New post about an old problem

[RECHRGD]

A couple of years ago I posted about a problem I was having.  The car would just seem to die on occasion when cruising at low speed and rpm.  It wouldn't actually die to the point of having to pull over or anything.  It would only last for a split second and then just carry on its merry way.  It felt like turning the key on and off, but much faster than you could accomplish that.  It seemed to occur more often on warmer days, but still could happen at anytime.  As I recall, I replaced the module in the old Mallory Unilite dizzy and thought it was fixed after a short drive.  It wasn't.  I quit posting about it, as it wasn't leaving me stranded (for now).  Fast forward to today.  Over the off season I did a lot of work on the car, including a new Firecore RTR dizzy, coil and wires.  I took it out for its first run of the season a few days back and the car has never run better, so I thought the old stumble went away with the old Mallory system and deletion of the ballast resistor.  Not so!  Took the wife for a nice ride today of about 120 miles.  Most of the trip was at between 45 and 75 mph and it ran like a Swiss watch (old saying) until in slow traffic or parking lots.  Under those conditions the old stumble reared it's ugly head again, maybe five or six times.  The voltage regulator is the electronic type, but has been in there several years.  The alternator is a 100 amp Power Master unit and the wiring has been upgraded for it.  The ammeter is no longer in the system and has been replaced with a volt meter.  I kind of doubt that it's a grounding issue, but that's always possible.  Now I'm looking at a fuel issue.  Could a fuel problem cause these symptoms?  The carb is a Holly 750 DP with a Proform main body upgrade (about seven years ago).  It has a 1/4" phenolic spacer under it that eliminated a fuel boiling issue years back.  I did pull the carb apart a couple of years ago and found a couple of jets clogged that I attributed to the ethanol blended fuel.  Any and all ideas for a solution to this are much appreciated.  This car is so close to being perfect after 18 years of trying.

[cdr]

it could be the fuel boiling .you my need to put a return type fuel system on the car.

[RECHRGD]

it could be the fuel boiling .you my need to put a return type fuel system on the car.

Return line has always been in the system.  Not a fuel boiling problem, don't think, it was previously dealt with and no overheating going on at all....

[c00nhunterjoe]

Is it a throttle tip in problem? A little more details surrounding the exact scenario this happens.

[XH29N0G]

What caused you to change your mind about it being an electrical issue to a fuel issue? 

I have what sounds like a similar issue.  The electrical turns off for a split second, sometimes longer (I think related to a connection shaking loose).  Last weekend it started running down the highway.  In my case, my suspicion is because I have a few gauges wired into the circuit and they completely reset. 

Do you have any gauges that are wired this way that could confirm/rule out one option or another.

[firefighter3931]

Bob, it sounds like an intermittent electrical issue to me. Keep an eye on the volt guage and see if the voltage drops significantly when the problem occurs & power drops off. You could also try running a secondary ground strap from the voltage regulator to the engine block. 

If the VR is not getting a solid ground the car can certainly act as you're describing. 

I used the one in the link below. Scuffed the paint on the VR underneath the ground strap tab and attached the other end to the engine block. Verified ground with my test light and multimeter ; solid ground with no voltage drop 


http://www.amazon.com/Heavy-Duty-Braided-Ground-Strap-Caps/dp/B001JT7DHE/ref=pd_sim_sbs_263_4?ie=UTF8&refRID=0ACHEHD0WQND8TG8TZ5B



Ron

[myk]

Only time my car ever acted like that was when it was having electrical issues...

[RECHRGD]

Bob, it sounds like an intermittent electrical issue to me. Keep an eye on the volt guage and see if the voltage drops significantly when the problem occurs & power drops off. You could also try running a secondary ground strap from the voltage regulator to the engine block. 

If the VR is not getting a solid ground the car can certainly act as you're describing. 

