Odd shut off issue on my 2F (1 Viewer)

[psulick3]

I can really figure how to search for this and the attempts I’ve made this far have been unsuccessful. My desmogged 2F with original carb has been acting a little funky lately. Runs great when on with no power loss or issues through out the RPM range. At certain times on acceleration I can hear a sort of tinny noise. I’m not sure how to describe the sound properly but then engine has a different tone on acceleration. Like an induction noise. Whenever I hear that noise, like 100% of the time, the engine will stumble and stutter on shut off and will then take a ton of cranking to start again. The issue is intermittent as the noise and shut off stumble is not constant. It used to be very rare; like so rare it wasn’t even worth bothering with. It has no become mush more frequent (50% of the time sort of thing).

My thought was vacuum leak so I checked all the hoses as thoroughly as possible but I don’t have a vacuum gauge. I haven’t touched the carb in a couple years cause it’s been running perfectly with the exception of this issue.

Any help would be greatly appreciated!

 

[Wildcat Walker]

clogged fuel filter? Takes more fuel under load, not much at idle or free rev. You say its intermittent, so if you had a major leak I would think it would be continuous. What visual inspection or other troubleshooting have you done so far?

 

[2mbb]

if it is a like a rattling upon acceleration this could be pinging (pre-ignition). This could seem intermittent because it may only happen under certain types of loads or when the truck is a little hotter than usual, etc. others may have better suggestions what it could be on a desmogged engine, but usual culprits are air fuel mixture is too lean, timing is wrong, engine is generally running too hot (problems with the cooling system).

Engine run-on is also called dielseling and may have similar causes as pre-ignition. In general, cylinders continue to combust without the spark plug generating spark.

Did you own the truck when the desmog was done? Do you know it was done correctly?

 

[psulick3]

clogged fuel filter? Takes more fuel under load, not much at idle or free rev. You say its intermittent, so if you had a major leak I would think it would be continuous. What visual inspection or other troubleshooting have you done so far?

I’ll check out the filter. No gas smell or anything so I don’t think it’s a fuel leak. Thanks!

 

[psulick3]

if it is a like a rattling upon acceleration this could be pinging (pre-ignition). This could seem intermittent because it may only happen under certain types of loads or when the truck is a little hotter than usual, etc. others may have better suggestions what it could be on a desmogged engine, but usual culprits are air fuel mixture is too lean, timing is wrong, engine is generally running too hot (problems with the cooling system).

Engine run-on is also called dielseling and may have similar causes as pre-ignition. In general, cylinders continue to combust without the spark plug generating spark.

Did you own the truck when the desmog was done? Do you know it was done correctly?

View attachment 3076616

I have some octane booster I’ll throw in with a fill up that might serve as a test against pinging. It’s not running hot (aftermarket 3 core aluminum champion rad keeps it super cool). I haven’t tried much else yet as I’m on vacation with the truck. I’ve got a simple set of tools but nothing crazy. If octane boost doesn’t do anything, I’ll mess with the idle mixture screw a touch. Thanks!

 

[psulick3]

if it is a like a rattling upon acceleration this could be pinging (pre-ignition). This could seem intermittent because it may only happen under certain types of loads or when the truck is a little hotter than usual, etc. others may have better suggestions what it could be on a desmogged engine, but usual culprits are air fuel mixture is too lean, timing is wrong, engine is generally running too hot (problems with the cooling system).

Engine run-on is also called dielseling and may have similar causes as pre-ignition. In general, cylinders continue to combust without the spark plug generating spark.

Did you own the truck when the desmog was done? Do you know it was done correctly?

View attachment 3076616

Forgot about your desmog question. PO did the work but it’s done right. It’s been desmoged for 7-8 years and Runs great. Other than a busted coil and a dead fusable link, this is literally the first problem I’ve had in 6 years of ownership.

 

[Seth S]

if the distributor advance curve wasn’t changed when the desmog was done you are likely experiencing pinging. Try throwing some high octane fuel in for a tank and see if it goes away.

 

[Wildcat Walker]

I’ll check out the filter. No gas smell or anything so I don’t think it’s a fuel leak. Thanks!

Not a fuel leak, a vacuum leak.

 

[Pighead]

How's that little advance pin bushing in your dizzy? If it is wearing out, or gone, can give you too much advance