Cuts out at high rpm
11-06-18, 01:09 AM
#1
Junior Member
Thread Starter
Cuts out at high rpm
On my 83 Ive noticed if I press my gas pedal down too fast while driving it tends to cut out for a second. It also happens if i rev it from an idle. But it doesnt really seem to do it when the choke is on. Im not sure if its a carburetor problem or something bigger. Im just really nervous to mess with the carb too much until i get some opinions. This is my first rotary car.
11-06-18, 07:12 AM
#2
Waffles - hmmm good
iTrader: (1)
Its either an issue with the accelerator pump or the carb body has gunk in it. The fact that it seems ok with the choke points to a lean condition at the transition point which the choke cures while on. Check to see if the AP is squirting anything when the throttle is opened from idle first. Either way you will probably need to cleanup the carb, Some advice, do not use the new needle/seats in the rebuild kit, they suck and also do the disassembly on a clean surface to catch any small ***** and weights that may pop out while working on it.
11-06-18, 11:18 AM
#5
I'd check the fuel filter first and then test for fuel delivery at the carb according to the FSM.
Could be a dirty filter or failing fuel pump.
No point in rebuilding a Nikki that doesn't need to be rebuilt, as likely as not to add problems rather than fixing anything.
Ask me how I know.
Could be a dirty filter or failing fuel pump.
No point in rebuilding a Nikki that doesn't need to be rebuilt, as likely as not to add problems rather than fixing anything.
Ask me how I know.
11-06-18, 12:15 PM
#7
I recently put my 83 LE on the road with a freshly built 12A and a newly rebuilt Nikki.
Right from the start I had the exact same problem Kyle is describing, ran fine while the choke was on but then it would bog when trying to accelerate quickly or even slowly from an idle, so that I'd have to race the engine a bit to keep it from stalling when starting from a dead stop.
Of course I started with the fuel filter and fuel delivery check to be sure the pump and filter were OK, which they were (but always do these cheap and easy items first).
So then I pulled the Nikki (for the first time) and took it apart to be sure I did everything right, which I had (I've rebuilt several Nikki's and never had this problem before, all the others were trouble free).
So I put the Nikki back in, hoping somehow I'd fixed the problem but no change.
So I decided it must be something with the accelerator pump or circuit, so I pulled the Nikki again (2nd time) and carefully cleaned and blew out the accelerator circuit, double checking to be sure the ball valve and brass weight were correctly installed and then, for good measure, replaced the new accelerator pump with another new accelerator pump (both CP Sorensen, excellent rebuild kit).
So I put it all back together, started it up and yep, no change, still bogging just like before. After doing all this it occurred to me that it would have been a good idea to check the accelerator pump function simply by looking into the primaries while a helper depressed the accelerator peddle, yup, nice even fuel squirts both sides. However this time, after running the engine a few minutes, the carb bowls flooded. Obviously the float valves weren't seating properly.
So I pulled the Nikki again (3rd time) to check on the float valves, which were new. New valves can be finicky, you need to seat them well and sometimes it takes a while for them to settle in an seal well. I think I've got that problem licked.
But I still had the bog, which turned out to be due to several contributing factors, none having to do with fuel delivery or the Nikki itself.
1) The engine wasn't warming up properly, never getting about 150 degrees and the cold running conditions weren't helping the Nikki transition off the choke. Installed a 180 degree thermostat and finally an instant improvement, although a little bogging still remained.
2) Found a small vacuum leak, fixed it and this helped a bit more, but still not perfect.
3) Discovered some linkage issues that needed a bit of adjusting, which helped a lot with the idle.
4) With all the other things finally in order, I readjusted the fuel/air mixture, which had gotten all out of whack trying to compensate for all of the above.
5) Nirvana at last, perfect 750 rpm idle, no bog and sharp acceleration.
Zoom Zoom!
