What does this sound like?

[84Monaco]

So I just got my drive rebuilt and took the boat out on the water, when the engine starts giving me trouble.

What do you make of this noise:

http://www.vimeo.com/4085294

It's very hard to tell exactly where it is coming from, but it seems to be somewhere around the distributor or maybe the risers. Hard to pinpoint. Anyway, I've read all the posts I could find on stalling and such. The thing will run fine when cold, but when it has been going for 20-30 minutes, it will not idle worth anything. This noise doesn't happen when the engine is running smoothly (soon after startup until about 15-20 minutes later) Finally just dies.

Starts the next day just fine! I've cleaned out the filter on the carb inlet and drained and checked the fuel filter/water separator. I know there are about a million things that can cause this symptom, but I am specifically wondering if anyone knows what the noise is or might be, and if it is a cause or perhaps just a side effect of the rough running.

Thanks in advance!

 

[Don S]

Re: What does this sound like?

I think the exhaust shutters (flappers) are causing the noise, but that's not your problem. Have you checked the oil level? Not over full is it. It could very well be areated oil due to being overfilled and lifters are collapsing and not opening casusing the shutters to slap open and closed.

 

[84Monaco]

Re: What does this sound like?

Thanks Don!

It only makes the noise when it's running rough. I ran out and checked the oil level again and it is just slightly over full. It's full up to the F on Full, which is maybe 3/16ish past the marker line for full.

I'm figuring I should pump out enough oil to drop it right down to the line. Am I correct in assuming that this is not what's causing it to run rough?

 

[Bondo]

Re: What does this sound like?

The thing will run fine when cold, but when it has been going for 20-30 minutes, it will not idle worth anything.

Ayuh,... That sounds like the Idle circuit is plugged in the Carb...
It runs on the Choke, but when the choke pulls off it Dies...

 

[84Monaco]

Re: What does this sound like?

Thanks Bond-o! I'm not sure how to troubleshoot the idle circuit. I took a photo of the carb. Could you point me in the right direction?

Thanks!

 

[84Monaco]

Re: What does this sound like?

I guess maybe a better way to put it is, how would I test to see if this is the problem? I can keep it running if I throttle to about 1200-1300 RPM, but below that it dies.

To me that makes it seem like it isn't a fuel quality, fuel delivery (to the carb), or a spark problem. I could be wrong...what do you think?

That does make it seem like a carb problem, but I know very little about them - more familiar with fuel injection. I've been doing some research on them, but still don't know what to do to check the operation of idle circuit.

I did run it with the fuel cap off to make sure the tank wasn't pulling a vacuum. That didn't make any difference.

If it is the idle circuit does that mean it needs a rebuild or could carb cleaner do the trick?

 

[84Monaco]

Re: What does this sound like?

Ok, so I've been reading everything I can find about carbs, including the service manual for my engine. I think I found the simple answer to my question here though:

http://videos.streetfire.net/video/Carb-Tuning-IdlingMixture_159114.htm

I'm planning to try this tomorrow and see if it helps! I'm also going to pump out a little oil and see if that quiets the funny noise when it starts to miss.

 

[Bondo]

Re: What does this sound like?

That does make it seem like a carb problem, but I know very little about them

Ayuh,... Give that old Rottenchester the "Float Test" at the dock,...

When it Fails,..... Go buy a new Edlebrock, bolt it on,+ Go Boating...

 

[fat fanny]

Re: What does this sound like?

I had the almost the same issue on a old pickup with the rochester 4brl replaced it w/ edlebrock they are far superior to the rochester and are turn key bolt on and run they are woth the money to eliminate the problem.

 

[84Monaco]

Re: What does this sound like?

Ok, I'm confused.

I ran the boat this morning with the spark arrestor off, and as far as I could tell there was about a 10 minute period of time between when the choke opened and when the thing started running rough.

Take a look here for smooth running:

http://vimeo.com/4116957

And here for nearly stalling a few minutes later:

http://vimeo.com/4116886


Also, I haven't tried blowing out the idle circuit yet, but I was able to turn the screw and alter the idle speed, which makes me think it can't be completely plugged - especially since it is running with the choke open.

Also, with the oil level ok, it's still making as much noise as ever. What else could make a noise like this?

