Help PLEASE with my 40 hp

[crossroads123]

Hello, I am fairly new to the forum and have been snooping around looking for hints on my 40 hp motor. The motor is a 1992 40 hp 4cyl 2 stroke with motor serial # OD1208859. I bought the boat a couple of months ago and it's been extremely hard to start since we bought it. She cranks fine, but doesn't start. Once it finally starts she dies almost immediately. If you can ever get it started and get the throttle pushed up (neutral) she will idle and run fine. If I stop to fish for 15/20 mins you must go thur the same starting trouble crank, crank, crank, ect. ect. she finally starts and dies.

I have replaced all the fuel lines and the bulb to no avail. I decided today to do a compression check on the motor. I pulled all the plugs inserted my gauge turn motor over the gauge bounces to about 30/35 and immediately falls to 0. I tried all 4 cyl and got the same responce on ALL cyls. All four show no compresion at all. I figure the gauge is faulty and get another compression tester, same thing all 4 cyl bounce to around 30 psi and immediately go to 0 when you stop turning the motor over. I shoot some oil into the cyl and repeat with the same result.

I am by no means the brightest bulb around, but i don't understand how all 4 cyls can have absolutely 0 compression???? Am I doing something wrong or not doing something right. I don't pretend to be a boat mechanic, but am fairly mechanical mind, so I can't understand how I can have no compression on all four cyls???

I would greatly appreciate any and all help or suggestions. But wife would be very happy things like this grind me to death, and make life hard on her........lol. I guess I forgot to mention that I am a retired Marine with 24 years Master Gunnery Sergeant/Sergeant Major.

 

[crossroads123]

Re: Help PLEASE with my 40 hp

Good morning again, well after 118 views and no replies I am somewhat shocked, but to update. I know every one who read my post thought gee, what an idiot, or he has no ideal what he's doing, or he's bsing, OR BOTH TESTERS ARE FAULTY. I made a trip to town today for a new compression tester and reran the compression test. I have 75 psi on all 4 cyl. I didn't think I was that stupid, but I wish someone had told me.

I think 75 psi is low, but i don't know for a 1992 40 hp 2 stroke motor. I am sure someone here must have an answer for me. Would compression that low cause my hard starting issues or do I need to look elsewhere. I have replaced all fuel lines, bulb and filter I am planning on rebuilding the fuel pump and the carbs are clean looking and were supposed to have been rebuilt prior to me buying the boat. I would surely appreciate any help or suggestions. SEMPER FI and thanks in advance.

 

[roscoe]

Re: Help PLEASE with my 40 hp

Hi, Welcome, and thank you for your service to our great country.


I'm really shocked at the lack of responses too.

I don't know how experienced you are in boating, or using motor such as these, so don't be offended as I try to cover some basic stuff.

Yes, 75psi seems awful low.
When checking compression, remove all plugs, push throttle to WOT (wide open throttle).


Have you checked for a good spark on all 4 plugs?
These motors will run on only 3, and it can be hard to tell just by listening.

Is your "choke" working? Push key in to activate choke.

Are you using the "throttle only" or fast idle lever when starting?

Here is a little starting procedure that should work for you.
***********************************************************************************


I'm 99% sure there is no conventional choke on that motor.
There is a fuel enrichment valve, that releases fuel directly into the intake manifold.
Functionally, the get the same results, they just go about it differently.


So:

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.

Activate the choke (fuel enrichment valve) by pushing in on the key. The valve is only open while the key is being pushed in.
This allows a little extra fuel to be supplied to the engine.

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.



Let us know if this helps the situation.

 

[crossroads123]

Re: Help PLEASE with my 40 hp

Thank you very much sir for your reply and the information.

 

[CharlieB]

Re: Help PLEASE with my 40 hp

Generally if a motor will start and idle, then compression is not the issue.
A slow cranking speed can contribute to hard starting. Check that all battery cable ends are clean bright and tight. Starter brushes good, commutator carefully sanded clean, and lightly lube the bushings.

