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View Full Version : Hard to Start at Altitude - '84 S&S w/ 454


sfitzgerald351
09-19-2012, 01:28 AM
After a few years away from the board (little kids and work will do that), I'm hoping the gang here can help me out.

I've got an 84 S&S with a 454 and a 4010 carb. We moved to Denver last winter and I've only had a chance to get out on the water a couple of times, but my boat is incredibly hard to start here. I did have the boat winterized here and tuned for the altitude by the local MC dealer. All they did was adjust the idle A/F mixture. I also repropped the boat. Once started it idles smooth and runs great. WOT is right at 4400 where it should be. It idles about 700 or so very nicely. I do notice a bit of a loss of power which is to be expected, but other than starting the boat seems to run great.

When cold, I haven't figured out the trick yet. It seems to take a 4-5 (or more) tries with lots of pumping and holding the throttle wide open to get it to kick over. When warm it'll start with just a bump of the key if it hasn't been off for more than a minute or two. After that, it'll take a pump or two and will then fire up.

At sea level, to start it I'd give it a good 4 or 5 pumps, leave it at half throttle and it'd generally fire on the first try. When warm, I'd occasionally have to give it a single pump if we sat for more than 5-10 minutes.

I'm at 6,000 feet now and heading up to 8,000 next weekend for a less crowded lake and some fall folliage and hope to improve this prior to then.

Unfortunately I was laid off late this summer (but seem to have good prospects) so taking it back to the dealer is out of the question right now.

Any help on where to start with this one is appreciated. I was thinking choke, but not sure how to start diagnosing this one.

Thanks!

Scott

thatsmrmastercraft
09-19-2012, 11:01 AM
Some things to deal with here:

Spark plugs...replaced and correctly gapped recently and replaced withing the last two years?

Points of electronic ignition.......if points, replaced within the last two years and dwell set correctly? Timing set correctly too?

Distributor cap and rotor replaced withing the last two years?

Check the accelerator pump operation. While you look down the throat of the carb, have someone work the throttle and watch for proper streams of fuel squirting into the carb. Likely this is the problem.

4010 carbs are notorious for poor running characteristics, but are usually good starters. You are likely due for a rebuild, but might consider switching to a 4160 of the correct size.

Also, I'm not altitude expert, but I think the main jets need to change for proper running.

sfitzgerald351
09-20-2012, 01:23 AM
Did some more checking tonight.

Plugs were replaced when the boat was tuned this winter. Dealer says they adjusted idle A/F mixture, idle speed and timing so I should be good there.

Definitely am in need of new cap/rotor. Boat doesn't get used much, but 2004 was a long time ago... :o Will order up a set tomorrow.

Accelerator pump works well. 2 nice streams of fuel.

I was looking at the choke and finally found my Holley/PCM manual from the move. Of course, this boat / engine combo isn't really documented well so it's hard to always know what's what. So I actually can't tell what kind of choke I have. It has 2 wires running to it, but I don't know what they do?

I was able to verify that the choke does unload at WOT, which may be why the boat has better success starting with the throttle there as it wants a bit more air? Just guessing here, really need to do a few more cold starts to see if I can spot a good trend.

Also came across an interesting statement that said I should "set" the choke by moving the throttle to WOT and then back to start the boat. I've never done this in my life. I've always (at sea level) just pumped the throttle a few times to get the fuel into the carb and then left the throttle at about 1/3 or so. I've never gone to WOT. In looking at the carb, I didn't see that anything happened at WOT other than the choke plate unloading/opening partially. Maybe this is something for a different setup? Like I said, it's tough with this boat since none of the manuals I have document the setup I have.

What procedures do you all use to start a cold engine? Maybe I should be doing something different?

Thanks so much!

P.S. I'm probably due for a carb rebuild this winter and will change the jets then. I have to partially tear down the carb to get to them right? Everyone I've talked to up here says the boat should run fine a bit rich and they don't usually bother changing jets.

thatsmrmastercraft
09-20-2012, 10:30 AM
Choke operation is simple. There is a coil spring inside the choke cap. When the key is in the run position, battery voltage is applied to the cap. The different metals in the spring heats at different temperatures, which causes the spring to wind up, thereby opening the choke. When you pump the throttle you allow the choke linkage to set to the cold start position. You don't need to go to WOT, but instruction manuals are written so that you don't just pump it a little and not allow the choke to set or provide full accelerator pump operation which is necessary for easy cold start. Choke adjustment is done on a cold engine. Set the choke with on stroke of the throttle. The choke blade should close almost all the way. Specs call for about 1/8" or so depending on which carb. Not a critical adjustment as long as it isn't closed tight. With key on, engine running or not, the choke should be fully open in roughly one minute. Adjustment is done by loosening the three screws and turning the choke cap accordingly. If you can't get the choke to open in that amount of time, it's time for a new choke housing.

Cold start is typically one pump of the throttle, and leave the throttle advanced slightly...then hit the key. If you have a points ignition that is worn and not set correctly, sometime it is necessary to be more active with the throttle as you crank the engine.

Are you still running points or have you converted to electronic ignition?

Last thought is these engines run rich under normal operation, so if your plugs are a little dirtier than usual, the starting won't be as quick and easy as it might be.

To change the jets, the primary fuel bowl needs to be removed. Not a big deal, but if you are planning on a carb rebuild, that is a fine time to do it. I would get a blue re-useable primary bowl gasket so that any future jet changes can be accomplished with a minimum of effort.

sfitzgerald351
09-20-2012, 12:07 PM
Thanks for the info. I am running electronic ignition.

