Random No Start?

[DeadMansOhms]

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!

[body bolt]

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.

[Lethal Tendencies]

Originally Posted by DeadMansOhms

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!

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

[DeadMansOhms]

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.

[Lethal Tendencies]

Are running headers or stock exhaust manifolds?

[DeadMansOhms]

Aftermarket headers

[HO455]

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.
Good luck and keep us posted.

[geezer#99]

Originally Posted by HO455

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.

Good luck and keep us posted.

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.

[CG]

Originally Posted by geezer#99

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.

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.

[D.PASSMORE]

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.

[body bolt]

Originally Posted by D.PASSMORE

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

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

[dmjlambert]

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.

[Sheepdip]

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.

[Ol Blue K20]

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.

[Sheepdip]

Originally Posted by Ol Blue K20

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.

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.

[Ol Blue K20]

Originally Posted by Sheepdip

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.

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.

[VetteVet]

Here is an excellent thread on this subject.

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

[Sheepdip]

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

[Ol Blue K20]

Originally Posted by Sheepdip

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

I agree 100 percent.....

[franken]

There are believers in the idea that hundreds of millions of GM vehicles used the same starters and wiring and they worked, which they did, and there are those who don't.
Fix the underlying issue and the solenoid will work. Typically, the underlying issue is bad wiring and/or poor connections, or worn out (resistive) switches in the circuit.
Of course, a bandaid solution is easier than troubleshooting so it's popular.
Yes, it's a bit of a long path from the battery to the solenoid, but I've jumped solenoids with a 20G or smaller jumper, so it doesn't draw that much.

Measure voltage to the block and to the battery from the S-terminal.

[schovil69]

Just dealt with a similar issue on my Dad's '70. His truck's issue was a wiring problem.
Turned out to be the ignition wire between the ignition and the coil. A wire loom mounted near the top of the firewall carries it across the engine bay. The wire had broke in two inside the wire loom. The problem did not recur after splicing the wire back together.