I am having a hard start problem with my L-78. It has been going on for a while now (like since I bought the car in november). I finally tired of the run battery down-charge it back up-run battery down again routine that I have bneen going through. Funny thing is that once it starts, it is a real beast! It runs great. When I turn it off, sometimes it starts immediately, sometimes I have to crank for 5-10 seconds so you see I have both hot and cold start problems, but especially cold. The engine cranks like mad, but does not try to fire most of the time. I had the carb redone by Jerry Luck (what a great job he did BTW. Anyway, this did not resolve the issue. I changed the ignition coil - nope. Changed cap and rotor. Uh, Uh. New plugs. Nada. I know I should check cranking voltage at the coil and I'll do that. I also understand that there is a resistor in the ignition coil circuit which is switched out for starting and I will check to make this is the case. But other than that, I am totally at a loss. where else do I look. BTW, at idle I have about vacuum of 15 in. and ignition timing is 10 degrees btdc. I was embarassed to call my mechanic over this seemingly simple issue but I finally relented and now we are both going nuts over this. I am seriously considering having the distributor changed over to points (TI now) to see if this helps, obviously an act of desparation being contemplated here. Any advice would be GREATLY appreciated.
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Sounds familiar
I believe the problem is in your wiring to the amplifier box or in the box itself. Try cleaning all the connections.
I had the same problem with a '69 TI system once. It turned out to be one bad terminal within the three prong box plug-in. I was tipped off when I discovered the car would start if I cranked it for a few seconds and then let the key pop back to the run position (even though the engine hadn't fired yet). Evidently one wire carries the cranking current and a separate wire carries the juice for running. -
Sounds familiar
I believe the problem is in your wiring to the amplifier box or in the box itself. Try cleaning all the connections.
I had the same problem with a '69 TI system once. It turned out to be one bad terminal within the three prong box plug-in. I was tipped off when I discovered the car would start if I cranked it for a few seconds and then let the key pop back to the run position (even though the engine hadn't fired yet). Evidently one wire carries the cranking current and a separate wire carries the juice for running.Comment
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Re: Sounds familiar
Yes, you're right about two circuits for running and starting. That is where the resistor comes in. It is out of the circuit to provide maximum voltage (and spark) during starting, while in the circuit while running to lengthen point life (this compliments of Jack Humphrey). Makes sense that it would be a separate connection at the switch and the box to accomplish this and a high resistance connection would produce the symptoms. When I get back home this week end I'll check that out. Thanks Jerry. Any other suggestions are still welcome. I need as many troubleshooting tools at my disposal as I can getComment
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Re: Sounds familiar
Yes, you're right about two circuits for running and starting. That is where the resistor comes in. It is out of the circuit to provide maximum voltage (and spark) during starting, while in the circuit while running to lengthen point life (this compliments of Jack Humphrey). Makes sense that it would be a separate connection at the switch and the box to accomplish this and a high resistance connection would produce the symptoms. When I get back home this week end I'll check that out. Thanks Jerry. Any other suggestions are still welcome. I need as many troubleshooting tools at my disposal as I can getComment
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Re: Sounds familiar
When you check at the coil for cranking voltage (a primary check, pun intended) and it isn't there, don't just go and blame the TI. The source of the override voltage during cranking is the starter solenoid (yellow) The main source of coil voltage is the key switch (through the resistor). If both the bypass isn't happening and (repeat: AND) the key switch was dropping the ignition coil feed during crank, you would then have zero coil volts during cranking. Summary: No voltage during start: both switch and solenoid bypass out. 4 to 7 volts run and start: bypass out. 4 to 7 run and 10 to 12 during crank: primary OK, look elsewhere. (IE secondary side, controlled by TI) Also: Don't forget that the key switch position is adjustable on the column, the pink "ign 1" wire is the one to watch for 12v run and start.Comment
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Re: Sounds familiar
When you check at the coil for cranking voltage (a primary check, pun intended) and it isn't there, don't just go and blame the TI. The source of the override voltage during cranking is the starter solenoid (yellow) The main source of coil voltage is the key switch (through the resistor). If both the bypass isn't happening and (repeat: AND) the key switch was dropping the ignition coil feed during crank, you would then have zero coil volts during cranking. Summary: No voltage during start: both switch and solenoid bypass out. 4 to 7 volts run and start: bypass out. 4 to 7 run and 10 to 12 during crank: primary OK, look elsewhere. (IE secondary side, controlled by TI) Also: Don't forget that the key switch position is adjustable on the column, the pink "ign 1" wire is the one to watch for 12v run and start.Comment
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L78 TI starting problems - a possible solution
A number of things can cause the problem you mention. However, here is an observation I have made concerning the same symptoms in TI cars of my own. In particular, a common and simple cause of the problem on the 396 system is the ground wire which mounts on the left ear of the amplier. If electrical contact is poor at that junction or if the body of the amplifier is not grounded to the radiator support properly the symptoms you describe are possible. The correction is a simple 5 minute fix to clean up contact surfaces.
I would be interested in knowing if this suggestion solves your problem.
Al GrenningComment
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L78 TI starting problems - a possible solution
A number of things can cause the problem you mention. However, here is an observation I have made concerning the same symptoms in TI cars of my own. In particular, a common and simple cause of the problem on the 396 system is the ground wire which mounts on the left ear of the amplier. If electrical contact is poor at that junction or if the body of the amplifier is not grounded to the radiator support properly the symptoms you describe are possible. The correction is a simple 5 minute fix to clean up contact surfaces.
I would be interested in knowing if this suggestion solves your problem.
