3.0L bogging/hesitating after running a while

F14CRAZY

Ensign
Joined
Aug 12, 2008
Messages
945
On 3 occasions now (two last season, and one today) I was cruising around 3k-3500 rpm and out of nowhere the engine will start running crappy and hardly go above idle. I can give it a little throttle above idle or WOT but it just bogs, stumbles, and won't hardly go above idle. Does it in forward gear and reverse. I've noticed that all 3 times this has happened (they were consecutive...I've been trying to figure out this problem for a while) it was around 10 minutes after leaving the dock. I can put it in neutral and it revs up fine but goes back to bogging when I put it back in gear.

I replaced the cap, rotor, condenser, and points but no change. I used a feeler gauge and set it to 0.18 (I think, whatever the manual says). I changed the fuel filter, no change. I pulled out the pickup tube that screws into the tank and it was clear. The check valve was free and seemed fine. The 2nd time this happened I pulled the fuel line from the carb and cranked and found it wasn't getting gas up there so I installed a new Sierra fuel pump (identical replacement). Another new fuel filter too, no change. The filter screen on the inlet of the carb is clear. I rebuilt the carb 2 seasons ago and have run the boat for a few hundred miles so I don't think it's an internal problem.

I know I should check the spark when this happens and I haven't yet. Is it possible my coil is bad? An old post I found said the coil casing could be grounding out to the clamp that holds it so I'll check into this and wrap it with electrical tape to rule it out.

The gas in the tank was bought on the hard about a year ago. I added Sta-Bil around October but due to outside issues the boat wasn't really run least year after the two times it had this problem. I topped it up with 2 gallons of midgrade today. I didn't think that so little was burned last year. Is it possible that I'm having ethanol issues? Do I have to pump it all out and refill?

My ignition stumbler system is properly adjusted and working but could it be making the engine stumble when it shouldn't?

Could my rubber fuel line be bad due to the ethanol content?

Any other suggestions guys?
 

jasper813

Recruit
Joined
May 23, 2011
Messages
5
Re: 3.0L bogging/hesitating after running a while

I had some problems like this with my 3.0l . I worked it down to the carb and pulled the float out and saw a bunch of trash and water in the carb. I removed it and it cleared up and ran good.
 

F14CRAZY

Ensign
Joined
Aug 12, 2008
Messages
945
Re: 3.0L bogging/hesitating after running a while

thanks I'll take a look in the bowl for any junk in there
 

F14CRAZY

Ensign
Joined
Aug 12, 2008
Messages
945
Re: 3.0L bogging/hesitating after running a while

any other ideas guys? I hope to fix this Friday morning so I can trailer it up north and cruise to Mackinac Island. Thank goodness for SeaTow though
 

F14CRAZY

Ensign
Joined
Aug 12, 2008
Messages
945
Re: 3.0L bogging/hesitating after running a while

I'm going to try spraying ether in the carb while it's bogging to quickly rule it as being an ignition or fuel issue aside from checking the vent. Any other tips?
 
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