The Stovebolt Site Forums The Parking Lot Big Bolts Strange starting/electrical problem

It seems I can't go too long with out some sort of drama out of my old truck. Its been running pretty good lately, Seems most of my previous issues, if you care to dig them up, were usually related to the coil. New one in and its all good. I played with advancing the timing quite a bit, trying to hear some pinging, but never did, I stopped advancing when it started getting hard to start, then backed off a bit. After that it started well and still ran good. Well at least till yesterday, it wouldn't start, acted like a down battery. Then I noticed some smoke coming out of the dash. (No worries I'm getting used to it now) This time was different though, I couldn't find any melting wires under the dash. "Odd" I thought. Kept trying and something was definitely getting hot under there but I could never find a hot wire, I felt them all too. Then I felt the manual throttle cable, it was REAL hot. Then I felt the choke cable, it was REAL hot too. Since it was getting dark I also noticed they only got hot while I was cranking the engine with the foot pedal, at the same time the dash lights and gauges would all come on. So, I'm at a real loss here, it seems my manual non electric carb cables are carrying electrical current, but I can't find where. (There are no chaffed wires). I am thinking that some how the starter or pushbutton is grounding the engine via those cables? But why? Any help suggestions? I'd bet that once the truck is started it would run fine. All the lights and gauges work as expected except when cranking the engine. Thanks for any tips on where to start looking.

Compression is pretty even with in 10 pSI of each other all around 120.

***EDIT*** Thanks for reading my novel

Make sure your ground strap from the frame to the starter is good and clean at the ends where it connects. Take the bolts off and clean them. Clean the flat surfaces of the starter and the frame where the straps attach. It sure sounds like your starter is trying to find ground and getting it through the throttle and choke cables, at least partially. The dragging starter is another sign of a poor circuit.

I would also clean the battery cable connector where it mounts to the starter, and check both connectors on the posts of the battery.

bald eagle has given good ideas if those don't provide the solution try over in the electrical bay with your post as well

That seems to confirm my suspicions. I looked all over for the ground strap but couldn't see it. Where on the starter is it? (It should be pretty obvious right?) Maybe the better question is where should it be?

I'm "less gooder" (as my 7-year old daughter would say) with the '50s stuff than the '40s stuff, but . . .

The starter, me thinks, grounds through its case and on through the engine.

The ground straps you need are: Battery negative to frame (on the '40s trucks, this is a braided, ribbon-style cable, going from the Bat. negative post to a bolt on the transmission corner), and . . .

Engine to Frame. This assumes the tranny-engine combo is cleanly isolated from the frame, which is unlikely in any real-life scenario (your carb. cables are a good example of one path the electrons can take to get from the starter, through the engine, carb, cables, dash, frame, for example). BUT, common wisdom is that a good-sized, dedicated engine ground strap to the frame is necessary. Don't think it matters where, as long as the connections are good and clean. Be sure to wire brush the paint away from the frame at the connecting point.

The little electrons will take the path of least resistance, and bigger cable means less resistance. If you have this, maybe it won't ground through the carb cables!!!

Hope I'm right, and that this helps!

-Michael

So we are all of one mind the engine is trying to ground itself via the throttle and chocke cable?

I suppose the ground 'official' ground strap if there ever was one could suddenly loose contact. Does this explain the dash lights illuminating when the starter is engaged? They are grounded via the metal dash, the same as those cables.

Would this mean the starter is shorting out through the throttle and choke cables? Sending positive voltage through the metal dash?

it could be sending the charge thru the dash and lights trying to find a ground. check towards rear of engine and transmission,bell housing area. once got myself in heck of a pickle removing an engine and transmission by myself and found out after I had my hand caught between engine and frame I had forgotten to remove the ground strap.

if it's a ground problem, you have a good ground to the cab [probably where the batt is grounded], but you may not have a good ground to the engine, so the choke/throttle cables [grounded each end to the cab and engine] are carrying the ground for the engine [why they get hot is the starter pulls mega current] .... if this is the case, you would fix it by adding a ground cable from the same place the neg batt terminal goes to a starter mount bolt

if that's not the problem, you have an internal short in the starter - either way, putting enough juice thru those cables to heat them up seems a poor idea, considering they attach to the carburator, so I'd figure out the problem before cranking it anymore!!

