Cursed Bucking!, Fuel injection issue |
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Cursed Bucking!, Fuel injection issue |
Gcotton92203 |
Mar 11 2015, 03:46 PM
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#1
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Newbie Group: Members Posts: 21 Joined: 14-February 14 From: Bermuda Dunes Ca. Member No.: 17,000 Region Association: Southern California |
Hey, here's a stupid question. Anyone know where I can get a "GOOD" 1973 2.0 throttle positioner. I've developed that cursed bucking just off idle during slow acceleration but the rest of the power band is fine. I've cleaned up the circuit board as best I can and a new board may fix my problem but I'm not sure the contacts are all that great either so I'd just as soon replace the whole relay. Yeah, yeah, I know. put a carb on it. Just trying to stay as original as possible.
Gary 760 702-7251 gary@musicmagic.biz |
monkeyboy |
Mar 11 2015, 04:35 PM
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#2
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Senior Member Group: Members Posts: 808 Joined: 8-June 08 From: Los Angeles, Ca Member No.: 9,147 Region Association: None |
Look up the number at Summit Racing. I am pretty sure Bosch still sells these.
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914_teener |
Mar 11 2015, 04:55 PM
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#3
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914 Guru Group: Members Posts: 5,197 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
Check the alignment of the board "wipers" on the switch.
There is a procedure on the Bird Board and many threads here on it. Dave Sprinkle is a member vendor and has new boards here. Also check your fuel pressure and the fuel rail. |
somd914 |
Mar 11 2015, 04:56 PM
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#4
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Member Group: Members Posts: 1,171 Joined: 21-February 11 From: Southern Maryland Member No.: 12,741 Region Association: MidAtlantic Region |
Take a look here:
http://www.914world.com/bbs2/index.php?sho...=95583&st=0 I bought one of these kits a few years back - good stuff. Not sure if he is still around and making them... |
mepstein |
Mar 11 2015, 05:25 PM
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#5
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914-6 GT in waiting Group: Members Posts: 19,258 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
Take a look here: http://www.914world.com/bbs2/index.php?sho...=95583&st=0 I bought one of these kits a few years back - good stuff. Not sure if he is still around and making them... I think 914rubber has them |
warrenoliver |
Mar 11 2015, 07:44 PM
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#6
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Member Group: Members Posts: 363 Joined: 11-November 06 From: McFarland, Wisconsin Member No.: 7,199 Region Association: Upper MidWest |
I got one from BDStone914 - good guy to deal with. (IMG:style_emoticons/default/beerchug.gif)
Changing the board didn't fix my issues completely. Changing out the whole unit helped a lot. YMMV Warrenoliver |
JawjaPorsche |
Mar 11 2015, 07:51 PM
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#7
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Advanced Member Group: Members Posts: 3,463 Joined: 23-July 11 From: Clayton, Georgia Member No.: 13,351 Region Association: South East States |
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davesprinkle |
Mar 11 2015, 08:18 PM
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#8
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Senior Member Group: Members Posts: 720 Joined: 13-October 04 From: Berkeley, CA Member No.: 2,943 Region Association: None |
I've got repair kits for the 2.0liter cars and the late 1.7liter cars. The new boards can help if the problem is caused by worn traces on the board.
However, there are other potential source of trouble -- the wipers can get corroded, there are little directional leaf contacts in the stem of the sensor that can corrode, and let's not forget about aged wiring terminals or broken wires. So, yeah, a new board can help, but everything else needs to be OK. A replacement board is only $35. If you need one, send me a PM. |
Gcotton92203 |
Mar 11 2015, 08:45 PM
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#9
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Newbie Group: Members Posts: 21 Joined: 14-February 14 From: Bermuda Dunes Ca. Member No.: 17,000 Region Association: Southern California |
I ordered the board today from 914 rubber. It's the cheapest I found at $48. and I've had good luck with their other products. I would have preferred to change the entire unit just to be sure. I'm sure someone somewhere in the world has a "new old stock" unit but I'm sure I'll never find it. I fully intend to keep this car as it is in great condition, no rust and I have very little money in it. Sooner or later I'm sure I'll switch to carbs but I'll always keep the F.I. parts for the day it's resold.
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914_teener |
Mar 11 2015, 10:13 PM
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#10
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914 Guru Group: Members Posts: 5,197 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
I ordered the board today from 914 rubber. It's the cheapest I found at $48. and I've had good luck with their other products. I would have preferred to change the entire unit just to be sure. I'm sure someone somewhere in the world has a "new old stock" unit but I'm sure I'll never find it. I fully intend to keep this car as it is in great condition, no rust and I have very little money in it. Sooner or later I'm sure I'll switch to carbs but I'll always keep the F.I. parts for the day it's resold. Unh hunh. (IMG:style_emoticons/default/WTF.gif) |
dknechtly |
Mar 13 2015, 01:50 PM
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#11
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Yellow 914 Group: Members Posts: 68 Joined: 11-April 03 From: Wylie, TX Member No.: 560 Region Association: None |
Hope you keep that FI in it. There are so many things to check. Do you have points? As they get closer is will run bad especially when first starting up. Also, check the resistance of the FI points. It should be as low as possible. Don't use emory cloth! Just a piece of note card or a jeweler's cloth. If it runs too lean, all kind of wierd things happen. Check that the mechanical advance is all nice and limber and no springs are broken.
