Carb rebuild - general rule of thumb (1 Viewer)

[dtrain]

I know there is not a definitive answer to this and many variables but wanted to guage this for troubleshooting purposes.

How long should you be able to go between carb rebuilds? The carb currently installed was rebuilt by JimC (PO had it done) roughly 6 yrs ago. I vary octanes a bit depending on how cheap I feel. The fuel filters have always been pretty clean when replaced (no debris - I believe the PO had the tank either replaced on recall or said it was cleaned and coated)

Does it seem right I would need a rebuild, already? (if so, I plan to send a core to either JimC or Mark A.)



EDIT: Grammar

 

[2mbb]

Have you tried an in-situ cleaning with spray carburetor cleaner. Take the air cleaner off, run the engine and spray the stuff down the carb throat while feathering the throttle. It's supposed to help clean off residues and such. There might also be a similar product you can put in your gas tank.

What problems are you experiencing?

 

[szester]

Basically just when it needs it. When you have exhausted all the other options(carb cleaner etc etc) and nothing is working then its time for a rebuild.

 

[dtrain]

Have you tried an in-situ cleaning with spray carburetor cleaner. Take the air cleaner off, run the engine and spray the stuff down the carb throat while feathering the throttle. It's supposed to help clean off residues and such. There might also be a similar product you can put in your gas tank.

What problems are you experiencing?

I started having hard starts (and a bit of pinging.. one issue at a time I guess ). In the morning, I used to stand outside the truck, pull the choke slightly out, and it started right up. A lot of the time I could just stand outside the truck and start it. Never had to pump the gas... maybe 1 or 2 on occasion. Now I have to do a small song and dance to get the it started.

I haven’t tried the cleaning but, it’s on my list for this weekend (Thanks for the procedure). Ran a can of seafoam through the tank prior to a tune-up but, didnt notice a difference.

A separate question...
I was replacing any exhaust gasket at the manifold last night (much better now but, still some leaks somewhere… EGR ruled out) and noticed a tube coming off the bottom of my charcoal canister and routes into the passenger frame rail. The tube coming out the bottom of the canister was very flat looking… almost like it was crushed flat. Is this normal?

 

[Spike Strip]

How many miles in those 6 years ?

Remembering the original went 15 + years, and since it was done by a guy what knows what's up, probably not.

But it's always possible some dirt got in there.

As 2mbb asked, what's wrong that makes you think carb fubar?

 

[2mbb]

A separate question...
I was replacing any exhaust gasket at the manifold last night (much better now but, still some leaks somewhere… EGR ruled out) and noticed a tube coming off the bottom of my charcoal canister and routes into the passenger frame rail. The tube coming out the bottom of the canister was very flat looking… almost like it was crushed flat. Is this normal?

The port on the bottom of the charcoal canister is just a vent. You should make sure that the other end of the tube isn't connected to anything and is free to let air into the canister.

 

[dtrain]

The port on the bottom of the charcoal canister is just a vent. You should make sure that the other end of the tube isn't connected to anything and is free to let air into the canister.

Cool. I will take a look and be sure. Good info. Thanks.

 

[dtrain]

How many miles in those 6 years ?

Remembering the original went 15 + years, and since it was done by a guy what knows what's up, probably not.

But it's always possible some dirt got in there.

As 2mbb asked, what's wrong that makes you think carb fubar?

~29k on rebuld. This is about what I was thinking but needed a sanity check. Not sure it is the carb. I have been doing a lot of reading and it seems be a solution that many bring up and or ask the question.

Basically just when it needs it. When you have exhausted all the other options(carb cleaner etc etc) and nothing is working then its time for a rebuild.

Can you be a bit more specific about "all the other options"? Here is a list of things I have started and plan to do throughout the week. My real issue is hard starts and it seems to just be running a little rough. I started chasing down a few exhaust leaks that started (I believe because of sloppy work from a mechanic I took her too… lesson learned.)

Already done -
- Replaced a ton of old tubing with silicone… 85% there
- Seafoam in tank – result: no luck. New plugs, air filter, gas filter, and changed oil (plan to do cap and rotor this weekend)
- Change fuel filter – result: replaced 4k miles ago with wix and results still the same

Created this list after searching and reading around hard starts… will do them this weekend and test between procedures:
(in order)

- New cap and rotor
- Carb cleaning
Carb on good and tight on the insulator plate. Possible leak at the vac port coming into the insulator and at the base of the carb
Check for vacuum leaks with carb cleaner (specifically intake and base of carb… been hearing a whistle like noise)
Check float level both cold in the morning) and hot (after getting to work) via the window
Okie rebuild (post 19 below) from Pinhead
- Vacuum check at manifold – NO idea how to do this and will need to buy a guage
- Spray Deep Creep down into the EGR (not sure where but guess I will figure it out)
- Inspect hose that runs to the manifold from EGR
- Valve system at front of breather main air inlet tube – check operation: closed when cold? (believe this is the unit built into air cleaner housing… can I “lube” this thing? )
- PCV – replace (Factory or auto store?)
- Unplug any carbon build-up on the PCV hardline at the manifold
- BVSVs - replace: two bolted into and around the water neck – one pink top, one purple top
- Idle cut solenoid – check to be sure grounded properly or if the contacts are dirty

That’s all I got for now

 

[FJ40Jim]

I started having hard starts (and a bit of pinging.. one issue at a time I guess ). In the morning, I used to stand outside the truck, pull the choke slightly out, and it started right up. A lot of the time I could just stand outside the truck and start it. Never had to pump the gas... maybe 1 or 2 on occasion. Now I have to do a small song and dance to get the it started.
I haven’t tried the cleaning but, it’s on my list for this weekend (Thanks for the procedure). Ran a can of seafoam through the tank prior to a tune-up but, didnt notice a difference.

