55.2-59 Sudden shutdown-58 Apache

[RostaRob]

I have a perplexing issue that happened to me a dozen times last night while driving my 58 Apache to a local car show. While driving on the freeway and side street it would just stop running. A few times it kicked right back on almost as if someone was pinching on the fuel line and then releasing it. If it didn't come back on by itself I was able to throw it into neutral and turn the ignition and it fired right up. Any thoughts? Fuel filter? Fuel pump is mechanical? Rob.

[mongocanfly]

Does sound like a fuel issue...I had a sb once that starting missing and cutting out....then the fuel pump went out...cheap to try that along with filters...look your fuel lines over for kinks or pinches while your at it..

[MiraclePieCo]

I once had a piece of rust scale in my fuel line that would float randomly around, block off the fuel delivery and stall the car. Since it was so intermittent it was hard to diagnose until it finally worked it's way up to the carburetor inlet screen where I found and removed it.

[dsraven]

just so we don't have to research your build, what do you have for a power plant, fuel delivery system and ignition system? a couple of under hood pics may help.

[RostaRob]

Thank you all for the replies. To answer your questions I just have a stock 350, mechanical fuel pump stock ignition... no pertronix. Still baffled by this. I have drove my truck a lot and never had this happen before...with this or any other vehicle. The other night when I brought it home and got out to open the shop door as I was walking back to it it just died...like the fuel was Jeff st cut off. Never had any issues with it not starting or staying on.

[pugs]

try running one of those generic 4-7 lb electric fuel pump and see what it does. if HEI maybe swap out the modulator and or coil, and if its a points setup try new condenser and or coil

[dsraven]

Hei- check wires on pick up coil. Just give them a tug and they should stretch
Ign module can also get hot and lose its mind. Ensure there is some silicone heat dissipating paste under the module. Might as well swap it out if you're gonna be in there anyway.
Check ign coil for heat discoloration Mark's
Check to ensure there is a ground strap on the coil and a ground wire in the related harness
Check the carbon contact and sealing washer under the coil
Check the dist cap towers

Points
Check contacts, condensor etc. Look for a overheated coil. Check ballast resistor, ign switch, wiring connections. If it shuts down like you turned the key off then look for ign probably. If it shuts down slowly like it ran outta gas do some fuel tests with volume and pressure.
Doesnt seem like fuel to me with a mechanical pump. If the carb ran outta gas it would take some cranking to pump fuel back up to the carb. It wouldn't just start right up.again. seems like ign prob to me..does it do it just when idling? Only when stopped? Have you taken the air filter off and checked to see if the accelerator pump works when it shuts down? No squirt would possibly mean no fuel in carb.

[dsraven]

Sorry. Pick up coil wires should NOT stretch. Missed that one little word.
Pretty common for those wires to fatigue and break inside the insulation.

[_Ogre]

Originally Posted by MiraclePieCo

I once had a piece of rust scale in my fuel line that would float randomly around, block off the fuel delivery and stall the car. Since it was so intermittent it was hard to diagnose until it finally worked it's way up to the carburetor inlet screen where I found and removed it.

this would be my suggestion too. easy to check as the fuel pickup is in the sending unit on top of the tank behind the seat. i'd run the tank low on fuel if possible.
i had a outboard boat motor with inboard tank and similar issue. po had sealed up the fuel filler with lots of rtv, that eventually broke loose and floated around in the tank.

[MiraclePieCo]

Originally Posted by dsraven

Ign module can also get hot and lose its mind. Ensure there is some silicone heat dissipating paste under the module. Might as well swap it out if you're gonna be in there anyway.

Those ignition modules are another thing that can cause hard-to-find intermittent problems. I once changed four of them before realizing that it was a weak coil that was causing them to fail.

[Black_Sheep]

Fuel starvation will usually cause a lean misfire or "stumble" before it quits. If it shuts off like you flipped a switch, it's probably an electrical issue.

[RostaRob]

Thank you all for your input. I swapped out the fuel filter and it did it a few more times. I put fresh gas in and it hasn't done it since. Maybe I got some bad fuel??

