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Jim
07-13-2001, 01:53 PM
I have a 1988 Z21 that I purchased last year which came with a 454 Mercruiser, which I believe is a 7.4l. I was only able to take it out a few times last year but I'm having a problem that has been occurring since the very first time I had the boat out. When the boat has been running for some time (20 - 30 min) and I take it off plane it won't throttle back up, not all the time more often that I like. The engine seems to be flooding but will still idle ok, once you start to throttle up it just seems to be dumping fuel down the engine. You can hear the engine trying to suck down as much air as possible and you can smell gasoline all the way up in the cockpit with the engine hatch close. The engine just seems to shake once you start to throttle up and wants to stall. I'm having the carb rebuilt by I was told it sounds more like a ignition problem. I checked the wires since their had been a recall on some of the Mercruiser wires and I also checked the ignition connections to make sure I'm not having a shorting problem. I also looked at the plugs which seem to show that the boat is running a little rich but that's not a surprise since its drowning in fuel when I have the problem. The funny thing that it last anywhere form 2 to 30 minutes and as soon as it comes it can go. The only reason I orginally started with the carb. was because the boat has only 150 hrs and it seems to have a problem idling when I first start it. I figured the boat had sat in storage for a few years and the owners only had it out a few times before they sold it. I should be getting the carb. back on Sunday but I thought I would see if anyone has experienced similar problems.

HeavyP
07-13-2001, 02:34 PM
I think you are on the right track. Sounds like a float in the carb sticking. You'll know soon enough.

Jamesbon
07-13-2001, 02:48 PM
Is your timing where it should be at idle, and advancing as RPM's increase?

Jim
07-13-2001, 03:20 PM
I have to check it but I was told that it could be possible that the timing is staying advanced which would be the mechanism within the distributor. Kind of unlikely but I don't really feel like running the boat in the yard for 20 minutes so I will have to bring a timing light out with me next time I go. The problem is we just had triplets and I don't really have much time. I have only had the boat out twice this year and the first time it only did it once for just a few minutes. The second time I had it out it lasted close to 30 minutes and then I only had a problem with it one other time that day for about 2 minutes.

FASTEDDIE
07-13-2001, 06:13 PM
Check the float level in the carb.It may be way out of whack causing this problem.

Blewbyu
07-14-2001, 11:50 PM
If you don't know the mechanical history,you really ought to change the wires and plugs just on general principles.If the plugs are glazed,toss them for sure (if they are Champions,toss 'em even if they aren't glazed).Often wires will test fine for resistance,and still be no good.Plugs can look good but have blowby on the insulator.
When you smelled gas, did you look to see if the carb or anything else was wet on the outside?Agree with the remarks above that float level probably the culprit.If it's a Holley,just unscrew the float level sight plugs on the side of the carb,and adjust the float/s with the screw/s on top of the carb (the ones with lock nuts)so that fuel just begins to dribble out the sight plug.
Good Luck
Regards-Jeff

Blewbyu
07-14-2001, 11:54 PM
BTW- If you have triplets,you are REAL lucky to have made it out twice!!!!You gonna be BIZZY!!!!!!