Al GrenningComment
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Re: Sounds familiar
Something's rotten in Denmark, methinks! L78 had mandatory TI option. TI did NOT use ballast resistor....
Your firewall should be virgin, undrilled, at the point ahead the driver's seat where the typical ballast resistor 'lives'. Since system is all electronic, there's no need for ballast resistor function.
I'd go back to basics. Cars don't start for three reasons:
(1) No fire in the hole (plugs not getting adaquete voltage to spark). (2) Lack of fuel (gas). (3) Lack of air (wrong mixture).
The 'acid' test used by olde boy mechanics before engine analyzers, was to pull a plug (or use a spare), connect the wiring loom to it, ground the plug against bare engine metal and have an assistant crank the engine while they watched the plug tip to verify proper/consistent firing of the plug. If you do this BEWARE you don't make yourself part of the ignition ground path (hold plug/wire with insulated pliers) or you'll 'yelp'.
If plug you test is firing properly/consistently, start looking upstream for gas/air funnies. When I initially fire my L78, it starts like a champ IF I pump the carb four times before keying the starter. Remove air cleaner lid and check to see that you're getting good healthy squirt into the carb primary when you pull the accel linkage by hand. If she's lean, I guarantee you engine will crank without turning over (happened to me in Operations Check once)....Comment
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Re: Sounds familiar
Something's rotten in Denmark, methinks! L78 had mandatory TI option. TI did NOT use ballast resistor....
Your firewall should be virgin, undrilled, at the point ahead the driver's seat where the typical ballast resistor 'lives'. Since system is all electronic, there's no need for ballast resistor function.
I'd go back to basics. Cars don't start for three reasons:
(1) No fire in the hole (plugs not getting adaquete voltage to spark). (2) Lack of fuel (gas). (3) Lack of air (wrong mixture).
The 'acid' test used by olde boy mechanics before engine analyzers, was to pull a plug (or use a spare), connect the wiring loom to it, ground the plug against bare engine metal and have an assistant crank the engine while they watched the plug tip to verify proper/consistent firing of the plug. If you do this BEWARE you don't make yourself part of the ignition ground path (hold plug/wire with insulated pliers) or you'll 'yelp'.
If plug you test is firing properly/consistently, start looking upstream for gas/air funnies. When I initially fire my L78, it starts like a champ IF I pump the carb four times before keying the starter. Remove air cleaner lid and check to see that you're getting good healthy squirt into the carb primary when you pull the accel linkage by hand. If she's lean, I guarantee you engine will crank without turning over (happened to me in Operations Check once)....Comment
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Re: L-78 starting problems - HELP!!!
Just because you had the carb rebuilt by a pro doesn't mean alll the choke adjustments are correct. I have seen many carbs (including the one I just had bkueprinted last week by Avanti) come back out of wack. Check to see that the choke plate isn't closing off totally and not unloading the way it should by vacuum while the engine is cranking. While in a no start condition try holding your foot to the floor and cranking to see if the carb unloads and the engine starts. If it is a Rochester carb, Engine cold-work the accellerator linkage once and the choke plate should slam shut. Push in on the primary choke pulloff and hold while looking to see if the choke plate opens up about 1/8-3/16 's. If not, turn the adjustment screw on the pulloff for the correct distance. I know this is basic but sometimes it is overlooked.Comment
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Re: L-78 starting problems - HELP!!!
Just because you had the carb rebuilt by a pro doesn't mean alll the choke adjustments are correct. I have seen many carbs (including the one I just had bkueprinted last week by Avanti) come back out of wack. Check to see that the choke plate isn't closing off totally and not unloading the way it should by vacuum while the engine is cranking. While in a no start condition try holding your foot to the floor and cranking to see if the carb unloads and the engine starts. If it is a Rochester carb, Engine cold-work the accellerator linkage once and the choke plate should slam shut. Push in on the primary choke pulloff and hold while looking to see if the choke plate opens up about 1/8-3/16 's. If not, turn the adjustment screw on the pulloff for the correct distance. I know this is basic but sometimes it is overlooked.Comment
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Re: Sounds familiar
Once again, thanks for the ideas. Jack's post re: decompositioin in the scandanavian country makes sense but I don't know whether or not the resistor was used on TI vehicles. If the intended purpose was saving points, true enough, it would not be necessary on a TI system. Again, when I get back to Cleveland this week end, I'll tinker and learn some more. I will update the board when I now more (hopefully with the solution to this mystery). Seems so simple - air, gas, spark, runs.
BTW, I have installed an extra plug in the circuit and grounded it while cranking the engine - one white looking spark every engine revolution. Hate to say it but this may be an operator problem. I would not dare (before now) punping the pedal 4 times for fear of flooding. I have flooded this car several times, and the carb does unload eventually when the pedal is depressed to the floor. I'll let you know how I make out this week end but please keep those suggestions coming in the meantime.Comment
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Re: Sounds familiar
Once again, thanks for the ideas. Jack's post re: decompositioin in the scandanavian country makes sense but I don't know whether or not the resistor was used on TI vehicles. If the intended purpose was saving points, true enough, it would not be necessary on a TI system. Again, when I get back to Cleveland this week end, I'll tinker and learn some more. I will update the board when I now more (hopefully with the solution to this mystery). Seems so simple - air, gas, spark, runs.
BTW, I have installed an extra plug in the circuit and grounded it while cranking the engine - one white looking spark every engine revolution. Hate to say it but this may be an operator problem. I would not dare (before now) punping the pedal 4 times for fear of flooding. I have flooded this car several times, and the carb does unload eventually when the pedal is depressed to the floor. I'll let you know how I make out this week end but please keep those suggestions coming in the meantime.Comment
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