Rebuilt Carbs Now Can't Get It To Idle

[TruckDrivingFool]

Bought a boat with a 1971 50hp. It ran but didn't idle the best. I've done a laundry list to this so here it is I rebuilt the carbs, added a tach, new throttle cable, new impeller, and changed the lower unit fluid.

1. For the new cable it with the controls in neutral and the throttle against the stop pictured if the trunion goes in it should be adjusted right correct?

2. Per the manual I set the low speed needles to ~5/8 turn out. It will run if I use the warm up lever and if I adjust #1 in just a bit it will smooth out enough to bring the warm up bar down just a bit but I can't ever get it down to an actual idle to do anymore adjusting with out it sputtering and dieing.

3. Don't know if it might be connected but my new tach isn't working. Per the instructions I ran a wire (no wire in the factory loom) from the yellow to the send pole on the tach. I have it set at the 6P mark. The instructions said any yellow so I even tried it on the other leg (yellow/grey) and still nothing.

I can get a video of it running if it will help.

 

[luckynickles]

Re: Rebuilt Carbs Now Can't Get It To Idle

sounds like to me you are starving carbs of air the air jets should be turned out 1 1/2 rounds out then more if it doesnt idle right when you get the air right your prob gonna have to reset the idle screw you have all the way out older models require 1 1/2 turns out newer models might even need 5 to 5 1/2 rounds out try that first let us know

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

Thanks Lucky, I'll give that a try in the morning.

Any ideas on the tach? Going to recheck the stator in the morning too hopefully that's not it.

 

[oldrudedude]

Re: Rebuilt Carbs Now Can't Get It To Idle

Does the tach zero when you turn on the ignition switch?

I also have a 1971 50hp. My low speed screws are set at 5/8 out according to the factory manual and it runs great with that. If yours doesn't then it has a different problem. Make sure the needles are not chewed or bent on the ends. Idle timing should be set at 3*. If you have good compression and good spark, fuel pump supply to carbs is good with no gas or vacumn leaks.... then carb passages are still blocked. You would not be the first to miss something in there. Some of those passages are tiny.

BTW - If you are running it on muffs, expect it to idle fast. The rpm will drop from when the boat is in the water.

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

The first time I turned it on it came up to zero. Now it sits close but does move just a tad when the key is turned on.

As for the idle - Needles looked great, all sightable passages I could see light through, pulled the welch plugs and they are good. Only problem I did have was I absolutely couldn't get the needles to go through the replacement needle retainer sleeves that were in the kit, so I reused the old ones. Should I try to find them in the trash and drill them out/whatever it takes to get them to work?

Going to comp and spark tests also in morning just to be sure.

Thanks for the reply.

 

[oldrudedude]

Re: Rebuilt Carbs Now Can't Get It To Idle

It should go to zero every time you turn on the ignition. When you turn off ignition it may stay at zero or may float somewhere else. If it isn't zeroing check connection from purple wiring on ignition switch. My wiring diagram shows the sender wire should be attached to the SECOND SCREW FROM THE RIGHT on the terminal block. It should connect with the yellow/grey wire from the stator.

 

[oldrudedude]

Re: Rebuilt Carbs Now Can't Get It To Idle

The carb throat has three or four tiny holes clustered around the bottom of the throttle butterfly. This is where the fuel comes out at or just above idle. You can't see through them or see light coming through, but they have to be clear or your engine will idle poorly.

http://forums.iboats.com/showthread.php?t=500920&p=3382957#post3382957 Check out some of the rants and comments on this thread.

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

LOL I know what you mean oldrudedude, I have come to the conclusion you were RIGHT! I know its long, skim if you have to but Please read on as I still have issues.

For the record there are three holes under the welch/core plug on these and if you open the butterfly and shine light down the throat you can see daylight throgh all of them.

Compression test - 150/150 - good there.
Spark - I don't have an air gap tester yet but I tried the screwdriver method on #1 and did finally through shear luck get it to jump about 1/2". I also used my inline tester that I can somewhat gage the brightness and that looked good. (weaker you have a hard time seeing in the day) - so I think I'm good there.

