3.0L GM OMC Problems

[hmmhesays]

So I finally got this engine back together. It seems to run fine in neutral. I got it out to the lake to take it for a test drive and under load I can't get it above 1000rpm. I get a backfire out the carburetor and the engine slowly dies. I'm thinking...

1. Check the timing
2. Check the point gap
3.... Any suggestions?

PS when I got back to home I did find one spark plug wire that was loose. I know this could have caused most of the problem, but 1000rpm?

 

[Silvertip]

Re: 3.0L GM OMC Problems

You didn't do number 1 & 2 before you went to the lake? How about valve adjustment?

 

[Bondo]

Re: 3.0L GM OMC Problems

It Sounds like a Fuel Delivery Issue,.............

Popping,+ Backfires are caused by a Lean condition........

 

[87baylinercapri]

Re: 3.0L GM OMC Problems

It Sounds like a Fuel Delivery Issue,.............

Popping,+ Backfires are caused by a Lean condition........

i beleive its caused by a rich not lean condition, you cant backfire in the exhaust without gas, and to have unused gas in your exhaust you need to be running rich, if you were lean you would of easily spent that fuel.

to me this sound more like a ignition issue, your plugs ain't burning that fuel and its being ignited in your exhaust. put a new cap, rotor, wires, plugs on your boat, gap them puppies right, lets see if that does it. your timing should be fine unless you changed it at one time or previous owner.

 

[Silvertip]

Re: 3.0L GM OMC Problems

It's popping back through the carb -- not the exhaust. Anything involving spark, fuel, timing, and valve adjustment can cause it. It may even be that the cam was not installed correctly putting the entire valve train out of time.

 

[4winnsskipper]

Re: 3.0L GM OMC Problems

It's popping back through the carb -- not the exhaust. Anything involving spark, fuel, timing, and valve adjustment can cause it. It may even be that the cam was not installed correctly putting the entire valve train out of time.

I think you should look at easier answers first. Timing is key, check your timing and set to manufactors settings.