4.3 MerCruiser Lack of Power

[AngryIrishMan]

Last summer I purchased a 1987 Four Winns 215 Sundowner with a 4.3L MerCruiser/Alpha One. It ran great the first few times out on the water then after a long day boating it suddenly lost power just as we were heading in. Heres what I know:

This seems to correlate around two events: First, The guy left me an empty tank of fuel the day I bought the boat. Being excited to get out on the water I failed to check the fuel gauge before leaving the dock and ran her bone dry about 20 minutes later. Second, a couple days later, after getting fuel, we were out on the water and the outdrive hit a stump in a no wake zone. This was the afternoon we lost power.

The boat will not plane out. The engine only runs up about 2200 RPM and is very loud, Sounds almost like a bad spark plug.

The guy I bought it from shortblocked the engine the summer before. He purchased a refurbished engine block and put all of the old parts back on it.

I ran several cans of SeaFoam through the engine thinking the pump may have sucked up some sediment in the tank.

I replaced the fuel filter and the carb in-line filter, which according to the local marina had the original 1980's filter. It was a sandstone filter. Never seen that before.

I rebuilt the carb. Trying to save some $ I bought a set of 205 Chevy plug wires and plugs. These will be replaced in the spring.

After all this I took it for a final run to see if my work had any sucess. Unfortunately when it would not plane out and ran rough I backed down to idle and the engine died. It would not start back up and I had to be towed in.

I went ahead and just had it winterized and put away for the winter. A friend believes that I may need to get MerCruiser wires and the correct plugs, as well as a new distributor. He also thinks replacing the fuel pump wouldnt be such a bad idea since it has been sucking up the sand from the original filter for who knows how long. I dont know. Im a DIY guy and would like to figure it out early this spring so I can back on the water in time for the walleye run

Any ideas will be AWESOME!!!

 

[RogersJetboat454]

Re: 4.3 MerCruiser Lack of Power

Welcome to Iboats.

Have a look at this;
http://forums.iboats.com/mercruiser...ives/list-possible-causes-low-wot-295070.html

Found here;
http://forums.iboats.com/mercruiser...tdrives/adults-only-no-exceptions-288430.html

 

[AngryIrishMan]

Re: 4.3 MerCruiser Lack of Power

Thanks!

A few of these I will have to look into. The flame arrestor being one. It was in pretty bad shape when I removed it. It will be a few more weeks before I get her out of the barn and start tinkering. Ill keep sending updates. Keep sending ideas!

 

[RogersJetboat454]

Re: 4.3 MerCruiser Lack of Power

A good place to start on that list is a compression test if you haven't done one.
Verify that the mechanical health of the engine is up to snuff before you start spending lots of time and money on all the other parts.
It's free if you already have a compression tester (or have a local Autozone you can borrow one from), and it only takes 20 minutes of your time.

Did the original owner ever give you a reason as to why the short block was replaced?

 

[tpenfield]

Re: 4.3 MerCruiser Lack of Power

You mentioned that the engine is loud and may have a bad spark plug . . . Did you check the spark plugs?

i would check compression first, as mentioned. See where that takes you. Be careful not to just throw parts and money at it.

 

[Don S]

Re: 4.3 MerCruiser Lack of Power

Not sure how a bad spark plug can make it louder, but it's going to take more than one bad spark plug to drop half the rpm.

But, with it put away for the winter, not much you can do to check anything so we will see you in the spring when you can look at things, answer some questions, and do some testing.

 

[Bondo]

Re: 4.3 MerCruiser Lack of Power

I went ahead and just had it winterized and put away for the winter. A friend believes that I may need to get MerCruiser wires and the correct plugs, as well as a new distributor. He also thinks replacing the fuel pump wouldnt be such a bad idea since it has been sucking up the sand from the original filter for who knows how long.

Ayuh,.... Welcome Aboard,.... Sounds like yer Friend likes to Blow, Yer money...

Like everyone else is sayin',... Do some Testin', 'n quit throwin' money at it, hopein' ya might get it right....

As for gettin' a set of Marine type spark plug wires,.... Didn't ya find those Chevy wires awfully short,..??

What carb ya got,..?? What'd ya see, when ya rebuilt it,..?? Crud,..?? Rust,..??

I'm also curious 'bout this Loud thing,... Exactly where's the noise,..??