Right from the start I had the exact same problem Kyle is describing, ran fine while the choke was on but then it would bog when trying to accelerate quickly or even slowly from an idle, so that I'd have to race the engine a bit to keep it from stalling when starting from a dead stop.
Of course I started with the fuel filter and fuel delivery check to be sure the pump and filter were OK, which they were (but always do these cheap and easy items first).
So then I pulled the Nikki (for the first time) and took it apart to be sure I did everything right, which I had (I've rebuilt several Nikki's and never had this problem before, all the others were trouble free).
So I put the Nikki back in, hoping somehow I'd fixed the problem but no change.
So I decided it must be something with the accelerator pump or circuit, so I pulled the Nikki again (2nd time) and carefully cleaned and blew out the accelerator circuit, double checking to be sure the ball valve and brass weight were correctly installed and then, for good measure, replaced the new accelerator pump with another new accelerator pump (both CP Sorensen, excellent rebuild kit).
So I put it all back together, started it up and yep, no change, still bogging just like before. After doing all this it occurred to me that it would have been a good idea to check the accelerator pump function simply by looking into the primaries while a helper depressed the accelerator peddle, yup, nice even fuel squirts both sides. However this time, after running the engine a few minutes, the carb bowls flooded. Obviously the float valves weren't seating properly.
So I pulled the Nikki again (3rd time) to check on the float valves, which were new. New valves can be finicky, you need to seat them well and sometimes it takes a while for them to settle in an seal well. I think I've got that problem licked.
But I still had the bog, which turned out to be due to several contributing factors, none having to do with fuel delivery or the Nikki itself.
1) The engine wasn't warming up properly, never getting about 150 degrees and the cold running conditions weren't helping the Nikki transition off the choke. Installed a 180 degree thermostat and finally an instant improvement, although a little bogging still remained.
2) Found a small vacuum leak, fixed it and this helped a bit more, but still not perfect.
3) Discovered some linkage issues that needed a bit of adjusting, which helped a lot with the idle.
4) With all the other things finally in order, I readjusted the fuel/air mixture, which had gotten all out of whack trying to compensate for all of the above.
5) Nirvana at last, perfect 750 rpm idle, no bog and sharp acceleration.
Zoom Zoom!
Last edited by ray green; 11-06-18 at 12:20 PM.
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11-06-18, 01:35 PM
#10
ancient wizard...
Good on ya,Ray. I call this"sorting". VERY rarely,even with utmost attention does a new engine/carb/install get completed,hood shut and test driven without having to revisit some small issue or address a driveability concern. As always,the devil's in the details.
There's a certain satisfaction that comes with working through the hiccups to end up with the perfect running vehicle=runs more better...
There's a certain satisfaction that comes with working through the hiccups to end up with the perfect running vehicle=runs more better...
11-06-18, 03:14 PM
#11
Yeah, and we discovered most of the details on the Annual OGTA Halloween camping trip up on Mt. Pisgah last weekend.
But we did eventually get everything sorted out on that trip, thank's to the Rotary Genius of Tim, Robert and Mike.
And she sure do run pretty now.
I think this "sorting" is what Kyle should be planning on before tearing into the Nikki.
Solve the problems you got before getting some new ones.
But we did eventually get everything sorted out on that trip, thank's to the Rotary Genius of Tim, Robert and Mike.
And she sure do run pretty now.
I think this "sorting" is what Kyle should be planning on before tearing into the Nikki.
Solve the problems you got before getting some new ones.
Last edited by ray green; 11-06-18 at 05:19 PM.
11-06-18, 04:46 PM
#12
Junior Member
Thread Starter
I recently put my 83 LE on the road with a freshly built 12A and a newly rebuilt Nikki.
Right from the start I had the exact same problem Kyle is describing, ran fine while the choke was on but then it would bog when trying to accelerate quickly or even slowly from an idle, so that I'd have to race the engine a bit to keep it from stalling when starting from a dead stop.
Of course I started with the fuel filter and fuel delivery check to be sure the pump and filter were OK, which they were (but always do these cheap and easy items first).
