Intermittent starting problem

[dzbowtie]

Hello all,

I've been having an intermittent starting problem with my truck. When it happens, I turn the key on, my red brake light turns on, but nothing happens (like a dead battery). However, battery is good and it doesn't always happen. The only relays I have is for the headlights.
The curious thing is I can attach jumper cables, or battery charger and it'll fire right up and never give me a problem. I dont even have to allow time to charge. Its almost like I just need a little extra power for the starting. Alternator works also.
Could this be a starter issue? I'm just lost as to why this happens sometimes and not consistently. I appreciate any help guys. I hate to carry a portable booster lol.
This is a 70 c10 with 350/th350.

[garyd1961]

Make sure all your cable connections are tight and clean including the starter and all grounds. Make sure you have a good ground from the engine to frame.

[Steeveedee]

Bring a test light with you from now on. The next time it happens, check the fat purple wire on the ignition switch. If it doesn't get "hot" in the start position, the contacts are worn. Is it the original ignition switch?

Also, it is a fairly common problem that the starter gets heat soaked, and the truck won't start until it cools off. I had the same problem with my '69 Camaro, but it usually happened after I had been driving it at speed, like 100+ MPH, for awhile. Since you probably had the hood up, the engine cooled off by the time the jumpers were hooked up, so it started right up. My truck has had a hot start problem for decades. I put in a reduction gear permanent magnet mini starter, a ground cable straight to the starter, and added more ground straps. It still gives me a problem, but about 3% of what it used to be like.

[dzbowtie]

The ignition switch has been replaced 4-5 yrs back due to not having keys when I bought the truck. The starter I am using right now is a jegs brand mini starter, also used 4-5 yrs. I have a multi meter in the truck and will try it next time it won't start. The switch is a LMC brand and may not have been the best choice. I'll check the starter connections also

[spoon3210]

your starter solenoid might be the culprit. Hold the key in the start position and have someone hit the starter with a hammer. if it starts you need a new solenoid.

[Steeveedee]

Originally Posted by dzbowtie

The ignition switch has been replaced 4-5 yrs back due to not having keys when I bought the truck. The starter I am using right now is a jegs brand mini starter, also used 4-5 yrs. I have a multi meter in the truck and will try it next time it won't start. The switch is a LMC brand and may not have been the best choice. I'll check the starter connections also

Based on this, I'd say that it is still heat soak. Has this been a problem the entire time you have owned the truck? What I'm driving at is, when did you notice the problem, what have you noticed made it better (or not) when replacing parts, that kind of thing. I'd be interested in getting data such that an actual solution was found, and could be made known here. I did all the stuff as posted above and still have an occasional problem with starting my truck hot. If we could get enough data, we could find a solution and make the hot start problem go away. Having to sit while the problem resolves itself is not an acceptable solution, in my book. It isn't acceptable to me that I pull into a gas station, while towing my camping trailer, and have to wait for it to cool off enough to get it to start again, when the other guys with their newer diesel-powered rigs pump their tanks full, and can fire up and drive off, except that they have to wait for me!

[dzbowtie]

I questioned the heat issue myself, having dealt with this in a camaro I used to have. However, this doesn't happen only when hot, there's almost no rhyme or reason as to when she'll decide not to start. Like mentioned previously, I did find it awful strange that merely putting jump/charger to it will fire it right up. I'm thinking the issue is limited to the ignition, wire to the starter, and starter/solenoid itself.

[Steeveedee]

OK, maybe a dead spot or a dirty contact on the starter armature. That would explain intermittent. But when it happens, do you even hear the solenoid click?

[davepl]

It's NOT heat soak, you DON'T need a heat shield, you DON'T need a new starter, and you DON'T need a Ford solenoid. All of those are reasonable suggestions that might help or work around the problem, but they're not the problem.

The problem is the purple wire.

From your ignition switch leads a purple wire. It runs through the neutral safety switch, then out to the starter solenoid.

Somewhere in that circuit you have a bad or weak connection. Sometimes people try to install a kill switch in this circuit (bad idea). Sometimes an ammeter pickup has been spliced in there. Whatever the reason, it's a bad circuit. Could be in the neutral safety or ignition switch themselves, but I've never seen either as the cause.

Proof? The Ford solenoid approach usually works because all it does is replace the purple wire with a bunch of other heavy gauge wires that use the weak purple wire to trigger a stronger solenoid signal. If there were a genuine starter, solenoid, or heat problem, the Ford solenoid to kickstart the GM solenoid would do nothing.

