340 ignition problem?

-
soaddrummer

soaddrummer

Well-Known Member
Joined
Dec 1, 2008
Messages
66
Reaction score
0
Location
canada
I have a 340 Scamp and has always had a hard time starting to the point where the battery dies. I am not too familiar with engines and how to fix them so take it easy on me please. I normally have to pump it 4-6 times to start and when its warmed up usually starts up fine. Other times it will just die at a stop and not want to start up and battery dies. It has all stock parts, aluminum heads 800 cmf carb. Is there a reason why it takes so much turning over to start up ? Thanks guys !
 
What model year and what do you have for ignition?

You have a multimeter?
 
It's a 73 scamp the motor is from a challenger. Uses the same distributor some new plugs and wires I put in a few years ago. I can get a multimeter
 
OK, very first thing is to try and split the problem as to whether it's "fuel" or "electrical."

Some things you should just HAVE, period end of story

You should have a multimeter of some sort. Even a cheapie Horrid Freight "if it works right" is better than nothing. You can pick up a decent meter at any parts store, or Sears or even Radi Shack for less than 50 bucks

Go to Radio Shack and get a bag of clip leads

Get a shop manual and by that I mean a CHRYSLER shop manual, not a Haynes, not Chiltons, or some other. You can buy reprint paper ones, or "on CD" Google around

You can download several shop manuals on this site, but unfortunately none of them are newer than 72, and in either 73 or 74, there were considerable changes in the wiring, so using a "wrong year" diagram can get you into trouble.

So pick up a multimeter and an auto store "spark tester." There are various kinds.

Make some tests:

Set your meter to low DC volts, and clip one lead to the coil plus terminal, the other to battery, such as the starter relay big battery stud. Remove the coil wire and wedge it against something to ground it, so the engine will not start

Prop the meter up so you can see under the hood gap, and crank the engine USING THE KEY. While the engine is cranking, read the meter. You are hoping here, for a very low reading, not over .3V (three tenths of one volt) or .4V at the very most.

Now clip the meter to the same battery source, and the "key" side of the ballast. If you have a 4 terminal ballast, this is the end of the ballast with a jumper across the two end terminals.

With engine not running, turn the key to run, and read the meter. Once again, not more than .3V is acceptable.

If this checks out, some "general" stuff.............

Remove the cap and check the rotor for debri, damage, dirt, moisture, or wear

Look over the reluctor and pickup coil for strike damage, rust, or debri. Get a .008" brass feeler gauge (inches not metric) and O'Reallys Auto had these last I looked. This is the gap you want to set the reluctor to pickup coil gap

Wiggle the dist. shaft while looking at this gap and check for side - to - side bushing wear.

Use your multimeter to check each plug wire AND the coil wire. If these are older resistor wires, you want no more than 1000 ohms per foot of wire. Most are less.

Use your spark tester to check spark. Ground the tester, hook right to the coil, and crank USING THE KEY. You should get a nice hot blue spark, at least 3/8" long, and usually about 1/2" As the engine cranks, this should be a nice rythmic spark, bang bang bang..................

Remove and inspect the ignition box. Clean/ scrape the firewall and rear of the box clean, and re-mount using star lock washers. Make sure it's tight.

Remove the ignition box connector, the ballast resistor connectors, and the distributor connector. Inspect them visually for damage or corrosion, and work them in/ out several times to "scrub" the terminals clean, and "feel" for tightness.
 
For your 4-6 times pumping when it's cold, do you know if your choke is closing? Knowing where you live and the temperature outside.
 
How long before the battery dies? Often they get where they can't hold much charge and become fairly useless. Get an in-line spark tester from Harbor Freight for $6. If the spark is strong, it is probably fuel. Block off the fuel line to the carb (remove hose and insert a bolt & clamp). Try to start it after spraying Starter Fluid down the open throttle (and closing throttle). Then give a little spray to keep it running. If it runs fine on starter fluid, that proves your carburetor is the culprit.

800 cfm is pretty big for a 340 engine, so it may never idle well. If the P.O. installed a big racing cam, it may never idle right. Many people like that "lopey idle" and cams are marketed on that. It sounds like "race car" to many people. I would never do that to my engines because I don't like unnecessary pollution, crappy mileage, and an engine that sounds defective. You only need that if your primary goal is to drag race, with the engine always screaming at high rpm.
 
67Dart273 said:
OK, very first thing is to try and split the problem as to whether it's "fuel" or "electrical."

Some things you should just HAVE, period end of story

You should have a multimeter of some sort. Even a cheapie Horrid Freight "if it works right" is better than nothing. You can pick up a decent meter at any parts store, or Sears or even Radi Shack for less than 50 bucks

Go to Radio Shack and get a bag of clip leads

Get a shop manual and by that I mean a CHRYSLER shop manual, not a Haynes, not Chiltons, or some other. You can buy reprint paper ones, or "on CD" Google around

You can download several shop manuals on this site, but unfortunately none of them are newer than 72, and in either 73 or 74, there were considerable changes in the wiring, so using a "wrong year" diagram can get you into trouble.

