225 rough idle

[fishman204]

Hello all I could use some help on my 96 ocean runner. This motor I bought used earlier this year looked very clean started rite up.But when I got her home she started lookin ruff. Took a while but I feel I'm close to running correctly.All new gaskets from carbs to intake manifolds to block 1 new head gasket new choke primer new thermostats then took to local marina for compression,leak down all good I also wanted them to adjust the carbs and check timing but they didn't before I picked her up they said the spark kind of bounced around on the plugs? Now when I start up on muffs runs a little off at idle and when we dunk the boat starts rite up on cold start idle drops a little then dies I've tried revving a few times it just runs crappy, then when you take off runs great from 2k to 5k rpm smooth as can be. I have the seloc manual I know they miss a few things. I hate to just throwing parts at it but I'm now leanig towards the power pack ps would u buy a mallory or omc thanks so much

 

[metriccrescentwrench]

Re: 225 rough idle

Just a wild guess, it sounds like maybe the idle timing needs to be adjusted. Your best bet is to get a factory manual and meticulously follow the link-n-sync procedure.

 

[fishman204]

Re: 225 rough idle

Just a wild guess, it sounds like maybe the idle timing needs to be adjusted. Your best bet is to get a factory manual and meticulously follow the link-n-sync procedure.

I just looked at the L-S procedure could be a long day might be worth it though

 

[fishman204]

Re: 225 rough idle

any other ideers .Today I checked cleaned some ground wires nothing dirty yet still a few more. I am going to read the link-sync procedure a couple times and give it a whirl this weekend.The spark thing has me baffled

 

[Greg_E]

Re: 225 rough idle

The coils have a metal strap that grounds the coil primary windings to the block. You can try cleaning them. I've had coils that were firing intermittently, and cleaning solved the problem. I use Scotchbrite then something to remove any grease or oil. While you're at it check and clean the plug wire connection to the coil.

If you have an inductive timing light you can check each plug wire to see if it is a particular cylinder that is misfiring.

Also, if you have one cylinder not firing you won't get full RPM's at WOT. It's sometimes difficult to tell when you have one cylinder not firing on the big V6 engines. You mention 2-5K. At WOT you should be around 6.2K. There are other things that can cause low RPMs at WOT like not having the correct prop for the boat, but it may be a clue to what's causing your problem.

 

[daselbee]

Re: 225 rough idle

"Spark kinda bounced around" What does that mean? Does this engine die abruptly? Quickstart releases, and then it just stops very abruptly? You know, I think I would look at the orange wires going to the coils for cylinder #2 and cylinder #4. If those are swapped, and it is very easy to do, the timing (using a timing light) looks like it is jumping all over the place. It will run real rough, but then abruptly stop when the misfire occurs. I have seen them try to run backwards at that point! So, look at the orange wires to the coils. The top coil PORT side #2, will have an orange wire with a blue stripe. The middle coil will have a solid orange wire, and the bottom coil will have an orange wire with a green stripe. Same for the STBD bank, too. By the way, that misfire occurs, and stops the engine...that is very, very bad on the crank and particularly the flywheel key. Very easy to shear the key when this happens. I don't know if this is your problem, but it is worth a look. EDIT: If it runs good from 2k to 5k, it probably is NOT the swapped primary wires. But look anyway.

 

[fishman204]

Re: 225 rough idle

I didn't get to talk to the mech that did the spark test so the bouncing around part has me stumped thats why i'm checking connections,grounds,terminals.The coil wires are correct maybe my plug wires? From just past idle to 5500 rpm runs strong havent pushed the max rpm yet.I also had a 14x19 prop just got a 14x21 try cause the 19 wasn't enough still had throttle left when the tach was sayin 5500. thanx mike

 

[Greg_E]

Re: 225 rough idle

If you had one cylinder not firing it would max out around 5200-5500 RPM.
Have you cleaned the ground straps on the coils?
In all the years I've owned these engines I haven't had any problems with plug wires unless they were physically damaged. The spring terminal can pull out of the insulation. If that happens, you can cut it back a little and put it back together (provided they are the OE wires).
If all that is good, I would continue on with metriccresectwrench's suggestion.

 

[fishman204]

Re: 225 rough idle

Okay today got out on the water with cleaning the connections,terminals,gronds some improvement.On the prop side I was wrong the new one is 14.25 x23 too much I think I need a 21. WOT 5500 @ 47mph 3500 got 32mph