I used the one in the link below. Scuffed the paint on the VR underneath the ground strap tab and attached the other end to the engine block. Verified ground with my test light and multimeter ; solid ground with no voltage drop 


Thanks Ron.  I'll double check the grounding the next time I'm at the storage unit.  I've never noticed any gauge variation, but it happens so fast, who knows........

http://www.amazon.com/Heavy-Duty-Braided-Ground-Strap-Caps/dp/B001JT7DHE/ref=pd_sim_sbs_263_4?ie=UTF8&refRID=0ACHEHD0WQND8TG8TZ5B



Ron

[firefighter3931]

Thanks Ron.  I'll double check the grounding the next time I'm at the storage unit.  I've never noticed any gauge variation, but it happens so fast, who knows........

Hey Bob,

Another potential problem area is the engine harness bulkhead connector. Have a look inside there for corrosion and moisture. Make sure the connection is solid and clean the contacts and pack in some di-electric grease.

Pretty sure your problem lies in one of these two areas 



Ron

[68 RT]

Did you check the ignition switch? They do wear out and can cause what you are describing.

[RECHRGD]

Thanks for the added ideas guys.  I'll let you know what I find....

[RECHRGD]

I was able to mess with the car some today at the storage place.  The voltage regulator does not have a dedicated ground terminal or screw on it.  It just grounds via the screws through the yoke into the firewall.  They weren't loose, but not real tight either.  I was able to tighten them a bit, but think Ill make a jumper to the engine ground as Ron suggested.  The bulkhead connector (middle one) was unlatched on one side, so I thought I found the problem.  I checked it for corrosion and grease, it looked fine.  I got it firmly clicked back in place and went for a drive.  Drove about five miles with no problem, then when turning into a parking lot I felt it again.  After sitting parked for about five minutes started up the car and felt it once more going through the lot.  I then drove another five miles to get lunch.  After eating started it up and when going through that lot it dropped out three times in about five seconds.  I then drove another twenty or so miles at speed with no issues. It even idled back into the storage area with no symptoms.  I know it's probably a bad connection somewhere.  But, I'm going to bump up the timing and go for a slow cruise next.  I set the initial timing the same as it was with the old dizzy (12.something) and it was having the same issues then.

[XH29N0G]

The thing that strikes me funny is that it happens when the car has been run, and does not start up right off the bat.  My connection issue did not care if the car was warm or not.  I am a watching you trouble shoot your issue because I may have had a recurrence of my issue, or something like you see.  Only my new gauges went off (new tach and an A/F gauge).  The old gauges did not change because the loss of power was too brief.  So you may not see it unless you have a new gauge. 

[RECHRGD]

I kept my eye on the new voltmeter today, but, of course I was not looking at it when the drop outs occurred.

[skip68]

Bad coil wire?   Does it happen at idle in park?   Maybe check it running with hood up at night for signs of arcing.  Put on a welding glove and with it running go around to all the wires and wiggle them.   Could be something loose and as the motor shakes it's causing this momentary loss of connection.        

[RECHRGD]

Skip, coil and wires are all brand new Firecore units.  No problems there.  In researching on the web, I have found some folks with similar problems had traced them back to not having enough initial timing and blocked air bleeds in the Holley.  My next move will be to bump the timing up a bit and make a positive ground connection on the VR.  If no change then I'll tear down the carb....

[Mebsuta]

Had some low speed stalling, usually when crawling through a parking lot.  Found secondary resistance in coil to be out of spec (low in my case).  Replaced coil and that fixed it.  This is for stock 383 RR.     

[RECHRGD]

Had some low speed stalling, usually when crawling through a parking lot.  Found secondary resistance in coil to be out of spec (low in my case).  Replaced coil and that fixed it.  This is for stock 383 RR.     

Good thought, but the coil is the third one that has been in use and the problem has persisted with all of them.....

[firefighter3931]

Bob, try running a hot wire from the battery post  positive to the coil positive and take it out for a spin. This will eliminate all of the wiring between the ignition switch and coil. If the problem persists you'll know it's not related to the wiring. 

Don't leave the coil permenantly wired hot as this will damage the coil but it's OK to do this for a brief period to diagnose the problem. 


Ron

[RECHRGD]

Ron, it may take more than just a few minutes before the issue rears it's ugly head.  Don't want to burn up the coil.

