heat soaked engine gets idle surge on restart. (1 Viewer)

[destin]

IDave runs a one-barrel carb - he isn't on here very often, but maybe you can PM him

do you mean, that should PM I dave him to see if his one barrel carb set up has the same weird symtoms as mine ?



I Just want to understand what you are suggesting.

 

[DSRTRDR]

do you mean, that should PM I dave him to see if his one barrel carb set up has the same weird symtoms as mine ?



I Just want to understand what you are suggesting.

yes, I am suggesting you describe your symptoms to him and ask him for advice, in a PM or e-mail

IDave KNOWS his trucks

 

[destin]

yes, I am suggesting you describe your symptoms to him and ask him for advice, in a PM or e-mail

IDave KNOWS his trucks

Cool will do !

 

[destin]

found a place with non ethanol super. Filled it up

See if this helps some.

No sparkplugs in the mail yet.

Might pull the plugs and photo them later today though just to get some feedback on em.

 

[destin]

ok da plugs

all look powdery white - ish, slight grey ,
maybe some black carbon build up underneath? I just start running some non ethanol super in it, drove it about 20 miles with new gas, maybe more.

IMG]https://lh3.googleusercontent.com/-6MQDIousmtw/UCBAv36XxhI/AAAAAAAAAWc/kZrDzzpk64w/s1024/IMG_20120806_144958.jpg[/IMG]

A squirrel dropped a walnut on my head while i was photographing these lol

look ok yeah?

 

[destin]

Hmmmm

Seems like the coolant in my overflow looks a bit dirty after a few days... Brownish tint (. Newly installed over flow )

Also... I might be crazy, but my oil level seems higher than it was 3 days ago..., only fluids I have been adding is coolant to the overflow....

Head gasket leak beginning ...

I hope not, Fawk.

 

[DSRTRDR]

uh uh

what does the oil look like ?

 

[IDave]

Destin I've had this happen rarely, and it hasn't happened for a long time. I don't have a lot to add to what's already been said. Did you check for a vacuum leak yet? I saw you were going to. I wondered about water in your gas. Also, I always use ethanol free gas now.

Your plugs look OK, if anything on the lean side. You might turn the idle mix screw in a little.

You probably have some rust in your water jacket coloring your coolant.

 

[destin]

hey bro!

no vacuum leak that i can find...
unless there is some sort of micro-sized crack on the intake i cannot see.
Def possible.

there is a stutter when it is cold and warming up...
And that weird thing when it is heat soaked, otherwise it seems fine.

gonna run non ethanol fuel from now on.

I will rich up the idle a bit ( would this be backing the idle mix screw out right? )

I did not notice and coolant in the oil yesterday, looked ok.
will check again cold.

meh

Destin I've had this happen rarely, and it hasn't happened for a long time. I don't have a lot to add to what's already been said. Did you check for a vacuum leak yet? I saw you were going to. I wondered about water in your gas. Also, I always use ethanol free gas now.

Your plugs look OK, if anything on the lean side. You might turn the idle mix screw in a little.

You probably have some rust in your water jacket coloring your coolant.

 

[destin]

the coolant looks dark but i cannot tell if it is oil or not. The oil seems fone on the dio stic , no foam or sludge...


i made a quick video showing the coolant, and a cold start.
Iddles seems om on a cold start, vacuum ok.

Any gas above idle will result in a miss or stumble ( blank spot ) until the engine gets warmed up.
take a watch and let me know if this is normal.

I noticed when warm the accelerator pump does nto always spray consistently, sometimes it is a good spray, or if you pump fast, no spray, other times spray but misty... I think i need a known working single barrel carb to swap out...

idave, does your carb run like this? is this normal?

video link here yo!

 

[primer7]

No Choke on that carb?

 

[destin]

Yeah, thought that might be the case. In the video it just sounds cold and since there is no choke...well.

choke was on!

 

[primer7]

Sorry, my mistake. How does it run without the air cleaner.

 

[destin]

Sorry, my mistake. How does it run without the air cleaner.

it still does that on cold starts with the oil bath cleaner off.

the heat soaked idle surge with air cleaner off happens too.

