1992 force 150 issues

[Dwamp2006]

Thanks for letting me join the forums! I am a new boat owner and am having issues with my 1992 force 150. For starters the lower unit is full of water almost to the motor if you look in with the cover off, any ideas on what thay could be? Also I have little to no power. It won't go over 3k rpms and I can only get maybe 8 knots out of it. The boat is 92 bayliner trophy 2003 if thay matters. I have a service manual on the way and am an auto tech by day so I'm mechanically incline but marine engines are a different animal. Thanks!

 

[Frank Acampora]

Well, I think you are talking about the rear shroud being filled with water. There is a sound attenuation gasket at the bottom but it usually does not keep out water. The water will simply find its way out when the boat gets on plane. However, Check the rubber bellows that directs used cooling water out the back of the engine. If this is split it will fill the chamber with water and with the cover on, exhaust fumes will fill the engine, starving it for air.

NOW: All these later Force engines used a semi-keystone top piston ring. They do tend to get caught in the exhaust ports and break. SO: First thing to do is check compression on all 5 cylinders. If it is good--like 140 PSI or even 120, then start checking for spark on all five plugs. Then if that is good remove both fuel pumps and replace the diaphragms. These twin fuel pumps are in series and one bad diaphragm will allow the engine to run but not at full power.

Since you are a new boat owner, you probably don't have a history on the engine. SO: It would not hurt to check the lower unit oil and change the water pump impeller. Where the engine swivels there is a zerk fitting. grease that well and keep it greased to prevent seizing the king pin.

Spark plugs are surface gap and set at the factory. They can be cleaned and re-used almost indefinitely.

 

[Dwamp2006]

I got a receipt from a marine shop showing compression was checked in October before it was winterized. Then I bought it with the shrink wrap still on. Now the cooling bellows you speak of, I did notice when while running it with the cover off there was alot of exhaust coming from in there, think that could be my issue? It also smokes alot and when going through a no wake zone the back of the boat is full of exhaust / smoke. I already ordered an impeller and lower unit seal package so ill be doing that this weekend. Also to note, it seems to run fine at first and half throttle but at wot is when the issue happens. It also will tend to stall on me in neutral and when switching gears after i get back to the dock and try docking it.

 

[Psychosis]

Might want to also check that your carbs are opening fully when the control is at full wot. You should he able to reach down and feel if the exhaust bellow is cracked or split. Dying in neutral sounds like either idle is too low or you need to Link and sync your carbs.

 

[Jiggz]

The rubber boot (exhaust relief when idling in water) at the motor leg is very easy to replace. Make sure you do replace this first before replacing the lower unit gasket. if the exhaust leak stops after replacing the rubber boot there is no reason to replace the lower gaskets. Using inline spark tester, test all spark plugs for sparks. If you do not have one yet, install a clear fuel filter between the fuel pump output and the carb's inlet for fuel related troubleshooting. Do some test ran in the water with the cowl off and watch the clear fuel filter if it at least stays 1/2 full at WOT. If not, then you have fuel delivery problem like faulty fuel pump, leaky fuel hoses, clogged pick up tube or vent line and also a faulty primer bulb.

If it stays at least 1/2 full then the problem is either with the carb or reeds assuming all compressions and sparks are good.

 

[Dwamp2006]

Here's the link to it running I put on youtube. The bellow didon't seem bad. But I am getting alot of exhaust inside the cowl and it seems to be coming from below that.

https://youtu.be/FU3Wez9SXA0

 

[Jiggz]

Yup, that is exhaust leak probably from the exhaust tube or from the plate spacer between the powerhead and the motor leg. And you are right it is not from the exhaust boot relief.

 

[Dwamp2006]

Any chance you know where to get the parts and how to change them? Guess I'll just do both.