I pulled the needles out to take this pic to make sure I wasn't missing something.

I think I may have even switched them carb to carb when I put them back. The 1 1/2 didn't do it (I tried just to be sure) and once warmed up I get this idle.

All I can think is that a small thread off of one of the inserts I had trouble with was in there. I will ask does that sound about right for running on muffs? Sometimes its a bit higher or lower and one time it really took off but that before I corrected another problem I found. For reference the video is the last time I ran it before coming inside.

Which brings me to testing the stator,

C&P from Joe Reeves found on an internet forum

The ohm reading between the stator yellow wires (charging circuit) should be 1.5 ohms +/- 0.5 ohms.


Between either yellow wire and ground, there should be no reading. Any reading indicates a short.


Between the Brown wire and ground, there should be a reading of 875 ohms +/- 75 ohms.

I know that when I tested it before I put everything back as it was when I got it but I'll take the blame for not catching it until resting today.

Pulled the wires off tested 1.5-1.4 ohms between the two stator leads

The to ground flumixed me a bit as the meter would quickly bounce between 0.00 and O.L (digital auto range) I did finally by making sure that the only thing touching the the wire was the test probe and I was in way touching anythin other than the plastic handle of the probe get readings of O.L which should be a no reading. Should stator is ok.(I think)

Paying closer attention to the wires this time as I had them really jumbled from making sure I had the right wires to test I noticed that the way it wired was wrong. Both stator leads were wired to the same terminal.

With the wiring corrected the tach still doesn't work and with the motor running a test of voltage across the battery posts shows 13.6v for a split second then drops to 12.4-12.5.

Finanlly - I ask does this sound as though the stator is ok and charging? Why will my tach not work? Could the wrong wiring have caused damage to it?

Also sometimes after shutting off I have to raise the start lever to get it to restart, is this normal for a warmed motor?

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

Well my magic moment is gone, I went out to try it again and it was very hard to start. Once I got it started it idled more like this which is similar to what it was doing before. I'll add I didn't shut it off it died out.

You can see its ruff and sputtering then it acts as though its running out of fuel. So I guess next weekend the carbs come back off and I'll try again. If there is anything else I should watch for in the process let me know.

Also anymore thoughts on the stator/tach/charging I still listening

 

[oldrudedude]

Re: Rebuilt Carbs Now Can't Get It To Idle

Sounds like you cleaned the carbs well, but have some electrical issues. The stator seems good, but if the coating on the stator winding is weak/cracked/burned the stator may still be shorting to ground from vibration or when hot. Check the rectifier connections and test rectifier diodes. A bad rectifier may cause the tach to not work. Do you know how to test the rectifier? Do you have a factory manual? http://www.marineengine.com/parts/parts.php

Before tearing the carbs down again you should check for consistancy of spark on each cylinder with a timing light. While your at it check idle timing to 3* btdc. Did you check ohms through brown lead of stator? Brown lead goes to the power pack.

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

Yes I have a factory service manual, am going to recheck the rectifier when I get home as a double check.

Spark consistancy am I just looking to make sure I'm not loosing spark? Do I need a special timing light or will an auto one work?

And no I didn't check the brown wire but will while rechecking the rectifier.

With time to think on the road today I'm considering just biting the bullet and replacing the stator and coils as insurance to not getting stranded. I noticed the lead on one to the power pack taped up to cover some spots that look chaffed or melted. I know it's throwing money at it but does that sound reasonable?

 

[oldrudedude]

Re: Rebuilt Carbs Now Can't Get It To Idle

An auto timing light will do. Yes spark consistancy to ensure you are not losing spark. While your at it check timing and adjust idle timing to 3* btdc. I am dead against replacing parts without doing a diagnostic and finding the problem first, but if that is what you are comfortable with I hope it solves the problem. The tests you have done to your stator so far seem to indicate that it is ok.

I have heard that the powerpack for that engine is no longer available but I am not sure about that.

Once the engine is warm it should restart with a flick of the key. If you have to use the cold start lever, I will guess the timing may be off. Using the cold start lever merely advances the timing a little.

