bog at 900 rpm

[hullofalottatrouble]

1982 merc 260 5.7 350.. reman rochester qjet carb.. comp is good all around..

got the reman fired up.. got it to correct idle 700 rpm.. and got timing set dead on last night.. vacuum at 18 and steady

noticed as i perhaps too gradually throttled up the engine would bog down and hesitate around 900rpm then would jump up to about 1200 RPM and run strong at that point..

the accel pump is working.. when i pump the throttle it shots 2 strong streams of fuel.. thou i have to say i dont know what if any fuel it pumps during my gradual throttle up..

the boat is on the trailer without the drive attached..

i didnt try to mess around with the carb to fix the problem.. it got to be too late so i packed it in for the night..

i am wondering if this is just really bad carb adjustments on my part? this perhaps a choke issue? bad idle settings?

thanks..

 

[Kevin70]

Re: bog at 900 rpm

Maybe it's getting too much fuel when you gun it?? Just a thought.

 

[hullofalottatrouble]

Re: bog at 900 rpm

i was thinking i might be running a bit rich at idle to tell ya the truth.. so would the accel pump squirt potentially be briefly way over rich causing a bog..

i am not completely familiar with all the inner workings of a carb by any means.. so any help.. insight.. guidance would be appreciated..

 

[milkyway]

Re: bog at 900 rpm

Optimize the setting of the idle mixture screw by using a vacuum gauge. This will correct over and under mixture. Then adjust the idle speed screw.

Do you have current spark plugs?

 

[hullofalottatrouble]

Re: bog at 900 rpm

milky.. yep.. corrent plugs.. new plugs.. new plug wires all that good stuff..

i was using the vacuum gauge.. it was a PITA.. and it was too hot.. so ill give it a go again tonight.. seemed like i could practically take the left needle out entirely.. ill give it another go..

 

[milkyway]

Re: bog at 900 rpm

From another thread that may pertain to you that concerns the accelerator pump:

---Have someone else push the throttle down while you listen to the carb. (engine OFF). You can easily hear it squirt if it's working. Then, you can remove the flame arrestor and look in to see the gas being squirted.

If it's working correctly, there should be "no lag between idle and throttling up".---

 

[milkyway]

Re: bog at 900 rpm

Why is the vacuum gauge a PITA and too hot?

 

[Blk-n-Blu]

Re: bog at 900 rpm

Help with Vacuum readings:
http://users.bigpond.net.au/ergoff/vac1.htm

 

[hullofalottatrouble]

Re: bog at 900 rpm

milky.. the temperature outside was too hot.. i was sweating like a stuck pig..

tuning the carb is PITA because I have minimal access to the idle mix screws.. thankfully they are hex with the flat head screwdriver heads on them or I would be in serious trouble..