Serious Problems , Loose Booster Venturi / Carb Icing / Throttle Stick / Dieseling

[A20A1]

All info contained herein was gathered from this or other sites and compiled here.

HERE IS A CHECK LIST OF THINGS YOU SHOULD KEEP IN MIND
IF THE PROBLEM DISCRIBED IN THIS THREAD DOESN"T APPLY.
Check for Vacuum leaks
- Intake Manifold Gasket
- Vacuum lines
- Carburetor Gaskets
- PCV Valve
Check your oil system
- Oil / Oil Level
- Oil Filter
Check the coolant system
- Radiator Fluid Level
- Thermostat
- Fans / Thermoswitch
- Waterpump
- Check your engine temperature
- Does the engine heat up to normal operating temp?
- Does the engine overheat?
Check Ignition
- Plugs
- Wires
- Ground Wires ( Battery / thermostat / radiator support )
- Cap / Rotor
- Ignition Timing
Check Fuel
- A/F Mixture
- Float level
- Fuel Filters
Check Idle Speed ( Cold / Warm )
- What is your idle speed when cold in gear and in neutral?
- What is your idle speed when the car has warmed up all
the way and you have driven for 10 mins, in gear and neutral?
Also Check the fuel solenoid at the back of the carb, it could cause idle problems if fit doesn't work.
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Check the carb venturi's since no fuel will cause the car to die.
A loose booster venturi will cause problems when trying to accelerate, and while driving, you can use the process below to check for a loose booster venturi.
THE BOOSTER SHOULD NOT MOVE AT ALL, IF IT MOVES WITH FAIR RESISTANCE IT MAY OR MAY NOT BE A PROBLEM... BUT IF IT"S VERY LOOSE THEN IT MUST BE TIGHTENED
To check if its a loose booster venturi remove the carb lid and the brass metal screen.
the 2 arrows point to the 10mm nuts securing the screen.

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with your finger try to wiggle the booster venturi's inside the barrels. The booster venturi's look like this: (yellow arrows in pic below)

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If any of the booster venturi's are loose then hope it's just the secondary booster because the primary booster venturi screw is very difficult to get to.
here are arrows showing where the 2 screws are located:

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here you go, primary left / secondary right:

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- Yes the screws hold the venturis in
- The problem with the primary screw is, the choke and fast idle unloader are in the way... and to remove it from the carb you will have to drill the rivets out to gain access to one of the screws.

Check the booster venturies.
You'll have to remove the gold screen thats inside the air box and stick your finger in both of the barrels and then check to see if the booster venturies are loose. If they can slide in any direction or wobble even slightly they could be causing problems.
I'm holding one of the screws that secure the booster venturi with my finger... in the top right of the pic I added a close up of the booster and screw.
The screw I'm holding is for the Secondary barrel.
The top hat of the carb is in the bottom of the pic, I removed it for clarity.



If the venturi didn't fix your problem
Check PCV valve
Check for Vacuum Leaks
Check coolant level
Check the fuel filters.
Check engine oil just in case

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[A20A1]

Here is how I removed the choke to get to the primary booster venturi.

Before removing the choke you need to remove the top hat of the carb...
If you don't know how click on the link
https://www.3geez.com/forum/showthread.php?t=5350

next remove the choke screws that are visable, there are two of them.

Use needle nose CLAMPING or VISE pliers if the two screws are stripped...

For the final screw that is covered by the electric choke cover, I used a long screw driver and wedged the tip near the rear base of the carb and then pulled the handle away from the carb pressing the shaft up against a safe part of the choke ( Basicly a safe area is the aluminum choke housing... do not put pressure on the choke mechanical moving parts or the plastic parts ) the pressure then snapped the thin part of the aluminum carb casting that was holding the final 3rd screw.







Don't worry the fast idle / choke installs and works fine once reassembled, if you want a little extra security epory the crack back together again.

[VTEC_Inside]

A20A1, feel free to move any information to your booster thread.

Although I tightened both boosters they were still pretty snug. They did move, but very little under pressure, so I don't believe they were contributing any trouble.

I was able to do it quite easily because I seem to be one of the only ones on here that has screws (vs rivets) holding in my choke spring. My Mastercraft mini ratchet screw driver is almost a necessisity to unscrew the choke puller, but its all good. If you remove the upper screw of the choke puller you can tap it a bit to rotate on the bottom screw (provided the rest of it is already unscrewed). You can tighten the secondary venturi pretty easy with the puller simply rotated down.

Also when I remove my choke mechanism, I unscrew the arm from the shaft and slide it off. Much easier than fiddling with the little pins.

Before I make that sound too easy. My car originally had the riveted choke. I had another assembly with screws and threaded holes, so it was a no brainer which one to put back on. My first attempt to remove the choke shaft/plate was hindered by that stupid screw on the end of the shaft. I drilled that out and replaced it as well. Cover the carb good if you are gonna drill around it.

