New plugs..Now running worse

[chriscraft87]

Still trying to get my boat in good running order. So I replaced the spark plugs a few weeks ago, the past 2 trips to the lake haven't been too good. The motor will take maybe 1/2 throttle, anything past that it bogs down. At WOT it bogs way down and almost cuts off unless i throttle it down.

I have already put a new fuel pump and all new fuel lines on it before the plugs. Also toped it off with 93 octane this past trip.

It will run smooth at low rpms, up to aout 2400 rpms. Anything above that it starts bogging down.

Any ideas??? I would like to have one more succesful baot ride b4
I have to winterize it.

Thanks

 

[Don S]

Re: New plugs..Now running worse

What are we working on?

Need engine make, model, year, type drive, etc.

 

[Jeepster04]

Re: New plugs..Now running worse

What did your old plugs look like?

Do you have any popping back through the carb? Checked the timing?

 

[Jerryh3]

Re: New plugs..Now running worse

Are you sure you didn't cross any spark plug wires?

 

[chriscraft87]

Re: New plugs..Now running worse

The boat is a 1987 Chris Craft with a 3.0 OMC Inboard motor.

Im pretty sure that the wires are not crossed. Haven't checked the timing, but before I changed the plugs it ran pretty good. The old plugs didnt look that bad, just felt like I needed to replace them. It did have alittle power loss but nothing like it is doing now.

 

[PitchFork]

Re: New plugs..Now running worse

Are you sure you didn't cross any spark plug wires?

2nd Check the wires. Did you use the same plugs and are they the recommended ones per service manual?

 

[chriscraft87]

Re: New plugs..Now running worse

i'll def check my wires. No used champion plugs, it had autolites in it. Champion was the only thing that NAPA had that would work

 

[Don S]

Re: New plugs..Now running worse

No used champion plugs,

There is your problem, get either AC, or NGK. Bet it will run better.
Have run into a lot of bad running Champion plugs.

 

[ziggy]

Re: New plugs..Now running worse

other than the campions being the issue.


did ya gap them new plugs... i R&R plugs every year and the ngk's i get are never gapped to my engine specs..

 

[honeys money]

Re: New plugs..Now running worse

Put old plugs back in and see if it runs like it did before plug change.

 

[chriscraft87]

Re: New plugs..Now running worse

I'm pretty sure I only kept one plug, I'll set some NGK's and try those this weekend hopefully.
Where can i find the correct gap for that motor?
Boat didnt come with a service manual..

 

[JetBote]

Re: New plugs..Now running worse

Sounds more like a carb issue to me.

 

[cr2k]

Re: New plugs..Now running worse

+1 on the carb issue.

Pull the flame arrestor have someone pump the throttle (not running) and see if you can see a stream of gas squirting in to the carb throat. If not through the whole throttle range you probably need a carb overhaul. Common problem for the accelerator pump to go bad. Since you also topped off the tank you may have stirred up some crud from the bottom of it. Did you change the fuel filter?

 

[sethjon]

Re: New plugs..Now running worse

The boat is a 1987 Chris Craft with a 3.0 OMC Inboard motor.

Im pretty sure that the wires are not crossed. Haven't checked the timing, but before I changed the plugs it ran pretty good. The old plugs didnt look that bad, just felt like I needed to replace them. It did have alittle power loss but nothing like it is doing now.

If you only changed the plugs and are having the problem check the wires first. Its easy to cross a wire.

 

[bruceb58]

Re: New plugs..Now running worse

Where can i find the correct gap for that motor?

If you don't know the gap, how do you know the plugs you put in were gapped properly?

 

[chriscraft87]

Re: New plugs..Now running worse

I have already re-built the carb. and everything is good on it. there is plenty of fuel getting to it.
I got the gap from NAPA, they were already gaped to what they told me. Just wanting to make sure that their source is right.

I'll double check my wires and the fuel filters. I put a new one in the carb when I re-built it.

I had to replace the Coil on it too, friends here at work say it may be with condenser.. they say it may be breaking down.

 

[ChrisCraftJohnny]

Re: New plugs..Now running worse

Your gap should be around .035
NGK's for my engine are always around .030 out the box.
But I am running a Mercruiser not an OMC.
Take your time and gap each plug inside at the workbench. Then go out and make sure each ignition wire is going to the correct place on the cap and the plug. Make sure. Follow them all the way to each point with your hand.

If that does not solve your problem make sure that your fuel system is 100% clean. A bit of dirt or foreign matter in the lines can slow the flow enough to make the engine hesitate like it's doing. Also, check for water in the fuel.

CCJ