Frustrated ...

[72TealnWhite]

ok so i traced that line (open) near the carb... i got underneath and it leads to the passenger side rear of the transmission... to a black circular thing (mod)? Then there's another line going from the (driver side) rear of the trans and that goes up into the firewall.. i'm assuming that is linkage ... I'm going to go give it a shot.. thanks

nate..

[Dunenutt]

If the vacuum tube is original, it will have a smaller end on it. That smaller end actually slides into the fitting on the intake manifold. It has a piece of vacuum line on it just to seal it and hold it in.

[sleepingbag]

You have found the issue I believe, Ill post a pic of mine if you need to see it..

[72TealnWhite]

ok.. so there is a vacuum conn. on the intake not being used... in the rear of the intake.. it sticks up .. and there is one or more things connected except the open connection on the passenger side of the intake .. i doubt the hose is original.. and i dont see anything on the fitting though... i need to get the old lady out and listen for a whistle when (not hooked up ) and no whistle ( hooked up) ... Crossing my fingers ... thanks all for the help

i'd love a picture .. thanks

nate

[72TealnWhite]

FIXED !!!!


THANKs for all the help .... It was the vacuum hose from the intake manifold to the trans modulator.. time to get so hose clamps and i'm going to shorten the hose... probably why it came off.

thanks
nate

[wwotr]

Originally Posted by 72TealnWhite

FIXED !!!!


THANKs for all the help .... It was the vacuum hose from the intake manifold to the trans modulator.. time to get so hose clamps and i'm going to shorten the hose... probably why it came off.

thanks
nate

Good Deal!
Dontcha just love it when a problem gets fixed with a simple look-see.

Good News!

[Dunenutt]

Originally Posted by 72TealnWhite

FIXED !!!!


THANKs for all the help .... It was the vacuum hose from the intake manifold to the trans modulator.. time to get so hose clamps and i'm going to shorten the hose... probably why it came off.

thanks
nate

Good to hear! It probably blew off when it was coughing due to lack of fuel.

[C20-67_N_MO]

Glad to hear thats all it was!

Now go out and enjoy your weekend with it.

[dukcaln]

glad I read this. sounds like my issue. runs great brand new motor and rebuilt trans.... other than the shifting issue described by 72tealnwhite. sounds like me exact issue just not to that extent. will take a look at mine this week... glad 72 tealnwhite got his running...

[sleepingbag]

I had this issue and spent hours looking at the trans before I noticed the hose had rotted out...glad you found it.

[dukcaln]

checking tuesday when I get time... keeping fingers crossed

[72TealnWhite]

may have spoke to soon... i took her out again late tnight and she really wanted to backfire ... and coughed again.. in 2nd gear (auto) .. i sprayed a little carb choke cleaner in the carb .. so i'm hoping thats it.. ... too much tday ... i'll wait until tomorrow to fig this one out..

gotta love having a 40 yr. old vehicle.. fix broke fix broke fix broke.. oh well, i think its fun and thats why i bought the truck .. so

good night

[dukcaln]

could be worse.....like a FORD...lol

[eagleuh1]

Glad you got the vacuum line found and replaced, but it still sounds like your not getting good gas flow like I had. Mine was peeling off the metal fuel line from fuel pump to carb, and blocking up the sintered filter at the carb. Ran great at idle, slow speed, hit a hill or floor it and it would miss, fall on its face. Stop idles fine again. Good luck.

[FlounderGDI]

I had a 70 Camaro a long time ago where the timing wasn't exactly right. It would cough and backfire and would blow the vacuum plugs and or hoses right off the side of the carb. When your truck coughed it could have blown off the vacuum line that goes to Transmission Modulator.

Also when I swapped carbs on my truck I forgot to put back on the vacuum line from the carb to the modulator and it did exactly what you describe. It stayed in first gear the whole time I drove it. Luckily I wasn't too far from home on the first test drive and then immediately realized there was an open vacuum port and hooked it back up.

[72TealnWhite]

Originally Posted by eagleuh1

Glad you got the vacuum line found and replaced, but it still sounds like your not getting good gas flow like I had. Mine was peeling off the metal fuel line from fuel pump to carb, and blocking up the sintered filter at the carb. Ran great at idle, slow speed, hit a hill or floor it and it would miss, fall on its face. Stop idles fine again. Good luck.

You have described it to a T ..... don't know what else .. It ran great for two days ....so I'm going back to then.... and rethink this through.

