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1978 mercruiser 260 alternator and electronic ignition problem

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ldillm

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I have a 1978 mercruiser 260 with a gm v8 350 engine. I inherited this from my father in law. It was running fine,and like an idiot I decided to fix a things that weren't broken. I replaced the starter,alternator and upgraded to a AAA marine electronic ignition. The engine turns over but fuel pump does not energize and I get no spark. My new alternator is a delco 10si. It has a red and black wire already connected. I cant figure out the wiring. Leading to the alternator are 4 wires. One Black, one small red, One large red/white and one large blue/red. I understand that if it is hooked up wrong the electric fuelpump will not work. My aaa marine ignition is HEI. I believe it is installed properly. the resistance wire was removed and a relay was installed by a boat shop. They couldn't get it to work s they put the old point system back in. If they fried the distributor, is there a way to test? The only thing I had to wire was the purple and gray wire. But alas no fuel and no spark. help!
 
do you have an ammeter or voltmeter ,electric fuel pumps are never hooked up to the alt
 
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Are there any other connections on the alternator?


If it only has two connections then One is Ground (BLACK) the other is output (Large RED WITH WHITE STRIPE) which should go to the large starter solenoid lug. (battery +)

This may be what is called a one wire alternator. It will self excite around 1200-1500 rpms.

The two remaining wires in the harness are excite and sense. Tape off individually real good and leave alone.

If you have an electric fuel pump then that is a separate wiring configuration not associated with that boat model/year. That motor would have had a mechanical fuel pump.

The White wire is equivalent to ignition on (purple) in current wiring code and was connected to coil +

See schematic of old wiring diagram/wire colors........
 
Yes the electric fuel pump was added later on and is separate. And the diagram is very useful. I have the selec manual and your diagram is much closer to my setup than the views that I have. Thank you very much! Also my distributor problem may be due to my shift interrupter being wired wrong. Gonna give that a shot and i'll post my resulys.
 
ok, I Have spark going to the plug wires, and a fuel pump that works. Spark problem was because there wasn't enough voltage going to the coil due to the fact that a tan wire had broken off the slave solenoid, along with the ground causing the fuel pump not to work. when I tried to start it , it did not start but I did get a small backfire. I thought it was properly marked when I took the old distributor off. Timing mark was dead on TDC cyl #1. backfire means I'm off 180 degrees? How many times does the flywheel have to turn before you really are on TDC? The #1 cyl was on the compression stroke. My new alternator is a delco si 10. It has a ground screw, a Batt and 2 wires coming out of a plug. Black and red. I hooked up the red one to the batt connection. and the black one to the purple ignition wire. Is this right?My old Motorola had a Big red and white wire, blackwire, a blue and red wire, and a small red wire with a white sleeve on the end. Also, on my AAA Marine elec distributor, the cutoff switch was to ground. They had me cut the wires, run the single black wire to the cutoff and out the other end to 12v+. Coil is a
hei. Thanks guys for the help!






,
 
backfire means I'm off 180 degrees?

Not necessarily. Could be firing order is off, re check firing order



How many times does the flywheel have to turn before you really are on TDC?

1 complete 360 degree turn of harmonic balancer, IF you 180 out will now be correct

The #1 cyl was on the compression stroke.


My new alternator is a delco si 10. It has a ground screw, a Batt and 2 wires coming out of a plug. Black and red. I hooked up the red one to the batt connection. and the black one to the purple ignition wire. Is this right?

Maybe go on line and search for wiring connections for a delco si 10????

The schematic shows SMALL red goes to slave solenoid (positive connection Large post on top of solenoid) Basically a battery + connection but not directly to battery.
SMALL black in your case (original color for you motor was white which went to coil+ or ignition on circuit)



My old Motorola had a Big red and white wire, blackwire, a blue and red wire, and a small red wire with a white sleeve on the end.

Big red with white would be output of alt, to main stud on starter solenoid
Big black is ground
Small Red should be to slave solenoid as described above.
small Blue should be excite and should be coil + Although I am not sure the wire is supposed to be blue....


Also, on my AAA Marine elec distributor, the cutoff switch was to ground. They had me cut the wires, run the single black wire to the cutoff and out the other end to 12v+.
In the original schematic the cut off switch, one leg is to ground, the other is to - side of coil. So I would put it there not the + side.

Coil is a hei.

If by HEI you mean internally resister coil then you are ok. If it is an external resister coil you need a different one. Point ignitions use external, electronic ignition typically use internal.
 
ok. getting low spark. this is a hei system from AAA Marine. it came with a external coil. (black, no markings 4 wire) and hei spark plug wires. The issue im having is with the resistor wire knocking coil down to 8-9 volts. Im told it is in the harness. Schematic shows a white wire(possible tied into the key switch?) I see a purple wire that leads to a terminal just above the circuit breaker with a red button. coil gets 12v with key on. drops to 8 or 9 while cranking. Can you tell me how to bypass this. AAA Marine said just cut it. and what does it look like? Purple? Tan? friggin polka dot? this has been the project from hell. Thx. Ps. my old points tdc was eleven "clock on he distributr. the hei system tell me to put that at 6:30. for cyclinder #1. very confusing. get different advise from all forums it seems, but I trust this one the most.
 
The resistor wire is in the wire harness at the motor not in the dash.

If you view the schematic I posted it shows this.

What you need to to is remove the white wire (s) going to coil + then see which one has the power to it with the ignition key in the on position.. This is the end of the resistor wire and then Tape it off good.