So pick up a multimeter and an auto store "spark tester." There are various kinds.

Make some tests:

Set your meter to low DC volts, and clip one lead to the coil plus terminal, the other to battery, such as the starter relay big battery stud. Remove the coil wire and wedge it against something to ground it, so the engine will not start

Prop the meter up so you can see under the hood gap, and crank the engine USING THE KEY. While the engine is cranking, read the meter. You are hoping here, for a very low reading, not over .3V (three tenths of one volt) or .4V at the very most.

Now clip the meter to the same battery source, and the "key" side of the ballast. If you have a 4 terminal ballast, this is the end of the ballast with a jumper across the two end terminals.

With engine not running, turn the key to run, and read the meter. Once again, not more than .3V is acceptable.

If this checks out, some "general" stuff.............

Remove the cap and check the rotor for debri, damage, dirt, moisture, or wear

Look over the reluctor and pickup coil for strike damage, rust, or debri. Get a .008" brass feeler gauge (inches not metric) and O'Reallys Auto had these last I looked. This is the gap you want to set the reluctor to pickup coil gap

Wiggle the dist. shaft while looking at this gap and check for side - to - side bushing wear.

Use your multimeter to check each plug wire AND the coil wire. If these are older resistor wires, you want no more than 1000 ohms per foot of wire. Most are less.

Use your spark tester to check spark. Ground the tester, hook right to the coil, and crank USING THE KEY. You should get a nice hot blue spark, at least 3/8" long, and usually about 1/2" As the engine cranks, this should be a nice rythmic spark, bang bang bang..................

Remove and inspect the ignition box. Clean/ scrape the firewall and rear of the box clean, and re-mount using star lock washers. Make sure it's tight.

Remove the ignition box connector, the ballast resistor connectors, and the distributor connector. Inspect them visually for damage or corrosion, and work them in/ out several times to "scrub" the terminals clean, and "feel" for tightness.
Click to expand...

I checked the coil with the meter and is reading between .32 and .35 v and also the ballast has the same reading. I also checked all spark plugs and they all have spark...I got an inline spark plug tester but i think it's a bit cheap because all it shows me is a red light that goes off when there is spark. I noticed one lose plug so i tightened it. I could not check the coil with the spark tester because the way the coil is I wasnt able to connect the tester to the top of the coil. It started right up and idles nicely now but I did not go out with it as it's raining and getting dark. Ill see what it does tomorrow once I warm it up and drive it for a bit. All electrical seems okay as to what you asked me to do.
 
Distributor is solid...I will get a feeler gauge tomorow fvrom Canadian Tire as i am from Ottawa :)
 
For a spark tester you need something with a gap, like a spark plug.
 
I have a 74 duster and had the same problem car would just not start good at all. After countless days trying to figure it out we pulled the distributor and relized that the reflector was really bad. I would say check the reflector against the pick up coil make sure neither is ground down at all and each gap it gaped properly. For my car the gap is .008 may be the same for your care. MAKE SURE you use a cooper feeling gauge.
 
Ive been starting it up all week and notice it slowly starts to have a hard time turning over which led me to the battery being bad. I had one just put in the beginning of this season. I'm reading 11.26 on the meter when not running and while its running as well. I drove it home after a boost and the battery still reads 11.26. Is the alternator may be bad? What numbers should I be looking for to see if i'ts charging or not. When i'm in drive at a stop it seems to be struggling to stay awake, not sure if maybe a bad battery or bad alternator may not be producing spark for when i'm at a stop? Thanks for your input guys::) Not a huge wrench head here so all you help is very much appreciated. I changed all the plugs and when the battery is charged it starts up real nice.
 
Not charging and battery is down. A fully charged battery should read over 12V

A running / charging system should read no lower than 13.5 and typically 13.8--14.2

Very very quick checks to separate the problem.................

Look at the alternator, there will be two "push on" connections. Identify and remove the GREEN wire. Take a clip lead and ground the alternator terminal from which you just removed the wire with the key in 'run.' You should see a small spark.

Start the engine and slowly bring up RPM. The ammeter should gradually rise more and more to charge. With your multimeter hooked to the battery, voltage should gradually come up

If so.......problem is in field wiring or regulator

If not, some more checks before condemming the alternator

Turn off engine, switch key to "run."

