Fails to choke at start

[gene8084]

Re: Fails to choke at start

You really need a service manual sir. That said -- I'll give you a brief overview. Setting the choke means moving the throttle forward to allow the choke plate to close. Whether or not it actually does is not important at this point. The point here is that you can't adjust the choke if the choke is not "set" (allowed to close). Now if the choke plate is not fully closed, adjust the disc. Then start the engine. When the engine starts, it develops manifold vacuum which is fed to a choke pull off. Vacuum acting on the choke pull off diaghram sucks the plunger inward, pulling on a linkage that pulls the choke plate open a little to allow the engine to idle properly. If the diaphram in the choke pull off is ruptured, you have a vacuum leak and the pull-off cannot operate so the choke remains fully closed hence the rough idle or no idle. On some carbs the choke pull-off is built into the carb itself and operates via a vacuum piston. Then the choke heater (the electric heating element behind the disc) begins to open the choke fully. If that's not working the choke will not open either. There you have it. Perhaps now you can understand the value of a service manual because this description would be accompanied by pictures. You might make a trip to the library as they often have service manuals you can check out.

I appreciate your patience. I have what I thought was a pretty good shop manual. It's great at describing overhaul (disassembly/assembly) of systems, but does describe how and why things work the way they do. I've also downloaded a couple and bought a CD based version of another on eBay. So, I'm going to paw through all three and see if I can find anything remotely like you provided.

If all that fails... I'll keep looking for a mechanic willing to work on this old tug. I certainly don't mean to impose.

 

[a70eliminator]

Re: Fails to choke at start

Update your public profile, there maybe someone closer than you think that could offer a helping hand, I know a Gene Brown, my kids baseball coach.

 

[Boomyal]

Re: Fails to choke at start

...... Setting the choke means moving the throttle forward to allow the choke plate to close. ......

at least this part is not correct Silvertip. Marine carbs do not have a fast idle cam that requires the throttle to be opened to allow the choke plate to assume it's temperature directed position.

In other words Holley marine choke plates will open and close as the temperature dictates, independant of the throttle position or actuation. If this was not the case, then you could never shift an OD into gear when the fast idle cam was actuated.

...and yes gene, a pet peeve of mine, not filling out ones location in the profile is very aggravating. Many a question could be better answered if ones location was shown there!

 

[gene8084]

Re: Fails to choke at start

Pull the flame arrestor off, note the position of the choke plate.....

Pump the throttle, the choke should close.....
Stick a pencil in it, to keep it slightly open.....
Start the engine......
Run it at 1300rpms, after it has run for 20 seconds, put a wad of duct tape in the linkage to keep it (choke plate) wide open......
If you have a '74 888 your firing order is 1-3-7-2-6-5-4-8......

After you bring it to TDC, do what A70 eliminator suggests, but I will bet the correct order is the one above......​

Your right...the order is 1-3-7-2-6-5-4-8.

 

[gene8084]

Re: Fails to choke at start

Hey guys...just reporting in.

Well I've done everything you said. (bottom line, she still won’t idle)

1. Set the electric choke disc when cold.
2. Talked to Pertronix and replaced the plug wires (had some concern that the old cables were solid core and that's not good for the Ignitor).
3. Replaced the coil.
4. Replaced the resistance wire from the choke heater to the coil with a piece of 12 gage wire to ensure the I'm getting full spark from the Ignitor after it's running.

Pump it a couple times, it'll start briefly (much better than before), so I’m sure I didn’t have the choke set right for starting. The choke behaves exactly as you've all described. It starts to open at as ambient temp rises or the engine warms from a couple momentary starts.

I suspect even after the Carburetor rebuild that I’m not getting enough gas to keep it running. I'm pretty sure the bowl is set right. I remove the sight plug and the fuel is right at the bottomg of the thread (although I haven't done this running). I can hear the vacuum. I’ve tried to jaz the throttle a bit once it starts, but it still quits.

Unless someone has a better idea, I’m considering pulling the carb again and taking it to a pro. I found a shop that sells and services Holley carburetors. I’m convince that’s where the problem is.

Last, I tried to find a mechanic throught the local boat yards. Left messages/emails, but no one seems interested in looking at this old boat. Guess they’re all busy winterizing for their regular customers…those with the big money. 

 

[Boomyal]

Re: Fails to choke at start

In the above, I did not see a confirmation that you had two distinct streams of fuel squirting down the venturis when you depressed the throttle. One or two slow throttle depressions should normally do. Choke settings count for naught when you do not have this intitial fuel charge.

 

[Boomyal]

Re: Fails to choke at start

Your right...the order is 1-3-7-2-6-5-4-8.

Correctamundo, the 888 uses the 351w firing order due to the camshaft.

 

[gene8084]

Re: Fails to choke at start

In the above, I did not see a confirmation that you had two distinct streams of fuel squirting down the venturis when you depressed the throttle. One or two slow throttle depressions should normally do. Choke settings count for naught when you do not have this intitial fuel charge.

It's a long thread -> October 12th, 7:41 p.m. post.