I suspect part of my issue may be that the choke plate is fully closed when cold. I'll need to check it out again tonight, but I'm pretty sure it's closed tight. Hopefully a couple of tweaks and the new cap/rotor will get this starting better.

Many thanks.

thatsmrmastercraft
09-20-2012, 01:51 PM
Sounds like you are on the right track. Keep us posted.

MikeyOrange88
09-20-2012, 02:11 PM
I used to have a similar problem on my '88 Tristar 351W with 4160 carb. When cold starting such as before I would head off to the boat ramp, No matter how much pumping of the throttle I would do, it would just not start. I would crank it continuously for 30 seconds or so. My standard procedure became to fire a shot of starting fluid into the primaries, then crank as normal with transmission disengaged and throttled up slightly. It would start up immediately. After the first start, it would fire up every time at the bump of the key, always would run fine. I rebuilt carb. and adjusted the choke (closed when cold and then opens soon after start). Problem solved. I believe it was more of a sticking needle or something in the carb.

sfitzgerald351
09-21-2012, 01:13 AM
Played with the choke tonight. There is nothing mechanical that sets the choke when operating the throttle. It seems to be all electric and I'm assuming there is a vacuum inside to help pull it open when the motor is on? With the key on it took a good 5 minutes to open and almost 10 to shut so it sounds like I may need a new choke. My only question is that the positive wire for the choke is hooked up to the positive on the coil and only getting 6V. Battery was putting out almost 12V before the ignition resistor. Is the choke supposed to be hooked up to the coil or should it be getting the full 12V and I need to use a different source (I'm thinking battery side of resistor, but maybe there are better options?).

Thoughts? Is switching wiring all I potentially need to do or should I get a choke on order as well?

Scott

j.mccreight@hotmail.com
09-21-2012, 10:09 AM
Played with the choke tonight. There is nothing mechanical that sets the choke when operating the throttle. It seems to be all electric and I'm assuming there is a vacuum inside to help pull it open when the motor is on? With the key on it took a good 5 minutes to open and almost 10 to shut so it sounds like I may need a new choke. My only question is that the positive wire for the choke is hooked up to the positive on the coil and only getting 6V. Battery was putting out almost 12V before the ignition resistor. Is the choke supposed to be hooked up to the coil or should it be getting the full 12V and I need to use a different source (I'm thinking battery side of resistor, but maybe there are better options?).

Thoughts? Is switching wiring all I potentially need to do or should I get a choke on order as well?

Scott

choke needs 12v for proper operation, a rewire is in order, yes use the 12v side of ballast resistor...

sfitzgerald351
09-21-2012, 01:35 PM
Re-wired the choke. Now it fully opens in a smidge over 2 minutes and gets to about 3/4 open in about a minute. It does take it a good 10 minutes to close. Does this sound about right? In either case, seems to be better and I think the next step is to simply wait for the new cap/rotor and then see what happens, unless anyone can think of anything else to try.

sfitzgerald351
10-01-2012, 05:58 PM
Got the boat out with the new cap/rotor and the rewired choke. Due to the weather we went down in altitude to 4900' instead of going up to 8000' (I live at 5900').

Cold starts the boat fired right up after 2 cranks and about 3-4 shots of the throttle. When warm it generally fired on the 2nd try, occasionally on the first, no throttle needed. So things seem to be better, but I'm curious as to how it'll start up higher to see if I get more problems or it's the same as this past weekend.

I suspect this carb would benefit from a rebuild. I've had the boat for 10 years and haven't touched the carb and who knows if anyone prior to me did. If one is generally mechanically able how hard is it to rebuild a carb? Are there good instructions somewhere to follow?

Also, noticed some funny discoloration on the new prop. Is this normal as the finish wears off? Sorry for the bad photo, the boat is stuffed in the back of the garage.

Thanks all!

thatsmrmastercraft
10-01-2012, 06:31 PM
Holley 4160 is extremely easy to rebuild. Not many adjustments, and they are all simple. Biggest issue is soaking it long enough to get everything loosened up and having a compressor with an air nozzle to really blow the circuits out well. Take lots of pictures of everything you take apart. Buy a marine rebuild kit. Go to the Holley site to get the correct part number and buy it through Amazon. No shortcuts or skipped steps.....follow the instructions exactly and you will be fine.

sfitzgerald351
10-01-2012, 06:52 PM
I've got a 4010 carb, not a 4160. Just as easy to rebuild?

GT500 MC
10-01-2012, 07:00 PM
Scott - Where did you guys get out on the water? Here in Denver? Not much water left around here.

sfitzgerald351
10-01-2012, 07:07 PM
Went down to Lake Pueblo. It was a beautiful weekend and we pretty much had the whole lake to ourselves. Only saw 1 other skier and a handful of fishermen.

thatsmrmastercraft
10-01-2012, 07:12 PM
I've got a 4010 carb, not a 4160. Just as easy to rebuild?

Same procedure, though from all I have heard on here, 4010 carbs are notorious for poor idle quality. Many here have converted to an appropriate sized 4160 as they are so bulletproof.

sfitzgerald351
10-01-2012, 08:22 PM
I've never had an issue with idle quality. Maybe the 4010 works better on the big blocks? In any event, until I'm employed again there's no money for a new carb so a rebuild is probably a good winter project for me.

Scott

thatsmrmastercraft
10-01-2012, 10:07 PM
I've never had an issue with idle quality. Maybe the 4010 works better on the big blocks? In any event, until I'm employed again there's no money for a new carb so a rebuild is probably a good winter project for me.

Scott

Been down that street before. Hit Amazon for the best deal on the carb kit and go to Napa for a gallon can of carb cleaner for best pricing.