kramttocs Posted August 12, 2020 Share Posted August 12, 2020 Ok, I kind of hate to post this as the internet is full of posts about restarting a 460 when hot but I figure if I have my own thread about it, it will prevent me from just living with it. Also most of the threads are about slow cranking which isn't my case. Rebuilt 460 Holley Quickfuel Slayer 600cfm carb New Odyssey battery (850 cca) All new 1/0 cables - Power and ground. Dedicated ground going to starter PMGR Starter: Powermaster XS Torque Starters 9505. Wrapped in a starter blanket Headers 1986 F250 with electric in-tank pumps Truck starts immediately when cold or after a short time shut off like filling up at a gas station. If I let it set though after being at normal operating temperature for a period of time [tonight it was around 40 minutes in Lowe's] I have to crank it for maybe 2 seconds before it fires. Usually on the first crank it sounds like it's going to catch but it never does (just gets my hope up). At that point I've stopped cranking since I thought it was going to start. I then have to crank again for the 2 seconds before it fires up and runs. It's not a slow cranking at all. It turns over smooth and fast; it just doesn't fire right off. I don't want to discount anything and happy to perform any tests but I feel pretty confident in the electrical components which leaves me with the carb/fuel. The coil and the pumps/relays are the only things that aren't new. It's probably not worth noting but the truck was kind of like this back when I first got it and before the restore/rebuild. It didn't seem to care about cold or hot starts back then though. If you missed the first fire then you had to crank it for a bit. I say 'not worth' because that was a different engine and carb as well as full emissions setup. The carb bowls have sight glasses and my fuel rail has a pressure gauge on it. One post I read mentioned the fuel expanding in the bowls so I will check that via the sight glasses the next time right after killing it and before starting it. Happy to provide any additional info and add more tests to the list. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 12, 2020 Share Posted August 12, 2020 I'm trying to figure out what the condition might be that is causing the extra cranking. And it seems like it could be that the choke might be on but the engine not cold and not needing the choke. So, have you tried to floor the throttle when you start it after 40 minutes? That should kick the choke open, but it will also squirt fuel in via the accelerator pump. Conversely, have you pumped the throttle, thereby sending lots of fuel in. The results of these tests might be informative. I'm thinking you may have just a touch too much choke. But, it could be that the idle mix is a little lean and you don't quite have enough choke. How does it run when it finally catches? Does it act like it is partially flooded and has to run a bit to clear out? Link to comment Share on other sites More sharing options...
kramttocs Posted August 12, 2020 Author Share Posted August 12, 2020 I'm trying to figure out what the condition might be that is causing the extra cranking. And it seems like it could be that the choke might be on but the engine not cold and not needing the choke. So, have you tried to floor the throttle when you start it after 40 minutes? That should kick the choke open, but it will also squirt fuel in via the accelerator pump. Conversely, have you pumped the throttle, thereby sending lots of fuel in. The results of these tests might be informative. I'm thinking you may have just a touch too much choke. But, it could be that the idle mix is a little lean and you don't quite have enough choke. How does it run when it finally catches? Does it act like it is partially flooded and has to run a bit to clear out? Thanks Gary. Great idea - it could very well be the choke. I haven't messed with it much so will check it out. Now that you mention it, the truck did the same thing when working on the A/C and my neighbor mentioned something about it possibly needing adjustment. As is, when it finally catches there might be a little bit of a pop out the exhaust but otherwise it is good to go as soon as it fires. That single pop also occurs when cold starting so maybe that is an indicator of something? I'll try to get a recording of it this evening. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 12, 2020 Share Posted August 12, 2020 Thanks Gary. Great idea - it could very well be the choke. I haven't messed with it much so will check it out. Now that you mention it, the truck did the same thing when working on the A/C and my neighbor mentioned something about it possibly needing adjustment. As is, when it finally catches there might be a little bit of a pop out the exhaust but otherwise it is good to go as soon as it fires. That single pop also occurs when cold starting so maybe that is an indicator of something? I'll try to get a recording of it this evening. I would guess that the pop is an indication of too much fuel, with it pooled in the exhaust and getting ignited by the hot exhaust gas as the engine finally fires. So that could be the choke. Or, it could be gas dripping out of the carb, either due to too high of a float level or a leaking accelerator pump or power valve. Link to comment Share on other sites More sharing options...
BullnoseLuvr Posted August 12, 2020 Share Posted August 12, 2020 I would guess that the pop is an indication of too much fuel, with it pooled in the exhaust and getting ignited by the hot exhaust gas as the engine finally fires. So that could be the choke. Or, it could be gas dripping out of the carb, either due to too high of a float level or a leaking accelerator pump or power valve. If a short soak doesn't cause it but a longer one does it could be vapor lock. You can also be getting a lean pop. Mark Link to comment Share on other sites More sharing options...
kramttocs Posted August 12, 2020 Author Share Posted August 12, 2020 If a short soak doesn't cause it but a longer one does it could be vapor lock. You can also be getting a lean pop. Mark I didn't think electric fuels pumps suffered from vapor lock? Also to note I have a 1" phenolic spacer under the carb. Link to comment Share on other sites More sharing options...
Rusty_S85 Posted August 12, 2020 Share Posted August 12, 2020 I didn't think electric fuels pumps suffered from vapor lock? Also to note I have a 1" phenolic spacer under the carb. electric fuel pumps can, its high pressure EFI that isnt effected as bad as like the radiator boiling point is increased with pressure. But a carb running a low pressure carb electric pump you could get vapor lock on the suction side or the pressure side. Link to comment Share on other sites More sharing options...
kramttocs Posted August 12, 2020 Author Share Posted August 12, 2020 electric fuel pumps can, its high pressure EFI that isnt effected as bad as like the radiator boiling point is increased with pressure. But a carb running a low pressure carb electric pump you could get vapor lock on the suction side or the pressure side. Good to know. Will the pressure gauge on my fuel log provide any indication of that being the cause? Link to comment Share on other sites More sharing options...
BullnoseLuvr Posted August 12, 2020 Share Posted August 12, 2020 Good to know. Will the pressure gauge on my fuel log provide any indication of that being the cause? You could give it a nice hot soak and check if you get a good squirt from the accelerator pump. If none the lock is in the carburetor. However, since you have a spacer the lock could be in the fuel line, which I assume is metal. If that's the case it would start on the fuel in the bowl and then stall. Mark Link to comment Share on other sites More sharing options...
Rusty_S85 Posted August 12, 2020 Share Posted August 12, 2020 You could give it a nice hot soak and check if you get a good squirt from the accelerator pump. If none the lock is in the carburetor. However, since you have a spacer the lock could be in the fuel line, which I assume is metal. If that's the case it would start on the fuel in the bowl and then stall. Mark Id also check the fuel tank side as well. Ive seen electric pumps added on the frame actually vapor lock on the suction side. Link to comment Share on other sites More sharing options...
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