JMUBullnose Posted March 30, 2022 Author Share Posted March 30, 2022 A drill bit shank is probably a better 'gauge' for this adjustment. Chokes are a challenge because of the whole 'stone cold' calibration thing. If you have electric assist I'd suggest unplugging it while you try to get the truck to start. That will prolong your testing window. I also have been reunited with all my tools so I'll have to use that instead! Now to figure out which drawer or box my set is in... Thanks! It does have an electric choke thermostat, I'll keep that in mind. Question on the choke thermostat - in the past I've noticed that moving the choke cap barely adjusts the butterfly opening. Might need to address that as well. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 30, 2022 Share Posted March 30, 2022 I also have been reunited with all my tools so I'll have to use that instead! Now to figure out which drawer or box my set is in... Thanks! It does have an electric choke thermostat, I'll keep that in mind. Question on the choke thermostat - in the past I've noticed that moving the choke cap barely adjusts the butterfly opening. Might need to address that as well. I would check for stiction behind the choke assembly on the carburetor. The butterfly and link rod are pretty easy to notice they are free. The coil in the cap is only what little spring pressure it has. Mark across cap and housing so you can set it back where it is now. Remove the cap and manipulate the pin that the loop of the spring fits over. Notice how that moves the butterfly and feel for any roughness or binding. Look behind this choke mechanisim and see how the high idle pawl fits the steps of the cam. Deposits back here like grease or grit can hang it up and you'll need a narrowed toothbrush, pipe cleaner or similar to clear them out along with a can of carb cleaner. My Edelbrock seemed particularly prone to this and I used Teflon dry lube (from PB Blaster) to lubricate without creating a dust and grit magnet. Bill Vose could probably offer better advice than me. Link to comment Share on other sites More sharing options...
JMUBullnose Posted March 30, 2022 Author Share Posted March 30, 2022 I would check for stiction behind the choke assembly on the carburetor. The butterfly and link rod are pretty easy to notice they are free. The coil in the cap is only what little spring pressure it has. Mark across cap and housing so you can set it back where it is now. Remove the cap and manipulate the pin that the loop of the spring fits over. Notice how that moves the butterfly and feel for any roughness or binding. Look behind this choke mechanisim and see how the high idle pawl fits the steps of the cam. Deposits back here like grease or grit can hang it up and you'll need a narrowed toothbrush, pipe cleaner or similar to clear them out along with a can of carb cleaner. My Edelbrock seemed particularly prone to this and I used Teflon dry lube (from PB Blaster) to lubricate without creating a dust and grit magnet. Bill Vose could probably offer better advice than me. Alrighty - I did as you said, first checked for stiction behind the choke assembly (after marking the choke cap location). Valve moved freely when I moved the pin inside the assembly. Reattached and tightened the cap. Without touching anything else, I looked at the butterfly valve opening. Wayyyy open compared to a 3/32" drill bit. Rotating the choke cap towards lean produced minimal change (but rotating towards front of truck would open up the butterfly). So I looked at the linkage behind the assembly - if I adjust the fast idle cam adjustment screw (hex head), it will tighten up the butterfly valve opening. So in the full confidence of blissful ignorance, I marked the screw and backed it out some to tighten the valve to make the gap 3/32" using a drill bit shank to check it. After that, I hopped in the truck, pumped the pedal once and cranked on the engine. After about 14 seconds it surprised the heck out of me and started. Petered out shortly afterward but turned over almost immediately again and held idle. To quote a certain youtube personality "Well, I'll be dipped!" I let the truck idle for ~10 minutes as I cleaned up a few things. (I was in between meetings) Engine sounded good and idled nicely. Not sure if this was a quick fix for a long term headache but it was gratifying for sure. If I just monkeyed this whole thing up, please destroy my blissful ignorance. Second thing, I noticed fuel on intake manifold. It seems to be coming out of the ported vacuum directly under the accelartor pump/power valve. The hose goes from the that PV to manifold vacuum. Should there be fuel coming out of there or do I also have an issue in the power valve? The vacuum hose itself shoud be replaced as is (I think it started to split at the port on the carb as well). Link to comment Share on other sites More sharing options...
