heat soaked engine gets idle surge on restart.

[DSRTRDR]

cool

ok update.

decided to replace:

radiator cap ( looked to be original lol ) with new 13psi cap.
added a cheap overflow and burped the system. ( will order OEM overflow later when CDan is back from vacation. )

Just wanted to eliminate the possibility of the system not getting fully pressurized, which could possibly cause the coolant to lower its boiling point... maybe making the engine heat soak at a higher temp on shut down...

See how that theory goes

going to pull the plugs later today when the new denso ones come in.
had 12,000 break in miles on the new motor, see how the plugs look...

maybe do a compression test and see how well the motor broke in ...



.

AFAIK, OEM overflow bottle has been discontinued - I have an el cheapo as well

 

[destin]

108 in Phoenix earlier this week and my 40 runs fine

wtf

singel barrel aislin small glass carb with solenoid?
stock intake exhaust manifold?


it might just be my carb is just old and warped inside and something is just going wack internally in the heating and cooling process...

 

[destin]

ok so new rad cap, added over flow, burped and keep adding fluid, now it seems to be equalized.

So far so good, no vapor lock yet.

Supposed to get in the 100's this weekend, we see if this in fact was related to the bad rad cap and lack of overflow or not. Or it is just a coincidence


Thanks for the help fellas, i will keep ya posted

/

 

[destin]

Well it did it again today after a hot start whirl grabbing some thing at the store.

Just seems weird that some people can have 100 degree weather and have no idle surgin.

Maybe a sall exhaust leak?

Maybe I should video it next time.

Get some feed back.

 

[desertpat]

Engine heat is vaporizing the fuel in the line to the carb.
You said bubbles were going from that line back to the tank.
On hot days, the fuel in the tank is warmer and vaporizes easier.

Insulate the fuel line from the fuel pump to the carb.
Toyota does this on a/c and heater lines where they want to maintain a temp differencial.

It's the easy fix coming from experience of a very hot place.

 

[91 4runner]

sorry to here about your trubles i live in corvallis and i have a 78 that i drive to CA and AZ in the summer, i never had a problem with the heat, other then not having A/C lol
and my carb cooling fan is missing.

what makes you think the carb base is warped? is your vacuum at manifold low?

i would carry a gage in the cruiser and the next time you experience the heat problems see what the vac is

 

[DRYHEAT]

Try a bag of ice, lay it on top of fuel line as a test, if it improves insulate the fuel line. No problems W/ my 79 W/carb fan at 109 today

 

[destin]

sorry to here about your trubles i live in corvallis and i have a 78 that i drive to CA and AZ in the summer, i never had a problem with the heat, other then not having A/C lol
and my carb cooling fan is missing.

what makes you think the carb base is warped? is your vacuum at manifold low?

i would carry a gage in the cruiser and the next time you experience the heat problems see what the vac is

I have a vacuum gauge in the cab.

Pulls 20 when warm at idle.

But when restart on heat soak, ( not every time ) it idle surges. Basically sounds like it is not getting gass, only gets gas at high rpms. You cannot rev it out at idle to gt it to go away. You have to load the engine a drive it a half a Block to " work I out "

You can even pull the air filter off and rev it by hand, just sounds like it is getting no fuel when you pull that throttle linkage up, until it gets higher in the throttle, like a miss.

Something has to be up.
Maybe a failing head gasket ?
A small intake crack that shows up when heat soaked.?

I will video it next time and post it here so you guys can hear it. It is weird. Idle bounces up and down, vacuum gauge goes up and down with idle from like 12 - 20

I think indeed to pop in a perfect known working carb to be sure it is not soething about the carb.
Whole fuel system is brand new, so it cannot be explained away as sediment. I just need to eliminate variables. Carb and fuel pump show up as 120 degrees heat soaked using the infared thermometer I have

 

[destin]

OR could be the carb is just dumping gas into the intake on shut off, causing pressure build up in ht intake?

Could this be the culprit?

 

[91 4runner]

I have a vacuum gauge in the cab.

Pulls 20 when warm at idle.