So confusing!

 

[84Monaco]

Re: What does this sound like?

Ok,

So I'm just going to try to follow a troubleshooting sequence. I haven't figured out a conclusive way to rule out either spark or fuel to the cylinder so I've just got two lists and I'm going to work my way down each in order of expense. Here's what I've done so far and what I plan to do next...

Poor Spark when hot:
-poor connection at battery terminals
o already checked and cleaned
-Bad Ground ? engine block
oClean ground
oRun temp ground for test purposes
-Bad Plug/distributer Wires
oReplace
-Bad ignition Circuit ? not hot/ground to coil
oRun temp lead from batt to low voltage hot side of coil
-Bad Distributor Cap/Rotor
oReplace
-Bad Coil
oreplace
-Bad amplifier
oReplace


Not getting fuel to cylinder(s) when hot:
-clogged fuel filter at carb
oalready checked and cleaned (not very dirty)
-fouled fuel filter/water separator
oChecked/clean
-clogged inlet in fuel tank
oOpen up tank/Check/Clean
-Bad boat fuel pump
oVacuum test for proper operation
-Bad Fuel
oRun off of separate gas tank with fresh gas
-Bad engine fuel pump
otest
-bad carb
oalready blew out idle circuits with compressed air and carb cleaner
oalready checked and saw that idle was still good after choke leaves
opened
orebuild or replace


What do you guys make of this list? Am I on the right track?

 

[Bondo]

Re: What does this sound like?

-bad carb
oalready blew out idle circuits with compressed air and carb cleaner
oalready checked and saw that idle was still good after choke leaves
opened
orebuild or replace

Ayuh,... I'd start at the Bottom,+ work my way Up....

So I'm just going to try to follow a troubleshooting sequence. I haven't figured out a conclusive way to rule out either spark or fuel to the cylinder

Ayuh,... Start it up, run it til it Dies.... Right then,+ there, is it lacking Fuel or Fire....
That's the Direction to take.... Chase whichever 1 is Missing....

 

[84Monaco]

Re: What does this sound like?

Ayuh,... Start it up, run it til it Dies.... Right then,+ there, is it lacking Fuel or Fire....
That's the Direction to take.... Chase whichever 1 is Missing....

I agree with you Bond-o. I'm just not sure how to tell the spark is the problem - at that point. It's sparking enough that it almost runs so I'm sure there will be some spark. Any thoughts on how to tell how much spark isn't quite enough? I'm not trying to be smart here, I honestly don't know.

As far as fuel, I have no idea how to tell if the carb is functioning properly. I guess that's when I would start by buying an Edelbrock 1409? Do you know where to source the fuel line and adaptor plate that I would need?

 

[Ridemywideglide]

Re: What does this sound like?

I agree with you Bond-o. I'm just not sure how to tell the spark is the problem - at that point. It's sparking enough that it almost runs so I'm sure there will be some spark. Any thoughts on how to tell how much spark isn't quite enough? I'm not trying to be smart here, I honestly don't know.

As far as fuel, I have no idea how to tell if the carb is functioning properly. I guess that's when I would start by buying an Edelbrock 1409? Do you know where to source the fuel line and adaptor plate that I would need?

Your carb is not functioning properly when your engine does what your engine is doing.
Take the carb off and either rebuild, or send to mechanic for a rebuild.
Your not going to have the spark "fade away" as the engine warms. It's running out of fuel for some reason. Your idle jets could be leaned out too far, richened too far, etc. On choke, you get less air/more fuel. With choke off, leading to engine dieing, I'd think your idle jets are lean. This is not the idle adjustment you already screwed with. Look at your carb from the front, down low there are 2 hex head "screws". These are idle mixture adjustments. Turn them in until they stop, then back out 2 turns. Start there and see how it idles. Then report back and we'll go from there.
Quadrajets are good carbs regardless of what is said here, but any carb needs to be clean to work right.

 

[Bondo]

Re: What does this sound like?

I agree with you Bond-o. I'm just not sure how to tell the spark is the problem - at that point. It's sparking enough that it almost runs so I'm sure there will be some spark. Any thoughts on how to tell how much spark isn't quite enough? I'm not trying to be smart here, I honestly don't know.

