Won't idle

[PAFJ]

Suddenly my engine won't idle unless the choke is pulled. This is accompanied by lots of backfire out the exhaust pipe once I get the vehicle moving, and a noticeable loss of power.

Engine is desmogged, w/ green wire mod.
Fuel filter recently changed, good fuel level in the bowl
Timing set to 7* TDC
No vac leaks that I could see, but it sure does act like a vac leak.
Valves done about 5-6K ago... probably will check them out tomorrow

What else? Could the evap system have any effect on idle? I ask because I get a fuel smell while driving now... this has never happened.

Thanks for any advice

 

[FJ40Jim]

Test operation of the ICS.

KOEO, plug/unplug the ICS, make sure it clicks whenever power is applies/removed.

 

[PAFJ]

Test operation of the ICS.

KOEO, plug/unplug the ICS, make sure it clicks whenever power is applies/removed.

The ICS is the fuel cut solenoid right? If so I checked, it clicks.

 

[PAFJ]

Anybody have any ideas? I'm at a loss... engine still will not idle at all w/o choke.

Things I've checked today are:

Valves... valves checked good
Fuel cut system... I've checked this system to death. If something is wrong here i'm not seeing it.

TIA-

 

[Marc311]

Just thinking out loud . . .

I am wondering if it is a spark issue rather than a fuel issue. The fact that you can use the choke to run seems to indicate fuel, but the backfiring/afterfiring means you're getting unburned fuel into the exhaust. I am wondering if poor ignition (coil, wires, plugs) could be the culprit and the choke just gives it more gas to help it ignite.

The other theory would be why aren't you getting fuel (or a good spray). You've checked the FCS sp maybe a clogged jet/dirty carb. Have you tried a good dose of carb cleaner or BG44K or similar?

 

[PAFJ]

Have you tried a good dose of carb cleaner or BG44K or similar?

Yes, both... seafoam though not the stuff you mentioned.

The problem just became intermittent. I started it up and everything seemed well... good idle, etc. I figured the problem miraculously fixed itself. After pumping the gas a bit, bringing the rpm's up to around 2K, it suddenly started backfiring on decel and would not idle anymore.

 

[FJ40Jim]

Yes, both... seafoam though not the stuff you mentioned.

The problem just became intermittent. I started it up and everything seemed well... good idle, etc. I figured the problem miraculously fixed itself. After pumping the gas a bit, bringing the rpm's up to around 2K, it suddenly started backfiring on decel and would not idle anymore.

That sounds like FOD in the carb. Junk floating aound in the bowl, gets sucked up against the jet, starving the engine for fuel. With enough starts and stops, the junk floats away from the jet, until fuel flow sucks it back up against the jet again.

 

[PAFJ]

That sounds like FOD in the carb. Junk floating aound in the bowl, gets sucked up against the jet, starving the engine for fuel. With enough starts and stops, the junk floats away from the jet, until fuel flow sucks it back up against the jet again.

Is this something that can be fixed by lifting off the air horn and poking around? Or is this a complete dismantle?

TIA-

 

[cruiser88]

Is this something that can be fixed by lifting off the air horn and poking around? Or is this a complete dismantle?

TIA-

How is the float level inside the float bowl?......the little window

 

[PAFJ]

How is the float level inside the float bowl?......the little window

Float level good.

Well, the Cruiser Whisper was spot on! I hope anyways. I went ahead and took the air horn off and started poking around. Luckly I haven't damaged any gaskets yet since I don't have replacements (knock on wood). I removed the primary "small venturi" and at the bottom next to the jet was some nice size chunks of dirt or something, maybe old hose. So I'm hoping that is/was the problem, I'm going to clean everything and put the carb back together and see what happens.

 

[PAFJ]

Sediment in the carb was the problem. Runs like a champ again!

On a side note... just thinking how it could of gotten there. Filter is good/new as of not to long ago. I'm thinking maybe some old gunk in the hose between filter and carb was dislodged and made its way into the carb. Hmm!

 

[FJ40Jim]

Sediment in the carb was the problem. Runs like a champ again!
On a side note... just thinking how it could of gotten there. Filter is good/new as of not to long ago. I'm thinking maybe some old gunk in the hose between filter and carb was dislodged and made its way into the carb. Hmm!

You are correct sir. That is hardened shards of rubber from either a decaying fuel hose or FP diaphragm.