4.3GL supposed to idle like it has a performance camshaft?

[USA_boater]

When on the trailer and out of the water it sounds like a hot rod idling/loping. When you start it in the water it starts right up but seems to barely be running; when it is warm I think it probably idles better but even then it idles like it has an aftermarket cam. Is that normal? My understanding was boats had very mild cams and therefore this motor should idle like a '95 chevy pickup w/ 4.3 motor?

 

[Scott Danforth]

what is your RPM?
what is your timing?

 

[USA_boater]

1.) tach broken, but boat is barely running at idle

2.) I do own a timing gun, but not sure if there is anything to unplug like on a TBI motor in order to get an accurate reading for initial timing. I can't imagine anyone ever messed with the timing on this boat though? What should it be, 0*TDC or what?

 

[GA_Boater]

Start with the basics - Compression and good fuel and spark on all 6 cylinders.

 

[USA_boater]

boat seems to run fine; 41-42mph is all I've seen out of it so far but that was with bimini top up and 4 adults and 3 kids plus gear onboard. Should this boat run 45-50mph?

Has a 3-blade aluminum prop, probably the stocker.

 

[Lou C]

You might want to pick up an engine analyzer tool (like Actron's ) so you can check idle rpm. On the water hose the exhaust is basically un-muffled so it will sound like a hot rod (V6 not so much). Idle rpm in gear should be about 600 rpm. With no tach you are just guessing.

 

[yoster]

Had this same issue a few weeks ago. Turns out it was bonehead simple - somehow the idle got turned down at the carb, causing it to try and idle way too low where it was almost dying (hence the loping sensation.) Turned it up a bit - good as new.

 

[USA_boater]

Thanks, is there a specific screw or knob? can you describe where? I'm sure I can find it but I don't want to inadvertently adjust something with the mixture and run it lean.

 

[poconojoe]

He means the idle set screw that the throttle linkage sits against. It's a small screw with a spring wrapped around it's shaft. The tip of the screw sits against a rotating cam shaped linkage. Mine is a Merc 4.3 V6 and the idle screw is on the port side of the 2 bbl carb.

 

[GA_Boater]

Thanks, is there a specific screw or knob? can you describe where? I'm sure I can find it but I don't want to inadvertently adjust something with the mixture and run it lean.

Do you have a manual? You need one.

 

[poconojoe]

Another note is that out of the water, on the muffs, it will sound a bit like you say since the exhaust isn't exiting underwater as it would normally be.

At first I was thinking you had some ignition wires in the wrong firing order. Timing could be the culprit as others have stated.

 

[jimmbo]

Since you give out little or no info, it is hard to say how/where to set the idle speed. It is different on a carbed engine than on a FI engine. Once adjusted, the throttle cable may need adjusting too or the gearshift lever might be difficult to operate
Since you don't say what size your boat is, who knows how fast a 4.3 may push it. it would have to be a small boat to see 50mph out of a 4.3
SInce you don't have a working tach, any suggestion regarding propping are no different than pulling numbers out of out the air. And since we don't know about whether it is carbed or FI, it is impossible to know the recommended WOT rpm range

 

[USA_boater]

Do you have a manual? You need one.

Seloc manual or factory manual? It came with an owners & operators manual but no repair manual (Seloc or Volvo). What do you recommend I get?

To the other guy asking:

It is a 18'4" four winns carbed 2bbl GL-C. It idles low/rough but seems better once warmed up. But all of the time when idling on water hose it sounds bad azz like it has a performance camshaft. It doesn't sound like that when idling in the water but it does seem to idle very low like it is barely running and when first started up it IS barely running. Based on my general experience with engines & equipment, I would guess it is idling 500rpm OR LESS and especially when cold started.

 

[Scott Danforth]

skip the seloc manual. not worth the paper its printed on.

if you want a factory manual, go here https://www.volvopenta.com/marineleisure/en-en/for-owners/your-engine/manuals---handbooks.html

 

[tripleblack]

same typr of problem as you have. i found that a new distributer cap and wires fixed it.

 

[USA_boater]

I checked the plugs and they are OEM platinum so prob won't go bad ever, but the cap & rotor is on my list...I have NEVER seen spark plug wires go bad without some sort of physical damage to them. I once Ohm'd out 10yr old plug wires and compared the numbers to a brand new set for the same vehicle and it was the same resistance after 10yrs of use. I'll start with cap& rotor, then replace plugs, then replace wires last if nothing more as a maintenance item since they are so old. But I bet your issue was the cap/rotor...I'll report back when I get around to it and thanks for weighing in and sharing this info.

 

[poconojoe]

Wouldn't be a bad thing to change the cap and rotor.
The condition of the inside of my cap and rotor were horrible. There were green stalactites hanging from the contacts. Scary stuff...
I changed the wires and plugs too.
I had a no spark condition which was caused by the ignition sensor under the distributor cap. But at least I did a good tune-up and it starts and runs smoooooth.

 

[USA_boater]

Wouldn't be a bad thing to change the cap and rotor.
The condition of the inside of my cap and rotor were horrible. There were green stalactites hanging from the contacts. Scary stuff...
I changed the wires and plugs too.
I had a no spark condition which was caused by the ignition sensor under the distributor cap. But at least I did a good tune-up and it starts and runs smoooooth.

Okay thanks again, can I ask if you were able to just use an automotive cap & rotor or if you bought marine ones instead?