[FastHonda]

I had this problem recently. My primary booster venturi bolt was missing. I found a bolt that fit with a little modification (to the bolt). If someone knows the appropriate bolt and thread size, it could be beneficial to others who may need to know it. I was unable to find that information using a search and it was not in my haynes manual, nor did any of the parts stores know the thread size. Thanks guys.

[A20A1]

it's in Milimeters mm it's small probably 6mm - 4mm maybe less.

Bolts are only a few cents at a hardware store... I may go by some time and pick out a ALAN Wrench / HEX KEY style headless bolt to act as a replacement for the stock bolts.

[lostforawhile]

Carb Icing


if your heat tube is off or missing,or the vaccume motor on the air cleaner is leaking,happens all the time, then i would say carb ice. was it cold and high humidity? remember as the air goes through the venturi it speeds up,and the temprature drops as much as 40 degrees. any moisture in the air will condense out in the carb and freeze. this usually blocks your jets. what happens is when you pull over and let the car sit, the heat from the motor rises up and melts the ice. then the symptoms disapear. there are three systems that are supposed to stop this. the main one is the hot air tube coming from the shroud on the manifold. the air cleaner can control the temp going to the carb, when it's too cold that air door motor lifts, and air coming into the air cleaner is pulled from around the exaust manifold.. the second is a heated intake manifold,thats why coolant flows through the manifold. it also has a thermostatic valve on the bottom of it. this controls coolant that actually flows INTO the carb base. it comes up through the intake manifold,into the bottom of the carb,and exits out the coolant hose on the back of the carb. the third is the EFE heater thats built into the carb base, this is the wierd looking grid thing. it comes on under a certain temp to help keep the fuel vaporized. this is the same thing that causes caburated airplanes to crash. they have a manual carb heat control to prevent this problem. ours is fully automatic. the interesting thing is it doesn't have to be freezing outside to get carb ice. if you calculate the temp drop caused in the venturi and subtract it from the outside air temp, you see you can get carb ice in even 60 degree temp. it depends a lot of relative humidity. in the old days you might have been more used to carbs and reconized this right away,but since carb cars are somewhat rare now, the symptoms are not as farmiliar. this is one thing you don't have to worry about in EFI cars.

[bluepunk18]

Would this be the reason that, even when the engine is at normal operating temperature, the car stutters under any kind of throttle? I've noticed this for a few days, while its been particularly cold. It sorts itself out after a little but, but while its happening, no amount of input from my foot with change the throttle in the least. It leaves me frustrated and my fiance panicky. I was wondering if its the carb icing up, or if its related to the fuel filters or if I need to just add some dry gas to my tank...Any ideas? and Thanks in advance, I've been reading a lot today...

[lostforawhile]

Would this be the reason that, even when the engine is at normal operating temperature, the car stutters under any kind of throttle? I've noticed this for a few days, while its been particularly cold. It sorts itself out after a little but, but while its happening, no amount of input from my foot with change the throttle in the least. It leaves me frustrated and my fiance panicky. I was wondering if its the carb icing up, or if its related to the fuel filters or if I need to just add some dry gas to my tank...Any ideas? and Thanks in advance, I've been reading a lot today...

that could be it, the dry gas wouldn't help any, it's ice forming in the venturi of the carb from the effect of the venturi causing a drop in temperature of the incoming air,this causes moisture in the air to freeze to the venturi throat blocking airflow and causing ice on the jets, make sure your heat tube system is connected and operating, make sure the coolant through the manifold is hooked up,there is also the efe plate under the carb,make sure it's plugged in. these systems work together to prevent icing.

[VTEC_Inside]

I'm positive I have this problem now.

The car is running great now after I fixed a leak in the choke puller, but it once again started to lose power and run like crap on the highway today. [Temperature around the freezing mark and raining]

I had long suspected an ignition issue, but I've recently replaced everything from the rotor to the plugs. Also if I floored it, it would run smooth right up the revs. That should have been the real tip-off to me when I first had this problem a couple years ago.

The secondary barrel remains closed at cruising and would not be affected by icing while the primary freezes up. Floor it and the secondary opens up supplying the fuel until it is also affect or you can't floor it anymore.

Pull over, try and figure out whats wrong and by the time you've opened the hood she is starting to smooth out.

I will be trying to source a non leaking hot air door diaphragm now since I believe that my leaking one is probably the major contributor to this condition.

[Bass Man]

Mine did this with the stock carb, but I had a hole in the bottom of the trunk and when it would start to ice up, it would run SUPER rich and come inside the cab. Made my eyes burn!

[TotaledTL]

Has this happened to anybody w/ a Weber? If so is there a solution?

[2ndGenGuy]

Has this happened to anybody w/ a Weber? If so is there a solution?

