Engine loses power when shifting gears(auto)

[JamesMilk]

Ok so didn't know where to post this, kinda transmission problem and kinda engine problem.
This is the problem I am having though.
When the transmission switches gears, I suddenly lose all power from the engine. Pressing the gas peddle makes it bog down, letting it idle just sounds like it's about to die. So I have to limp it back home probably restarting it every 100 ft or so. Kinda embarrassing lol.

When I first drove the truck off the lot she ran fine, only didn't ever get into 3rd. So I did the usual tune up stuff.
Topped up the ATF, swapped the spark plugs and got new oil/filter. After I did this she ran as before just never got into 3rd.

So I looked on here for help, was told to check the vacuum modulator/lines. Changed the modulator, same problem happening. Have since then changed the distributor, same problem.

Now she will start up and sound great, but as soon as I get her down the road far enough to switch into 2nd, she gets the same problems again. And anytime I start her up while trying to get it back home she's running like my timing is just jacked, whole truck shaking, will die if I give it any gas.

And if I let it sit for 10 mins, it's like she has a factory reset and runs great again like nothing was ever wrong. This is very confusing to me, thinking of flushing the transmission and changing filter.
If y'all have any pointers I'd sure love to hear them.

 

[JamesMilk]

Oh yeah to add to this, during this limp mode there is an audible clicking coming from the engine bay, thinking timing. But how does timing work fine at startup and bad after a gear change?

 

[Radiohead]

Do you know which transmission you have?

 

[greyghost]

very well cud be timing, bent valve, bent push rod, vacuum leak, or what my first thot carburator float level needs adjusted or replaced. motor not getting enough fuel and starts running low after second gear. is engine warmed up? like idling for 15 minutes or more? smog pump still connected? possibly bad gas, hole in fuel line to where its sucking air or blowing out fuel. best starting place is to start ruling out what its not. start with vacuum plugmodulator line at carb or intake or swap it to diff place. shud be on intake vacuum.drive it n shift manually , after its warmed up to operating temp coolant is flowing. if still acting up, move on. pull fuel line from carb place clear jar or bottle under it to catch fuel. shudn't take very long to fill up, minute at most for cup full, engine shud idle for couple minutes before it dies. look at fuel. is water present, water is heavier than gas so water on bottom gas on top, if not obvious dump on concrete, bubbles or rainbow colors water is present, fuel filter? replace it they're cheap. fuel is ok, pump ok, fuel filter changed. reconnect and test drive again after warmed up.check timing with a timing light.pull air filter is choke flapper closed or open on cold engine and on warmed up engine .depending on ur mechanical skill and tool supply where next adventure lies. before we go there try those. get a more detail of circumstances when rodeo begins, how long can you drive in second before it starts, 1 mile or 5 miles and normal to help deciphering exact situation in helping to eliminate causes. like if stay in low can you leave rubber on pavement. try stepping on brake same time. how long has it been like this. you just bought it like that no test drive. lemon laws in ur state? good luck bucket wat you think?

 

[JamesMilk]

Do you know which transmission you have?

It's a th350

 

[JamesMilk]

very well cud be timing, bent valve, bent push rod, vacuum leak, or what my first thot carburator float level needs adjusted or replaced. motor not getting enough fuel and starts running low after second gear. is engine warmed up? like idling for 15 minutes or more? smog pump still connected? possibly bad gas, hole in fuel line to where its sucking air or blowing out fuel. best starting place is to start ruling out what its not. start with vacuum plugmodulator line at carb or intake or swap it to diff place. shud be on intake vacuum.drive it n shift manually , after its warmed up to operating temp coolant is flowing. if still acting up, move on. pull fuel line from carb place clear jar or bottle under it to catch fuel. shudn't take very long to fill up, minute at most for cup full, engine shud idle for couple minutes before it dies. look at fuel. is water present, water is heavier than gas so water on bottom gas on top, if not obvious dump on concrete, bubbles or rainbow colors water is present, fuel filter? replace it they're cheap. fuel is ok, pump ok, fuel filter changed. reconnect and test drive again after warmed up.check timing with a timing light.pull air filter is choke flapper closed or open on cold engine and on warmed up engine .depending on ur mechanical skill and tool supply where next adventure lies. before we go there try those. get a more detail of circumstances when rodeo begins, how long can you drive in second before it starts, 1 mile or 5 miles and normal to help deciphering exact situation in helping to eliminate causes. like if stay in low can you leave rubber on pavement. try stepping on brake same time. how long has it been like this. you just bought it like that no test drive. lemon laws in ur state? good luck bucket wat you think?

