Is this normal??

[Fishfearme1174]

2004 mercruiser 3.0 carb engine. Haven't had it out in a while. But on trailer with muffs maintains a good smooth idle. If you advance the neutral throttle to 2500+ Rpms for a few seconds then pull back down to idle throttle the engine dies and does not reclaim idle.

 

[Bt Doctur]

need more info, carved, injected, tks system,etc. could just be a cable adjustment

 

[alldodge]

Going 2500 rpm on muffs is not a good thing, you can burn out your impeller, I would suggest no more then 1500 to 1600. Your carb is having trouble so more then likely it either needs some cleaning. You also mentioned that it has not run in a while so it might need some fresh gas. As BT mentioned, if its a TKS carb there might be some other things.

How long did you run it?

 

[Fishfearme1174]

Have the muffs that push water on both sides so it intakes well. At idle it ran for minutes at increased Rpms no more than 2-3 seconds. How can I tell which carb it is?

 

[alldodge]

The TKS carb is in the link below and has a solenoid on it (item 1) in the link below

http://www.mercruiserparts.com/bam/subassembly/30906/11669/70

 

[Fishfearme1174]

Thx for that. Yes I have a tks carb. So is this normal for it to behave the way I described? And if not are there any adjustments I could make? Or what should I look at? I can't have it dying on me in the water.

 

[Fishfearme1174]

I should say I attempted a fuel pump pressure test at the metal fuel line inlet into the carb. I couldn't connect my t connector tight enough so when I started the engine it absolutely spewed fuel everywhere so I concluded the fuel is adequately making its way to the carb.

 

[alldodge]

It could be carb needs cleaning, idle needs adjusting if its not going fast enough. Timing may need to be checked. Need to know if it only does it when the motor is cold or all the time.

What's your engine serial number?

 

[Fishfearme1174]

I'll get the serial number for you. I did notice last time I took it out it would die mostly at the launch coming and going when trying to maneuver onto trailer. So both hot and cold. The idle is really smooth at about 750rpm so I'd say it prolly doesn't need an idle adjustment. More of a carb cleaning prolly. Any additives that may be a good simple first attempt at cleaning it?

 

[Fishfearme1174]

When I bought the boat in October I changed the oil which was filthy and replaced the plugs which were very worn. The fuel filter was recently removed and a fuel water separator added but runs just as good as always except for its ability to reclaim idle after revving. It did this just before the recent fuel filter and water separator installation also. Would it be a good idea to replace the distributor cap and spark plug wires?

I think what I have is a really good engine that just hasn't had the proper maintenance over the years so Im open to doing everything that could possibly impact the current issue I'm having.

 

[alldodge]

If the items look like they need replacing then yes go ahead, but right not I don't see where this is that kind of problem. If you loosing out as rpm's are increased, getting some hesitation, got a miss or other things, then yes

 

[Fishfearme1174]

Why did you need to know whether it does it when it's cold or hot because I answered that and nothing came about it. Was it relevant? Were you just curious?

 

[alldodge]

Why did you need to know whether it does it when it's cold or hot because I answered that and nothing came about it. Was it relevant? Were you just curious?

Your right, thought I did respond to it, thanks for reconfirming. Since it does it cold or hot then I would lean more to carb cleaning. You mentioned it's doing around 750 rpm which should be able to keep it going in neutral. If it drops below 600 in gear then may need to check timing and then compression if timing is good. Only other issue is if it was hard to start warm, but your good.

 

[Fishfearme1174]

Roger that. Got any suggestions on where to start on the carb cleaning? I'll google and search the archives to see what I can find. Thx for all your help.

 

[alldodge]

Need to get a kit (gaskets and seals) may also need an accelerator pump but maybe not. Need to make sure what model kit you have and get the kit for it. Needs a container to soak the parts and carb cleaner. Need air pressure to blow things out and thin wire to clean the small channels. Carbs are not difficult, just take time and correct measurments

 

[Fishfearme1174]

So can't just use a bottle of seafoam??

 

[alldodge]

So can't just use a bottle of seafoam??

No, IMO seafoam is snake oil, only thing I like about it, is wish I would have bought stock in it is stock holds are making a fortune from it.

You need carb cleaner

 

[Scott06]

Had a similar issue with a non tks mercarb, wouldn't hold an idle consistently. On back of carb where throttle linkage is , the screw holding the half moon shaped linkage piece that idle speed adjustment screw seats against had backed out - sometimes the idle speed screw would have something to stop against sometimes not. Real easy fix if this is it.