ArdWrknTrk Posted January 14 Share Posted January 14 Any chance the PV has been leaking a bit all along, which masked a lean condition? Otherwise it acts like you have a vacuum leak. But you've already tested and replaced everything I would have. I seriously doubt it. The truck was running great. And even when this happened it wasn't a big bang, just a little pop as the mechanical pump caught prime. But I'm FAR from having seen everything. I just do my best to eliminate possibilities before I dive into a rabbit hole. Maybe Bill has a solid answer. Link to comment Share on other sites More sharing options...
85lebaront2 Posted January 15 Share Posted January 15 I seriously doubt it. The truck was running great. And even when this happened it wasn't a big bang, just a little pop as the mechanical pump caught prime. But I'm FAR from having seen everything. I just do my best to eliminate possibilities before I dive into a rabbit hole. Maybe Bill has a solid answer. Jim, does the 80508 carb have external float adjustments? Level should be at the bottom of the sight plug hole. Check that the choke blade is closing snugly against the body, the newer Holleys with the snap-in choke blade will sometimes not close fully. Check that your accelerator pump settings are still correct after R & R of the front bowl & metering block (you would be surprised how often I saw issues there). If you wish to check for air leaks, a propane torch or acetylene torch, on but not lit can be used to find leaks, it will change the idle quality when you hit the leak. Are you sure it's not just the "colder than the proverbial hags chest" issue? Good luck with it! Link to comment Share on other sites More sharing options...
salans7 Posted January 15 Share Posted January 15 Jim, does the 80508 carb have external float adjustments? Level should be at the bottom of the sight plug hole. Check that the choke blade is closing snugly against the body, the newer Holleys with the snap-in choke blade will sometimes not close fully. Check that your accelerator pump settings are still correct after R & R of the front bowl & metering block (you would be surprised how often I saw issues there). If you wish to check for air leaks, a propane torch or acetylene torch, on but not lit can be used to find leaks, it will change the idle quality when you hit the leak. Are you sure it's not just the "colder than the proverbial hags chest" issue? Good luck with it! Today I got suckered into buying a NOS 1980-1981 4-speed shift knob (3/8-24 thread). Seller marked it down 30% and that put it into the range I'm willing to pay. I REALLY don't need it since I already have two well-loved 1980-1981 4 speed shift knobs, but how many chances do you get to have a new one at a decent price? Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 15 Author Share Posted January 15 Today I got suckered into buying a NOS 1980-1981 4-speed shift knob (3/8-24 thread). Seller marked it down 30% and that put it into the range I'm willing to pay. I REALLY don't need it since I already have two well-loved 1980-1981 4 speed shift knobs, but how many chances do you get to have a new one at a decent price? And now you can take multiple high res pictures so we can add them to the page. 👍 Link to comment Share on other sites More sharing options...
salans7 Posted January 15 Share Posted January 15 And now you can take multiple high res pictures so we can add them to the page. 👍 Haha, I can try. My digital camera died and I don't know how to use my phone's camera that well but I can see what she'll do. I know I should still have some good ones of the transfer case knob from the F150. I'm watching two listings for one of those as well, but I also already have two well-loved transfer case knobs that are in better shape than the transmission ones so I may not pull the trigger on a NOS one. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted January 15 Share Posted January 15 Jim, Are you sure it's not just the "colder than the proverbial hags chest" issue? I'm not really sure what this means? Our days start out with a little frost (high 20's) but no colder than we have already seen this season. https://www.holley.com/products/fuel_systems/carburetors/street/parts/0-80508S The only real change is a quick change secondary spring cap and a slightly stiffer spring due to heavy truck with an RV cam. I've checked the flap closes, the fast idle cam comes into play and that when I get a squirt from the accelerator pump the choke is free to move, with only coil spring pressure holding it shut. The center hung float was set by measuring with a scale while the bowl is inverted. It has the unintuitive nut & lock screw float valves. I cannot blow through the seat in this position. There is no 'window' but if I remove the level plug I just get a little wetness, not any gas really flowing out. The little plastic baffle is properly in place under the gasket. After having hosed down all around the base flange & spacer with ether looking for leaks I sprayed some Teflon dry lube on the choke/fast idle linkage and the secondary lockout arm and rod. I did not have a propane torch in the Advance parking lot that night, nor the next morning when I got off and drove home. The accelerator pump gap is set to fifteen thou per almost every rebuild kit and tuning book I've ever read.(remember the days of setting points gap with a match book?) I did not check for volume of the pump shot and I did not disassemble or change the cam hole the screw is in. From how it's acting, if this carb had a PV in the secondary metering plate I'd say that was blown too. But it doesn't, and I didn't get a 'bang!' when this apparently happened. I was merging onto 95, noticed the sign of running out of fuel and switched tanks. The truck sputtered and coughed as it came back to life. Couple of miles later I get to the light at the bottom of the ramp and it loads up and dies. Have a hard time getting it started because it's flooded. Now it is acting 'fat' but I'm not sure why. Sluggish to accelerate, burbles and hangs as it returns to idle. Edit, im overlooking something, and I'm not sure where/what I should be looking for next. 🧐 I can get a propane torch if you think that will make it act any different than a can of starting fluid would. Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 15 Author Share Posted January 15 Jim, Are you sure it's not just the "colder than the proverbial hags chest" issue? I'm not really sure what this means? Our days start out with a little frost (high 20's) but no colder than we have already seen this season. https://www.holley.com/products/fuel_systems/carburetors/street/parts/0-80508S The only real change is a quick change secondary spring cap and a slightly stiffer spring due to heavy truck with an RV cam. I've checked the flap closes, the fast idle cam comes into play and that when I get a squirt from the accelerator pump the choke is free to move, with only coil spring pressure holding it shut. The center hung float was set by measuring with a scale while the bowl is inverted. It has the unintuitive nut & lock screw float valves. I cannot blow through the seat in this position. There is no 'window' but if I remove the level plug I just get a little wetness, not any gas really flowing out. The little plastic baffle is properly in place under the gasket. After having hosed down all around the base flange & spacer with ether looking for leaks I sprayed some Teflon dry lube on the choke/fast idle linkage and the secondary lockout arm and rod. I did not have a propane torch in the Advance parking lot that night, nor the next morning when I got off and drove home. The accelerator pump gap is set to fifteen thou per almost every rebuild kit and tuning book I've ever read.(remember the days of setting points gap with a match book?) I did not check for volume of the pump shot and I did not disassemble or change the cam hole the screw is in. From how it's acting, if this carb had a PV in the secondary metering plate I'd say that was blown too. But it doesn't, and I didn't get a 'bang!' when this apparently happened. I was merging onto 95, noticed the sign of running out of fuel and switched tanks. The truck sputtered and coughed as it came back to life. Couple of miles later I get to the light at the bottom of the ramp and it loads up and dies. Have a hard time getting it started because it's flooded. Now it is acting 'fat' but I'm not sure why. Sluggish to accelerate, burbles and hangs as it returns to idle. Edit, im overlooking something, and I'm not sure where/what I should be looking for next. 🧐 I can get a propane torch if you think that will make it act any different than a can of starting fluid would. Jim - Just for clarification, I was assuming it is lean, but you said it is fat. Even when starting? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted January 15 Share Posted January 15 Jim - Just for clarification, I was assuming it is lean, but you said it is fat. Even when starting? Yeah. It feels fat when driving and if I leave it idle too long before shutting it off it acts a little flooded on startup. But with the float height confirmed, the powervalve sealing as well as the check ball of the accelerator pump, the only thing I can think left to check is the float height of the secondary. This seems a stretch because the front bowl was spotless (I run a metal filter from a 2002 Altima just before the fuel log, where it bends 90° around the thermostat housing) Link to comment Share on other sites More sharing options...
mat in tn Posted January 15 Share Posted January 15 Jim, Are you sure it's not just the "colder than the proverbial hags chest" issue? I'm not really sure what this means? Our days start out with a little frost (high 20's) but no colder than we have already seen this season. https://www.holley.com/products/fuel_systems/carburetors/street/parts/0-80508S The only real change is a quick change secondary spring cap and a slightly stiffer spring due to heavy truck with an RV cam. I've checked the flap closes, the fast idle cam comes into play and that when I get a squirt from the accelerator pump the choke is free to move, with only coil spring pressure holding it shut. The center hung float was set by measuring with a scale while the bowl is inverted. It has the unintuitive nut & lock screw float valves. I cannot blow through the seat in this position. There is no 'window' but if I remove the level plug I just get a little wetness, not any gas really flowing out. The little plastic baffle is properly in place under the gasket. After having hosed down all around the base flange & spacer with ether looking for leaks I sprayed some Teflon dry lube on the choke/fast idle linkage and the secondary lockout arm and rod. I did not have a propane torch in the Advance parking lot that night, nor the next morning when I got off and drove home. The accelerator pump gap is set to fifteen thou per almost every rebuild kit and tuning book I've ever read.(remember the days of setting points gap with a match book?) I did not check for volume of the pump shot and I did not disassemble or change the cam hole the screw is in. From how it's acting, if this carb had a PV in the secondary metering plate I'd say that was blown too. But it doesn't, and I didn't get a 'bang!' when this apparently happened. I was merging onto 95, noticed the sign of running out of fuel and switched tanks. The truck sputtered and coughed as it came back to life. Couple of miles later I get to the light at the bottom of the ramp and it loads up and dies. Have a hard time getting it started because it's flooded. Now it is acting 'fat' but I'm not sure why. Sluggish to accelerate, burbles and hangs as it returns to idle. Edit, im overlooking something, and I'm not sure where/what I should be looking for next. 🧐 I can get a propane torch if you think that will make it act any different than a can of starting fluid would. any chance that the choke is being kept from opening fully? Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 15 Author Share Posted January 15 Yeah. It feels fat when driving and if I leave it idle too long before shutting it off it acts a little flooded on startup. But with the float height confirmed, the powervalve sealing as well as the check ball of the accelerator pump, the only thing I can think left to check is the float height of the secondary. This seems a stretch because the front bowl was spotless (I run a metal filter from a 2002 Altima just before the fuel log, where it bends 90° around the thermostat housing) Then disregard all I’ve said. It doesn’t seem like you have a vacuum leak or it would be lean, not rich. And with the float level not leaking out the inspection hole it isn’t that - unless it is the secondaries. And I don’t know how to test that. So, is there any chance the new PV is leaking? Maybe through the valve and not the diaphragm? Link to comment Share on other sites More sharing options...
Recommended Posts