RPM dropping too far when shifting into gear. 4.3LX (Gen +)

[rderenzy]

1997 - 4.3 Merc LXgen+

I did not have this issue until a mechanic took my engine out of my boat to fix an oil leak

NOW, even at idle it was starting to sputter
I had him tune the carb up, so now when in N and idle, its around 900 rpm - which is good and strong - no signs of sputter

HOWEVER, as soon as I shift it in gear, it drops to about 600...it sputters a little bit but does ok ....if I baby it and give it some gas (like barely want to move) it will bog down and stall. I basically have to throttle it hard to get passed that stage
Reverse is pretty much the same

then after the boat has been running for a good 20-30 min - I don't get that bogged down, sputter at low throttle where it will die

Please help.

 

[thumpar]

It doesn't sound like it is adjusted right. Your idle should be about 650-700 RPM.

 

[rderenzy]

hmm...well when it was idling around 700, it seemed like it wanted to die...sounded like it was stuttering, maybe it wasn't ...I could put it back and play with it - but it seemed that adjusting the idle had no affect on the main problem, which is putting it in gear and giving it a little gas it bogs it down and wants to die (but if I give it some good throttle, takes right off like a champ)

 

[thumpar]

900 RPM in neutral is too high. You will be banging on the clutch dogs pretty hard. On my carbed boat the RPM in neutral and in gear was not even noticeable.

 

[rderenzy]

well great! so how do I fix this

 

[achris]

Sounds like the carb is either not set up properly or needs cleaning. But me being me, do the other checks first. Check compression, check timing, then start working with the fuel system.

Chris. ......

 

[rderenzy]

I bet the guy hooked up the plug wires wrong

That would make sense

Carb was great before he took the engine out

 

[s.hadley81]

I don't think your plug wires are it, as achris said compression, timing , and fuel. Might just be mixture adjustment or timing off.

 

[rderenzy]

oh - i thought the spark plug wires(being rearranged, was the timing part)
are there any handy guides out there or walkthroughs for stuff like this? I'm not sure how to adjust or set the timing or what that means

 

[rderenzy]

Im just having a very very hard time understanding how the carb could get dirty or messed up - it ran like a CHAMP, then engine was pulled (new timing cover) and put back in, and now runs this way at super low throttle

 

[bruceb58]

Just so you know, it's normal for a carb'd engine to drop RPM when you put it into gear. That is why the specs state idle rpm in gear.

 

[rderenzy]

yea, I realize that now - I wish I could edit the title (so I don't have to make a new thread)

So idle and idle in gear is different right? I'm idling in neutral (lever at top) around 900, but my idle in gear is when I move it forward and it shifts, and as soon as it shifts, release of the lever, would be the idle in gear, correct?

 

[rderenzy]

Mods - this can be closed - I fear that the title is super misleading

 

[thumpar]

The RPM may be a little different when in gear than when in neutral but 200 RPM is a lot of difference. My carbed boat RPMs changed maybe 50 RPM.

 

[rderenzy]

yea, I cant tell on muffs, i'll get more info - I want this closed I opened a new one w/ a more accurate title, here:
http://forums.iboats.com/forum/engi...tle-throttle-makes-the-engine-sputter-and-die

its got much better info

I don't think its a dirty carb, I think something ins't set correctly

 

[bruceb58]

and its idle in gear in the water. Has to be a load on the prop

 

[achris]

Mods - this can be closed - I fear that the title is super misleading

I've change the title for you .As for firing order, it should be 1-6-5-4-3-2. If you look at the distributor cap you will see each post has a number next to it. This is the number of the cylinder that the lead going from that post should go to. The cylinder numbering is

 

[airdvr1227]

1
I had him tune the carb up, so now when in N and idle, its around 900 rpm - which is good and strong - no signs of sputter

There's your answer. I'd take it back and have him fix it correctly.

 

[achris]

900 rpm in neutral is too high, way too high, you'll start destroying drives. Take it back and get him to fix it properly. Shouldn't idle any higher than about 750 in neutral to attain 650-700 in gear in the water.

 

[rderenzy]

i'll adjust the rpm in N
the only reason we (I was with him testing it) upped it, is because I thought it was idling too low (as a little gas bogged it down) and I thought upping it would fix the low throttle bog down - which apparently it did not (although it appeared that way, because when we were done it dindt have that issue, but that was because the engine was warm)

SO! even when the idle is set correctly, I still have the light throttle stalls/bogs down the engine

forgot - I did check all wires and they are connected correctly