JMUBullnose Posted March 30, 2022 Author Share Posted March 30, 2022 Alrighty - I did as you said, first checked for stiction behind the choke assembly (after marking the choke cap location). Valve moved freely when I moved the pin inside the assembly. Reattached and tightened the cap. Without touching anything else, I looked at the butterfly valve opening. Wayyyy open compared to a 3/32" drill bit. Rotating the choke cap towards lean produced minimal change (but rotating towards front of truck would open up the butterfly). So I looked at the linkage behind the assembly - if I adjust the fast idle cam adjustment screw (hex head), it will tighten up the butterfly valve opening. So in the full confidence of blissful ignorance, I marked the screw and backed it out some to tighten the valve to make the gap 3/32" using a drill bit shank to check it. After that, I hopped in the truck, pumped the pedal once and cranked on the engine. After about 14 seconds it surprised the heck out of me and started. Petered out shortly afterward but turned over almost immediately again and held idle. To quote a certain youtube personality "Well, I'll be dipped!" I let the truck idle for ~10 minutes as I cleaned up a few things. (I was in between meetings) Engine sounded good and idled nicely. Not sure if this was a quick fix for a long term headache but it was gratifying for sure. If I just monkeyed this whole thing up, please destroy my blissful ignorance. Second thing, I noticed fuel on intake manifold. It seems to be coming out of the ported vacuum directly under the accelartor pump/power valve. The hose goes from the that PV to manifold vacuum. Should there be fuel coming out of there or do I also have an issue in the power valve? The vacuum hose itself shoud be replaced as is (I think it started to split at the port on the carb as well). Also, I checked - the charcoal canister and purge valve are hooked up. Thinking the fuel smell might be from whatever this slight leak is under the power valve/accelerator pump. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 30, 2022 Share Posted March 30, 2022 Also, I checked - the charcoal canister and purge valve are hooked up. Thinking the fuel smell might be from whatever this slight leak is under the power valve/accelerator pump. Progress is GOOD! I'd say it's safe to assume you are smelling raw fuel dribbling onto the intake manifold and since the bowl vent is connected that it isn't contributing to fuel evaporating prematurely. I'm not sure why you would see fuel coming from the ported vacuum connection. This should be above the throttle valve when closed. Without being there looking at it I would first suspect the accelerator pump diaphragm is leaking, or the pump cover isn't seated correctly. But if the pump is draining out while the engine is off it would explain why you don't get that fuel shot to richen the mixture when you first set the choke on a cold engine. Fuel leaks are something to address right away. I'm going to ask you to look for accelerator pump function the next time you check the engine cold. With the air cleaner housing off climb a step ladder or something so you have a good view straight down the carburetor. Use a stick, screwdriver or your left hand to carefully hold the choke plate open. Watch closely down between the boosters while you use your right hand to open the throttle from where the cable attaches. You should see a little stream of fuel going down each bore. If you don't the pump is not doing its job and I suspect it's dry because all the fuel drained out. You can repeat this a few times to confirm because if the engine is off the pump is not working to refill the bowl. If the truck is able to start from the 3/32" setting you might try marking your new choke cap position (or noting which line the arrow is pointing at) and tightening it up even more like Mat suggested. By tightening the spring you're going to change how long the choke stays on. This will effect driveability while the truck is warming up. Let's work on getting the truck to start consistently first. Link to comment Share on other sites More sharing options...
mat in tn Posted March 30, 2022 Share Posted March 30, 2022 Progress is GOOD! I'd say it's safe to assume you are smelling raw fuel dribbling onto the intake manifold and since the bowl vent is connected that it isn't contributing to fuel evaporating prematurely. I'm not sure why you would see fuel coming from the ported vacuum connection. This should be above the throttle valve when closed. Without being there looking at it I would first suspect the accelerator pump diaphragm is leaking, or the pump cover isn't seated correctly. But if the pump is draining out while the engine is off it would explain why you don't get that fuel shot to richen the mixture when you first set the choke on a cold engine. Fuel leaks are something to address right away. I'm going to ask you to look for accelerator pump function the next time you check the engine cold. With the air cleaner housing off climb a step ladder or something so you have a good view straight down the carburetor. Use a stick, screwdriver or your left hand to carefully hold the choke plate open. Watch closely down between the boosters while you use your right hand to open the throttle from where the cable attaches. You should see a little stream of fuel going down each bore. If you don't the pump is not doing its job and I suspect it's dry because all the fuel drained out. You can repeat this a few times to confirm because if the engine is off the pump is not working to refill the bowl. If the truck is able to start from the 3/32" setting you might try marking your new choke cap position (or noting which line the arrow is pointing at) and tightening it up even more like Mat suggested. By tightening the spring you're going to change how long the choke stays on. This will effect driveability while the truck is warming up. Let's work on getting the truck to start consistently first. certainly find and fix the fuel leak . first for safety but if its leaking out then that could be a lot of the problem as a whole Link to comment Share on other sites More sharing options...