Make sure that you have "battery" voltage at the blue field wire hooked up to the alternator. Remove/ replace your clip lead and look for a spark. If none, bad brushes

If the above is OK, restart the engine, and put your multimeter on the alternator output stud and to ground. Bringing up RPM, see what the voltage does

No change, bad alternator

If voltage goes up "some" recheck battery voltage. The output stud and battery should be within 1 volt or so of each other

If the voltage at the alternator output stud is "way high" but the battery is pretty low, say, several volts difference, you have a wiring problem in the output feed, usually top suspect is the bulkhead connector
 
I have to go with 67dart270 on all the electrical tests, particularly alternator output, and voltage regulator condition. That said, I suspect your choke is also out of adjustment.

After a full night cool down, before starting engine, remove air cleaner, and crack open throttle by hand about 1/4 turn and observe the following actions: does choke plate fully snap shut with authority; is there a good strong shot of fuel ejected into carburetor from accelerator pump; and does the high idle cam freely move to keep throttle plates from full closing? If any of the three conditions listed above are not happening, you have choke problems.

If choke plate won't snap shut with authority the bi metal spring that activates it is out of adjustment or broken. Electric choke can be adjusted by loosening three screws securing round black disk and rotating it enough until choke closes snugly and pulls off once engine starts by about 3/16", or if bi metal spring is mounted in manifold remove tin cover and adjust tension.

Accelerator pump shot is either good or the carburetor needs to be rebuilt with a kit.

High idle cam if sticking generally responds well to being cleaned with carb cleaner.

One other malady of choke articulation found on high millage carburetors is worn linkage connections that bind when rods are moved when closing choke. The fix is to dress worn spots at connections points by smoothing them with a fine file.
 
67Dart273 said:
Make sure that you have "battery" voltage at the blue field wire hooked up to the alternator. Remove/ replace your clip lead and look for a spark. If none, bad brushes
Click to expand...

I got spark from the green lead wire but no the blue one at all....Should I continue on with the other checks?
 
No "what" on the blue? I'm concerned you are not doing the test right Re-read what I posted

Unhook the green wire at the alternator AND LAY IT ASIDE

The thing you are GROUNDING is the terminal on the alternator from which you just got done disconnecting the green wire. You do not ground the wire itself.

You do NOT ground the blue. Check it for battery voltage with the key in "run."

What do you have for a meter / test light, etc?
 
I also did the test on a half dead battery i'm getting a charger tonight. Its only at 11.06-11.10 now,...thats the reading i get at both battery and blue wire at alternator
 
I am using a clip lead wire, hooked up to the green terminal and then grounding it, and i see spark. I do the same to the blue terminal and see no spark. There is volateg but the same has battery
 
I'm trying to get through to you you do NOT short the blue wire or the blue terminal.

The way this works is, the blue wire supplies 12V coming from the switch. it is HOT with the switch in "run."

That 12V goes into and through the rotor magnet, out the terminal normally hooked to green, and back to the regulator. The regulator controls the "ground" on the green

So to bypass the regulator, you ground the ALTERNATOR terminal which was hooked to the green

DO NOT ground the blue. Blue should have battery voltage with key in run. Sounds to me like it does.
 
Okay so I did a few more tests. I put in a fully charged battery. The output stud on the alternator and battery have a one volt difference. When i bring up the rpm the voltage goes up at the alternator but not at the battery. I'm only reading 12.23 while running and when i turn on the lights fan and radio it drops down pass 12.09 at the battery. I'm assuming bad battery now? Could the stalling at a stop when the rpm drops is the cause of a bad battery maybe?
 
also the ammerter does not go up as i bring up the rpm...i notice in drive at a stop as the motor is idling it will go up and down a bit...in park it stays in the middle or close to it
 
soaddrummer said:
Okay so I did a few more tests. I put in a fully charged battery. The output stud on the alternator and battery have a one volt difference. When i bring up the rpm the voltage goes up at the alternator but not at the battery. I'm only reading 12.23 while running and when i turn on the lights fan and radio it drops down pass 12.09 at the battery. I'm assuming bad battery now? Could the stalling at a stop when the rpm drops is the cause of a bad battery maybe?
Click to expand...

Are you checking this with regulator hooked up, or with the "green" field terminal grounded as I mentioned above?

Refer to the diagram. I don't remember who originally posted this but THANKS

This does not show the OUTPUT stud, but diagrams the blue and green.

ALL BLUE WIRING is switched 12V power coming from the key. It is NOT fused so do NOT short it to ground.

It does NOT matter which field wire, blue or green, go to which field terminal.

So for the third time, step by step

1---remove the GREEN wire from the alternator and do nothing else with that wire. Do not connect anything to that wire

2--At the alternator TERMINAL from which you just got done removing that wire, hook a clip lead from the alternator field terminal to ground

3--Start the engine, monitor battery voltage with your multimeter, and bring up RPM. If the ammeter does not show a substantial charge, and if battery voltage does not come up, the alternator is bad.

attachment.php
 
Okay the alternator is good. I got plenty of charge on the voltmeter on the battery and the ammeter was showing substantial charge
 
You must log in or register to reply here.
-

Back
Top