[mr48chev]

Could be that you did have some bad gas. I try to only buy gas at newer high volume stations where I can expect them to have clean gas, Those ancient gas stations that have since been converted to mini marts often have tanks that are rusted inside and quite often don't take care to keep their gas clean and water free.

My brother in law used to deliver gas and said that Costco was the most picky about keeping their gas clean with no contamination as they won't even allow the delivery driver to stick the tank like they do at other stations.

Still keep tabs on it as you might still have an electrical problem. I had a lesson in those pickup coil leads a number of years ago while working on one that was doing about the same thing. Because the leads flex when the advance plate moves they ten to break inside the insulation right at the pickup coil. They might make contact most of the time and then loose contact momentarily.

[dsraven]

quote
Fuel starvation will usually cause a lean misfire or "stumble" before it quits. If it shuts off like you flipped a switch, it's probably an electrical issue.

thats why I mentioned earlier to check electrical stuff. the pick up coil and ignition coil (HEI) ground strap missing are common. the power plug into the HEI is another common problem with a poor connection. usually the engine will misfire and then take a few cranks to restart if it runs out of gas. it has to pump gas back up to the carb so a quick restart time usually means an electrical issue when it dies fast and then restarts fast. a quick check would be to pull the air filter and flip the accelerator lever on the carb while looking down the bore (engine off, right when it stalls) if it has a good accell squirt when the throttle is blipped then the prob is likely not a fuel issue because the carb has gas in it. another test could be installation of a clear fuel filter, for testing purposes, that would show fuel in the see through filter. when you get it figured out put the system back to how it was before. (not a fan of the see through filters for ongoing use. seen too many car fires in my time).

[RostaRob]

Thank all of you for your replies and tips. I thought I had it fixed with the new fuel filter and better gas but no. Did it again several times on a recent outing. I forgot to mention that it has started to backfire..LOUD...did this a few times but not every time I drove it. Still fires right back up so I guess I have a few more things to check that all of you suggested. I'll report back when I get this figured out.

[1948ChevyDumpFixer]

sounds electrical for sure. I'd start with the coil, then move to the ignition switch, or the wiring inbetween the switch and the distributor/ points.

[dsraven]

when they cut out and backfire it is usually ignition. it is like turning the key off then on again while driving. it backfires because the carb still feeds fuel in, which collects in the exhaust system as well mixed fuel/air, then when the spark works again that fuel in the exhaust ignites just like in a bomb. if you continue to run it like that there will likely be some exhaust damage or even a blown apart muffler. it happened to me once, muffler on road blown wide open. nice rumble though. the problem was the ignition pick up coil. the wire strands break inside the insulation and the wire still looks fine. give the wires a little tug and if they stretch at all they are broken. while you're in there you might as well change the ignition module. ensure to put the thick silicone grease (usually supplied) under the module because it is a heat dissipation paste to help cool the module. since the dizzy cap will be off you might as well bust the coil out and check for heat marks on the sides. it could be breaking down when it gets hot. while the coil is out ensure the carbon stud under the coil is good and make sure there is a ground strap on the coil that connects to the plug in on the dizzy cap. next flip the cap over and ensure there is no cracks or carbon tracing marks that would indicate a path for spark to follow. when you put it all together ensure the electrical plug to the dizzy is in good shape and has a good snug fit on the electrical connection, no loose or floppy plug ins. check inside the plug to ensure the actual connector is nice and shiny and not corroded. the power wire to the dizzy should be a 8 or 10 ga wire right from the igniton switch and have no splices or taped up spots. check the spark plug wires as well. a resistance check should tell if you have a bad wire. I like to run the engine in a dark space and look for blue light near the wires. next go to the ignition switch and check the plug on that. same as the dizzy plug-tight connection and clean connector contacts. check the switch for signs of heat which would indicate a poor connection inside the switch. at this point you can decide whether you simply want to replace the parts as you go if you haven't found a problem yet. maybe cheaper than exhaust parts or a tow truck.
if you really think it is a fuel issue and suspect poor gas you could try some seafoam motor treatment in the fuel tank. it has fixed several issues with poor performance for me. I use it in my fuel every oil change and it keeps everything nice and clean. it disperses water as well if that is a concern.

[mr48chev]

I'm not sure how far you are driving before it acts up.

