JMUBullnose Posted June 7, 2018 Author Share Posted June 7, 2018 Glad you found the pic. Sometimes that's all you need - a reminder of what went where.Good luck!Thanks Gary! Still getting some rough performance while driving as well - engine will start to stumble if I let off gas and then re-apply, it then powers through. So not sure what could be causing that. Once I dial in the idle that's my next step...along with the new plugs/wires. On Thu, Jun 7, 2018 at 12:19 PM, Gary Lewis [via Bullnose Enthusiasts] <redacted_email_address> wrote: Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2018 Share Posted June 7, 2018 Check the accelerator pump. If it is split or the check ball is stuck the engine will stumble when you apply throttle. Link to comment Share on other sites More sharing options...
JMUBullnose Posted June 7, 2018 Author Share Posted June 7, 2018 Check the accelerator pump. If it is split or the check ball is stuck the engine will stumble when you apply throttle.Ahhh - okay. Just had to look it up - that makes sense. That's the next step then! Thanks Gary! On Thu, Jun 7, 2018 at 12:26 PM, Gary Lewis [via Bullnose Enthusiasts] <redacted_email_address> wrote: Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2018 Share Posted June 7, 2018 Just pull the air cleaner, climb up on top of the engine, and look down the carb while opening the throttle briskly. With the engine off, I should say. You should see two streams of gas squirt down the throats of the carb if the accelerator pump is working. Link to comment Share on other sites More sharing options...
JMUBullnose Posted June 7, 2018 Author Share Posted June 7, 2018 Just pull the air cleaner, climb up on top of the engine, and look down the carb while opening the throttle briskly. With the engine off, I should say. You should see two streams of gas squirt down the throats of the carb if the accelerator pump is working. Funny enough - found a great reference on how to do an accelerator pump test: Accelerator Quick Pump Test Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2018 Share Posted June 7, 2018 Funny enough - found a great reference on how to do an accelerator pump test: Accelerator Quick Pump Test That is a good one. But the warming up bit is questionable in my book. First, the accelerator pump usually (always?) has its own supply of fuel, so if the accelerator pump doesn't have fuel when the engine is cold there is a problem. Second, it isn't much fun to kneel on a hot radiator and put your hands on a hot engine. Anyway, test it and let us know. Link to comment Share on other sites More sharing options...
JMUBullnose Posted June 7, 2018 Author Share Posted June 7, 2018 That is a good one. But the warming up bit is questionable in my book. First, the accelerator pump usually (always?) has its own supply of fuel, so if the accelerator pump doesn't have fuel when the engine is cold there is a problem. Second, it isn't much fun to kneel on a hot radiator and put your hands on a hot engine.Anyway, test it and let us know.You going to sit there with popcorn if I go the warm engine route? Hahahaha (I'd rather do cold engine personally....) On Thu, Jun 7, 2018 at 2:26 PM, Gary Lewis [via Bullnose Enthusiasts] <redacted_email_address> wrote: Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2018 Share Posted June 7, 2018 Yes, I'll happily eat popcorn and watch you toast your extremities. So far, I've not had a carb fail the cold test unless the accelerator pump was truly bad. But, it is your call. Link to comment Share on other sites More sharing options...
JMUBullnose Posted June 22, 2018 Author Share Posted June 22, 2018 Yes, I'll happily eat popcorn and watch you toast your extremities. So far, I've not had a carb fail the cold test unless the accelerator pump was truly bad. But, it is your call. Gary - finally got an opportunity to test the accelerator pump. Truck had been sitting a week so there was likely no fuel in the bowl - initial tests had nothing coming out of the nozzles. After a quick start to get the carb pulling gas, I shut the truck down and worked the pump - two solid streams of fuel came out of the nozzles so the accelerator pump seems to be good (as far as I can tell). I had been doing some other research on tuning the 2150 and came across one tech that suggested looking at the power valve - his exact words were something along the lines of "If you're getting power issues or stumbling going up hills...it could be your power valve." Thoughts? Next steps? I defer to those wiser than me! I need to do an overall retune on this badboy I think. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted June 22, 2018 Share Posted June 22, 2018 Gary - finally got an opportunity to test the accelerator pump. Truck had been sitting a week so there was likely no fuel in the bowl - initial tests had nothing coming out of the nozzles. After a quick start to get the carb pulling gas, I shut the truck down and worked the pump - two solid streams of fuel came out of the nozzles so the accelerator pump seems to be good (as far as I can tell). I had been doing some other research on tuning the 2150 and came across one tech that suggested looking at the power valve - his exact words were something along the lines of "If you're getting power issues or stumbling going up hills...it could be your power valve." Thoughts? Next steps? I defer to those wiser than me! I need to do an overall retune on this badboy I think. Do you know if your stock power valve (PV) is a single or 2 stage unit? I had seen it posted (other forum) that someone had a 2 stage in the carb but the rebuild kit came with a single stage. PV's come in different sizes of HG they work. To see what size you need you will need to hook up a vacuum gauge to the motor in a way you can see it when driving. When driving you take the average of vacuum when driving under steady speed. Once you have this reading cut it in half and that is the size PV you want as a good starting place. Say you are pulling 13 HG half of that is 6.5 and this just happens to be what comes in rebuild kits. You can go up or down to see what works best for you. I know on older Holley's if the carb sneezed (back fired thru carb) it would blow out the diaphragm of the PV. New Holley's have a check valve to prevent this. I am thinking the Motorcraft 2100 & 2150 carbs would also blow out the PV if it sneezed but not 100% sure. Dave ---- Link to comment Share on other sites More sharing options...
Recommended Posts