Pretty sure it is not the oil bath cleaner but i could be wrong.

I think maybe the carb is just beat, and i need to find a new one.

 

[kurtnkegger]

Your idle sounds a little high, but that could be because of the choke being engaged. What is your idle set at?

 

[destin]

Your idle sounds a little high, but that could be because of the choke being engaged. What is your idle set at?

Idle was at 750, but I richened up the idle mixture a bit too.
I coul recheck it warm.

I do not think my idle adjustment has anything to do with the symptoms correct?

 

[miker]

my neighbor said surging is usually a vacuum leak, said to mix soap and water in s spray bottle and hit around the carb and look for bubbles... bad idea?

My 2 cents...

I've never tried your neighbor's method but I'm curious if this how you checked for a vacuum leak?

Basically, I don't understand how bubbles would ever be created on the outside of the engine from a vacuum leak as the leak means that air is being sucked into the intake, so I would think that the soapy water would be sucked into the intake if there was a leak. This might create bubbles inside the intake at the leak site, but you wouldn't be able to see those, would you?

Generally, to check for a vacuum leak you use propane (unlit) or some spray liquid like carb cleaner. Something like WD40 might work too. You do need to be careful using carb cleaner or other liquids as some are very flamable, but that I think is the reason this works. If you get the propane gas near the vacuum leak it will draw in the propane and the engine will respond by increasing RPM or smoothing out as the air is replaced by the propane and it is burned in the cylinders.

For the spray method, like carb cleaner, the same thing will happen. Engine will pick up RPM as the flamable liquid is sucked into the intake and burned and as well, the liquid temporarily restricts the amount of air, or replaces the air being sucked in with a flamable liquid and enrichens the mixture.

Spraying soapy water? I think you are just cleaning your engine. Not that it needs to be cleaned.

The plugs look like the engine is running lean to me as well. IDave mentioned this. I think you need to keep looking for a vacuum leak, or something else causing the lean condition like the carb. Maybe one of the carb's circuits is plugged or restricted. Maybe the jet size is too small. If it runs better when warm and the choke is on, then this is agood indicator you are lean.

The video you posted of the engine running also sounds like it's dying or stumbling from a lean condition.

I agree that the fan may help but my opinion is that it will be masking the real problem. It also looks like you are using copper for a fuel line. Perhpas this is stock, not sure, but copper is a great heat sink and I would think it could contribute to a vapor lock issue. Again, could be a secondary issue to deal with, not the primary cause of the problem.

Again, just my two cents.

 

[kurtnkegger]

My idle was set too high, and I had surging issues. Fuel would get sucked in to the throat of the carb from the primary, and the extra fuel would, in turn, would cause the RPM's to jump. After I turned down the idle to 650, the vacuum settled, and so did the surging.

Oddly enough, you helped me get my issue squared away...Got the "tick" in the valves quieted too...

https://forum.ih8mud.com/40-55-series-tech/410446-need-advice-carb-gurus.html

 

[destin]

I adjusted the idle down to compensate for the change in the idle mix.

So a vacuum leak huh.
I have sprayed carb cleaner when it was warm and could not find a leak... I guess I should othis when cold yes? So I am running lean. Would this be changed by the metering rod thickness ? Maybe my acellerator plunger is just too weak? ( stream seems to get wierd when hot sometimes )

I guess I be pulling the carb apart again tomorrow.

I have had shops check for vacuum leaks for me too, they say I am fine, but it must be somewhere yeah
?

I feel like I keep going in circles.

Everything is new but the carb in the fuel sytm.
New points, dwell correct, timing, plugs seemingly ok.

If I cannot sort this problem by summer end I might ave to sell it to save my sanity

 

[IDave]

I agree that the soapy water method won't help you find a vacuum leak. The method I was taught involves a little bottle of propane and a hose to direct it around the manifold gaskets and base of the carb, where most leaks occur.

http://www.ehow.com/how_12170503_vacuum-leak-propane.html

Other spots are around the brake booster when present and the vacuum shifter mechanism for the low gear.