Have you by chance changed gas caps lately? I went though three correct part number before I got one that was actually vented.

On a quarter of a tank I could go about four miles before it acted up and acted like it was running out of gas. First time I walked almost a mile to a gas station and back and put a gallon of gas in it and off I went. Second time It quit in the same spot but I had the gas jug full and when I loosened the cap air rushed in the tank and you could hear the top or bottom pop back out after the vacuum was released.

You could check that by firing it up and letting it run in the driveway until it quits and open the gas cap and see if you hear a rush of air and maybe a pop as the the tank pops back out after the vacuum is released. No rush of air = that isn't the issue and you have pretty eliminated that aspect.

On a V8 gm distributor with points I had a loose screw on the hold down for the condenser cause the rig to act up once. We lost the high school drags that night over that one.

[dsraven]

I am assuming you have HEI? if points there are other things to check. a pic of the under hood would be good, maybe we spot something.
if points you could easily swap it over to HEI.

points type ignition
https://www.liveabout.com/point-type...systems-262557

[1project2many]

Yes, please let us know if you're using points or an electronic ignition.

Some of the older folks here might have experienced a broken resistor in days gone by. The engine will run fine while the ends of the wire touch but once they heat up the engine begins stumbling, stalling, or running poorly. The original GM wiring bypassed the resistor during crank so the vehicle would always try to fire during cranking.

Changing to HEI from points should include rewiring the truck or using a relay to deliver current to the HEI through a 10Ga wire. Although original HEI at saturation is limited to a maximum current of about 5A, it can have a very high instantaneous current draw while the engine is running. Using the original 18Ga wiring to power the HEI can lead to insufficient voltage and strange problems.

A simple light on the power wire to the coil can be a good diagnostic tool. The light can be placed on the dash and the driver can observe it while in the truck. If it turns off you are losing power to the coil. Better yet, an LED connected to the coil negative wire and ground will turn off each time the coil is charging and turn on when the coil is saturated. If the problem is in the ignition primary you will likely find it this way. It is amazing how good the human eye and brain are at picking out faults in a pattern such as a blinking light.

[Ironworking]

mr48chev is spot on. I have seen the advance open and cause a short to the points. When the advance dis-engaged; no short. Only happened when engaged. Also, have seen the condenser cause the same problem. A bad coil can do this as well. If it is the coil, it will be overly hot when the vehicle dies. Touch it very carefully to check for heat. Overly hot, it needs replaced.

[RostaRob]

Sorry it's taken me so long to report back. I appreciate all of your input. So I replaced the coil and condenser and drove out out 10 miles with no shutdown. Turned around to head home and about halfway back it did it again. I am using points and not HEI. Still looking for the answer to this. Strange that it will shut down and fire right back up, I've gotten so good at it now people driving behind me may not even notice.

Chevydumpfixer/Raven-I'm going to check the ignition switch and wiring next.
Mr48Chev-I haven't changed gaps..or really anything..just started doing this out of the blue.

[mr48chev]

Are there any male/female slide connections in the ignition circuit between the switch and the coil?

I know you don't have an HEI but on my 71 GMC I had a female slide connecting the ignition lead to the distributor that loved to come slightly loose at inopportune times. Usually when I was on my way to work at 03:00 and it was raining. I just had to take it lose and plug it back in or sometimes it started right back up and away I went. I finally bought the correct connector and never had another problem.

Condenser good and tight in the holder? Holder tight in the distributor? We lost the high school drags on night because I didn't get the screw tight on the condenser when I changed points and condenser. That thing spit and coughed all he way down the quarter.

Any other connections that might be suspect including any crimp on a wire connector? Think something that works great until the truck starts shaking around a bit going down the road. Especially if it dies when you have just passed over a section of road that is a little rougher than the rest of it.

I'm thinking electrical now but any possibility that there might be something floating around in the tank that is blocking the fuel flow at times then floats away when the engine shuts off We pulled the tank off one one time that had a sheet of paper like typing paper in the tank. Probably someone tried to use it as a funnel to put gas in at one time and it went down the filler. The paper would cover the pickup tube and kill the engine and then float around in the tank for a while before it did it again.
I've also seen one with a shop rag in the tank.