Ayuh,... When it Dies,... Pour a 1/2oz. or an ounce of Gas down the carb throat....
If it starts,+ Dies again,...
It's the Carb....
Fix it, or Replace it....

 

[84Monaco]

Re: What does this sound like?

Thanks guys! I'll try the gas like you recommended. Exactly what part is the throat? Is it just down the primary barrels or does it need to go into one of the smaller orifices? Would a can of carb cleaner do the same thing? I was spraying that stuff into the carb while it was running and it was making it die.

For the record, I wasn't messing with the big idle lever adjustment screw on the side, I removed the two small cone shaped ones low on the front and blew carb cleaner and compressed air through the holes, then screwed them all the way in and backed them out a few turns.

In trying to troubleshoot yesterday I pulled the wire off the coil and it seems like something fell apart. What is that connection supposed to look like? Does the wire have a terminal that goes into the coil? ...or does the coil have a terminal that goes up into the boot and meets a bare wire? It all fell apart on me: boot with bare wire in it/terminal thing/coil - three separate pieces.

Anyone have a brand/source of wires they recommend?

Thanks for all your help!

 

[84Monaco]

Re: What does this sound like?

Does anyone know what the specs of the fuel line fittings on my boat - '84 Mercruiser 350 V8 - would be. Is it a good idea to switch over to braided stainless if I switch carbs? Looks like the Edelbrock has the inlet in a different place.

Also, summit racing has the Edelbrock 1409 rebuilt for $260. Any thoughts on rebuilt vs. new on this carb?

 

[84Monaco]

Re: What does this sound like?

Well, I went out ant tested it tonight - was interrupted by a downpour, but found some interesting things.

For some reason it ran a lot better tonight than it did yesterday. It ran a full 45 minutes before stalling, and in general ran a lot smoother the whole time.

Once it stalled I poured a little gas in the carb, and yes it did crank right back up...and continued to run for several more minutes. When started running a little rough again I found that if I pumped the accelerator pump it would come right back up.

This tells me one thing for sure. It is fuel, not spark, that is the problem. The one thing that has me scratching my head is why it ran so much better in general. On previous start ups this spring, it would idle fine for a while, but once it died, it became very hard to start - it was possible if you throttled to about 1200RPM, but it wouldn't idle at all.

This time it ran longer and smoother, and I think would have kept running for a good while if I hadn't decided my neighbors might not want to hear the sound of a no muffler V-8 any later at night.

I'm wondering if the carb cleaner I sprayed in yesterday, along with being run a little more might be cleaning out some gunk. I winterized with SAE 20 non-detergent oil - flooded the carb on shut down. The manual said 20 weight oil was ok to use for this. The only kind I could find was non-detergent - said it was for antique cars...

Anyway, I'm just kind of wondering/hoping that some more cleaning and running might clean things out and get it back to idling better. It has run perfectly the last two seasons (since I bought it). I just spent $1000 getting the prop shaft straightened/outdrive back in good shape, and I'm a bit strapped to buy a carb right now. I feel a lot better knowing that I can at least get the thing restarted now so I can get it into gear - not be stranded on the water - if I decide to brave the lake again.

Anyway, I sprayed it all out with cleaner again tonight and am letting it soak - whatever doesn't evaporate instantly.

Tomorrow I'll try again and see if there's any improvement and go from there.

 

[Ridemywideglide]

Re: What does this sound like?

I don't think I'd fog the motor with motor oil as a seasonal procedure. Get a product that's actually made for such use.

As for the carb. Either take it off and rebuild it, or replace it if you've got the $260 for the 1409.
Take if apart, soak it for a few hours/overnight in some carb cleaner, then put new parts in, blow it all dry and you'll be much happier.
Continuing to dally around with that dirty carb will only result in less hair for you.
Rebuild kit for my quadrajet was $21.47 at autozone. $20 for some dip cleaner, and a few hours watching tv while it did it's work.

 

[Bondo]

Re: What does this sound like?

Anyway, I'm just kind of wondering/hoping that some more cleaning and running might clean things out and get it back to idling better.

Ayuh,... The carb needs to be Removed, Completely Disassembled,+ Rebuilt, or Replaced....
Dicking around with a can of carb spray is Wasting your time...