"...Now I have the two distinct streams of fuel squirting from the 'uvulas' down into the venturis and I confirmed that I'm getting full actuation on the accel pump lever..."

That was not the case before rebuiling the carburetor, so there has been progress here. I'm sure resolving the two streams has been the difference in getting it to start consistently. Now it's getting it to idle or run with the trottle advanced. It just feels starved for fuel even if I try to jaz the trottle as soon as it starts when it won't idle.

Somthing I had not considered earlier was restriction in/from the builtin fuel tank. So, I'm going to pick up a small deck tank (3-6 gal) and rule out a fuel delivery problem. The fuel pump is new, the fuel lines look good, but when I watch the small inline bowl fill from empty state it seems slower than I'd expect. So, I was thinking maybe a clogged/restricted fuel pickup in the tank. Make sense?

Gene

 

[a70eliminator]

Re: Fails to choke at start

By now we're all thinking (at least I am) that you are persistant but probably about ready to get the torch out if your 6 gal. can trick don't work.
I'm sure you probly already tried this but just in case you haven't here goes, bring up #1 to TDC with timing marks aligned @ TDC, take off cap and look at the rotor it should be pointing directly at the #1 contact pin not a little after or a little before but directly on it, this test could determine if harmonic balancer sliped or chain jumped. When you crank on the starter does the engine seem to crank as fast as the starter can turn it or does it kinda pulse with compression as a normal engine should. If your cam was wiped a compresion test would be the tell tale. I don't remember you performing a compression test?
Also on a side note, when you installed the pertronix, did you
gap the module corectly? I think they give you a piece of thin plastic to gauge between the module and the pick-up.

 

[MikDee]

Re: Fails to choke at start

.

Somthing I had not considered earlier was restriction in/from the builtin fuel tank. So, I'm going to pick up a small deck tank (3-6 gal) and rule out a fuel delivery problem. The fuel pump is new, the fuel lines look good, but when I watch the small inline bowl fill from empty state it seems slower than I'd expect. So, I was thinking maybe a clogged/restricted fuel pickup in the tank. Make sense?

Gene

Gene, this is a Good Idea! Those built in tanks usually get debri in their fliters, and antisiphon valves, over the years. Nice boat by the way, I was seduced by the styling of those many years ago, but never had the opportunity, or money, to get one.

a70 has a point, retarded timing, another item to check if it has consistent hesitation, & backfiring thru the carbs, but I would check each of these items one at a time.

 

[gene8084]

Re: Fails to choke at start

By now we're all thinking (at least I am) that you are persistant but probably about ready to get the torch out if your 6 gal. can trick don't work.

Well, I have a 1952 Ford 8N tractor that has given me fits at times. I guess I've just learned that you can only eat and elephant a bite at a time...but if I do get the torch I'll take pictures.

I'm really hoping after this exhaustive exercise I'll have a reliable boat that I can rely on. That's why I'm not too concerned throwing a few extra dollars at new parts.

I'm sure you probly already tried this but just in case you haven't here goes, bring up #1 to TDC with timing marks aligned @ TDC, take off cap and look at the rotor it should be pointing directly at the #1 contact pin not a little after or a little before but directly on it, this test could determine if harmonic balancer sliped or chain jumped. When you crank on the starter does the engine seem to crank as fast as the starter can turn it or does it kinda pulse with compression as a normal engine should.

I haven't done this. Actually, my goal had been to get it running and verify the timing. It sounded really good when it was running so I figured the timing was not so far off that it wouldn't start and idle.

At this point I'll add this test to the list.

If your cam was wiped a compresion test would be the tell tale. I don't remember you performing a compression test?

I don't have a compression gauge. I was looking at one at sears the other day but held back from buying another toy. I reasoned that since my oil pressure was good when it was running that compression was not a significant problem. Good/Bad assumption?

Also on a side note, when you installed the pertronix, did you
gap the module corectly? I think they give you a piece of thin plastic to gauge between the module and the pick-up.

Yes, got this. I actually had to drill a slighly bigger hole in the Ignitor plate because there was virtually no gap as shipped.

 

[gene8084]

Re: Fails to choke at start

...I was seduced by the styling of those many years ago, but never had the opportunity, or money, to get one.

It really caught my eye and seemed like something where I'd have a lot to work with. I've poked around a lot to try to find others with this boat. Haven't found anyone yet. I'd love to get my hands on some of the original design data on the boat itself. I/O is well documented.

It looks like you did pretty well in the end when you bought your boat.

 

[a70eliminator]

Re: Fails to choke at start

I really think your problem is ignition related and not the carb, I think I would go back to points and condenser at least till you get it hashed out. Good luck and keep posting.

 

[gene8084]

Re: Fails to choke at start

I really think your problem is ignition related and not the carb, I think I would go back to points and condenser at least till you get it hashed out. Good luck and keep posting.

ok, I considered that.

So I have simply priortize.

1. back to points and condenser
2. external tank ($$)
3. carb work/adjustment ($$) and a bigger job

 

[Boomyal]

Re: Fails to choke at start

I wouldn't futz with an external tank. The fuel pickup in your '74 tank is pretty straight forward and easy to check. (assuming you can get to the pickup fitting.) Your boat predates the requirement for an anti siphon valve so it should be straight through and I doubt there is any kind of filter on it.

