FrazerJames Posted July 31, 2020 Share Posted July 31, 2020 Ok, I’ve run all new nylon fuel lines, replaced the tank and fuel sender. It’s getting uninterrupted fuel now. Yet, I’m still stalling after about 10 seconds in idle. I suppose I need to dig into vacuum lines now? Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 31, 2020 Share Posted July 31, 2020 As you've started a new thread, which is fine, I don't have the history to easily review. So, can you remind us if this is 10 seconds from initial start of the day, or any start? And, haven't the symptoms gotten worse? Didn't the truck run for several minutes initially? Help us understand how things have gone from that to now. Now to the question at hand, perhaps you have too much choke. If the choke is set too rich the engine could easily start after setting a few minutes and then stall because it is too rich. Let it sit for several minutes and it would do it again. So pull the air cleaner and start it. Does the choke stay closed or does it pull off a bit as the engine stalls? Link to comment Share on other sites More sharing options...
FrazerJames Posted July 31, 2020 Author Share Posted July 31, 2020 As you've started a new thread, which is fine, I don't have the history to easily review. So, can you remind us if this is 10 seconds from initial start of the day, or any start? And, haven't the symptoms gotten worse? Didn't the truck run for several minutes initially? Help us understand how things have gone from that to now. Now to the question at hand, perhaps you have too much choke. If the choke is set too rich the engine could easily start after setting a few minutes and then stall because it is too rich. Let it sit for several minutes and it would do it again. So pull the air cleaner and start it. Does the choke stay closed or does it pull off a bit as the engine stalls? I considered keeping the same thread, but was trying to be cognizant of proper subjecting. But you’re right, I should have at least brought over the history. Yes, it was able to drive for a few minutes prior to replacing the tank and fuel line. The line was definitely gunky and had an air leak. I’m wondering at this point if the carb was adjusted with those issues present. I’ll run that test tonight, Gary! Thanks again! I owe you at least a donut. Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 31, 2020 Share Posted July 31, 2020 I considered keeping the same thread, but was trying to be cognizant of proper subjecting. But you’re right, I should have at least brought over the history. Yes, it was able to drive for a few minutes prior to replacing the tank and fuel line. The line was definitely gunky and had an air leak. I’m wondering at this point if the carb was adjusted with those issues present. I’ll run that test tonight, Gary! Thanks again! I owe you at least a donut. LOL! Proper subjecting? What's that? Truthfully though, there's no "right" on how to use threads. My philosophy has been to keep almost everything about Big Blue's transformation in that thread so I can search just that thread to find what I'm looking for. But that has problems as many people have grown tired of such a long thread that they no longer even read the posts. So on one-off items that may be more general in nature I may start another thread briefly, but tie it back to the main thread. For instance, fuel delivery modules. I wanted a larger audience to see that one, so started a new thread. But when I'd gotten to a point I jumped back to the main thread. Meanwhile, back at the ranch, you may be resolving problems introduced while they tried to fix problems induced by the fuel system grunge and air leak. As for the doughnut, as long as it comes from a little shop on a weird corner with almost no parking I'm in! Link to comment Share on other sites More sharing options...
FrazerJames Posted July 31, 2020 Author Share Posted July 31, 2020 As you've started a new thread, which is fine, I don't have the history to easily review. So, can you remind us if this is 10 seconds from initial start of the day, or any start? And, haven't the symptoms gotten worse? Didn't the truck run for several minutes initially? Help us understand how things have gone from that to now. Now to the question at hand, perhaps you have too much choke. If the choke is set too rich the engine could easily start after setting a few minutes and then stall because it is too rich. Let it sit for several minutes and it would do it again. So pull the air cleaner and start it. Does the choke stay closed or does it pull off a bit as the engine stalls? Ok Gary - here’s the weird part. I pulled off the air filter and the choke is stuck OPEN. That said, I did lower the idle a half turn (I contacted the PO and he says he’d been messing with it) and it started right up and stay smooth with the air filter off. But the choke remained open. Here’s some video of it. Here it’s been only running for about 10 seconds. Still stone cold. For some bonus footage, I’m still getting bubbling in the filter... Link to comment Share on other sites More sharing options...