JMUBullnose Posted March 31, 2022 Author Share Posted March 31, 2022 Progress is GOOD! I'd say it's safe to assume you are smelling raw fuel dribbling onto the intake manifold and since the bowl vent is connected that it isn't contributing to fuel evaporating prematurely. I'm not sure why you would see fuel coming from the ported vacuum connection. This should be above the throttle valve when closed. Without being there looking at it I would first suspect the accelerator pump diaphragm is leaking, or the pump cover isn't seated correctly. But if the pump is draining out while the engine is off it would explain why you don't get that fuel shot to richen the mixture when you first set the choke on a cold engine. Fuel leaks are something to address right away. I'm going to ask you to look for accelerator pump function the next time you check the engine cold. With the air cleaner housing off climb a step ladder or something so you have a good view straight down the carburetor. Use a stick, screwdriver or your left hand to carefully hold the choke plate open. Watch closely down between the boosters while you use your right hand to open the throttle from where the cable attaches. You should see a little stream of fuel going down each bore. If you don't the pump is not doing its job and I suspect it's dry because all the fuel drained out. You can repeat this a few times to confirm because if the engine is off the pump is not working to refill the bowl. If the truck is able to start from the 3/32" setting you might try marking your new choke cap position (or noting which line the arrow is pointing at) and tightening it up even more like Mat suggested. By tightening the spring you're going to change how long the choke stays on. This will effect driveability while the truck is warming up. Let's work on getting the truck to start consistently first. Agreed on the fuel leak - previously when it occurred it was because that hose had fallen off the PV. In my ignorance (and listening to someone else) I would just reconnect it and go. Once I actually looked at vacuum diagram yesterday and realized what it connected to, I started to go "Well something's not right here" I'll pull the hose off and go get a new section of it from the parts store. (About 20-30 minutes away) Of all the things this neat town has, it doesn't have an auto parts store! Question - fresh hose should *not* require a hose clamp or anything to secure it to the vacuum ports right? (That's why they have a lip on them, correct?) Going to go out and check the accel pump function now before it starts raining. Link to comment Share on other sites More sharing options...
JMUBullnose Posted March 31, 2022 Author Share Posted March 31, 2022 Agreed on the fuel leak - previously when it occurred it was because that hose had fallen off the PV. In my ignorance (and listening to someone else) I would just reconnect it and go. Once I actually looked at vacuum diagram yesterday and realized what it connected to, I started to go "Well something's not right here" I'll pull the hose off and go get a new section of it from the parts store. (About 20-30 minutes away) Of all the things this neat town has, it doesn't have an auto parts store! Question - fresh hose should *not* require a hose clamp or anything to secure it to the vacuum ports right? (That's why they have a lip on them, correct?) Going to go out and check the accel pump function now before it starts raining. Alright, follow up! I went and checked the accelerator pump function while holding the choke plate open. Both times I worked the throttle there were 2 very strong streams of fuel being shot out. Pulled the vacuum hose off and only a couple drops came out (huzzah?). Pulled out my calipers and checked the ID of the hose - the end that connects to the manifold vacuum port is about 1/4" but the end that connects to the PV on the carb is wallowed out to ~5/16". No wonder it is falling off, probably causing a vacuum leak too. So, I'll get a new length of vacuum hose to fix that problem. However, the fuel coming out of there in general still concerns me. What's next? Also warmer today, noticed the choke plate was a bit more open than yesterday - figures since it's about 15 degrees warmer today and finally cracking 60. Link to comment Share on other sites More sharing options...
JMUBullnose Posted March 31, 2022 Author Share Posted March 31, 2022 Alright, follow up! I went and checked the accelerator pump function while holding the choke plate open. Both times I worked the throttle there were 2 very strong streams of fuel being shot out. Pulled the vacuum hose off and only a couple drops came out (huzzah?). Pulled out my calipers and checked the ID of the hose - the end that connects to the manifold vacuum port is about 1/4" but the end that connects to the PV on the carb is wallowed out to ~5/16". No wonder it is falling off, probably causing a vacuum leak too. So, I'll get a new length of vacuum hose to fix that problem. However, the fuel coming out of there in general still concerns me. What's next? Also warmer today, noticed the choke plate was a bit more open than yesterday - figures since it's about 15 degrees warmer today and finally cracking 60. Replaced the hose with 1/4" hose that was about an inch longer so it won't put such a bend on the PV side of the hose. Hopefully that takes care of that issue (at least fuel dribbling out). Now to figure out if there is a problem with the power valve or accelerator pump that's allowing fuel into that vacuum passage. Looking at a diagram of the enrichment system - it shouldn't be making it into that PV! Link to comment Share on other sites More sharing options...
JMUBullnose Posted April 1, 2022 Author Share Posted April 1, 2022 Replaced the hose with 1/4" hose that was about an inch longer so it won't put such a bend on the PV side of the hose. Hopefully that takes care of that issue (at least fuel dribbling out). Now to figure out if there is a problem with the power valve or accelerator pump that's allowing fuel into that vacuum passage. Looking at a diagram of the enrichment system - it shouldn't be making it into that PV! If I can find it, I have a rebuild kit laying around with a new 2-stage power valve in it for my carb from Mike's Carburetor Parts. What do I need to pay attention to if I pull off the carb to check on the power valve? Any recalibration I should be aware of ? Link to comment Share on other sites More sharing options...
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