Engine Rpms jump around around 3000!

[Jfreeman1412]

Hey guys I got the Rochester quadjet on my 305. When we are cruising around 3000 rpm my starboard engine will bog down and drop 200 Rpms and then 10 seconds later it will jump up to 3200-3400. It won't take any more Rpms either. We just changed both fuel filters (small one in carb and fuel water seperrator.) Did it before and still does it after filter change. Seems like the four barrels aren't opening or not responding when they do. I can open them manually but they don't seem to respond. Any ideas? Is it an mixture issue? Any help would be great! Thanks.

[prowlersfish]

I would check the fuel linew check valve at the tank .

[Jfreeman1412]

Just did pull that to check the intake screen. I could blow through it both ways. And there was no intake screen on the intake. Just open tube.

[Cmount]

I had this issue last year...New carb fixed it right up...the best purchase of this year so far.

When I pulled the old one off I was amazed at how fouled it was.

[Jfreeman1412]

Hey guys, I wanted to let you know that things have gotten much better since we opened the crossover valve on the fuel lines. However we are using fuel out of the tank of the engine that ran good at a rate of 3:1.

My thought is that we are getting debris stuck in web of the anti-siphon valve and it is automatically pulling gas from the other tank? What are your thoughts?

Thanks for taking time to look.

[Commissionpoint]

Hey guys, I wanted to let you know that things have gotten much better since we opened the crossover valve on the fuel lines. However we are using fuel out of the tank of the engine that ran good at a rate of 3:1.

My thought is that we are getting debris stuck in web of the anti-siphon valve and it is automatically pulling gas from the other tank? What are your thoughts?

Thanks for taking time to look.

Yeh. Sounds like a restriction of some kind on the side thats not pulling well.

Solid copper, or some other kind of fuel lines on there?

[Jfreeman1412]

Solid Copper to the fuel filter and then flex from the filter to the pump.