I would think that leaving the coolant lines connected to the intake manifold should help quite a bit.

[citizencia]

I've found much of the info in this post very helpful for getting my 89 accord lx back into great mechanical shape. But I am still having a bit of a problem with it. It likes to stall when taking my foot off the gas once the car is warm and it will sputter as the engine decelerates. When I start it cold, it fires right up, within a second or two. It will start and drive great, but once I've driven it to a normal operating temp. Once I put the clutch in, the car will try to die unless I keep giving it gas. I've followed the checklist provided, the only thing I have yet to try is checking the intake and carb gaskets for a leak. It's been a while since I've worked with vacuum systems. I've done almost a complete tuneup in this car (Both fuel filters, cap, rotor, plugs, wires, pcv valve, breather filter). I know I have to change the oil, it's dirty, but otherwise shows no signs of contamination and doesn't appear to burn or leak oil for the most part, on a side note I have to replace the valve cover gasket due to a slight leak that was only evident when driving on the highway. I checked the venturies and they were tight. It is a high mileage motor 250k+ miles, 5pd. I want to guess a vacuum leak, but I've looked at the vacuum lines and they look and feel ok. The only problem I can find that is obvious is that vacuum line #20 was broken and someone sealed it off with a screw. I think the line only goes to a thermal check valve. I'm stumped. Anyone have any ideas? By the way, when I'm driving around and on the highway, the car drives like it has plenty of life, and I have an exhaust leak somewhere (I can both hear it and smell it leaving the garage in the morning).

[Dr_Snooz]

We get this problem a fair amount, and I don't think any one specific answer has emerged. Some things to try would be,

1. 1. Use a can of MAF Sensor Cleaner or carb cleaner to check for vacuum leaks. With the engine idling, spray the cleaner on the vacuum lines and connections. The idle speed will change when you hit a leak.
2. 2. Run a bottle of injector cleaner (Techron or otherwise) through your next tank of gas, in case it's just a dirty carb.
3. 3. Try using a better grade of gasoline.
4. 4. There are a lot of electric and vacuum controllers on the carb that are getting tired after 24 years on the road. Make sure that the vacuum controllers still hold vacuum and operate well. For the electric solenoids and other controllers, there are tests listed in the Honda manual for most of them.

Manual is available on the wiki: 1989 USDM Honda Accord Factory Service Manual
The carb section starts on p. 11-1.

Let us know what you learn.

[2oodoor]

I wouldn't use maf cleaner for that, too expensive and evaporates too fast. Throttle body cleaner, non clorinated flammable brake cleaner work good and are .99 cents to 3 bucks a can. MAF cleaner is around 10 bucks a can and Ive only found it in one brand, CRC.

[Dr_Snooz]

Won't brake cleaner eat the rubber lines?

[2oodoor]

There's so many different kinds out there now, you're right, some of them could finish off some old rubber lines. Im saying the cheep Non Clorinated Flammable kind like Advance has on sale all the time for .99 to 1.99 a can.
A blanket statement as to aerosol brake cleaner though would have to be considering brake wheel cylinders rubbers and caliper rubbers are in the line of fire of these sprays!
Definatley don't spray plastics with any of them... Clorinated or tri III brake clean will shatter plexiglass and lexan if it gets on any edge or drilled spots on it.

[A20A1]

I'm positive I have this problem now.

The car is running great now after I fixed a leak in the choke puller, but it once again started to lose power and run like crap on the highway today. [Temperature around the freezing mark and raining]

I had long suspected an ignition issue, but I've recently replaced everything from the rotor to the plugs. Also if I floored it, it would run smooth right up the revs. That should have been the real tip-off to me when I first had this problem a couple years ago.

The secondary barrel remains closed at cruising and would not be affected by icing while the primary freezes up. Floor it and the secondary opens up supplying the fuel until it is also affect or you can't floor it anymore.

Pull over, try and figure out whats wrong and by the time you've opened the hood she is starting to smooth out.

I will be trying to source a non leaking hot air door diaphragm now since I believe that my leaking one is probably the major contributor to this condition.

maybe block your radiator some, this would keep the coolant warmer while driving on the highway when the outside air is very cold. The hotter temps will help warm the carb and manifold.

[George89]

Is there any way the pictures from the OP used in the guidance of this procedure can be re-uploaded? Unless of course they can be found somewhere else on the thread, help is appreciated.

[AWH]

I would also like to be able to see the pictures as well.

[a20adam]

No one has mentioned the car dieseling. Mine does this. It will stay running after I shut it off. It diesels. I can't figure out what's wrong with it. I put a weber 38/40 dges but it did it with the stock carb too

[Ryan706]

Mine diesels as well. I’m thinking I need a little higher octane. I’m going to try it today. I have a 83 prelude with the es-1