Bill

The starter motor draws a tremendous amount of current, more than all the other electricals combined. For that reason it needs an excellent ground connection to work as designed. On my '48 there is a braided metal strap that is bolted to the frame and to the bottom mounting bolt of the starter motor.

In the factory assembly manual there's an entire page dedicated to grounds. Factory builds had a braided strap that was bolted to the frame and to the bellhousing on the passenger side. I'd be very surprised if yours didn't have one from the factory. If it doesn't have one now, go to the parts store (after measuring how long it needs to be) and get one and install it.

It doesn't matter where you put it so long as it connects the frame to the engine (because the battery's ground is connected to the frame.) It needs to be a braided cable because, as your throttle cable and choke cable have pointed out, a lot of current will be going through that cable. The average battery has around 400 to 500 cranking amps. (I use an 800 CCA Optima battery in my truck.) The biggest fuse a vehicle will usually have is 30 amps. So the battery's ability to push current is more than 10 times that of the biggest circuit in your truck. Wires can't handle that much current. That's why you use a braided cable. Connecting it directly to the starter is simply convenient. There's a bolt right there. It grounds the engine as well, and it's close to the battery.

So, I'll add a ground cable from the starter mounting bolt to the frame.

Could this lack of a ground cause any sort of driveability problems? Perhaps this is why some days it seemingly runs better than others.

Oh how I wish this truck gave me trouble codes.

Many times if you think it is ground related use a pair of jumper cables to "add" grounds to different components to see if that changes anything. I usually hook to battery ground first, then try engine, body, frame, etc. You will usually find the issue pretty quickly.

Ryan

Bad grounds can cause all sorts of problems, from flickering lights to a coughing engine. Remember, it takes electricity to run the engine. Anything less than 12 volts can make an engine sluggish or tempermental or erratic. The lower the voltage, the worse the problem. Humid weather can make it perform better, because the moisture helps ground things. Hot dry weather can make it worse, because the grounds are poor.

For an electrical circuit to work as designed there needs to be good connections at every connecting point and no additional resistance added to the system. Poor grounds add resistance to the circuit, which lowers the voltage available to components that need it.

Here's my theory then...

The factory engine to body ground does not exist. So I don't have a good ground for the engine, causing this new starting problem. Since this isn't a new problem, the ground has been gone forever to my knowledge, this could be why over the course of my owning it runs sporadically poor. If the engine is not grounded the spark plugs won't give off a very strong spark leading to poor running. Add a good ground, the starter will function better, the spark will be better so the engine should run better. Right? Perfect sense to me!

The wisdom behind attaching the short (length) ground strap from the negative battery terminal to the bolt on the transmission is that the starter motor frame is the ground for the starter motor. The starter motor frame is bolted to the engine, the engine is bolted to the transmission, and voila the transmission is grounded to the negative battery terminal via the braided ground strap. Shortest path = least loss due to resistance and heat.

Grounding connections between the cab, fenders, other body parts and the frame will help the lights and peripheral stuff to have a good ground. The starter motor ALWAYS needs a low resistance (beefy connection, shortest distance) ground.

I'll report back once the strap is on, I used the suggestion above to substitute jumper cables for the ground.
The engine fired right up. It seemed to be running well too.

Seems that the electrical problem has been temporarily cured. Now back to a hesitation/bog then backfire through the carb coming off idle speed.

GRRR.

the hesitation and bog may be your vacuum advance on the distributor isn't working properly but others may have better idea

That part appears to be in working order. It rotates the distributor when accelerating. I think the idle screw may be set too lean. Then I might try setting the valves, I've never done that so they could be off. Usually when its acting this way performance overall is down. If its not doing this performance is up.

check if the distributor is worn so it's not tight in it's mount and 'wobbles' when running - if the grease cup was neglected for years that could cause the erratic nature of your symptoms .... another part of the bad ground situation, might try just adding a ground wire from the dist body to one of the cover screws

Bill

Played with it a bit this morning, the time was a little retarded, I richened the idle mixture some too. I think most of the backfire is gone out of it. Thanks again everybody.