76 SB, FI with a bucking issue
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76 SB, FI with a bucking issue
We have a 76 SB that is 1 year plus into a restoration, engine is back in however it has developed a bucking problem after it is totally warmed up (10 to 15 miles of driving). The FI computer has been checked as well as the temp sensor, aux. air valve, air monitoring valve, spark plugs (and wires) points, condensor, coil, fuel pressure, We did replace the alternator as it was putting out 19 volts. Is it possilble the alternator putting out too much voltage damaged the fuel injectors? Any suggestions would be appreciated.
- Gypsie
- rusty aircooled mekanich
- Location: Treadin' Lightly under the Clear Blue!
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Re: 76 SB, FI with a bucking issue
Likely an obvious item but did you have a Vacuum leak hunt after full warmup? Maybe something is leaking once it is warm?
Checking the temp sensor included assuring securely seated? Does the SB have two temp sensors?
Fuel injectors damaged by overvoltage may be possible but further down on my list of maybes. Other electrical failures (points, coil, condensor) at full warmup are higher on the list.
Restoration? What is the condition of the fuel tank. Could it be that fuel flow is suffering interference. Not just pressure but flow rate.
Where you at? Come to the Lab if you can....
Checking the temp sensor included assuring securely seated? Does the SB have two temp sensors?
Fuel injectors damaged by overvoltage may be possible but further down on my list of maybes. Other electrical failures (points, coil, condensor) at full warmup are higher on the list.
Restoration? What is the condition of the fuel tank. Could it be that fuel flow is suffering interference. Not just pressure but flow rate.
Where you at? Come to the Lab if you can....
So it all started when I wanted to get better gas mileage....
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Re: 76 SB, FI with a bucking issue
Have not looked for vacuum leak after warm up..is there a good technique for this?
All ingnitinon components have been checked or replaced (points, plugs, wiring, etc)
Temp sensor near cyclinder #4 is critical one, there is another near the alternator pully that is for cold starting only. Both appear are seated and working.
Fuel tank is new.
I had thought about the flow but don't know what it should be or how to check it.
We live in Plymouth, Wisconsin (eastern portion of the state, near Milwaukee)
Thanks for the input
All ingnitinon components have been checked or replaced (points, plugs, wiring, etc)
Temp sensor near cyclinder #4 is critical one, there is another near the alternator pully that is for cold starting only. Both appear are seated and working.
Fuel tank is new.
I had thought about the flow but don't know what it should be or how to check it.
We live in Plymouth, Wisconsin (eastern portion of the state, near Milwaukee)
Thanks for the input
- RSorak 71Westy
- IAC Addict!
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Re: 76 SB, FI with a bucking issue
Easy way to check for vacuum leaks is to spray something combustible like ether, at suspected leaks. If and when the engine sucks in the additional fuel, the idle speed will rise and or smooth out.
Take care,
Rick
Stock 1600 w/dual Solex 34's and header. mildly ported heads and EMPI elephant's feet. SVDA W/pertronix. 73 Thing has been sold. BTW I am a pro wrench have been fixing cars for living for over 30 yrs.
Rick
Stock 1600 w/dual Solex 34's and header. mildly ported heads and EMPI elephant's feet. SVDA W/pertronix. 73 Thing has been sold. BTW I am a pro wrench have been fixing cars for living for over 30 yrs.
- Amskeptic
- IAC "Help Desk"
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Re: 76 SB, FI with a bucking issue
If the engine behaves cold, but misbehaves warm, see what the mixture is cold, and compare to what mixture is warm.tswillow wrote:We have a 76 SB that is 1 year plus into a restoration, engine is back in however it has developed a bucking problem after it is totally warmed up (10 to 15 miles of driving). The FI computer has been checked as well as the temp sensor, aux. air valve, air monitoring valve, spark plugs (and wires) points, condensor, coil, fuel pressure, We did replace the alternator as it was putting out 19 volts. Is it possilble the alternator putting out too much voltage damaged the fuel injectors? Any suggestions would be appreciated.
If richer cold .... richen it up for warm.
If leaner cold .... lean it out a bit for warm.
Yaah?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
- Gypsie
- rusty aircooled mekanich
- Location: Treadin' Lightly under the Clear Blue!
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Re: 76 SB, FI with a bucking issue
I am interested in how this works.Amskeptic wrote:
If richer cold .... richen it up for warm.
If leaner cold .... lean it out a bit for warm.
Yaah?
Colin
Is this a similar procedure to the AFM adjustment sticky?
viewtopic.php?f=50&t=7761
Ether is found in what products? I have used gumout carb spray.
We found that a bucking issue reported for a type 4 turned out to be a lean condition. We richened it up (to the tune of 8 clicks ccw on the cog) and it appears at furst blush to have helped though it is still under observation.
So it all started when I wanted to get better gas mileage....
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Re: 76 SB, FI with a bucking issue
Temp sensor 2 or vacuum leaks.