If you can short the starter terminal to the main lug with a screwdriver and it cranks, you know I'm right :-) Just be careful, don't weld anything with the screwdriver! All I'm saying in this step is "make your own purple wire circuit and see if that starts the starter to prove that it's the purple wire", if that makes any sense.

All of the above is predicated on one assumption - that when you turn the key, NO sound comes from the starter. If it's clicking or clunking, I'm 100% wrong. But if it's silent...

[El Dorado Jim]

Originally Posted by firedemon

I had a 74 monte carlo that I put headers on it left me stranded all over the place till it cooled off . I did all the same stuff added grounds heat shields changed starters . an old greybeard told me put a ford starter solenoid on the fender . he also had me hammer flat a piece of copper pipe and drill two holes for the battery and start posts on the starter . couldn't believe I never had that problem again loved that car

where did the flattened copper pipe connect to?

[prodjay10]

I know you said your battery is good, but how old is it and how did you test it?

I had this exact same problem. It had me chasing my tail because the battery had good voltage but I went and replaced it anyway and I don't have this issue anymore.

Edit: nevermind, my starter would click. Yours apparently doesn't.

[dzbowtie]

I suppose I failed to mention this in my previous posts. when the key is turned to the start position, there is NO clicking or noise of any kind (just like a dead battery). however, all lights, gauges, etc work. red in-gauge brake light comes on when key is start position.

the battery is less than a year old. my old battery tested good but had several years on it so I replaced it thinking somehow it may have been the issue.

also should be noted and I never thought of it before, but sometimes I can turn the key to the start position, there is a half second or so delay before the engine begins to turn over. when this happens, it is generally followed by the issue above where nothing happens.

I really appreciate all the info guys.

[hamjet]

You might as well check the small wire going from the + battery post that goes to the passenger fender stand off block. maybe when you're jumping the battery you're moving the wire a little causing it to make the circuit.. can't hurt..

[davepl]

Sometime when it doesn't start like that jumper the solenoid post to the battery post with a heavy gauge wire and see if that causes it to crank. If so, there you go.

[VetteVet]

Originally Posted by El Dorado Jim

where did the flattened copper pipe connect to?

The copper pipe connects the S terminal with the large cable on the gm solenoid when the Ford solenoid kicks in via the purple wire the S terminal gets power the same time as the GM solenoid and it is getting the same voltage as the starter windings.

Here is a diagram. You can buy a small metal jumper plate that takes the place of the copper pipe.

The diagram uses a common jumper wire and the plate is shown below.






Here is the plate jumper.




Here is some good reading by yours truly.

http://67-72chevytrucks.com/vboard/s...d.php?t=655903

[davepl]

Ah, I see. I'd earlier said the Ford solenoid just took the place of the purple wire, but it appears from the diagram that it unions the starter and solenoid together and then engages them as a unit using the Ford solenoid. My bad.

Still preferably to me to find the problem in the crank circuit wire, but this'll fix it.

[Steeveedee]

Originally Posted by davepl

Ah, I see. I'd earlier said the Ford solenoid just took the place of the purple wire, but it appears from the diagram that it unions the starter and solenoid together and then engages them as a unit using the Ford solenoid. My bad.

Still preferably to me to find the problem in the crank circuit wire, but this'll fix it.

The fix you mentioned earlier for the start circuit purple wire is a good one. In my case, it cranks hard when hot. If I open the hood, it cools enough in about 10 minutes and will then start.

[weq92f]

If anybody does the screw-driver trick/test, please use caution:

From below:

lift and support the vehicle with multiple failure tolerance ( jack stands, a jack and wheels under there with you

Use wheel chucks.

make sure the transmission is OUT of gear, in Park or otherwise secured against the starter causing the vehicle to move off the jack stands

From above:

Same thing about the tranny being OUT of gear.

Stand to the side

-klb

[garyd1961]

What size battery cables are you using? I went to 2 gauge cables on my truck. I'M not sure what came from the factory but most have been changed over the years and my truck had 4 gauge cables when I got it.

[davepl]

Originally Posted by firedemon

yes exactly and the reason it works is it only takes 3 to 5 amps from the purple wire to engage the ford solenoid instead of the 50 to 60 the gm solenoid takes . and because the gm is now getting all the amps it can ask for on the s terminal it will usually turn over way easier . its also way more gentile on a nearly 50 year old key switch and neutral safety and bulkhead connector kind of like the headlight relay mod way less chance of a fire or burned wires . however don't do this for a modern hi torque mini starter the starter will actually generate a small amount of electricity winding down (when you let go of the key ) and back feed from the battery terminal to the s terminal through the solid lug and keep the starter engaged . mini starters have the same current draw on the solenoid 50 to 60 amps so most of the time mini starters are a waste of money unless your running some serious compression . but if you are running high comp a ford solenoid is still a good idea just wired differently .