But when restart on heat soak, ( not every time ) it idle surges. Basically sounds like it is not getting gass, only gets gas at high rpms. You cannot rev it out at idle to gt it to go away. You have to load the engine a drive it a half a Block to " work I out "

You can even pull the air filter off and rev it by hand, just sounds like it is getting no fuel when you pull that throttle linkage up, until it gets higher in the throttle, like a miss.

When your reving it when it's " heat soaked" what dose the fuel level in the bowl look like?

 

[destin]

When your reving it when it's " heat soaked" what dose the fuel level in the bowl look like?

full to the line in the site glass window.

NO visible bubbles in the site glass.

Have any insights?

I know I can pop on a carb fan, but if there is a larger issue i rather sort it properly then bandaid it up...

 

[91 4runner]

werd.


just to clarify, your fuel is the correct level in the bowl, and your vac is 20 inches when you your cruiser runs rough?

out of curiosity have you checked to see if your choke blade is FULLY open?

my cruiser will cough, sputter if its warm and i (out of habit) pull the choke.

and what do your plugs look like?

any ways
i would keep poking around. something must be out of spec
adding a carb cooler might solve the problem, but i think it would look out of place under your hood being that your cruiser is much earlier.

 

[fj404life]

I doubt your cooling system has anything to do with it...you tried some better gas yet?
You have been putting the miles on that old girl! Im impressed!!!

 

[JohnnyC]

How old are your plugs?

Did you ever readjust your valves or chech your valves in a while?

 

[destin]

werd.


just to clarify, your fuel is the correct level in the bowl, and your vac is 20 inches when you your cruiser runs rough?

is surges up and down, from like 13 - up to 20 on the vacuum gauge.
you have to load the engine and drive a block to blast it all out. from the loopy idle, it seems the engine stumbles until it gets up to 2000 rpms to power through it to make it stop. ( again has to be loaded driving, no dice reving it at idle to make it stop )

out of curiosity have you checked to see if your choke blade is FULLY open?

my cruiser will cough, sputter if its warm and i (out of habit) pull the choke.

choke is open ( or whatever it means to be not engaged )
Hooked up to the cable, and does not move independently of the cable actuator, checked to be sure it was not messed up )

and what do your plugs look like?

any ways
i would keep poking around. something must be out of spec
adding a carb cooler might solve the problem, but i think it would look out of place under your hood being that your cruiser is much earlier.

have not checked the plugs yet. ( waiting on a fresh set of densos in the mail )
Motor has about 12k miles on the rebuild.

 

[destin]

I doubt your cooling system has anything to do with it...you tried some better gas yet?
You have been putting the miles on that old girl! Im impressed!!!

I love driving this thing

Putting in non ethanol super in it today, and I am going to run it that way for about a month. See if there is an improvement

 

[destin]

How old are your plugs?

Did you ever readjust your valves or chech your valves in a while?

plugs are from when the engine was rebuilt i think. ( unless the changed them when the head gasket popped )

When I get new plugs i pull the old ones, line them up on a label number board and take some photos and post back here. Could be maybe some fouled plugs causing this?

Going to have my local landcruiser shop do a compression test too, engine motor warentee ends soon, want to be sure the engine broke in well considering all the bs that happened early on

Anyone ever use one of those coolant combustion test to check for leaky head gaskets?

It was a 100 here in portland yesterday.

I went to the river all day with the dog yesterday.
Drinking wobble pops and getting some sun
A good day for sure

 

[eazzrider]

Same symptoms on mine. New Trollhole carb and all problems went away. It was 110 here yesterday with no issues.

 

[destin]

Same symptoms on mine. New Trollhole carb and all problems went away. It was 110 here yesterday with no issues.

Thats interesting

Same symtoms huh>?

I PM'd trollhole about and F engine carb, I will see what he has to say ( he might be in moab for all i know )

Tough bit is I would have to find a two barrel early intake manifold. I am not sure how easy those are to find.

drove around all morning trying to find a Marina that had non ethanol fuel that would let me fuel up ( without having to shuttle 3 gallon gas cans to fill the truck.

I found one place that has non ethanol gas in super, but i need to call em monday and sign up for their business account ( card holder type filling club for commercial stuffs, since i have my own business it seems like i might qualify )

 

[DSRTRDR]

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