grumpin Posted April 6, 2021 Share Posted April 6, 2021 I haven't tried running a wire through them, but I've sprayed carb cleaner about everywhere I can think of and nothing seems to be blocked. I also would think obstruction. How is the carb base gasket? Link to comment Share on other sites More sharing options...
Nothing Special Posted April 6, 2021 Author Share Posted April 6, 2021 I also would think obstruction. How is the carb base gasket? What do you mean? I think the gasket is a pretty good fit. It certainly doesn't get in the way of the throttle plates moving. Is there a different obstruction you're thinking of? Link to comment Share on other sites More sharing options...
grumpin Posted April 6, 2021 Share Posted April 6, 2021 What do you mean? I think the gasket is a pretty good fit. It certainly doesn't get in the way of the throttle plates moving. Is there a different obstruction you're thinking of? I’m sorry, two things. An obstruction in the carb. And a leak around the base gasket. Link to comment Share on other sites More sharing options...
Nothing Special Posted April 6, 2021 Author Share Posted April 6, 2021 I’m sorry, two things. An obstruction in the carb. And a leak around the base gasket. OK, got it. I don't get any change in idle when I spray carb cleaner around the base of the carb (or anywhere else other than a slight drop at the throttle shaft). So I don't think I have a leak there. I agree that an obstruction somewhere in the fuel delivery path seems like a likely candidate. But my go-to method for dealing with that (carb cleaner) hasn't got me over the hump. The first attempt did help a lot, but it's not as good as it was last year, so I know it can be better. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted April 7, 2021 Share Posted April 7, 2021 OK, got it. I don't get any change in idle when I spray carb cleaner around the base of the carb (or anywhere else other than a slight drop at the throttle shaft). So I don't think I have a leak there. I agree that an obstruction somewhere in the fuel delivery path seems like a likely candidate. But my go-to method for dealing with that (carb cleaner) hasn't got me over the hump. The first attempt did help a lot, but it's not as good as it was last year, so I know it can be better. Have you checked your plugs Bob? Internal leaks usually only affect one or two cylinders but can be a bear to diagnose. Otherwise I'm at a loss as to why choke helps higher RPM's. Maybe you know someone with an ultrasonic tank? Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 7, 2021 Share Posted April 7, 2021 Have you checked your plugs Bob? Internal leaks usually only affect one or two cylinders but can be a bear to diagnose. Otherwise I'm at a loss as to why choke helps higher RPM's. Maybe you know someone with an ultrasonic tank? What about a fuel supply restriction ahead of the carb? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted April 7, 2021 Share Posted April 7, 2021 What about a fuel supply restriction ahead of the carb? Choke wouldn't help if the bowl was empty. 💡 Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 7, 2021 Share Posted April 7, 2021 Choke wouldn't help if the bowl was empty. 💡 True, but if it is getting some the choke might help it run. I dunno. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted April 7, 2021 Share Posted April 7, 2021 True, but if it is getting some the choke might help it run. I dunno. Certainly couldn't hurt to check fuel delivery. I'm not sure what a 302 calls for, but it can't be 63 GPH like a 460. Link to comment Share on other sites More sharing options...
Nothing Special Posted April 7, 2021 Author Share Posted April 7, 2021 Certainly couldn't hurt to check fuel delivery. I'm not sure what a 302 calls for, but it can't be 63 GPH like a 460. OK, that's annoying, but I'll take it. It's running fine now. Backing up a bit... I decided to test a few things. I do have a fuel pressure gauge, but i haven't been looking at it that much as I've been trying things. So I thought I'd check the fuel pressure at a high idle (2000 - 3000 rpm) and then see what it was under load at the same engine speed. Maybe not an iron-clad diagnostic, but it seemed likely that if there was a fuel delivery issue it may well show up as lower fuel pressure under load. Second was still looking for a vacuum leak. As I said before, it's a pretty simple vacuum system. But the one thing that seemed most suspect was easiest to check. So I pulled off the hose to the PCV valve and capped the port. The third thing was getting back to fuel delivery. I was thinking that the issue must be related to the work I did over the winter. But the carb wasn't the onlt part of the fuel system I worked on. I also replaced the fuel tank switch valve. What if the holes through that are too small? So for starters I pulled the PCV hose and went for a drive to look at the fuel pressure gauge. I figured I'd leave bypassing the switching valve for another drive. But on this drive everything worked great! No bogging under heavier throttle, even with the choke all the way in! The fuel pressure gauge was rock-steady at 4.25 psi no matter what the load (it did drop a bit as the engine speed went below about 1500 rpm). So it must be the PCV, right? Wrong. I hooked the PCV back up and it's still running great. The only thing I thought of after I had parked it and Lesley and I were on a walk was that over the winter the main tank was full of fuel and the aux tank was empty. I was running on the main, but on my last test drive before today I filled the aux tank, and near the end of that drive I switched to the fresh gas. It was still acting up a bit at the end of that drive, but it wasn't long enough for much of a test. So maybe it's just bad gas? That's my best guess at this point. I did turn the low speed screws in another turn, so they're now at 1.5 turns out, which seems more normal. I'll drive the Bronco to work tomorrow and see if it stays good. Then later I'll probably switch back to the main tank and see if it starts to hiccup again. So it's a little annoying when a problem just goes away and you don't know if it's going to come back. But for now I'll take that it's running well. And if I can turn the problem back on by switching to the main tank I'll be a lot happier. Link to comment Share on other sites More sharing options...
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