my 82 302 learned a new trick today.start it up and it runs fine at idle.give some gas and it hits on all 8cyl.let off the gas and it will not idle but for a second then dies.if you put it in any gear then it seems to run on 4 cyl.is this a carb issue?or what....oh yea the acl. pump has a leak just a small drip from the bottom of it.any help would be great.or any ideas for things to try i have done all i know to do.(witch is not a lot)

 

Sounds like a vacuum leak somewhere. Broken or disconnected hose, most likely.

 

that sould be fun to track down. the po must have thought all those rubber hoses where just for looks. everyday i find more of the pluged off or unhooked. by the way its a 2 bl carb

 

The one that got me for a while was on the back of the carb. and was very hard to see...

 

thank you for the tip if it ever stops raining here i will have a look

 

You might want to look into a smoke machine sometimes Autozones have them. You hook them up to a vacuum like and it pumps smoke throughout the engine and vacuum lines and youll be able to find your vacuum leak very quick.

 

thanks for the tip

 

You could also unplug one vacuum line at the engine at a time, and see if you notice any change. I say one at a time so that you can more easily figure out which one is leaking, if there are any leaking.

I actually had a very similar problem early this year; my truck's power steering box blew a seal and my truck was parked for around nine months. It ran great before I parked it, and ran terribly once I got the replacement box installed and went to get it back on the road. It was like you describe, it'd run fine at idle and rev okay, but as soon as you put any load on the engine, it'd either misfire if you kept your foot in it, or die if you didn't.

It ended up being worn-out spark plug wires that were causing the problem. The plugs were fuel-fouled as a result too. After replacing the wires and plugs, I started my truck and it ran better than when I first parked it!


I also had another issue with poor performance not long ago...My truck wouldn't idle worth a flip and it'd try to stall at idle in gear, but if I was off-idle it'd run perfect. Turns out that the green wire that runs from the DSII box to the coil was worn through where I had put a Y-connector so I could tee off the wire to feed my Sunpro tach (I was unaware of the FACTORY tach connector near the DSII box...oh well).

I tried all sorts of things to try and track down the problem (replaced carb gasket, replaced vac lines, tested various lines for leaks) to no avail. It wasn't until one evening that I was warming up my truck in the driveway and it died on me (not like fuel starvation, but like turning the key off) that I found the wire just hanging loose near the coil; it had finally worn through and killed power to the coil.

I swapped in a non-cut up section of harness and it ran great. I was so glad it failed in my driveway....I had taken a trip out of town a few days before and had to take the interstate home at night, I don't even want to imagine what would've happened if that wire had come loose at 2600RPM with me doing like 60!!

 

thank you i will check those thing as well before this started. the truck would surge like crazy at idle. were talking from norm to like 2500 rpm then back down.i adjusted idle screw and all that stuff .but no help all the folks i have ask say its sucking air from some place.going to rebuild the carb and new gaskets and track down some vacum lines in the am.hope it works.i need my truck!i miss the thing lol

 

Sounds like a vacuum leak to me. If you can't get a smoke machine you can use starter fluid. Spray it carefully around the vacuum lines and if it causes your engine to change idle that is a good place to start looking for a leak.

 

Tried that with mine I could never really find it. Just new it was somewhere around the carb... Eventually found a diagram which I followed and pinpointed the issue.

 

Have you tried replacing your carburetor gaskets? Leaking gaskets there could cause a vacuum leak.

When I replaced mine, I had like three or four gaskets total...there were like two spacers under the 2bbl carb. I yanked all that and just put a single spacer and gasket (spacer had a built-in spacer-to-carb base gasket, so I just needed the one separate manifold-to-spacer gasket). It wasn't the cause of my problem (the worn tach wire was), but at least I got a nice little tune-up out of it. lol

 

Takes a lot of patience and a certian degree of skill to find em usually (not saying you dont have it) I remember it took me forever and almost two full cans before I found mine the first time I tried to use that method but in the end it does work.

 

do you still have that diagram if so scan it in so i can find this leak