Random No Start?
 

Been having an issue for a few years now. It happens on and off.

I have a 1969 C20 with a 350 5.7l. I'm having an issue with the truck not starting somewhat randomly. Always seems to happen after I've been driving a bit and I'll stop at a store and when I come back it doesn't start. Doesn't happen after sitting over night or after working a full shift, just when I come back to it 20 mins later.

When it doesn't start, there is nothing. Lights come on, music, voltage is good. It does nothing. No clicking no nothing. I have to jump start it to get it to start and then it will start after that again just fine until another random day. Troubleshooting has been hard because I can't get it to recreate the issue at home.

I have replaced the battery, starter, alternator, negative battery cable and clamp, distributor, plugs, wires, ignition switch, neutral safety switch. I've tested and cleaned grounds and wiggled wires...idk what else to do other than replace the starter and battery again.


Any ideas? Thank you!

Re: Random No Start?
 

Carry a test light with you so the next time it happens you can check if there's voltage on the solenoid when you turn the key. You might want to rehearse this so you know you can put the test light in a visible location from the cab. Or you could temporarily wire up a light into the cab.

EDIT: Perhaps replace the positive cable also.

Re: Random No Start?
 

Are you running the stock external voltage regulator for the alternator?

Re: Random No Start?
 

Good idea on the tester! I'll throw one in the truck today. I have replaced the voltage regulator! Forgot to add that to the list.

Re: Random No Start?
 

Are running headers or stock exhaust manifolds?

Re: Random No Start?
 

Aftermarket headers

Re: Random No Start?
 

Does the truck have headers? If not how close is the down pipe to the starter?
Have you cleaned the connectors on the firewall?
When you use the test light be sure to check it on the battery before to get an idea how bright full voltage is in the ambient light. Then hopefully you can tell if the voltage has dropped or not.
Another test would be to put a clamp-on DC amp meter on the purple solenoid wire an see what it is drawing. It should have an initial surge of 40-50 amps then dropping to 12-14 amps. If it stays high the solenoid plunger is not moving.
I battled this kind of problem for years on my GTO. Basically what happens is the wiring and starter gets heat soaked causing the resistance in the circuit to rise until the voltage at the solenoid is insufficient to operate the plunger. This is why some folks install a Ford style solenoid to provide power to the solenoid.

However I personally don't feel that is necessary on our trucks. The larger engine compartment and the design of the SBC heads help keep the starter cool enough.
Unlike my perfect heat storm GTO. :lol:
Good luck and keep us posted.

Re: Random No Start?
 

I had to a install a heat shield and thermal wrap on my starter/solenoid eliminate that issue. Also, if you are running a HEI, your description kinda fits symptom of the internal module going bad.

Re: Random No Start?
 

I resorted to a Ford solenoid on my 70 ss396 chevelle after trying everything. It was the ultimate cure.
Strangely my 70 ss with an LS6 and my buddies L78 69 camaro never had a problem starting.

Re: Random No Start?
 

This and the starter being baked by the headers are all good points.

Re: Random No Start?
 

Do you have emergency repair terminals on your battery like this where a metal plate pinches the cable for a connection? This caused my random no starts.
http://67-72chevytrucks.com/vboard/a...1&d=1471392012

Re: Random No Start?
 

I love it when people Poo Poo this fix trying to tell you that wasn't the cure. I too tried everything, smaller high torq starter, heat shield, on and on. Did the Ford solenoid trick and boom problem gone.

Bypassed the solenoid just to see ... problem came back.

Re: Random No Start?
 

I have done many Ford solenoid magic tricks over the years for friends never had a call to say "it's doing it again" A relay, if you need room, or don't like Ford parts on your truck will do the same magic.

Here's diagrams for both: http://chevellestuff.net/tech/ford_solenoid.htm

Re: Random No Start?
 

I've had a Type F solenoid on my '71 GMC Jimmy for years. No more cooked solenoids. The Heddman hedders are so tight that you have to pull the passenger side one to get at the starter/solenoid.

Re: Random No Start?
 

This has been a topic of discussion for some 60 years as to whether the ford solenoid fixes the no start or hard start problem or not.
GM vehicles from the factory did not begin having a hot start issue until thousands of miles, typically, were accumulated. Back in the 60s and 70s hard starts were more prevalent on big block vehicles but small blocks were also affected. An old local starter/alternator repairman would beef up a starter to help and suggested both new battery cables and clean grounds. The beefed up starter most often cured the problem. The cheap parts store replacements did nothing.
I am no electrician so I fail to understand how adding the extra ford solenoid cures the problem. There is still a positive battery cable running down to the starter subject to the same heat soak as the OE cable and the power is still going through the stock solenoid which still heats up with the starter.
I won't deny some of you may benefit from the ford solenoid addition and I don't believe I have ever heard of hot start problems on ford vehicles.
I just cannot grasp how adding a 2nd solenoid in line to a GM system helps.
Help me understand.

Re: Random No Start?
 

The Ford solenoid is mounted away from the heat and bypasses the original GM solenoid so it's not going through it. It's not inline.

Re: Random No Start?
 

This explains it better than I could

Modified wiring with the remote Ford solenoid
If you are running an GM HEI distributor, don't worry about wiring to "I" terminals.