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Gcotton92203 |
Mar 13 2015, 02:18 PM
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#12
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Newbie Group: Members Posts: 21 Joined: 14-February 14 From: Bermuda Dunes Ca. Member No.: 17,000 Region Association: Southern California |
Hope you keep that FI in it. There are so many things to check. Do you have points? As they get closer is will run bad especially when first starting up. Also, check the resistance of the FI points. It should be as low as possible. Don't use emory cloth! Just a piece of note card or a jeweler's cloth. If it runs too lean, all kind of wierd things happen. Check that the mechanical advance is all nice and limber and no springs are broken. Wow! lots of good info. I just converted to a Pertronix but it still did the same bucking just off idle. I'm pretty sure it's a worn circuit board. I just hoped I could find a new complete replacement but I guess people in Hell want ice water too. I also believe I'll be facing the vapor lock issue as I sometimes hear gurgling in the gas tank when starting warm after several minutes rest. Other than that I have no other issues with the way it runs and intend to keep it injected as long as humanly possible |
marksteinhilber |
Mar 13 2015, 02:53 PM
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#13
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Member Group: Members Posts: 229 Joined: 18-October 12 From: Foothill Ranch, CA 92610 Member No.: 15,057 Region Association: Southern California |
Hope you keep that FI in it. There are so many things to check. Do you have points? As they get closer is will run bad especially when first starting up. Also, check the resistance of the FI points. It should be as low as possible. Don't use emory cloth! Just a piece of note card or a jeweler's cloth. If it runs too lean, all kind of wierd things happen. Check that the mechanical advance is all nice and limber and no springs are broken. Wow! lots of good info. I just converted to a Pertronix but it still did the same bucking just off idle. I'm pretty sure it's a worn circuit board. I just hoped I could find a new complete replacement but I guess people in Hell want ice water too. I also believe I'll be facing the vapor lock issue as I sometimes hear gurgling in the gas tank when starting warm after several minutes rest. Other than that I have no other issues with the way it runs and intend to keep it injected as long as humanly possible Try the suggested repair where you clean the contacts and /or move the finger to run on a new groove! |
Amphicar770 |
Mar 13 2015, 05:48 PM
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#14
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Senior Member Group: Members Posts: 1,188 Joined: 20-April 10 From: PA, USA Member No.: 11,639 Region Association: MidAtlantic Region |
Circuit board from 914 rubber had my 914 purring like a kitten.
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TheCabinetmaker |
Mar 13 2015, 05:56 PM
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#15
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
Gently clean up the board with some 2000 grit wet/dry sandpaper then some lacquer thinner or alcohol.
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DRPHIL914 |
Mar 13 2015, 10:41 PM
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#16
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Dr. Phil Group: Members Posts: 5,766 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
I got one from BDStone914 - good guy to deal with. (IMG:style_emoticons/default/beerchug.gif) Changing the board didn't fix my issues completely. Changing out the whole unit helped a lot. YMMV Warrenoliver (IMG:style_emoticons/default/agree.gif) This is exactly what I saw too. The very slightly used one i got from bruce Has worked flawlessly. Absolutely no bucking! Drove it 250 miles this week and didn't happen once. |
Gcotton92203 |
Mar 27 2015, 10:50 AM
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#17
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Newbie Group: Members Posts: 21 Joined: 14-February 14 From: Bermuda Dunes Ca. Member No.: 17,000 Region Association: Southern California |
Replaced the circuit board. Seems better but still bucks. Improved greatly when fully warm. I have a sneaky suspicion there's a loose ground somewhere.
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PancakePorsche |
Mar 28 2015, 12:17 AM
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#18
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Member Group: Members Posts: 236 Joined: 29-July 11 From: Southern California Member No.: 13,373 Region Association: None |
Identical to my car a year ago. A NOS TPS did not help.
I went through the distributor by removing breaker plate and precisely setting trigger point opening, set timing, set ECU, and fuel pressure to 34 PSI. Now has power everywhere, milage 30+ MPG highway, no bucking. Remember modern fuels are at least 10% methanol so you need to increase volume accordingly. Bucking=lean. |
TheCabinetmaker |
Mar 28 2015, 08:30 AM
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#19
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
Tps does not typically cause bucking at off idle, but at cruise. 3200-3600rpm. I would look at dwell and timing.
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Bleyseng |
Mar 28 2015, 08:59 AM
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#20
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Aircooled Baby! Group: Members Posts: 13,034 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
Identical to my car a year ago. A NOS TPS did not help. I went through the distributor by removing breaker plate and precisely setting trigger point opening, set timing, set ECU, and fuel pressure to 34 PSI. Now has power everywhere, milage 30+ MPG highway, no bucking. Remember modern fuels are at least 10% methanol so you need to increase volume accordingly. Bucking=lean. yes, off idle is usually caused by sticking advance plates in the dizzy. TPS bucking occurs at 3000 rpm. |
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