So then I pulled the Nikki (for the first time) and took it apart to be sure I did everything right, which I had (I've rebuilt several Nikki's and never had this problem before, all the others were trouble free).
So I put the Nikki back in, hoping somehow I'd fixed the problem but no change.
So I decided it must be something with the accelerator pump or circuit, so I pulled the Nikki again (2nd time) and carefully cleaned and blew out the accelerator circuit, double checking to be sure the ball valve and brass weight were correctly installed and then, for good measure, replaced the new accelerator pump with another new accelerator pump (both CP Sorensen, excellent rebuild kit).
So I put it all back together, started it up and yep, no change, still bogging just like before. After doing all this it occurred to me that it would have been a good idea to check the accelerator pump function simply by looking into the primaries while a helper depressed the accelerator peddle, yup, nice even fuel squirts both sides. However this time, after running the engine a few minutes, the carb bowls flooded. Obviously the float valves weren't seating properly.
So I pulled the Nikki again (3rd time) to check on the float valves, which were new. New valves can be finicky, you need to seat them well and sometimes it takes a while for them to settle in an seal well. I think I've got that problem licked.
But I still had the bog, which turned out to be due to several contributing factors, none having to do with fuel delivery or the Nikki itself.
1) The engine wasn't warming up properly, never getting about 150 degrees and the cold running conditions weren't helping the Nikki transition off the choke. Installed a 180 degree thermostat and finally an instant improvement, although a little bogging still remained.
2) Found a small vacuum leak, fixed it and this helped a bit more, but still not perfect.
3) Discovered some linkage issues that needed a bit of adjusting, which helped a lot with the idle.
4) With all the other things finally in order, I readjusted the fuel/air mixture, which had gotten all out of whack trying to compensate for all of the above.
5) Nirvana at last, perfect 750 rpm idle, no bog and sharp acceleration.
Zoom Zoom!
Right from the start I had the exact same problem Kyle is describing, ran fine while the choke was on but then it would bog when trying to accelerate quickly or even slowly from an idle, so that I'd have to race the engine a bit to keep it from stalling when starting from a dead stop.
Of course I started with the fuel filter and fuel delivery check to be sure the pump and filter were OK, which they were (but always do these cheap and easy items first).
So then I pulled the Nikki (for the first time) and took it apart to be sure I did everything right, which I had (I've rebuilt several Nikki's and never had this problem before, all the others were trouble free).
So I put the Nikki back in, hoping somehow I'd fixed the problem but no change.
So I decided it must be something with the accelerator pump or circuit, so I pulled the Nikki again (2nd time) and carefully cleaned and blew out the accelerator circuit, double checking to be sure the ball valve and brass weight were correctly installed and then, for good measure, replaced the new accelerator pump with another new accelerator pump (both CP Sorensen, excellent rebuild kit).
So I put it all back together, started it up and yep, no change, still bogging just like before. After doing all this it occurred to me that it would have been a good idea to check the accelerator pump function simply by looking into the primaries while a helper depressed the accelerator peddle, yup, nice even fuel squirts both sides. However this time, after running the engine a few minutes, the carb bowls flooded. Obviously the float valves weren't seating properly.
So I pulled the Nikki again (3rd time) to check on the float valves, which were new. New valves can be finicky, you need to seat them well and sometimes it takes a while for them to settle in an seal well. I think I've got that problem licked.
But I still had the bog, which turned out to be due to several contributing factors, none having to do with fuel delivery or the Nikki itself.
1) The engine wasn't warming up properly, never getting about 150 degrees and the cold running conditions weren't helping the Nikki transition off the choke. Installed a 180 degree thermostat and finally an instant improvement, although a little bogging still remained.
2) Found a small vacuum leak, fixed it and this helped a bit more, but still not perfect.
3) Discovered some linkage issues that needed a bit of adjusting, which helped a lot with the idle.