The wire that goes to the "S" terminal on the GM solenoid (closest to the block on GM engines having the starter on the passenger side of the engine) is removed and wired to the "S" terminal on the Ford solenoid.

The wire that goes to the "I" terminal on the GM solenoid (farthest from the block) is removed and wired to the "I" terminal on the Ford solenoid. The "I" terminal on the GM solenoid will not be used. When you purchase the Ford solenoid, make sure that it has the "I" terminal needed for non-HEI/points-type distributors.

The positive battery cable is removed from the GM solenoid and is put on one of the large terminals on the Ford solenoid.

Another cable is run from the other large terminal on the Ford solenoid to the large terminal on the GM solenoid where the hot battery cable was just removed.

Also on the large terminal on the GM solenoid, you have to add a heavy gauge (10 gauge) wire to the "S" terminal on the GM solenoid, or use a shunt. This can be bought or easily made.


Solenoid shunt for GM starter solenoid
This is what happens when you hit the start switch:

The electricity from the starter switch only has to energize the Ford solenoid (that is mounted in a relatively cool location).

The "battery" cable to the GM solenoid goes hot. The Ford "I" terminal also goes hot, providing non-ballast/full battery voltage to the coil.

The GM solenoid now gets a solid "high capacity" current supply and works the plunger and contacts. The internal contacts send voltage to the starter motor.

This set-up DOES NOT make the GM solenoid any cooler. It just gives it a better current supply. Anything that can be done to shield the starter from the header heat would be beneficial.

Re: Random No Start?
 

I've did it did fix it on multiple vehicles and it worked on all of them. I put a jumper plate across the positive and the start on the GM starter. The purple wire now goes to the f solenoid. But now I just use the GM modern mini starter and haven't had a problem since.

Re: Random No Start?
 

My 49 Chevy pickup uses a mini starter 350 GM with block hugger headers, no problems to date in 20 plus years.

My 40 Ford Coupe also uses a mini starter 350 GM with fender well headers and it developed the hot start issue right away.

The main difference is engine bay area/heat....I cured the 40 with a Ford solenoid.

Re: Random No Start?
 

My K20 has a big block with long tube headers. The mini starter has a lot of air space compared to the old heavy high torque. Maybe it stays cooler because of it.

Re: Random No Start?
 

Here is an excellent thread on this subject.

http://67-72chevytrucks.com/vboard/s...d.php?t=574411

Re: Random No Start?
 

I have heard all the debates over the years as to if this fix is right or wrong the only answer I have is it works!

Example: My 40 Ford coupe I built as a frame off, every thing was new ...battery cables, wiring was a quality kit, grounds galore, battery to engine, engine to frame, frame/engine to body, dash etc.

I used a high torque mini starter with fender well headers so the heat is theoretically away from the starter, but these old Fords are known for the hot engine compartments from lack of air flow. I had heat soak issues develop within a week of getting this car on the road.

I used the Ford solenoid trick and it has started every time even on 100 degree days and running the A/C

Just my experience

Re: Random No Start?
 

I cured the problem on my GTO not by using a solenoid or relay but, by replacing the factory solenoid wiring with 8 guage stove wires to a push button starter switch under the dash. It does the same thing by ensuring that the solenoid voltage doesn't drop below 10.5 volts. This set up is just under 5 feet of wire with 4 connections.
Compare that to the 12 guage factory wiring starting at the connection on the core support, next to the horn, through the firewall connector, to the fuse box connections, to the ignition switch, to the neutral safety switch, back through the firewall connector and down to the solenoid.
Every one of those components have resistance and that resistance goes up when the temperature goes up. More heat, more resistance and less voltage at the solenoid.
Every connection has to be perfect or a voltage drop will occur. Some connections are static like the connector plug at the firewall. Others are moving like the ignition switch, the neutral safety switch. (See the link for just how small the contacts inside the ignition switch are.) Which leads us to your statement that GM vehicles didn't have this have this problem until the vehicle had thousands of miles on it. Which is true but, GM designed vehicles to make money and getting through the warranty period was the minimum any part had to meet. Once it was sold it was the dealership's problem. And if GM built the perfect vehicle who would ever need to buy a second one? :lol:
I hope this helps you understand. Basically you bypass the factory solenoid circuit to get the starter to operate in extreme conditions.

https://67-72chevytrucks.com/vboard/....php?p=8906149

Re: Random No Start?
 

The problem is as the heat goes up the GM solenoid gets hot and requires more current to activate it. The small purple wire coming from the ignition switch can not carry the required current. Using the Ford solenoid and a larger gage wire for the GM solenoid fixes that current issue. You could change the purple wire to a larger one but the ignition switch is not made to carry much current and would likely fail.

Re: Random No Start?
 

Wow!

Thanks everyone for all the suggestions! I've researched this issue for awhile now and after replacing practically everything. This heat issue with the starter solenoid makes the most sense. I've ordered a solenoid and I'll throw it on tomorrow and then hope it's fixed. I can't recreate it on purpose, so I'll just have to wait and see!

Thanks again for taking the time to write out some solutions. I'll post an update when I feel confident that it's fixed!