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

First and foremost THANK YOU VERY MUCH for sticking with me on this oldrudedude I appreciate your time and efforts.

Don't know where my head was the other day when I was testing so I retested everything I have up to this point.

Stator is good, 1.4 across yellows, no readings yellows to ground, and between brown and ground 853ohm.

Rectifier no reading yellows to ground, either way <-----Junk

I can't find my timing light (can't remember last time I used it) I may have even decide it was a POS last time I used it and threw it away. I did run it and watch my inline spark tester #1 very consistent except for when I get a pop out the exhaust, it brightens up on that hit. #2 Not as consistent but close, once it starts dying out its shaking so its hard to tell, sometimes it looks like its dropping spark sometimes it doesn't.

I'll add - #2 coil isn't the one w/ the less than pristine lead. I notice the inline speak tester takes some of the bite out the spark on both cylinders but enough so that it starts hard and doesn't run long with on #2.

Will get a rectifier on the way still considering both coils, trying to find a timing light, and I obviously don't have the neon test light they talk about so where do I go from here?

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

Oh and as far as everywhere I've looked they list power packs for little over $100.

 

[oldrudedude]

Re: Rebuilt Carbs Now Can't Get It To Idle

Oh and as far as everywhere I've looked they list power packs for little over $100.

Yes, you are correct. Good news.

Before you toss the rectifier, ensure it has a good ground. I think you will find your tach will work and your engine will probably run better with the charging system working. You should find/borrow/steal a timing light.

BTW: the manual suggest surface gap plugs, but I (and others) have found your engine will idle better if you use regular electrode plugs. I am using Champion QL 77JC4 gapped at 0.030 in.

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

$30 I already ordered one, I will clean the mounts when I change it and see what happens. Also trying to find a no good friend that has a timing light.

You mentioning the power pack could that be weak and causing the slight irregularity on #2? Or would it be likely a coil? I already pulled the ground wire for both and scuffed between it and the mount may pull coil all the way off and scuff the block mount point.

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

New rectifier installed and now the tach works! WooHoo

But this led me to read on in my manual and I find this which adds to my charging questions,

Alternator Output Check

a. While the engine is running, an AC voltmeter connected to common engine ground and touched to either yellow stator lead connection at the terminal block, should indicate around 12 volts.

b. If no voltage is indicated when touched to each lead, check rectifier or stator assembly.

The first time I checked it on DC (I need better reading comprehension) and got 6.6 VDC once I reread I checked on AC and got 7.7VAC on each leg. Am I suppose to add them for my around 12? Should I assume so long as I have voltage of some sort its charging ok?

On to the idle problem, the tach shows it at 600-800 (no warm up lever) on the muffs for the short time it will idle. Could the idle just be set too low? Using my limited knowledge I'm guessing this is where the 3degBFTDC comes into play correct?

Still no timing light but I will have one by hook or crook tomorrow. What rpm should it idle on muffs to get me close to the correct in water idle?

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

I'm now the proud owner of the finest $40 timing light Autozone had to offer.

Its dark and getting late so I couldn't run it long but my initial run at it I could only get the idle down to 1200 timing was about 6deg and every hiccup is dropped spark.

Test the power pack? Throw coils at it? Would a sparkplug fouling show through the timing light?

Any thought on the above about charging will be accepted too.

 

[Daviet]

Re: Rebuilt Carbs Now Can't Get It To Idle

Does it drop spark on both cylinders or just one? A fouling plug will not show up with a timing light.
When I do a basic check on a charging system I use a volt meter on the DC setting, attach it to the battery to get non running voltage, probably arond 12 volts. Start the engine and run it at about 1200-1500 RPM and watch the volt meter, it should climb to somewhere around 13.5 to 14.5 volts. If it does that the charging system is OK. Some voltages will vary according to the out put of the charging system, you want to see the voltage increase with the engine running.

 

[TruckDrivingFool]

Re: Rebuilt Carbs Now Can't Get It To Idle

#1 seems to do it more but both cylinders are dropping spark.

When I checked the voltage across the battery posts with the motor running my meter shows 13.something volts for a split second then drops to 12.4-12.5.