I just bought it, I have chagned the fuel filter. Carb is pretty dirty tbh. Carb is this model number: https://www.carburetion.com/CarbNumber.asp?Number=17058202

I hope it's not a bent anything in the engine, I'm newish to carbureted engines.
I'm still relearning old engines. It is warmed up before I take it for a spin, and it loses all power as soon as it switches gears. It seems like a healthy run until I drive it, like just in parking revving the engine.
It's a GM 350 replacement engine, not the original. Where can I find the info badge for my engine?
Haven't checked the fuel tank yet kinda hesitant on playing with that, but it does leak fuel when I put the gas pump into the filler hose.(I already bought the replacement for that, just not installed)

Doesn't seem like a fuel pump issue, there is a lot of pressure in the line, and no leaks.
Really don't want to take it to a mechanic, I think their labor charges are a little much.

 

[Vbb199]

Is there a electrical plug over on the passenger side of the transmission ? Maybe around the circular piston cover?

I believe some th350 equipped vehicles had a spark control switch as part of emissions or mpg crap one of them ... i was thinking thats only 305 cid equipped stuff.....

 

[Vbb199]

Also, it could be possible its slipping badly

Whats the color and odor of the ATF

 

[JamesMilk]

Also, it could be possible its slipping badly

Whats the color and odor of the ATF

Here is the ATF.

 

[JamesMilk]

Is there a electrical plug over on the passenger side of the transmission ? Maybe around the circular piston cover?

I believe some th350 equipped vehicles had a spark control switch as part of emissions or mpg crap one of them ... i was thinking thats only 305 cid equipped stuff.....

I see that connection under there, gunna clean up the tranny fluid and filter first

 

[JamesMilk]

Ok, well transmission filter and fluid definitely needed changing, but it still shuts off by itself in idle now. I'm thinking there may be water in my gas....

 

[Grit dog]

Trans sludge aside (that will be a current or future issue for sure), start with the simple stuff.
Verify fuel supply from pump. And if it’s good, run it off a gas can to verify or isolate any issues with the tank/water/fuel pickup etc.
timing, if you don’t have a timing light, you need one and verify initial timing and (presumably) vaccum advance is working properly.
Also check vacuum for leaks but not likely if it runs fine then doesn’t.
That’s where I’d start as well as verifying it is or isn’t spitting fuel the same into the carb when it’s running good and again when it’s running poorly.
Good luck!

 

[JamesMilk]

Trans sludge aside (that will be a current or future issue for sure), start with the simple stuff.
Verify fuel supply from pump. And if it’s good, run it off a gas can to verify or isolate any issues with the tank/water/fuel pickup etc.
timing, if you don’t have a timing light, you need one and verify initial timing and (presumably) vaccum advance is working properly.
Also check vacuum for leaks but not likely if it runs fine then doesn’t.
That’s where I’d start as well as verifying it is or isn’t spitting fuel the same into the carb when it’s running good and again when it’s running poorly.
Good luck!

I'll try the jar trick with gas, to see if I have water in the tank.
Also added some water remover to the tank to see if it runs better.
I did notice that before it died the muffler had more than the usual amount of water shoot out of it before it died.

 

[Grit dog]

I'll try the jar trick with gas, to see if I have water in the tank.
Also added some water remover to the tank to see if it runs better.
I did notice that before it died the muffler had more than the usual amount of water shoot out of it before it died.

Don’t worry about the condensation. That’s what old engines with no Cat doo…
Yes you can check for water in fuel like you just said but I was suggesting running it off of a gas can. It could be your fuel sock/pickup, bad gas, whatever. You isolate everything south of the fuel pump by running off a gas can.
Maybe runs the same maybe narrows down the problem.

 

[Vbb199]

I see that connection under there, gunna clean up the tranny fluid and filter first

I asked about the timing tip in switch because there could be something going haywire there, but it sounds like youve got bigger issues