Took her out today and its the same ... just as described above... Well it is sunday Chevy GODS ... out to the garage.... i go

[sleepingbag]

Clear those fuel filters, I bet your in biz. Now im off to my white whale, wish I had a garage, looks like rain...

[72TealnWhite]

Originally Posted by sleepingbag

Clear those fuel filters, I bet your in biz. Now im off to my white whale, wish I had a garage, looks like rain...

well... i replaced the fuel filter to the carb about a month ago .. put in one of those clear wix filters... pretty neat.. i unclamped the hose from the i.m. to the trans modulator... Its on good.. maybe had it to tight (my thinking) .... Fuel filters ? where should i be looking?

I did notice .... There is a black cylinder looking thing located to the left and a little lower than the battery which has hoses connected ... and one of those hoses from the cylinder is cut ... and i put my thumb on it and felt vacuum.. What is this .. and is that supposed to be cut ? i'm looking to see what it is now... Running good at idle... running good when revved in park... i'm going to try this n take a ride.. and see whats up.. but if anyone knows what i'm talking about above.... please reply.. thanks
staying positive
nate

[Stocker]

Originally Posted by 72TealnWhite

I did notice .... There is a black cylinder looking thing located to the left and a little lower than the battery which has hoses connected ... and one of those hoses from the cylinder is cut ... and i put my thumb on it and felt vacuum.. What is this .. and is that supposed to be cut ?

Pretty sure you're talking about the vacuum storage tank -- and no, that hose should not be cut. You should never have a vacuum hose or port exposed and leaking.... if something is disconnected for a reason, it needs to be plugged.

[72TealnWhite]

Originally Posted by Stocker

Pretty sure you're talking about the vacuum storage tank -- and no, that hose should not be cut. You should never have a vacuum hose or port exposed and leaking.... if something is disconnected for a reason, it needs to be plugged.

The vacuum storage tank would make sense... it has a larger hose going into it ... and then on the top of the tank one coming out that is cut .. or open rather and definitely vacuum wanting to go in...... I'm going to plug it up with a bolt or golf tee... and see if thats it.. crossing fingers again.. maybe it popped out when it coughed due to lack of fuel also..... thanks ...

i'm going to go do some more research on this vacuum storage and go try it in a bit .. keep ya posted...

nate

[72TealnWhite]

Back to where i began FRUSTRATED !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

everything seems fine until i step on it a bit .. .. then it wants to do something..cough backfire.. so i take it easy on the way home.. don't want to do anything internal.... Is it safe to say that this isn't due to internal damage .. because i just had the heads refurbished and new valves.. and the whole shot? I don't know .. i can always take it back to the f------- shop.. and spend more money i don't have ..

off to brainstorm

nate

oh.. and i did fill that vac hose.. didn't seem to do any difference either way

[71swb4x4]

I believe the black cylinder is your charcoal canister.

Start with the basics on your backfiring. I am not a mechanic, but here is what my untrained experience is telling me:

Backfiring would most likely be caused by either a spark issue, or the valves opening at the wrong times. Either the spark is a tad early/late, or the valve is opening at the wrong time.
So start simple, is the timing set correctly? Did you set the timing with a vacuum gauge, and with the vacuum advance unhooked?
Is your distributor functioning correctly?
Are the valves adjusted correctly? (no idea if that would even cause your problem)

[72TealnWhite]

just took her for a drive ... and she ran perfectly The backfire wants to happen at about 30 mph and accelerating... So that's why she is named "my old lady" She keeps me confused and frustrated and takes all my money..

as for the valves... I just had all of that redone by professionals in a shop of mechanics.. im no mechanic either ... so i guess im giving them the benefit of the doubt that they did things correctly like i said above... i had the heads redone.. new valves rods rockers.. ect....

ho hum i think ive had enough of looking at her for the day.. time to watch the tiger game and forget about it ..

[72TealnWhite]

oh, next i was thinking ... carb re-tune ... not sure why but .. its worth a shot.

[71swb4x4]

With it only happening at 30 and above I wonder if it could be your advance.

Don't walk into these repairs blindly, do some research. If you tune the carb on a hunch, what if that gets messed up? Now you have one more piece that isn't working correctly. You can fix a lot of parts on a hunch and spend a lot of money and time quickly. If you are defeated, take it to a shop.

Don't discount suggestions people give you simply because you have replaced that part of someone has done that repair. We all know people make mistakes, and new parts sometimes come broken.

Of course it doesn't help that you are getting random replies from people who can't see your truck acting up. We are all guessing to some degree.

Good luck!! You will get it fixed, and the problem probably is easy, you just have to find it.