To be sure, locate the fitting, remove the gas line and unscrew the fitting from the tank. Or to start, just disconnect the fuel line at the fuel pump or before any filters and blow back thru it into the tank. You should have very little resistance once you get a little pressure up.

I also really doubt you have a fuel (other than carb or possibly ignition) issue. Partial fuel line restrictions usually let a motor idle and only show themselves when the demand gets higher. When you are able to start it, it is not soaking wet down around the venturis is it?

 

[gene8084]

Re: Fails to choke at start

I wouldn't futz with an external tank. The fuel pickup in your '74 tank is pretty straight forward and easy to check. (assuming you can get to the pickup fitting.) ... To be sure, locate the fitting, remove the gas line and unscrew the fitting from the tank. Or to start, just disconnect the fuel line at the fuel pump or before any filters and blow back thru it into the tank. You should have very little resistance once you get a little pressure up.

I tried to get a close look at the fitting yesterday but I can't tell if the fitting is welded or threaded. I can't aford to break it or crack it. I'll try to blowing the line out as you suggested first.

I also really doubt you have a fuel (other than carb or possibly ignition) issue. Partial fuel line restrictions usually let a motor idle and only show themselves when the demand gets higher. When you are able to start it, it is not soaking wet down around the venturis is it?

I wouldn't say its soaking wet, but I am pumping it a couple times before trying to start. So, when it quits and I look down the barrel you can certainly see that it's been wet...but no puddle.

 

[gene8084]

Re: Fails to choke at start

1. back to points and condenser

Pulled the Ignitor, bought and installed new points and condenser. No change. Starts briefly, fails to idle and also quits when advancing the throttle.

 

[MikDee]

Re: Fails to choke at start

I wouldn't futz with an external tank. The fuel pickup in your '74 tank is pretty straight forward and easy to check. (assuming you can get to the pickup fitting.) Your boat predates the requirement for an anti siphon valve so it should be straight through and I doubt there is any kind of filter on it.

To be sure, locate the fitting, remove the gas line and unscrew the fitting from the tank. Or to start, just disconnect the fuel line at the fuel pump or before any filters and blow back thru it into the tank. You should have very little resistance once you get a little pressure up.

I also really doubt you have a fuel (other than carb or possibly ignition) issue. Partial fuel line restrictions usually let a motor idle and only show themselves when the demand gets higher. When you are able to start it, it is not soaking wet down around the venturis is it?

Boomyal, I don't know what you mean by predating an antisiphon valve? or not having a tank filter? many years ago, I had a 1971 Wellcraft Airslot 18.5ft Bowrider with a 165hp Merc straight 6, and then a 1972 Wellcraft Airslot 18.5ft bowrider with a 188hp Merc 302V8, and both had twin aluminum gas tanks by the driver, & passenger, with an antisiphonvalve on each, and a slip in screen type stainless filter that fit inside the aluminum gas line, that almost had the shape of 1/2 an eyeliner pencil, and was clogged with debri, it drove me crazy with poor fuel flow till I got them out, & cleaned! Plus it was the first time I ever saw or figured out what an antisiphon valve was, because previous to this I just had outboards, with portable tanks.

I took my cousin a certified Chevy mechanic for a ride one time, on the latter one, before I did all this, and got stuck, until we both took turns blowing, & sucking on the gas line, to get the boat to run, and get home, he still kids me about it today how I made him drink gas,,,lol. True, this may not be the problem here, but this deserves to be checked especially on an older boat.

 

[gdombroski]

Re: Fails to choke at start

Not meant to be a smart question. But, if you can't get it to stay running how do you know it runs fine after that? If it's starting like when the safety switch is not connected, kicks on but dies quickly. You might want to check that. I had one engine that won't stay started and it was one of the ESA switches. Easy test for that disconnect the small ESA connector. Also, had ESA go out which causes same problem. Disconnect that next but don't try to do any shifting with it disconnected unless idle set real low.

 

[gene8084]

Re: Fails to choke at start

Not meant to be a smart question. But, if you can't get it to stay running how do you know it runs fine after that? If it's starting like when the safety switch is not connected, kicks on but dies quickly. You might want to check that. I had one engine that won't stay started and it was one of the ESA switches. Easy test for that disconnect the small ESA connector. Also, had ESA go out which causes same problem. Disconnect that next but don't try to do any shifting with it disconnected unless idle set real low.

No such thing as a bad question:

It's just that there was a point when it ran. At this point I've lost the chain of events. Started and ran off the hose a number of times when I first bought it, took it out for a trial and it quit on the lake, and would not start again.

After that I learned the starter was fried, the alternator was shot (had both rebuilt), replaced cap, rotor, points to Ignitor and now back to points, coil, wires, rebuilt the carb...and so on.

Now, on the ESA. I've done a great deal of reading on the Mercruiser 888 and haven't seen a reference to an ESA switch. 1974 Mercruiser, Ford 302. Does it have one? Called something else? Maybe shift cutout switch?

A picture would be great!

Thanks.

ESA