Hey guys, '74 Maverick, 6 cylinder 200. For the past month or so, while the car starts up just fine, it doesn't seem to have any power or oomph until I have had it on the road for about 5 minutes or so. After that it is fine all day, even after sitting for a few hours while I'm at work. Took it our Friday night, ran great, no problems. Started it this morning and the lack of oomph was even more prevalent. I didn't even think that I would get it up the driveway! Taking the kids to school, it's worse than ever. 5 minutes driving, little or no change. Same at 30 minutes. It never really gets any better. Let me try to describe it: I push on the gas pedal and there is a little surge but then the engine bogs down again. If I lightly "pump" the accelerator while I drive I get a lot of little surges but it quickly bogs down again. I feel like I can find a "sweet spot" on the gas pedal, but even there it doesn't feel right. I came home and changed the fuel filter and air filter, pulled the dist cap and checked my Pertronix unit, all seemed fine. Checked all of the vacuum lines. Took it back out on the road, same thing. Ugh. Any ideas what I should check next? Should I pull the carb? Any thoughts? Thanks, CommieHook
Agreed, also a weak fuel pump or dirty strainer in the tank can cause similar... Pumping the accelerator gives the engine additional fuel that compensates for the lean fuel condition of the carb... Pay close attention to the main jet and associated passages, likely there is a bit of trash in there... Also be sure float level is correct on reassembly...
Rebuilt the carb (It was nasty up in there!), changed the dist cap and rotor, new plugs and plug wires, still no change. It seems to idle fine, when it's in park I can really give it the gas and it sounds/feels great. But in gear, it surges and falters any time it is under much of a load at all. I don't know what else to check at this point. It is pumping plenty of gas. Could the Petronix unit be having problems? CommieHook
Probably 99% of the time bogging under load is carb/fuel issues... Things not mentioned is the power valve must be functioning, I believe it's external on these carbs?(sorry I'm a V8 guy) Also back in the day removing the hot air pickup to the air cleaner often caused a bog because the carbs were lean anyway... I doubt it's iginition but would be worthwhile checking the vacuum advance & timing... If timing is correct, vac advance functioning and flash from light is steady at higher RPM(say 3000), put the light away...
I'm pretty sure that we got all of the little passages clean, the float level set right, etc. I don't think that it's a fuel supply problem, and here's why: I have a clear inline filter installed, and it stays full, even when I'm really revving the motor. And when I loosened the hose clamp on the inline filter that screws into the card, there was enough pressure in the line that it SQUIRTED under quite a bit of pressure, even when it was just barely loose. Could this be a valve problem at all, you think? CommieHook
Vacuum will be fluttering around if that's the case, not much chance it would wipe all the lobes... Flat exhaust lobes will cause backfiring through the carb, flat intake creates a dead cylinder(s)... Pumping the throttle to get improved performance just about 100% indicates a lean fuel condition...
The plot thickens! This morning with the motor running I poured a bottle of Sea Foam in with the oil. The motor died. It was a little hard to get it started back up. Driving it after that, it feels quite a bit better. The dead spot on the accelerator isn't as noticable, and it definitely has more pickup. It is still not back to it's smooth running self, however. So what does that tell us? (I'm not being smart, I really want to know!) Any ideas? Thanks, CommieHook
Update on the plot thickens: After parking the car for a few hours, it has regressed to it's pre-Sea Foam crappiness level. Ugh. Why was the Sea Foam help so temporary? Why did it help at all? CommieHook
Is the choke open? Is your timing right? I don't think this is your problem but the rubber line from the gas tank to the steel line had collapsed on my 74 I6 and kept starving the carb. It would idle and rev just fine, but under load it couldn't keep up with the demand. Was a simple fix once I figured it out. Just a thought and easy to check.
