Fails to choke at start

[gene8084]

1974 Mercruiser Mdl 888, Ford 302, Engine SN: 3893895, Holley Carb.

The engine runs great once I get it started.
a. recently had the Starter & Altenator rebuilt
b. replaced points and condenser with and Ignitor
c. replaced plugs, cap, rotor.
d. replaced fuel pump
e. replaced fuel/water separator

Still have trouble starting. Pulled the backfire preventor and I could see that the electronic choke was not closing.

How to diagnose / isolate the problem to the electronic choke?
1.) should it be open when off?
2.) should it close when cold and cranking?
3.) can I test for voltage when cranking?
4.) if so, how many volts should be there when cranking?
5.) are there other components prior to the electronic choke that could effect its function?

I'm not opposed to replaceing the electronic choke, but I'd like to isolate the problem to the choke itself before spending the money...and I'm not sure how to do that.

Thank you.

Gene

 

[a70eliminator]

Re: Fails to choke at start

There ia an adjustment on the choke housing, it's right on that black plastic cover here the wires are plugged in, you have to loosten the 3 screws around the retainer ring and rotate the plastic cover till the hash marks line up, if you look close on the black cover it should have a rotation arrow and it's marked lean-rich. The choke should be closed when the engine is cold wires or not, the electrical only comes into play when the engine is warm. If you can't get the choke to close by turning the plastic choke cover than look for the linkage off the choke plate out of the actuating arm, though i cant see that ever happening even if the clip came off. I'm quessing someone just spun the choke cover to completely take the choke out of the sytem for some reason or another, probably had a flooding condition and tried to remedy by takeing out the choke.

 

[wncrjb]

Re: Fails to choke at start

IF the first thing you do is pull the spark arrestor when the engine is cold and not run in a while ( over night ), the choke should be OPEN. You need to open the throttle a little bit to SET the choke to the closed position.

IF the choke does not close when the throttle is moved off the idle position, you may have a linkage problem or the choke has been adjusted to a very lean position as a70 eliminator has said.

IF the ambient temperature is warm then the choke may not close at all or may only close part way. I have an electric choke on mine that is adjusted right on the money and anything above 65 degrees ambient temp, the choke remains open when starting the engine "cold".

To test the choke electric unit, turn the key to the ON position, you should have 12 volts ( +/- )at the wire going into the choke housing.
Turn the adjuster to a position where the choke is closed but not touching real tight. With the key on, the choke should begin to open real slow after a few minutes.

If you have power going into the choke housing, and the choke butterfly does NOT open, you have a bad choke electric unit. IF the butterfly does open after a few minutes, then it works, and you only need to get it adjusted.

Hope this helps.

wncrjb

 

[gene8084]

Re: Fails to choke at start

wow, that was fast. Thank you. At least I understand how it should be working.

To my surprise when I went out this morning to check it the choke was in the closed position. I check and it certainly moves freely and no clips missing.

So, I'm stumped as to why it was open yesterday. I had been cranking it trying to get the engine to start, but it had not started and therefore not warmed up before I pulled the backfire preventer and saw it open.

Looking at the hash marks, left to right, clockwise, it's set about 2/3. I could not read whether that more rich than lean, but I'll see if I can see with a magnifying glass.

I'm open to more suggestions, else I'll start checking it before attempting to start to see if I can find a pattern ...intermitent problems rrrrrggg!

I managed to ruin my seawater pickup in the process when it started unexpectedly with the water off, so I'll have to resolve that before getting back to troubleshooting this issue. (I'm learning more than I'd like to about boat engines ... this one was a hard way to learn a lesson)

Thanks again...I'll be back.

Gene

 

[gene8084]

Re: Fails to choke at start

Ah, now there a thought... it was quite warm outsite yesterday, probably the reason it was open. However, warm or not this engine does not want to start without choking first.

Can you tell me more about the spark arrestor? Where's it located? How does it work?

Thx

 

[Haut Medoc]

Re: Fails to choke at start

Ah, now there a thought... it was quite warm outsite yesterday, probably the reason it was open. However, warm or not this engine does not want to start without choking first.

Can you tell me more about the spark arrestor? Where's it located? How does it work?

Thx

Didn't see that mentioned anywhere......
Are you referring to the flame arrestor?.....
I have the same engine, carb......
The first thing you need to do is check for voltage at the choke.......
How clean are the connections?......

 

[gene8084]

Re: Fails to choke at start

I was referring to "wncrjb's" post to me...he said, "IF the first thing you do is pull the spark arrestor when the engine is cold and not run in a while".