A carb needs rebuilt when enough trash has accumulated inside to negatively impact performance. Might not happen for 10000 gallons, or might happen after 1 gallon. Just depends on how dirty the fuel is.

The seafoam and other "miracle in a can" cures can not remove sand and rust flakes from the bottom of the float bowl and jet wells.

I was replacing an exhaust gasket at the manifold last night and noticed a tube coming off the bottom of my charcoal canister and routes into the passenger frame rail. The tube coming out the bottom of the canister was very flat looking… almost like it was crushed flat. Is this normal?

Yes, the canister overflow hose is molded almost flat. Dunno why, but they all look like that.

 

[dtrain]

A carb needs rebuilt when enough trash has accumulated inside to negatively impact performance. Might not happen for 10000 gallons, or might happen after 1 gallon. Just depends on how dirty the fuel is.

The seafoam and other "miracle in a can" cures can not remove sand and rust flakes from the bottom of the float bowl and jet wells.



Yes, the canister overflow hose is molded almost flat. Dunno why, but they all look like that.

Thakns for chiming in Jim. Much appreciated.

That makes a lot of sense. I just posted a list of things I will try (pretty sure most are cheap). If no success... you will be getting a PM

Flat overflow... I look at and though "how the hell did I do that ". Good to know... I will make sure it breaths and check it off.

 

[2mbb]

When was the last time you tuned it up? spark plugs, (maybe) plug wires, valve adjustment, set timing?

 

[dtrain]

When was the last time you tuned it up? spark plugs, (maybe) plug wires, valve adjustment, set timing?

plugs, filters, oil ~5k (just checked my "log")

Plug wires ~1yr

valve adj - no sure its ever been done

timing - I know its slightly retarded and not sure how to set it... need to do some reading

 

[Michael Hanson]

I DONT THINK THERE IS A SET MILAGE,JUST BASE IT ON PERFORMANCE. I hate hard to start motors on anything,usually I find it to be based on the carb. Old ,dirty gas,and dirt roads require more frequent rebuilds. Good luck Mike

 

[hank14]

Do you have the factory service manuals? If you haven't worked through the emissions one that troubleshoots each system, I would start there.

 

[Tinker]

Dunno if this is the official owner's manual start procedure (too lazy to go outside & look), but our '83 sits for days & sometimes months at a time, but I depress the throttle while pulling the choke completely out, pump it twice more, & it cranks & fires. Almost always.

 

[SDFJ60JFK]

I replaced the choke cable on my 60 and I adjusted it properly and now my cruiser starts much better than it had been. I had been having starting problem with the old cable. Not really any thing to do with the cable, but make sure the choke works properly.

John

 

[dtrain]

Do you have the factory service manuals? If you haven't worked through the emissions one that troubleshoots each system, I would start there.

I have the emissions manual and had planned to use it in conjunction with the list I posted earlier.

 

[dtrain]

Thanks for the replies everyone... any additional advice always helped.

 

[Pin_Head]

How long the truck sits without running can also determine how quickly the carb will need rebuilding. Repeated evaporation of the fuel leaves behind a residue ("lacquer") that can clog some of the tiny ports. Sometimes you can clean out plugged ports and vents using the "Oklahoma rebuild".

For the Okie rebuild, you just remove the air cleaner and hose down the entire inside of the carb and the bowl vents with spray type carb cleaner. Let it sit a couple of minutes. Start the engine, rev it up to 2,500 RPM and then hand choke it until it stalls (eg. put your hand over the air horn). Repeat as necessary. When you hand choke it at high RPM, this puts a high vacuum on the inside of the carb and pulls fuel out of every port and air vent, which may unplug them.

 

[dtrain]

How long the truck sits without running can also determine how quickly the carb will need rebuilding. Repeated evaporation of the fuel leaves behind a residue ("lacquer") that can clog some of the tiny ports. Sometimes you can clean out plugged ports and vents using the "Oklahoma rebuild".

For the Okie rebuild, you just remove the air cleaner and hose down the entire inside of the carb and the bowl vents with spray type carb cleaner. Let it sit a couple of minutes. Start the engine, rev it up to 2,500 RPM and then hand choke it until it stalls (eg. put your hand over the air horn). Repeat as necessary. When you hand choke it at high RPM, this puts a high vacuum on the inside of the carb and pulls fuel out of every port and air vent, which may unplug them.

I DD my truck but still think the procedure you detailed below couldnt hurt. Thanks for the info!