82 OMC 5.0L surges under load

[apane]

I have an 82 OMC Stern Drive 5.0L, I justed put in a brand new gas tank and fuel lines. New plugs, filters and oil. The engine starts right up on the first crank, the engine idles fine no sputter at all. Last night is the first time I took her out on the water and as soon as I left the dock and gave it about half throttle she started to bog down. If I let off on the throttle she would run ok at very low speed almost at wake speed. Then once I gave it more gas she would bog down and back fire through the carb and seemed like it wanted to shut off.

I have not taken my carb off yet, but to me it seems like the carb is probably all gummed up and clogged. I have rebuilt the carbs at least twice a year ever since the ethynol issue in the gas. I am running an Edelbrock 4 barrel carb with electric choke.

Is there anything else I should check before I take apart my carb again.

 

[apane]

Re: 82 OMC 5.0L surges under load

By the way the carb is an Edelbrock 1409 600cfm.

 

[Haut Medoc]

Re: 82 OMC 5.0L surges under load

Backfire through the carb is generally either lean mixture or a bad intake valve.....
It's probably your carb......
You could do a compression test to rule out the valve train....
I'm assuming the timing & advance are functioning.....​

 

[apane]

Re: 82 OMC 5.0L surges under load

I am going to check my timing & advance but in the past I have noticed that the carb always builds ups some kind of sandy residue. After rebuilding it than it runs fine. I have talked to a few people and they said the residue is due to the ethynol in the gas and the aluminum carb.

The wierd thing is that this is the first year that the engine fires up on the first shot and runs so smooth at idle.

Where can I find all of the tune-up specs for an 82 OMC 5.0L?

 

[Haut Medoc]

Re: 82 OMC 5.0L surges under load

A service manual.......
Maybe some of the guys who run OMC can help.....
Is it a GM or Ford block?......​

 

[apane]

Re: 82 OMC 5.0L surges under load

It is a GM 305 block with points and rotor.

 

[apane]

82 OMC 5.0L surgging. Problem Solved

82 OMC 5.0L surgging. Problem Solved

Ok it seems like I have fixed the problem. I took off my Edelbrock carb, dismantled it and let it sit in carb cleaner overnight. Rebuilt the carb replaced the base gaskets and now the engine is running real nice. Took it out for a test run and she does not hesitate at all throttle response is great.