Next, I did check the voltage at the choke electric unit, key to the ON position, and I had 12 volts.

Now that the engine was exposed to the sun I sat there for 5 minutes and watched it open slowly before my eyes...very cool.

So, alass ... my question is, with an electronic choke, how do you choke when it's warm outside?



"

 

[Haut Medoc]

Re: Fails to choke at start

You will need to fiddle with the aforementioned adjustment.......
The only time my engine needs choke is when it is dead cold, other than that it will either start with no pumping, or one pump if it sat for awhile...​

 

[gene8084]

Re: Fails to choke at start

ok, thx for that.

We'll see hw that goes. Pumping didn't do it for me yesterday without choking, but I guess I'll have to check a few more things first.

 

[MikDee]

Re: Fails to choke at start

All that was explained about how an electric choke works previously here, is right, But I think if you do not start your engine right away, the longer you leave the key on without starting, the warmer the electric element heats the choke, rendering it open all the way, sometimes when your engine is still cold. Usually once your engine is warmed up once for the day, you shouldn't need the choke anymore.

 

[Boomyal]

Re: Fails to choke at start

Look down the carb throat while having someone slowly pump the throttle. (you may have to hold choke butterfly open). You should see two distinct streams of fuel, squirting from the 'uvulas' down into the venturis. If you do not, you have an accelerator pump problem. This can affect you, hot or cold and for proper acceleration as well.

If the whole inards are soaking wet, then you have a ruptured power valve.

As you may have discovered, unlike an automotive carb, you do not have to goose the throttle to get the choke plate to close when it is cool out. That butterfly will respond to temperature (assuming everything is freed up and your thermostat cap is properly adjusted) in real time. Marine carbs do not have the fast idle step cam that auto carbs have so there is nothing to hold the choke open when the temperature drops.

 

[Haut Medoc]

Re: Fails to choke at start

Definately check the accelerator pump......​

 

[gene8084]

Re: Fails to choke at start

Thanks all.

I'll follow your advice and let you know how things work out soon as I finish the sea water pump project and I can getting running again.

 

[gene8084]

Re: Fails to choke at start

Ok, I'm back. Pump project done.

It appears your right about the accelerator pump problem. I do not see two distinct streams of fuel squirting from the 'uvulas' down into the venturis.

What I see is a slight gurggling of fuel from in between the barrels. I can get it to start by choking and it will run, idle, and start again, but won't idle well until I've given it some gas in neutral.

Should I pull the carb and have it rebuilt by someone with experience or is this a job I can reasonably do myself? and if so, any suggestions on getting parts?

These are the numbers I can read on the main body below the butterfly choke.
D1JJ-5510-B1
LIST-6317-1
322
and on the "Primary Metering Body Assembly"
6804
63171

All of the numbers above are stamped, not cast.

Thanks...

 

[Boomyal]

Re: Fails to choke at start

Most likely a bad accelerator pump diaphram. Should be easy enough to change yourself. Also make sure that you're getting full actuation on the accel pump lever. It has about 5/16" total downward travel and should be fully depressed when you have the throttle wide open. There is an adjustment screw that rides on an arm actuated by the main butterfly linkage.

For test purposes you can insert a flat blade and press it down by itself without opening the throttle, but you need to be sure that is fully depressed when the throttle is wide open. If not back the screw out until it is.

 

[gene8084]

Re: Fails to choke at start

ok, I ordered a rebuild kit from Aftermarket Marine. I assume everything I need is in standard kit.

Fingers crossed.

Thanks again...stay tuned. (it'll be a another week)

 

[Don S]

Re: Fails to choke at start

ok, I ordered a rebuild kit from Aftermarket Marine. I assume everything I need is in standard kit.

I would assume just the opposite from aftermarket kits from anyplace. But that is only from my experiences after years of working on these things for a living. Things don't fit, or aren't there, or not quite right, or not even close.

 

[Boomyal]

Re: Fails to choke at start

I would assume just the opposite from aftermarket kits from anyplace. But that is only from my experiences after years of working on these things for a living. Things don't fit, or aren't there, or not quite right, or not even close.

Heck Don. I don't think I ever saw an OEM Holley kit that you could ever figure out what to do with. Too many variations and too many parts so you never know what you missed when you put yours back together.

I suppose, at least, that every thing in the OEM kit at least fits.

 

[MikDee]

Re: Fails to choke at start

Been there, done that, you guys just put it into words!

 

[gene8084]

Re: Fails to choke at start

hmmm, so I'll take that to mean it's a roll of the dice, damed if you do, damed if you don't.