Because you do not have an electric choke you need to find another source for (ignition on) power to the + side of the coil.

Do yourself a favor and make this wire color PURPLE....That is the current standard.

WHat I would do is remove the tape on the engine side wire harness at the main big connector.

Find the white wire and confirm it is ignition on first. About 3-4 inches away from the connector either cut it or splice in the purple wire and run that to coil +.
Use 14 gauge wire. You will need about 3-4 feet of it and make sure when you route it, it is no where near any high heat source.

This should give you full battery/charging voltage at the coil.
 
TA DAAAAAAAAAAAAAAAAAA! Thanks to expert advise I found the resistor wire. Confusion was because there are two white wires running to the coil via a purple wire. In the start position the starter solenoid feeds the coil 12v+. When you are in the run position the alternator feeds 12v to the white resistor wire bringing 7 or 8 or 9 volts to the coil. I replaced this with a length of 14 ga purple wire. the resistor wire was soldered onto the red wire in the harness going to the alternator. Position of the resistor wire splice in the wiring harness is at cylinder #4 on the engine portside. Had to remove a lot of tape, but I an replacing it with that tubular accordion black plastic wire protector kind of stuff. Will try starting it tomorrow. I Will save the resistor wire in case I ever want to retro upgrade back to points. I'm guessing that the resistance is determined by gauge and length of wire(copper}. it was resisting my attempt to run 12v+ but is resisting no more. Thanks for the info from those that contributed. you are the best!
 
kghost said:
The resistor wire is in the wire harness at the motor not in the dash.

If you view the schematic I posted it shows this.

What you need to to is remove the white wire (s) going to coil + then see which one has the power to it with the ignition key in the on position.. This is the end of the resistor wire and then Tape it off good.

Because you do not have an electric choke you need to find another source for (ignition on) power to the + side of the coil.

Do yourself a favor and make this wire color PURPLE....That is the current standard.

WHat I would do is remove the tape on the engine side wire harness at the main big connector.

Find the white wire and confirm it is ignition on first. About 3-4 inches away from the connector either cut it or splice in the purple wire and run that to coil +.
Use 14 gauge wire. You will need about 3-4 feet of it and make sure when you route it, it is no where near any high heat source.

This should give you full battery/charging voltage at the coil.
Click to expand...
Working on a 79 mercruiser 260, had the electronic inginition for 20 years and ran ok, but recently starting acting up. Can you show that sketch for this? This sounds like exactly what I need. The white wire felt warm to the touch.

My coil is at 4.4v with the key on and 9.9v cranking.
 
If the engine had a points distributor in it originally you can pull the WHT or PUR wire (depends on serial number and dash config) off of the + terminal of the coil, follow it down into the engine harness...you will to remove the tape...you will find the crimp for the connection to about 3 feet of resistance wire that has been folded back on itself. The other wire connected to the coil + terminal goes to the starter solenoid.

If the engine originally had the TB-IV system, there won't be any resistance wire.
 
No thunder bolt ignition was originally a points motor.

Am I looking for a white tan wire soldered or a red soldered as the resistance wire?

I apologize as I'm not the best electrian.
 
I did find the wire going to the coil unhooked has 11.5v and when I hook it up it drops, also hooked up another wire that must of went to a electric choke and it was the same 11.5v , so between the 2 power wires I now got 9v with key on and 9.9v cranking at the coil.
 
Ok, now I disconnected the white wire from the coil and wired in another wire that goes to the key switch. 11.8v at the coil with key on and 13.3v running, but voltage is constant running 2v-14volts. Guess that's my question what's a normal voltage at the coil for a running engine? Engine does fire right up now and the coil get warm.
 
Point ignition must have a external resistor, Approx 2 ohms. Commonly called a ballast resistor. GM type point ignitions used a resistor wire.
Mercruiser uses a wire.
The purpose is ro reduce running voltage so the coil does NOT over heat.

So your running voltage should be approx 9-11 volts DC.

As far as starting, there needs to be a wire from I terminal on starter solenoid so when cranking engine, full batter voltage goes to coil to start engine.
Once key is returned to run postion the votage now becomes 9-11 vdc. So that is why there is two wires to coil +

Electronic ignitions (thunderbolt) uses a internal resistor coil. No ballast or resistor wire.
 
Ok, the boat has electronic ignition and the points were removed years ago. Think it got 10v cranking and 12v-14.3v running now.
I think I got it figured out removed the tan wire from positive coil and found a wire that got 12v with the key and replaced the tan wire. Hooked it up and it seems to work well will need to test later this week. Petronix said as long as the voltage doesn't go over 15v will work great. I just left the resistor wire tan off to side and will tape up good and retape the harness. Engine starts super easy now on the muffin had to crank a bit b4.
 
A word of caution,

Just because there is a Petronix conversion kit does not mean the Coil was replaced. Unless you can confirm it was.

Point coil uses a external resister which the original coil would be. Absent of the resister the coil may get hot and fail.

It is not about the parts in the distributor!! I am sure as you learned, they can handle up to 15 VDC.

If you have removed the resister wire, you may want to consider going to Napa and buying a internal resister coil (~$35.00) and installing it.
 
I did put on the flame thrower 1.5 ohm resistor coil from pertronix. Guess I should of mentioned this earlier. The coil that was on there before was a mercury 1.5 ohm resistor coil. It tested to be 1.6 ohm.
 
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