NoseHair

1980 302 V8 C6 w/ AC and smog delete:

It started with my truck wanting to stall at initial acceleration from a stop.I had to feather the gas then stomp on it to keep her going. She acceleratedand cruised fine until I reached 35 mph and wanted to stall but didn't and lostthe ability to accelerate then started to decelerate until I reached ~5mph again or after I came to a stop. That occurred for 2 days. Then on the way homeyesterday, it continued to display the same symptoms but instead of startingthe stalling/deceleration at 35mph, it seemingly steadily decreased severaltimes after repeating the aforementioned cycle until it would not acceleratebeyond the initial press of the gas pedal before it would want to die, diesseveral times and started back up right away, and I luckily was on a downhillstretch to my house so I was able to idle home in drive.

She seems to idle a little rough and fast with a slight misfire.

Gas sprays into the carb when engine is off and throttle is pressed.

It looks like there is a very light deposit of rust in the in-line fuelfilter. Also, after getting home yesterday, the inline fuel filter was abouthalf full (not sure if that is normal).

The engine starts up with no problems other than being rough right off thestart until I give it a little gas then is smooths out.

The PO said they dropped and cleaned the tanks, replaced the fuel pump,replaced the fuel filters, replaced fuel lines, replaced fuel sending units(both tanks), replaced the fuel tank selector valve, and selector dash switch,new spark plugs and wires, new Distributor cap and rotor.

I have replaced the PCV, reconnected most of the vacuum lines, and have tried afew carb clutch positions.

Please help me out.

GhostriderI

Have you pulled and checked the plugs? Could be fouling. Was there a lot of rain in your area before the last fill-up? Could have gotten water in the fuel tank or moister in the distribute or both. Pull the dipstick and see it the oil smells like gas if it does the pump is bad.

Hope this helps

burnthelight88

Well, as long as they did everything correctly, it sounds like most of the larger fuel issues probably aren't the problem.

I'd be seriously considering a carb rebuild if I was you. A lot of the issues may be able to be ironed out with some carb tuning, such as the rough idle upon starting and the sound of a "fast" idle. A lot of those things point to an out-of-whack carb. I'd start by trying to tune yours, lots of decent YouTube videos on the matter.

In the long run though, your carb is probably loaded with carbon and could use a thorough cleaning along with some new parts. If you've got the time, I'd pull it sooner than later. It'll eliminate a lot of your worries.

NoseHair

I have not pulled plugs and wires yet. But that is next on the agenda. There was a lot of rain, but haven't seen any evidence of water in fuel. No gas smell eminating from the oil. The distributer looks as if one small area on the side of the cap has a carbonesque residue. I plan on pulling that tonight to inspect.



I just ordered a "new" motorcraft 2150 for her. The PO has put an autolight on and stated that he wished he hadn't gotten talked into using that one and wish he had rebuilt the stock. Leads me to believe she ran better with her ole motorcraft.


This was my most recent venture:

I ran a vacuum test and fuel pressure test last night.

Vacuum:

@ idle I got a shakey but consistent 20inMg (shakey: the needle moved quickly back and forth ~1 inMg)

@ higher rpm (roughly 2000) the needle dropped to a shakey 15 inMg


Fuel Pressure:

@ idle it registered 8 psi

I have not checked the amount of fuel pushed/per time yet (should be 1 pint per 20 sec.). What are some ways to run this test?

I don't think it is a fule issue either, but thought I would confirm.



Anyone have a good way to check to see if the cat is clogged?


Thanks for your insight in helping me trouble shoot

NoseHair

What transpired last night:

I replaced the plug wire set last night but it did not get rid of the slightmisfire. The condition of the wires was quite bad (bulges, nicks in sheathing,ripped boot, and melty distributer boot on one of the wires) so they neededreplacing anyway and at least I ruled the wires out.

I original had the EGR connected via vacuum line to a port on the PVD valveand the other port on the PVD valve connected to the carb. I followed thevacuum diagram the best I could but wasn't sure which port to use on the carb.I disconnected all vacuum lines mentioned above but I did not have plugs forthe EGR port and PVD valve ports.

Here is what happened when running:

It took a bit to start after sitting a few days and then when she did turnover, the start was a bit hard. After she warmed a little, the idle was ~ok (alittle rough with the slight miss). Initially, at the very top of the gas pedalstroke, while in neutral, the engine would stall. After a few restarts, shewould hesitate at the beginning of stroke and then regain power and would rev.

I then took her out for a spin and every time I stepped on the gas, at thevery top of the stroke, the engine would hesitate then accelerate smoothly (noreal jerk/lunge). I drove it about 10 min with smooth acceleration and shiftingthrough ~40mph with no bogging unless I let off the gas and then depressed again,then I would get the hesitation again. After ten minutes I noticed thishappening less and less and felt confident enough to take her to the freeway totest out higher speeds. She got to ~45-50mph and the same issue occurred *seefirst post in thread*.

Made it home, parked, and noticed a small damp area under where my tail pipewould have been when testing the idle previously. However, there was nomoisture in the tail pipe when inspected.

Thoughts?

GhostriderI

Did the moisture smell like gas? if not it could just be condensation from all the rain and sitting, as you ran and things warmed up the moisture was vaporized and blown out of the tailpipe to re-condense when it hit the cooler air outside. My old truck blows "white smoke" out the tailpipe and has a drip for about 5 minutes after starting if it has come a hard rain, or has sit for a few cool damp nights, it is just water getting out of the tailpipe.

Chris_1

iTrader: (1)

Your carb is screwed up. Or your fuel pump or both.

burnthelight88

Did you get the new carb on yet? The more you describe, the more it leads me to think carb issues.

NoseHair

Got the carb in and hopefully will get it installed tonight. I'll report back

Manuellabour247

Sounds like carb issues, but have you timed it yet to make sure it's set correctly? Timing being a little off and a dying carb could produce a lot of the symptoms you're describing. Look at the underside of the distributor cap for corrosion. If it's white residue and crusty, might as well replace that so that it's ruled out also.