[firefighter3931]

Bob, the coil won't burn out....it's designed for a 12V power feed, unlike the stock coil it replaced. 

You just don't want to leave the coil sitting there overnight without the engine running being supplied with a constant 12V supply.....and nowhere for the power to go. That will fry it 


Ron

[RECHRGD]

Thanks Ron, I thought about that after I posted.  I suffer from delayed common sense........

[RECHRGD]

OK, today I was able to get back to the car.  I first checked for resistance between the VR yoke and engine ground.  It read zero, so didn't bother with an auxiliary strap for now.  I then disconnected the hot lead from the VR to the coil and ran a jumper directly from the battery plus to the coil plus, as Ron suggested.  I drove it like that for about an hour with only two small blips that did not seem to be as noticeable as previous events.  All in all the car ran great and the ignition system seemed a bit more 'stable', if that makes any sense.  I then returned the wiring back to normal and felt the same old gremlin again.  It didn't do it a lot, but enough to pretty well convince me that this is an electrical issue.  I did bump up the timing a bit, but there was no change.  My VR is one of those OEM looking units that has solid state innards and has been in the car probably 12 or so years.  My voltmeter in the car reads around 14 volts going down the road and the battery seems fine.  Could the VR be having issues?  Maybe I'll throw on my old mechanical one and see if anything changes.  If not, then I'll just start tearing into the wiring.....

[firefighter3931]

The aftermarket electronic VR could certainly be an issue. If you have the old mechanical VR it won't hurt to pop it on there and go for a spin. 


Ron

[RECHRGD]

The aftermarket electronic VR could certainly be an issue. If you have the old mechanical VR it won't hurt to pop it on there and go for a spin. 


Ron

Will do!  The weather forecast is less than favorable, so we'll see how quickly I can give this a try.......

[don duick]

I have same problem with my MSD 6AL when  my voltage drops below 12V. Relay fixed the problem. On another occasion my wire from the alternator fell off and when the battery voltage dropped the problem came back.

[RECHRGD]

Note to self:  if you have a defective part, do not throw it back in your parts box.  Waisted time today trying my old voltage regulator out.  It was bad and I should have known.  NAPA has a new one coming for me.  To be continued.....

[RECHRGD]

OK, went to get the VR from NAPA. It was the stronger unit that was suggested (VR34?) but was not a physical match for mounting as expected.  I decided to get the standard unit (VR32) because of the physical compatibility and just for testing purposes.  Upon further reflection, I decided to research getting another electronic restoration unit like the one that has been in use for over ten years.  Keep in mind that about four or five years ago I upgraded to a high amp alternator (68amp at idle and 103amp at cruising speed).  When finding some tech info on the electronic unit, I discovered that it is not rated for alternators over 65amp.  I realize that the amp rating on any alternator is only what it is capable of, depending on demand.  Over the last several years I may have reached the limit of the electronic unit with the use of an electric fan (no longer installed) and upgraded stereo.  The electronic unit may have been degraded during during those events.  So there lies the problem, do I just get another electronic unit and carry on without the fan or what?

[RECHRGD]

Went ahead and installed the OEM mechanical VR today just to see what would happen.  Started the car up and the voltmeter was at a little under 13 volts, but it slowly crept up to a little above 13.  I checked the voltage at the battery and it read 14.2, so I was good to go.  Keep in mind that with the electronic VR the voltmeter would instantly jump to 13+ volts when started.  I took the car for a good long drive and no dropouts even under the conditions that it would have before.  The goofy thing is, the voltmeter would read higher than before (close to 15 or better) when going down the road above 2000rpm and drop to under 13 at slow speeds or idle.  The electronic unit was always rock steady at 13+ volts.  After driving for over an hour and heading home at 25mph it dropped out a couple of times with the voltmeter reading low.  The battery is probably over five years old.  Seems to me that that big ol alternator should be keeping the volts up even at idle.  Maybe get a new battery and have the alternator checked.  Anything else come to mind guys?