 

[Jiggz]

Unfortunately, the seal or gasket for the seal spacer plate is already obsolete. But that doesn't mean you can't make one up from gasket material. However, it can still be available from other stores like the link provided from partboat dot com. The part number is F694278

Item #13 from the diagram below is what you are looking for.

http://www.partboat.com/25-f694278-mercury-quicksilver-spacer-plate-o-ring-force-150hp

 

[Dwamp2006]

how about the exhaust tube? also, I did order a lower unit gasket/O ring kit, would that be included in it?

 

[Dwamp2006]

also the spacer plate seems to be up higher than where the exhaust is leaking, the exhaust seem to be coming from below there and the water outlet bellow, almost from the lower unit.

 

[Dwamp2006]

Does the block need to be removed to replace that spacer plate seal?

 

[Jiggz]

I believe at this point the best thing to do is to remove the motor leg cover. Ran the motor on earmuffs on the driveway and visually check where the exhaust leak is coming from. identify the source of the leak using the diagram provided on the link above. I understand with earmuffs there will probably very little exhaust leaks since there is no back pressure to overcome compare when the LU is submerged. But with that much leak as shown in the video, there would still be some leaks.

If there is no leak using earmuffs then you can use a large trash can to submerge the LU. It shouldn't take that long to locate exactly where the leak is coming from. As for replacing that spacer seal yes this requires lifting the powerhead off. If you find out the leak is still way below the spacer plate, then the leak could be from the exhaust tube lower seal.

 

[Dwamp2006]

Ok thank you very much for the help. I really appreciate it! Now how is the motor leg cover removed?

 

[Jiggz]

You can't miss it. Just look around it and there are 1/4" bolts holding it against the motor leg and also on the lower cowling.

 

[Frank Acampora]

You remove the six 1/4 inch bolts holding it to the front of the engine. Then you go inside the cowl and remove the six 1/4 inch bolts from the rear half. Two of them MAY be buried under the massive exhaust cover. After all the bolts are out, wedge the top of the cover outward and slide a screwdriver as far down as possible. With the screwdriver still in place tap the top with your fist to loosen the bottom. There are two roll pins at the very bottom which need to be wedged out.

I just went out and looked at two of my 150s. You may be in luck-- I have never had the rear shroud off either BUT it appears that there is not a bolt hidden under the exhaust. There may be only 5 bolts inside the lower cowl.

 

[Dwamp2006]

I think I may have found my root cause for the rpm issues.

If you follow the rod for the throttle/idle set screw up the side of the block to the top. There is a linkage coming out from under the flywheel thay is not connect to that idle rod and looks like it should be. Will not having that connect screw with my rpms at wot?

 

[Frank Acampora]

Definitely! That screw controls timing advance. Without advancing timing in synch with carb opening the engine simply will not make power. There should be two plastic blocks with the screw in between. The screw is reverse threaded on one side so when you screw it in or out the blocks will open or close to advance or retard base timing.

Once you re-connect the timing link, retime the engine to 28 degrees before top dead center at wide open throttle at cranking speed. Remove and ground all 5 plugs so you do not damage the CD boxes. Connect a timing light to the top plug wire. Crank the engine. There are three marks on the flywheel The center mark is 30 degrees and the mark to the left of it is 28.. When the mark lines up to the mark on the block pointer (above the top carb) the timing is correct.

 

[Jiggz]

I think I may have found my root cause for the rpm issues.

If you follow the rod for the throttle/idle set screw up the side of the block to the top. There is a linkage coming out from under the flywheel thay is not connect to that idle rod and looks like it should be. Will not having that connect screw with my rpms at wot?

This is just probably one of the causes of your rpm issue. But for sure, the leaking exhaust inside the cowl will affect your idle and WOT speed the same way that if the timing tower is not connected to the trigger advance plate. Both should be corrected.

 

[Dwamp2006]

I planned on fixing both anyway, boats getting pulled and brought home sunday so I can work on it next week. also have to install a depth finder and change the impellar anyway. thanks for the help guys!