Cleaned Carb...Won't Start - Maxum Boat Owners Club

Rob Allen · 06-14-2010, 12:43 AM

I have a 1992 Maxum SCR2700 with a 7.4L Merc with a Rochester 4BBL Carb. I have noticed that since I bought it, it has been running a little rich. I went to make the adjustment to the "Leaner" setting and it idled perfectly with no smoke and no excess gas fumes. I should have left well enough alone, but noticed that the carberator was dirty. I took some carb cleaner and cleaned the carb, but made the mistake of not having the engine running. As soon as I attempted to start it, it start for about three seconds and shut off. Since then I have not been able to get it started. I have cranked it over for a while and a couple teases, but it will not start. I have let it sit for over an hour of doing nothing thinking it was flooded and still nothing. Just to be safe I moved the setting back to "Lean" and still no difference. Why was my caked up carb running and my clean carb not?

Thanks in advance,
Rob

seapuppy · 06-14-2010, 01:32 AM

well...a couple of things could be happening...1) now that it's running a bit leaner and cleaner...the fuel filter at the carb fuel inlet is crapped up and blocking the fuel...the needle valve is blocked from crap......the carb is flooded...if flooded..open the throttle all the way full and crank it till it catches...also check the the dwell and timing....points??...are they in good shape..one rich burning carb can really mess up timing...

just to think of a few things..
welcome to the zoo..
SP

ss3964spd · 06-14-2010, 01:34 AM

Sounds like you probably fouled the plugs Rob, squirting all the carb cleaner into the engine without it running.

Take a plug out, see if it looks wet. If it does just replace them all and it'll probably fire right up.

One other thing you might try is to push the center button on the throttle lever to disengage the shifter, open the throttle (and probably the choke too) and try cranking it.

Dan

Rob Allen · 06-14-2010, 01:43 AM

Thanks Dan, that is what I figured. What is the easiest way to access the plugs? I can get to one side, but the other.....

seapuppy · 06-14-2010, 01:59 AM

yeah..that's the other thing.....fouled plugs...

SP

ss3964spd · 06-14-2010, 01:17 PM

No prob Rob.

Easiest way to get to the plugs is have someone else do them, they'll give them back to you in a little bag.

Tongue in cheek aside, on your boat I have no idea, but it probably involves hanging upside down, body contorted in uncomfortable ways, and at least one REALLY long arm.

Dan

Quote:

Originally Posted by Rob Allen

Thanks Dan, that is what I figured. What is the easiest way to access the plugs? I can get to one side, but the other.....

TonyA · 06-14-2010, 01:57 PM

Hi are you shore you haven’t dislodged any wiring? , first thing I would do is to pull off a spark plug lead, ( the most easiest one) stick a spare spark plug in it ,ground the body ,crank the motor over and see if you have a spark at the plug , that will eliminate the electrics if you have a spark. Next is to pore a little fuel down the carbie and try to start it if it starts you have a fuel blockage somewhere (be careful with the fuel and put the flame arrester back on)

Rob Allen · 06-14-2010, 07:49 PM

Thanks Dan. I try to do as much myself as possible. Growing up around cars, racing, working with my dad on engines, I have no excuse. Actually no excuse for making this booboo either. Last year I had the outdrive completely rebuilt, gimble ring replaced and a number of blisters repaired, all of which I am not comfortable doing and glad to outsource. Changing plugs, wires, rebuilding distributor (as long as I can reach) I am capable of (maybe

). Yes, the contortion thing, that is exactly what I will have to do. I need one of those spy repellers to hang upside down.

Quote:

Originally Posted by ss3964spd

No prob Rob.

Easiest way to get to the plugs is have someone else do them, they'll give them back to you in a little bag.

Tongue in cheek aside, on your boat I have no idea, but it probably involves hanging upside down, body contorted in uncomfortable ways, and at least one REALLY long arm.

Dan

Tony - thanks for the feedback. I would be more apt to think something like this could have happened except the boat was running minutes before I made the mistake of cleaning the carb and absolutely nothing changed except for carb cleaner being sprayed. I was actually going to check for spark and talked myself out of it for this exact reason. I truely think Dan hit the nail on the head and was my first thought, fouled plugs. Thanks again.

Quote:

Originally Posted by TonyA

Hi are you shore you haven’t dislodged any wiring? , first thing I would do is to pull off a spark plug lead, ( the most easiest one) stick a spare spark plug in it ,ground the body ,crank the motor over and see if you have a spark at the plug , that will eliminate the electrics if you have a spark. Next is to pore a little fuel down the carbie and try to start it if it starts you have a fuel blockage somewhere (be careful with the fuel and put the flame arrester back on)

Seapuppy - I somehow missed your first post -- sorry, didn't mean to snub you.

seapuppy · 06-14-2010, 09:29 PM

no problem...I have that affect on women and dogs...

SP

ss3964spd · 06-16-2010, 04:23 PM

Ditto Rob. I know the basics about out drives but can bore anyone completely to death talking about engines and transmissions. First question is always "what was the last thing I did". Usually points me in the right direction and the problem is typically turns out to be self inflicted. LOL

Were you able o resolve the no start?

Dan

Quote:

Originally Posted by Rob Allen

Thanks Dan. I try to do as much myself as possible. Growing up around cars, racing....