Cutting out at night on freeway

[vw donvieira]

Dello All.
-I have a 1971 bus with a 2017cc motor
-Dual DRLA 40's with elec fuel pump at 2.5 psi
-Mallory unilite from ACN (mech/Vac advance) with circuit guard.
-Seems to run fine during the day

twice while merging onto the freeway at night (lights on and voltmeter at 12v) the engine started to sputter when I hit 3rd gear. Had to slow down and downshift but it seemed to resolve once I turned the headlight off (running lights still on).

Another note (getting forgetful in my old age) is that my brake lights are not working. I have Flasher/turn/driver side running light in the rear.

Not sure if a tired battery could cause this, is the Mallory malfunctioning.
Carbs were rebuild 6 months ago with high quality kit from the carburettor shop in Europe.

TIA
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"No Give Up"

[BFB]

did you do what alot of ppl do and wire your fuel pump off of the power wire to the coil?
if it seems directly related to you shutting off the headlights and not just coincidental, then start looking in the wiring and check you amps not just v.
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"how am i supposed to torque the rear wheel nut to 250 ft lbs??? " - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't.

[vw donvieira]

Great point.
I will check since VW Jim in Lodi wired the fuel pump
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"No Give Up"

[Stripped66]

[vw donvieira]

Thanks Stirpped66
WIth headlights off I am at 14 volts
I do have HID headlights, probably time for LEDs
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"No Give Up"

[daveblank]

[mikedjames]

The Voltage Guard is described as a voltage regulator as well as a spike protector: when things are near the edge, maybe it is dropping the voltage to lower than 12 volts at the Unilite, causing it to shut off.

A standard ignition system should be working at 9 volts AFAIR.

But the underlying issue is that your charging system is weak. If it is using an alternator it could just be worn brushes.
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[mikedjames]

The Voltage Guard is described as a voltage regulator as well as a spike protector: when things are near the edge, maybe it is dropping the voltage to lower than 12 volts at the Unilite, causing it to shut off.

A standard points/condenser ignition system should be working at 9 volts AFAIR.

But the underlying issue is that your charging system is weak. If it is using an alternator it could just be worn brushes.
_________________
Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[Stripped66]

[vw donvieira]

I appreciate all the input and will get back once I have tested the alternator and load test battery at Battery Bill.
Thank you
vwdon
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"No Give Up"

[vw donvieira]

Went to Battery Bill this morning.

Battery checked out good.
Alternator checked out good with lights off (14v at idle)
Lights on at idle, the alternator registered bad and was down below 12v
I have something excessively draining the alternator's ability to charge with the lights on.
I am checking the brake switches tomorrow and then go from there.
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"No Give Up"

[Dale M.]

[BFB]

55 amps isnt shit , its nothing for a more modern vehicle to have 120 , 150 and were so used to having so much electronics that we dont think about how much it adds to straining our older systems when we add more & more to them.
I actually had to do a bit a reading because i thought stripped66 was wrong because the set of HID’s i added to my rail are the reason it got a 95 amp alternator. They draw a lot. But turns out he’s right, HID should draw less while running than halogen. BUT i bet the difference is in the fact that i didnt go with a similar equivalent, i went with some mega out put HID’s.
_________________
"how am i supposed to torque the rear wheel nut to 250 ft lbs??? " - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't.

[vw donvieira]

[quote="Dale M."]

[94touring]

Since I have a large power inverter in my bus to run various items occasionally, a trailer with all it's lights, and h20 injection pump, I upgraded to an 85amp. It came with a sheet with it's power curve output based on rpms as I recall. Anyways, whatever boost it gave me showed up on my volt gauge. Lights off no accessories went from 14-14.2 to 14.5 and all lit up and max power being drawn to 13.3-13.8, up from maybe 12.8 at it's lowest. I run led brake lights.

[vw donvieira]

Thank you.
I am going to a 75amp alternator.
I have a retired alternator/magneto/generator/starter rebuilder that is going to test the alternator for me before I install.
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"No Give Up"

[VW_Jimbo]

Check your ground path from the alt body to the battery negative. A voltage drop check should do fine. If you get more then .25 vdc, you got a ground issue!

You need a solid ground for the alternator to tell how much juice to put out! Not saying it is good. Just saying a wire can read good with only one strand connected. A voltage drop test will let you know if you wiring and connection are good or bad.

I have seen a lot of good parts changed due to a bad wire terminal!
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[vw donvieira]

Thank you VW Jimbo

-I will check the ground from the alternator. I did not go directly to the battery. I had a spot on the deck lid area that I grouped a few grounds to, but should have a wire from there to the battery negative. I use a military grade fully tinned copper stranded wire 10 gauge for my critical grounds.

-I have had this configuration for over 15 years, so it is odd.

-I am checking the brake light switches tomorrow and then will check the grounds.
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"No Give Up"

[vw donvieira]

This should be moved to 1968-1979 bus forum, but I do not know how.

-Took bus on freeway today, just under 14v., then I turned the lights on, while at 3300 rpm and volts went to about 12.2

I checked the brake light switches on the master cylinder and they had continuity when I pressed the brake pedal.

I got a power probe, so it is time to learn how to use it.

Thanks for all the help.
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"No Give Up"

[74 Thing]

You have a serious voltage drop.

Check your grounds first as advised above and clean them to bare metal.

Check the hook up at the starter as well since the battery/alt/and headlight and fuse box wires all connect there.

Then pull your headlight and start doing voltage drops at the ground wire then low beam then high beam.

You need to get a voltmeter and learn how to use it-I had to and solved my problems-some wires at the headlights were really and needed to get cut back and a new 3 wire pigtail put on. Re did the grounds throughout.

Your alt should be putting out approx 14v at 3k rpm checked at the battery.

Ashman is a great resource and very helpful on electrical problems.