I just recently took off the muffler and cat off my 79 2wd with a 302. It use to start great a day ago, but now with just a glasspack and 16ft. of 2.25in. pipe for exhaust I have to pump a lot of gas in it even after I just shut it off to get it started and keep it running. The truck runs great once you get it started. Whats going on here?

Redneck-Cowboy

 

Sounds like you broke something while installing the pipes. Did it have an electric fuel pump that is now disconnected?

 

Red,
Assuming you have damaged nothing?
Try this:
1. Advance timing 1 or 2 degrees.
2. Check accelerator pump. My guess is, it isn't working.
3. Check your choke and see if its working.
4. Check your coil voltage during startup, should be 9VDC? I think?
Decreasing back pressure in the exhaust system shouldn't be detectable from the fuel side. Unless you were running lean before the mod.
I got to admit, I'm guessing out my *** on this one. I'd really have to see this one to get a better idea.
KingFisher

 

First, the trucks a 79 so it has a mechanical fuel pump. The timing is advanced a little bit anyway. Accelerator pump I'm pretty sure is fine or else the truck wouldn't run so good once it's started. The choke is working and that's the thing, everytime I shut it off I need to reset the choke to get it started (it has an auto choke). Coil voltage I don't have the tools to check. It was never running lean b/c you would step on it and a little black smoke would come out and still does. When it's not warmed up it also likes to flood out sometimes, but that's normal on any carbed vehicle. It's also fouled out plugs before. My 86 F-150 with a 300 runs lean and the plugs stay real clean. So I don't know, my dad thinks maybe oxygen sensor?

Redneck-Cowboy

 

Red,
I think you spilled the beans!
You may very well be suffering from a vacuum leak.
By setting the choke, you are compensating for a vacuum leak.
At this time of year (summer), a choke shouldn't be that big a deal. How does the tranny shift, early, late? What was the drivetrain? I forgot.
This wouldn't explain fouled plugs though?
Are they oil fouling? Does it burn oil?
If the idle is set rich to compensate for a vacuum leak, that may or may not foul plugs. No definite evidence either way.
Check your vacuum harness. If you find a hose off or something, retune the carb afterwards.
How do the power brakes work? Do you have a hard/stiff pedal?
KingFisher

 

No oxygen sensor on these old trucks. You could have had both an electric and mechanical pump. An electric pump that may have had a wire knocked off during exhaust work was the only thing that I could think of that might be related to that exhaust system work. Something else must have gone wrong and it is pure coincidence that it happened at the same time as your exhaust work.

 

Choke worked fine last summer and all other times, so I see no problem there. I think the plug was just shot on the truck, bought it with 25K, so they could have been original, anyway no big deal. Just to set things straight here, I know for sure it's not a electric fuel pump. Next the tranny shifts fine, it's a C-6 3 spd auto. 2wd truck. I only tapped on to the exhaust where the cat was, so I wasn't even close to the fuel pump since I did all the work on the right side. The brakes work, I've already put in a vacuum booster and master cylinder last winter and no vacuum leaks to be found.

Redneck-Cowboy
P.S I got 5th place out of 25 tractors in a tractor pull a few days ago, with my farmall H.