 

[Prophammer]

Re: 4.3 MerCruiser Lack of Power

I rebuilt the carb.

It died and would not start on your last run. Did it at least start up and run before you rebuilt the carb?

 

[achris]

Re: 4.3 MerCruiser Lack of Power

Standard troubleshooting....

Engines require certain things to operate properly... Basically they need the correct fuel/air mixture to be compressed and then fired at the right time.

So, in this order.

1. Compression tests.
2. Check spark plugs, replace if needed.
3. If points, replace, along with condenser and rotor. Check and adjust, if needed, points cam dwell angle.
4. Inspect distributor cap and leads, replace if necessary.
5. Check spark quality (needs to be a nice BLUE spark drawn over 1/2").
6. Set timing. Check timing advance is working correctly.


Chris........

 

[ktbarrentine]

Re: 4.3 MerCruiser Lack of Power

Add this to the list of static checks: Firing order.... You'd be surprised (or maybe not) at the folks that get a plug wire out of place during a plug wire replacement project. Just sayin'.

 

[fat fanny]

Re: 4.3 MerCruiser Lack of Power

While you rig is layed up get yourself the Merc service manuals for the engine and drive and read them cover to cover! Educate yourself or this will get exspensive real fast. Throwing parts at these issues is not the answer as mentioned above trouble shooting is. The tools worth having as a boat owner are compression gauge,timming light (with advance),multi meter and test light these are very helpfull when proceeding with the above proceedures. Also having the serial and model #'s of your engine and drive along with the year is very helpfull in getting good and accurate responses on this forum. Good luck and post back!

 

[BRG25]

Re: 4.3 MerCruiser Lack of Power

Standard troubleshooting....

Engines require certain things to operate properly... Basically they need the correct fuel/air mixture to be compressed and then fired at the right time.

So, in this order.

1. Compression tests.
2. Check spark plugs, replace if needed.
3. If points, replace, along with condenser and rotor. Check and adjust, if needed, points cam dwell angle.
4. Inspect distributor cap and leads, replace if necessary.
5. Check spark quality (needs to be a nice BLUE spark drawn over 1/2").
6. Set timing. Check timing advance is working correctly.


Chris........

Chris said it all. You're missing spark, fuel or compression. Find out which it is before throwing parts at it or rebuilding anything. What if you rebuilt your carburetor incorrectly and now have an additional problem that you didn't have before? Did the engine ever run well?

 

[AngryIrishMan]

Re: 4.3 MerCruiser Lack of Power

Did the original owner ever give you a reason as to why the short block was replaced?

Thanks! Ill give that a shot too. The original owner said that he attempted to winterize on his own and messed up. Cracked the block over the winter.

 

[AngryIrishMan]

Re: 4.3 MerCruiser Lack of Power

While you rig is layed up get yourself the Merc service manuals for the engine and drive and read them cover to cover! Educate yourself or this will get exspensive real fast. Throwing parts at these issues is not the answer as mentioned above trouble shooting is. The tools worth having as a boat owner are compression gauge,timming light (with advance),multi meter and test light these are very helpfull when proceeding with the above proceedures. Also having the serial and model #'s of your engine and drive along with the year is very helpfull in getting good and accurate responses on this forum. Good luck and post back!

Thanks. Thats part of the reason I put it up for the winter, to stop myself from throwing more money into it than needed.

I have a SELOC manual. Thats about all I can find that covers my motor. I dont have the drives # but here is the engine's B740596

 

[achris]

Re: 4.3 MerCruiser Lack of Power

I have a SELOC manual. Thats about all I can find that covers my motor. I dont have the drives # but here is the engine's B740596

You have a knee pad, not a manual....

That's a 1987, 4.3L (175hp, 2 bbl carb)
Here's the OEM service manual for it.

https://docs.google.com/open?id=0B1TAvwZ3TjhfNWFyczBmVUE4Wlk

and the drive should be an Alpha One, here's it's manual.

https://docs.google.com/open?id=0B1TAvwZ3TjhfOVRUNEk0anBUR3lQYTkwcUh5RElUQQ

Chris......

 

[AngryIrishMan]

Re: 4.3 MerCruiser Lack of Power

Chris,

You could not be more correct. This is so much better. Ill give it a good once over in my free time.