Intermittent Starting Problem

[Peter Kovacevich]

I'd appreciate any suggestions the group has to diagnose and remedy an intermittent issue I'm having starting my 1965 SC. I've used the same starting procedure for the last 17 years and never had a problem starting the car. The starter (6 volt) will turn the car over but the engine does not fire. It doesn't seem to matter if the engine is cold or hot. Occasionally, I can get the car started with one or two attempts, however most of the time I'll run the battery down before I can get the car started (I wait at least 30 seconds to let the starter cool down after each attempt). If I can get the engine to fire, the car runs well.

I put new spark plugs in and I am getting a spark. I cleaned the ground straps at the battery and transmission. I replaced the distributor with a 123-Ignition (I had planned to replace the distributor anyway), and the car runs much smoother, but replacing the distributor (as well as the cap and rotor) did not address the starting problem. The coil was replaced in the last 2 years with a NOS blue coil. Spark plug wires were replaced about 15 years / 15K miles ago when the engine was rebuilt.

The engine appears to be getting enough fuel. I have a clear fuel filter and can see the fuel level rise. I can catch a whiff of gas near the carbs after I have repeatedly tried to start the car. The fuel pump was rebuilt in the last 3 years due to a leak. I've been able to drive the car enough to fill it with a tank of fresh fuel this spring.

I hope I've provided enough information about the starting issue. Thanks in advance for your your advice to get my 356 on the road again.

[David Jones]

Peter, may I suggest you remove the air filters and look down the carb throats while actuating the throttles. Look for a spray of fuel from the brass tubes which point down in to the throats. There should be a short squirt of fuel from all four upon every actuation which will last a second or so. You need this extra fuel to start the car as there are no chokes. It will usually take 5 or more strokes of the throttles when cold to get enough fuel to get ignition if they are working properly. When the engine is hot the reverse is required. Just hold the throttle down till the engine catches to clear out an over rich mixture which invariably happens with a hot engine. As soon as it catches release the throttle so as not to over rev the engine.

[Doug McDonnell]

And if you don't have gas spray from accelerator nozzles read this link: viewtopic.php?f=1&t=40128&hilit=solex+accelerator+pump

[Norm Miller]

Peter,

I would suggest testing the ignition switch to confirm there is power to terminal 15 when it is in cranking mode.
Jump the terminal 15 to 30 then crank the engine.

Norm

[Dave Wildrick]

The engine appears to be getting enough fuel. I have a clear fuel filter and can see the fuel level rise. I can catch a whiff of gas near the carbs after I have repeatedly tried to start the car. The fuel pump was rebuilt in the last 3 years due to a leak. I've been able to drive the car enough to fill it with a tank of fresh fuel this spring.

You may be able to see the level rise, but that doesn't mean the carb bowls are full.

I suggest installing a rubber fuel priming bulb (with 5/16 inch fittings on the ends) ahead of the fuel pump. You just squeeze it until you feel some resistance when the carb bowls are full. Then operate the down rods a few times to squirt some gas down the carb throats before applying the ignition.
These are cheap and easy to install. Here's one brand I have used:
http://www.amazon.com/Attwood-Universal ... bulb+1%2F4

[Jerry Garwick]

I agree with the comments regarding a cold engine that has been standing for some time, but why with a hot engine? In my experience at that point, the carb bowls shoiuld already be full, and starting not a problem. If that is the case with a hot engine, why does the car have a starting problem? Is this a float problem?

[Peter Kovacevich]

I'll have a chance to go work on the car today. I installed a priming bulb many years ago and in the past it worked well to get the car started if it has been sitting for more than a few days. I pump the bulb until it starts to get firm and the floats close the needle valves. I'll pull the air cleaners and see if the accelerator pumps are working and check power to terminal 15.

Thanks everyone for your suggestions - I appreciate your help.

[Peter Kovacevich]

I removed the air cleaners and the accelerator pumps produce a nice squirt of fuel down each barrel.

I'm sorry if this is an ignorant question, but I'm not confident I know how to bypass the ignition switch by jumping terminal 15 to terminal 30. I assume I just connect a wire between the open slot on terminal 30 (next to the red wire) to a slot on terminal 15. I took a photo, but I can't see if the slot next to the blue / green wire is on terminal 15. Unfortunately my 356 is in storage about 5 miles away so I can't easily access it to see what is going on. Also, should I crimp a couple bullet connectors on a short heavy gauge wire to make the jumper?

[David Jones]

Peter, save yourself the trouble. Procure a length of wire enough to span the engine compartment with a croc clip on each end. Connect one to the +ve of the coil (usually the left hand connection) and the other end to the Batt +ve connection on the voltage regulator. Your ignition and oil light should now come on. This is the easy way to jump the ignition without the hassle of touching two wires together to run the starter. Now turn the key and as long as the starter turns you can be sure you have ignition. If the engine runs you will have to to remove the jumper to turn it off. Also if it does not start on the key but does start this way all the time then it is likely you need a new or repaired ignition switch.

[Norm Miller]

Sorry Peter I was a bit too technical.
Thanks David for making it simple.

Norm

[Peter Kovacevich]

Thanks David for the explanation. I jumped the coil from the voltage regulator and the car fired up on the first try. I removed the jump wire and the car started immediately. I tried several more times and started the car without an issue. Now I can't reproduce the starting issue to confirm the ignition switch is at fault. At least I have my 356 at home now so it will be easier to diagnose the problem. When I can reproduce the starting problem, I assume I should see a voltage drop at the coil if the ignition switch is at fault - is that correct?

Thank you again for your suggestions and advice.

[Peter Kovacevich]

After I let the car sit for an hour I could not start it. I tried jumping from the voltage regulator to the coil as I did before and the car would not start. the voltage at the coil and at the voltage regulator were identical (6.44 volts). I swapped out the coil for an old coil as I keep as a spare and it did not start. Any other suggestions to diagnose the starting problem?

[Doug McDonnell]

See if it will start with a push start/dopping the clutch when it won't start.

[David Jones]

Distributor. With ignition off, check the installation of the points and also check with a voltmeter using the ohms range at 200 ohms across the points while turning the engine by hand or remove the cap and turn the engine until the points are about to open then twist the rotor enough to break the points and see if you get an open circuit every time you do that.
The points may need replacement or re-gapping or just plain cleaning.

[Peter Kovacevich]

David, thanks for your patience to help me resolve this starting issue. As I mentioned in my first post, I changed the 022 distributor to a 123-Ignition after I began to have an issue starting my 356. The car would occasionally stumble at higher rpm (above 4500) so I decided to try to address two issues at once by replacing the distributor. When I can get the car started, it runs much better with the 123-Ignition; the idle is smoother and the car doesn't stumble above 4500 rpm. At this point I'd take my 356 to a specialist to address the starting issue, but I don't know anyone locally (Des Moines, Iowa) who I'd trust to work on my 356.

It seems odd the car will start immediately, run great and then refuse to start. I'll continue to try to diagnose the issue and look at options to have someone else look at the car. I'd appreciate any other thoughts or suggestions anyone has to fix the starting issue.