the guage connected until the needle will climb no further. This stopping point will be your true psi.

 

[onemeanfisher]

Re: Stumped on this problem!!!!

ok new compression check results.......... 10 rotations on each cylinder top cylinder was 120, middle cylinder was 125 and bottom cylinder was 119, 120. so compression is fine. So I'm thinking fuel and timing!!!

 

[onemeanfisher]

Re: Stumped on this problem!!!!

tator76 do you mean limit the number of crank because that is what swamp thing says. He says it is useless to crank it until it stops

 

[tater76]

Re: Stumped on this problem!!!!

No, he said cranking until you get your desired number. I think he is under the impression that you just cranked the engine until you hit 120psi then stopped. You need to crank the motor over until the needle stops climbing, this is your true psi.

 

[onemeanfisher]

Re: Stumped on this problem!!!!

SwampThing can you confirm. crank till you get tired or the same rotations each cylinder??? I have done it both ways only difference is middle cylinder goes to 130 when I crank it endlessly and 124 on 10 cranks other two cylinders stay the same either way.

 

[jerryjerry05]

Re: Stumped on this problem!!!!

Stop cranking when the pressure stops building.Usually about 7-8 or more cranks.
Rebuild the fuel pump.Make sure the carb floats are all set right.Clean the carbs.Make sure there is no water in the fuel.
The idle should be about 750rpm in gear,motor warm.New plugs.Any inline connectors? They go bad and suck air.A new squeezie can be bad.
While the carbs are off look at the reeds.
There is a thread at the top which spells out a linc and sinc by FrankA follow it when you put it back together.J

 

[onemeanfisher]

Re: Stumped on this problem!!!!

The carbs were just rebuilt I am thinking the carb ajustment was wrong by intitial guy. Is the ajustment for fuel mixture easy to get too. Do you ajust like a car, turn ajustment till motor runs rough then back it off a qaurter of a turn? Is the screw ajustment inside the mouth of the carb or on top or better yet do anyone have a link to a diagram to look at?? Jerry fuel should be good had complete fresh fuel last trip, Mechanic should have done everything nessessary to carbs (I paid him 200 bucks) What does rebuilding the fuel pump intail???

 

[onemeanfisher]

Re: Stumped on this problem!!!!

http://www.crowleymarine.com/mercury-outboard/parts/1214_40.cfm

Here is a diagram of the carb for anyone looking!!!

 

[SwampThing]

Re: Stumped on this problem!!!!

What does rebuilding the fuel pump intail???

Pretty much replacing a $5 rubber diaphragm and a gasket. Clean or replace the screen filter that's in there and clean the and or replace the valves that are in there. Do you have a manual for your motor?
For anyone that's going to be doing their own repairs, IMO a manual is another essential tool to have.

 

[SwampThing]

Re: Stumped on this problem!!!!

Back to compression testing:

I wanted to consult the manual for what it states concerning compression testing, before I stuck my foot in my mouth .... again.

From the Manual:
"Disable the ignition system and remove all plugs and ground. Open the throttle to the WOT position. Crank the engine an equal number of times for each cylinder you test, zeroing the gauge for each cylinder. Compare your readings and determine if pressures are within 15 psi criterion." (I know the book says 15 but I would go with the 10 psi difference standard)

If compression readings are lower than normal for any cylinders, do a "wet compression test". Use a can of fogging oil (WD40?) Fog the cylinder with a circular motion to distribute oil spray around the perimeter of the piston and retest the cylinder. If compression rises significantly then the piston rings are sticking. You maybe able to cure the problem by decarbonizing the powerhead.

If no change was evident between the dry and wet testing, then this is evidence that that there is internal damage or excessive wear to the cylinder or piston and the powerhead needs to be removed for further inspection. If two adjacent cylinders give similarly low reading this would be indicative of a faulty head gasket.

 

[SwampThing]

Re: Stumped on this problem!!!!

onemeanfisher,

I also discovered something on the same page that compression testing info was on that is worth noting. This may also be why your mechanic (hastily?) came to the conclusion your engine was "blown".

(I'm not retyping the whole thing but here is the jest of it):

"Air leaks are possible around any seal.... The base of the powerhead and lower crankshaft seal is impossible to check on an installed powerhead. When every test and system have been checked out and the bottom cylinder seems to be effecting performance, then the lower seal should be tested.

*** The stuff I've been referencing can be found on page 42 of the Force 1984-99 manual. Look under primary and secondary compression testing. Do a search or check under my previous post for the thread where I put the links for downloading PDF versions of the manuals.

HTH.