4) With all the other things finally in order, I readjusted the fuel/air mixture, which had gotten all out of whack trying to compensate for all of the above.
5) Nirvana at last, perfect 750 rpm idle, no bog and sharp acceleration.
Zoom Zoom!
11-06-18, 05:11 PM
#13
I think that's the air hose to the shutter valve, probably disabled by the PO.
The shutter valve cuts off fuel supply to the rear rotor during deceleration, saves fuel and reduces emissions, they say.
But mostly just a nuisance and expensive to replace, so most folks just disable or, if they have the Nikki off, remove it.
I think the accelerator pump will only shoot an initial blast of gas when the pedal is first depressed.
It's not meant to be a sustained flow so the little dribble sounds normal.
PS, it looks like the clip on your choke cable is in the wrong place, the rear clip should be on the back side of that bracket with the clip connector extending through the gap in the bracket and the front clip flush with the backside of the adjuster nut.
The shutter valve cuts off fuel supply to the rear rotor during deceleration, saves fuel and reduces emissions, they say.
But mostly just a nuisance and expensive to replace, so most folks just disable or, if they have the Nikki off, remove it.
I think the accelerator pump will only shoot an initial blast of gas when the pedal is first depressed.
It's not meant to be a sustained flow so the little dribble sounds normal.
PS, it looks like the clip on your choke cable is in the wrong place, the rear clip should be on the back side of that bracket with the clip connector extending through the gap in the bracket and the front clip flush with the backside of the adjuster nut.
Last edited by ray green; 11-06-18 at 05:16 PM.
11-06-18, 05:26 PM
#14
Junior Member
Thread Starter
I think that's the air hose to the shutter valve, probably disabled by the PO.
The shutter valve cuts off fuel supply to the rear rotor during deceleration, saves fuel and reduces emissions, they say.
But mostly just a nuisance and expensive to replace, so most folks just disable or, if they have the Nikki off, remove it.
I think the accelerator pump will only shoot an initial blast of gas when the pedal is first depressed.
It's not meant to be a sustained flow so the little dribble sounds normal.
PS, it looks like the clip on your choke cable is in the wrong place, the rear clip should be on the back side of that bracket with the clip connector extending through the gap in the bracket and the front clip flush with the backside of the adjuster nut.
The shutter valve cuts off fuel supply to the rear rotor during deceleration, saves fuel and reduces emissions, they say.
But mostly just a nuisance and expensive to replace, so most folks just disable or, if they have the Nikki off, remove it.
I think the accelerator pump will only shoot an initial blast of gas when the pedal is first depressed.
It's not meant to be a sustained flow so the little dribble sounds normal.
PS, it looks like the clip on your choke cable is in the wrong place, the rear clip should be on the back side of that bracket with the clip connector extending through the gap in the bracket and the front clip flush with the backside of the adjuster nut.
11-06-18, 06:17 PM
#15
That Nikki looks good from the outside too, I wouldn't touch it unless you have too.
Hose those tubes with carb cleaner while the engine is idling, if you hear any changes in idle speed you found a vacuum leak.
Is it getting cold up there in ID about now? And did you have this problem during the summer when it was warmer?
It might be a cold weather issue that will go away when the Nikki and 12A get up to the proper running temp of 180 degrees.
Look for gradual warming on the stock dash temp gauge equivalent to the difference between 150 and 180 degrees (low to midway on the gauge).
It takes 12As and Nikki's some time to warm up when it's cold outside.
Hose those tubes with carb cleaner while the engine is idling, if you hear any changes in idle speed you found a vacuum leak.
Is it getting cold up there in ID about now? And did you have this problem during the summer when it was warmer?
It might be a cold weather issue that will go away when the Nikki and 12A get up to the proper running temp of 180 degrees.
Look for gradual warming on the stock dash temp gauge equivalent to the difference between 150 and 180 degrees (low to midway on the gauge).
It takes 12As and Nikki's some time to warm up when it's cold outside.
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