Rig your trusty battery jumper cables and while a helper is cranking the motor strike the positive to the starter cable post to see if cranking speed increases which can indicate a poor connection within the starter relay.

 

[Laddies]

Re: Help PLEASE with my 40 hp

It really sounds like the carbs are dirty, if it don't start with Roscoe's suggestions when clean the carbs. It is sad that you did not get a response as you would have years back but it seems that there are only a few people left that give experienced advice and the majority are talkers and the linkers that have taken the site over but have little practicxal experience with engines.

 

[Bob_VT]

Re: Help PLEASE with my 40 hp

Carbs are a key item and they need to be spotless and adjusted properly.

However, there is hope 75 lbs PSI is okay since it is even across the board. There is a way to get the PSI number's up that is fairly simple and is actually what I consider regular Preventative Maintenance.

The process is called de-carbonization. The rings in 2 strokes get gunked up with unburned oil and tend to reduce the efficiency of the rings. Once this carbon is broken up the PSI will go up. (I once took an older motor from 75 PSI up to 100 PSI by a simple cleaning)

Mercury makes a cleaner called "Mercury Precision Power Tune" and if you google it you will see. It is available at 99% of the dealers or online.
If you want to stay conventional then use the Mercury product. Some people have used penetrating oil and some have even used water however, the Mercury mechanics swear by the original product.

I personally use Sea Foam Now here is a brief write up on iboats about the process http://forums.iboats.com/showthread.php?t=158076

Bob (Retired 20 years AD Army )

 

[Sea Rider]

Re: Help PLEASE with my 40 hp

You must do the compression test with engine warmed to working temp, remove plugs, install gauge and throttle fully opened with at least 4 engine cranks per cylinder to read well. Is that a 2 stroke 40HP, 4 clylinder engine with double carbs, one for each 2 cylinders or 4 carbs, one for each cylinder ? Check factory specs about compression for that model, should be around +,- 100 psi. Apply a good overdose of Power Tuner or equivalent which is a decarbonizer through each carb throat, follow can instuctions, hopefully should rise compression, fingers crossed, a matter to go for a second gauge reading afterwords and compare to first readings.

Happy Boating

 

[crossroads123]

Re: Help PLEASE with my 40 hp

Thank you gentlemen for your response and for the the great info. I too am a believer in seafoam and will be trying the cleaning process this week. Sea rider I have two carbs and four cyl. I again want to say thank you for your help Gentlemen and happy boating. Chuck

 

[crossroads123]

Re: Help PLEASE with my 40 hp

I forgot to give an update, sorry (damm memory). I ran the compression test and replaced the fuel line from filter to carbs I pressurized the system to check it and discovered the top card was leaking fuel at the bowl. I removed the bowl and the gasket and the baffel fell out. I finally found it and got it back in replaced the gasket and crush gaskets on the drain. I discovered the fuel supply line to the bottom carb from the enrichment valve was torn amd not attached to the carb. I replaced it and dry adjusted carbs to 1 1/4 turns out preset I have the motor all cleaned up and ready to head to the water to see if I have helped the starting I will update after the de- carbonization and test run. The starter spins very free and the cranking speed is good. I once again want to THANK YOU GENTLEMEN for your help and info.

 

[Bob_VT]

Re: Help PLEASE with my 40 hp

LOL that memory thing will NOT get better

Do not ignore the de-carb procedure and since you are running it is a great tune up item. Sea Foam can really become one of the better can's on the shelf.

 

[crossroads123]

Re: Help PLEASE with my 40 hp

YAHOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO I finally got a chance to take my boat out this morning for a test run and the de-carbonization. She starts better and faster than anything I own!!!!!!!!!!!! I have a leak........correction pouring at the fuel bowl on the top carb, but it was leaking (dripping) before. I have order 2 carb kits and will pull both and clean them.

I want to thank you Gentlemen for you help and information. Roscoe your starting procedures worked great, thank you very much Sir. I want to wish all a happy and safe Memorial Day weekend and please pause to remember those who gave all.