It works, no doubt, but so do the 50 year old purple wires in my Camaro, my 2 Pontiacs, and my truck. So long as they're not damaged, they'll start the car properly no matter the temperature for 100 years, I'm sure.

My only point is why not fix the truck rather than patch it up? You're going to be relying on the purple wire anyway to fire off the Ford solenoid, and while it certainly will take less amps than the hot Chevy solenoid, you're still going to be relying on a circuit that has undiagnosed failure in it somewhere.

Now if the Ford setup is inherently better than the Chevy, you could argue for the conversion so long as originality isn't a concern. I can see the argument for not having the solenoid down by the hot exhaust, etc.

[KQQL IT]

I also approve of the Ford solenoid. For purely not having battery voltage at the starter.

And I've also learned the Chevy mini starters do not like the jumper wire from battery to start terminal, it will hang the bendix in the flywheel a 1/2 second longer than it should.

It shouldn't work, but my 68 and 73 both have a ford solenoid and a jumper wire down to the start solenoid. Weird but works.

[HO455]

Originally Posted by davepl

It works, no doubt, but so do the 50 year old purple wires in my Camaro, my 2 Pontiacs, and my truck. So long as they're not damaged, they'll start the car properly no matter the temperature for 100 years, I'm sure.

My only point is why not fix the truck rather than patch it up? You're going to be relying on the purple wire anyway to fire off the Ford solenoid, and while it certainly will take less amps than the hot Chevy solenoid, you're still going to be relying on a circuit that has undiagnosed failure in it somewhere.

Now if the Ford setup is inherently better than the Chevy, you could argue for the conversion so long as originality isn't a concern. I can see the argument for not having the solenoid down by the hot exhaust, etc.

Back in time before mini starters I dealt with this issue on my daily driver GTO (the only car I owned) With a set of headers and the 10:1 compression that Poncho would eat a starter solenoid every couple of months in the summer. I couldn't tell you how many times I had to push it out of a gas station. Toss in weekend drag races and it got to be a real problem. (Nothing worse than losing because your car won't start) I tried buying a new GM starter ($180 bucks in 1983. Big money for a sailor) but it only helped a while. I rewired the neutral safety circuit (purple wires) with 10 guage high temp stove wire and connectors. I replaced the neutral switch and bypassed the bulkhead connector. It all only helped some. I ended up putting a push button override in the circuit and only then was I able to start the engine every time I wanted to. The Ford solenoid is just a variation of that idea.

[dzbowtie]

So guys, update on the starting problem. Reading another post by VetteVet, I ran jumpers from power wire/purple wire on starter and solenoid. With the use of a push button, the starter turned over. I then moved to the cab. The power wire in the back of the switch was receiving 12volts per the multimeter. Then I jumped the red power with purple wire on back of switch, again starter turned over. So, this leaves the switch itself not making the connection all the time as it should. Hopefully a replacement will fix this problem...

[VetteVet]

Originally Posted by dzbowtie

So guys, update on the starting problem. Reading another post by VetteVet, I ran jumpers from power wire/purple wire on starter and solenoid. With the use of a push button, the starter turned over. I then moved to the cab. The power wire in the back of the switch was receiving 12volts per the multimeter. Then I jumped the red power with purple wire on back of switch, again starter turned over. So, this leaves the switch itself not making the connection all the time as it should. Hopefully a replacement will fix this problem...

Well maybe:
If you jumped the ignition switch when it was in an intermittent phase and not working and then it worked when you jumped the switch, I'd agree. I'm thinking that's the case. Otherwise there's the possibility that it might be the neutral start switch not closed by the position of the gear selector, or the connection between the purple wires in the firewall block behind the fuse block.

It might be worthwhile to wait until the no start happens again and then jump to the ignition side of the neutral start switch. Don't bump the shift lever and if the starter turns it confirms that the key switch is bad. If not jiggle the shift lever and see if the starter turns then.

It is quite common for the NSS to get out of adjustment or wear down where it won't close the circuit between the purple wires.

[dzbowtie]

I will wait until this happens again, then test as you described. Thank you all for the help