FrazerJames Posted July 31, 2020 Author Share Posted July 31, 2020 Ok Gary - here’s the weird part. I pulled off the air filter and the choke is stuck OPEN. That said, I did lower the idle a half turn (I contacted the PO and he says he’d been messing with it) and it started right up and stay smooth with the air filter off. But the choke remained open. Here’s some video of it. Here it’s been only running for about 10 seconds. Still stone cold. For some bonus footage, I’m still getting bubbling in the filter... Also, I’ve never worked with a carb before - I expected there to be some springiness to the choke? I can close it by hand and it doesn’t move. Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 31, 2020 Share Posted July 31, 2020 Ok Gary - here’s the weird part. I pulled off the air filter and the choke is stuck OPEN. That said, I did lower the idle a half turn (I contacted the PO and he says he’d been messing with it) and it started right up and stay smooth with the air filter off. But the choke remained open. Here’s some video of it. Here it’s been only running for about 10 seconds. Still stone cold. For some bonus footage, I’m still getting bubbling in the filter... If the choke has no spring to it then it isn't set up correctly. When the engine is cold and you slightly open the throttle the bimetallic spring should close the choke to within ~1/8" of being fully closed. And it will be held there by spring pressure. As the bimetallic spring warms up it slowly uncoils and causes the choke to open until it will stand straight up and down. And, it will be held there by some spring tension. But you say the engine is now running well at idle? Have you tried to drive it yet? EDIT: I forgot the filter. I've seen bubbling in filters on most trucks, and I don't know why. So if yours runs right I wouldn't worry about it. Link to comment Share on other sites More sharing options...
FrazerJames Posted July 31, 2020 Author Share Posted July 31, 2020 If the choke has no spring to it then it isn't set up correctly. When the engine is cold and you slightly open the throttle the bimetallic spring should close the choke to within ~1/8" of being fully closed. And it will be held there by spring pressure. As the bimetallic spring warms up it slowly uncoils and causes the choke to open until it will stand straight up and down. And, it will be held there by some spring tension. But you say the engine is now running well at idle? Have you tried to drive it yet? EDIT: I forgot the filter. I've seen bubbling in filters on most trucks, and I don't know why. So if yours runs right I wouldn't worry about it. I haven’t tried driving it yet, no. I’ll give it a shot tonight. That was my understanding of the choke so I thought it was weird. I’ll see if I can figure out where it may not be connected correctly. Link to comment Share on other sites More sharing options...
FrazerJames Posted July 31, 2020 Author Share Posted July 31, 2020 I haven’t tried driving it yet, no. I’ll give it a shot tonight. That was my understanding of the choke so I thought it was weird. I’ll see if I can figure out where it may not be connected correctly. It looks like I have the Motorcraft 7700 carb. Came accross this in documentation. Sounds like no spring? Link to comment Share on other sites More sharing options...
old55pete Posted July 31, 2020 Share Posted July 31, 2020 It looks like I have the Motorcraft 7700 carb. Came accross this in documentation. Sounds like no spring? Just a question? Have you put a fuel pressure guage between the fuel pump and the carb? If memory serves, it should be between 5 or 6 lbs of pressure with the engine running. Another thing you might want to do is to look down the throat of the carb and, by hand, quickly open the throtal linkage and see if there is two sprays of gas coming from the bowl side of the carb. Do it several times. If the spray quits after a couple of pumps then the bowl is empty then the float in the carb or the needle valve may be stuck. If I understand correctly, it sat for several years with bad gas in it, that being the case, it might be time to rebuild the carb. Link to comment Share on other sites More sharing options...
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