'83 351 stalls in idle gear.

Hi everyone this is my first post here on the forum, I'm also a new boat owner as of the beginning of June, and we have been having a great time so far with the old 2001.

The current issue with the boat is a stall in idle gear, seems to run great otherwise, but the stalling is a potential hazard when docking, loading the trailer, or picking up a skier. And it's an annoyance on a couple of long no wake zones on a nearby lake.

When the boat stalls, it seems like the motor bogs down to a stop while trying to idle fwd. then less often, after idling through a no wake zone the motor stalls when I give it throttle.




As far as what I've tried and a little background on the boat, the PO installed electric ignition, and apparently did not treat the gas before storing the boat. He also had a spare carb that needed rebuilding. So on my first lake test the cab was flooding the primaries, I got a needle and seat, as well as a rebuild kit for the spare carb. I swapped the needle and seat, then realized the floats needed adjusting, I got the float to a point that is no longer flooding the barrels (idk if I over adjusted). I siphoned a lot of the old gas out, and have been topping the tank off with good fuel each weekend, most all of the old stuff is probably gone. I used a vacuum gauge to set the idle mixture and it seemed to help the stalling but did not solve the issue.


I don't exactly know where to go with the issue next, I have the rebuilt spare carb done, but it is not installed/ adjusted. And I am not an engine guy so please bare with me.

I appreciate the help in advance.
Trevor

Also check timing. Should be set between 8-10 BTDC at idle.

I will put that on the to do list, I was told by a car guy (not a boat guy is what I'm getting at) that if the timing were off, it would generally run like crap, so I kind of wrote that off as a possibility

Power valve has nothing to do with a idle problem.
Check your idle mixture adjustments, 600 in gear is your target. A vacuum gauge will help track down a leak and get you setup right.

Lots of good Utube videos by Holley on how to tune your carb correctly.

PS:   timing is everything

Thanks for the replies guys, I finally got to the water on a day that wasn't overly crowded, i.e. Not a Saturday or Sunday. Anyway, I now have the idle down to the 6-700 range in gear, I also made a relatively descent attempt to adjust the idle mixture at that speed, the boat runs good under throttle but still tries and does sputter to death in idle.

On the to do list is check the timing and fuel pressure.

Anyone have a tips on where to gain access in to the fuel system?

Also I may not have mentioned it before but the PO did install electric ignition instead of points, and he also did a fuel filter conversion, if I recall he said it was a mercruiser filter. I will have time again this week to mess with the boat, so id love to have it figured out.


Thanks again for any help

Are both idle mix screws effective? Can either stall the engine at idle when closed? They should, else metering block is boogared up.

GottaSki wrote: Are both idle mix screws effective? Can either stall the engine at idle when closed? They should, else metering block is boogared up.

Both will choke out the motor separately.

Ok, it is either not getting enough fuel or getting too much air. By pumping it to full throttle you are injecting 30cc of fuel into the primary venturi via the accelerator pump.

Usually, if you have a vacuum leak the idle mixture screws will not kill the engine but do look for vacuum leaks for good measure. Confirm timing setting and check back with results.

Following my last post yesterday, I found this thread http://www.correctcraftfan.com/forum/forum_posts.asp?TID=7620&PN=3&title=forward-idle-and-stalling
And I saw the comment about some gaskets not fitting correctly, as well as an unrelated carb page about older auto motors having incorrect gaskets. A pep boys near the lake had "cut it yourself" gasket material that I had picked up yesterday just in case, so I decided to give it a shot. I traced an ultra thin Holley gasket that seemed to fit better. I cut out 1 for the carb and another for the spacer. I threw them on the boat and fired it up.

The boat ran better than I have seen it run yet, granted it was in the driveway, but it was noticeably better idling then I've experienced in the 2 months I've owned it. Also I let it run for 20-30 minutes, which was also longer than any other time I've seen. So tomorrow first thing, I will lake test. Double checking the idle speed, timing, idle mixture, etc. in Neutral, the idle was at 900 rpms, timing was at 9*

Thanks guys, I will continue to update as progress is made for future searches.

phatsat67 wrote: Very nice, Keep truckin. Another way you can test vac leaks quickly is to spray carb cleaner or brake cleaner at the base of the carburetor. If the motor idles up when you do that you still have a leak somewhere. The carburetor base to the intake manifolds take a specific gasket but the carb to spacer doesn't. I doubt the base is warped as that is pretty thick cast metal. The carburetor base is most likely to be warped. Sometimes you just have to bite the bullet and buy a new carb..

Thanks, if it will get me by tomorrow I will be glad to continue diagnosing the issue. The pro wakeboarders are in Atlanta at lake Allatoona and the finals are tomorrow. Ideally, the boat runs great out to the tournament area and then runs great back to the ramp at the end of the day. I will be getting there early and toting the tools, vacuum gauge and timing light. Hopefully the idle mixture and a double check of the timing will be all I lack for tomorrow.

Hopefully the last update on this thread. I went ahead and replaced the pcv valve, grommet and vacuum hose. The new pcv has an extra smaller port that is perfectly sized for the tubing on my vacuum guage, so it will stay capped when not in use.

The accelerator pump is now properly adjusted and solved the hesitation problem mentioned above.

I will be starting a new thread about a separate issue that I think is unrelated to this post.

Thanks for all of the help.