Starting issues

[Rosco234]

Good afternoon everyone,
I was hoping to get some advice on a recurring issue that I have.  I've got a 71 Challenger with a 440 and mechanical six pack setup.  The car runs and drives great.  It starts very easily when cold.  However, when the car is hot, it is a bit finicky to get started.  I end up having to crank it quite a bit on occasion when I flood it or if it doesn't start right away.  Aside from the finicky starting, my battery seems to drain down very quickly while cranking it.  I can only crank it 3 or 4 times, for a few seconds at a time before the battery goes completely dead.  Does this seem normal that it drains that quickly?  The battery was in the car when i got it last year and is dated 2019.  I keep it on a battery tender if the car is parked for prolonged periods of time.
any thoughts on if this is normal?
Thanks.
Greg

[dodj]

Finicky when hot is likely the gas gets boiled out of the bowl from heat soak when you shut it down. Then it takes a few cranks to top up the bowls again. Fairly common issue.
The battery seems weak to me but maybe you have a really high compression engine?

[tparker]

Batteries arn't cheap, but it might be time to get a new one. it should not only last a few strokes. Not sure how much a high compression engine would tax a battery, but I think a decent battery should get more than a few cranks.

Not so sure about why it wouldn't start when it's hot but I would focus on fuel first. As a sanity check, I would also check wiring just to make sure there isn't a bad connection that is going bad when it's hot. Seems weird, but I have seen weirder stuff.

[Poolshark314]

If you let it sit for a bit before trying again, does it start right away? Could also be heat soaked starter motor

[DeathProofCuda]

If you let it sit for a bit before trying again, does it start right away? Could also be heat soaked starter motor

I had a similar issue that was starter related.  Are you using an original starter or one of the newer mini units?  Swapping out the original starter for a mini was one of the best upgrades to my car.  It turns over so fast that it now starts like a new EFI car.  You lose that classic Mopar starter sound, but totally worth it IMO.

[nsmall]

Are you running a plastic spacer in between your carb and intake?

[Chryco Psycho]

I agree that new fuels evaporate quickly , you can help this by using a FelPro 1215 intake gasket that blocks the heat crossover port in the intake keeping the intake much cooler .
1 Place to check is the fuel pump pushrod , they will often wear down & not cycle the fuel pump fully making it very hard to refill the fuel bowls .
You should have both the battery tested & starter tested for draw , it could be either but the engine should crank longer , it can also be bad cables with corrosion / green death causing resistance .

[Rosco234]

If you let it sit for a bit before trying again, does it start right away? Could also be heat soaked starter motor

I had a similar issue that was starter related.  Are you using an original starter or one of the newer mini units?  Swapping out the original starter for a mini was one of the best upgrades to my car.  It turns over so fast that it now starts like a new EFI car.  You lose that classic Mopar starter sound, but totally worth it IMO.

Its a new mini starter that I put in last year. When it cranks over, it cranks nice and strong. But it quickly drains the battery.  If i let it sit for a bit and come back, it usually will not turnover or i might get a rotation or two out of it before the battery cant turn it.


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[Rosco234]

Thanks everyone. Its a new ministarter. I dont have any spacer between the carb and intake at all. Do they make those for a 6 pack manifold/2-barrel flange?


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[Strawdawg]

It could be the fueling problems mentioned above, or, it could be electrical.

On the electrical side, I agree with Neil and suggest that the starter and battery both be load tested as either could be the source of the apparent battery problems.    It is not uncommon for a hot starter to pull more current than it should.  It would not hurt to measure the alternator output as well to be sure the battery is being properly charged.

Also, on the electrical side:  If the starter is drawing too much current, the voltage to the ignition could be quite a bit lower than normal and this may cause a weak spark that makes it harder to start when hot.  Another possibility is a (old) wiring problem that causes a voltage drop far greater than normal to the ignition/coil.  The wiring path on our cars makes it easy to incur a loss of voltage between the alternator/battery and the coil.

Years ago, my car was not the fastest starting car and it got to be very difficult to start when hot.  I did all the usual insulating the carb from the intake, etc.  I noticed one day that the voltage going into the ballast resistor was a bit over 2v less than coming out of the alternator.  Note that I said going into the ballast, not coming out

I found a number of places that were contributing to the voltage drop and in the end, I figured it was not worth the cost and effort to redo everything including the bulkhead connector which was charred on the terminals.  I then installed a hot wire to the ignition by taking power straight off the alternator thru a relay and on to the ignition module (I used an H.E.I module in order to get rid of the ballast resistor).  I triggered the relay using the blue and brown wires that came from the ignition switch.

After doing this, the car started faster than it had ever done since I had bought it and it makes no difference hot, or cold.  The moral to the story is that if one has a lot less voltage going thru the ignition system that it was designed for, it can certainly affect the starting.

In your case, it may be the starter causing the problem, the battery may have a weak cell, or both...  without a meter, to check the voltage going thru the circuit(s) before starting, and after, it is impossible to say that it is the wiring as was my case.  I would check that after testing the starter current draw and the battery.

[wes473]

Yea I had a similar thing...  Got headers?!?! The starter could be part of the issue when hot but sounds like fuel issue to me. Headers will hurt both.

I had a 70 RR with a VERY troublesome 440-6pack(383 mag factory), untill I fixed the fuel delivery system. Mine would drive OK until I stopped when hot it would be very hard to stay idle and would die, then Really not want to start. Ran awesome when cold.

After getting stuck at a very helpful neighbors house we figured out the 6pack was heat soaked and ANY fuel hitting the bowels was boiling right out. Found the fuel pump pushrod was barely doing anything and I was running 90% from VACUUM , also researched 440-6 and hemi stock fuel systems had a 3/8 fuel line (383 was 5/16) AND an Vapor lock filter/can. After many experienced Hotrodder conversations, I redid the fuel system. E-pump from the tank, New 3/8 line up to the engine(used old 5/16 line as vapor return from engine), space all fuel stuff FAR FAR away from headers/exhaust, VAPOR lock can/filter, 3/8 to the carbs.

NO MORE ISSUES! (bonus I added a theft switch on the fuel pump under the dash) With fuel flowing/circulating constantly in the lines=cold delicious POWER=cool carbs, literally. No heat soak issues, idling in 100+ heat or at hot startup. Ever. Also ran like efi.

Later my header, heat soaked starter(old style) fried, but if worked fine(maybe weaker tho) untill it died. Next time I'll ceramic coat or wrap headers.... For both issues.

[Chryco Psycho]

Coolcarb does make a 6 pack heat isolator that can significantly drop temps in the carbs

[Rosco234]

Thanks for the replies everyone. I have a few different things to look into.  One thing i noticed when going to replace my faulty fuel gauge sending unit was that i have a blocked off fuel connection. Im not familiar with mopar fuel systems but this is not correct right. Wondering if this might be contributing to the hard starting issue.



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[Chryco Psycho]

The tank has to be vented so either through the vented cap or a vent from the second connection , there were different venting routes depending on the year .

[Rosco234]

The tank has to be vented so either through the vented cap or a vent from the second connection , there were different venting routes depending on the year .

Thank you. Im pretty the tank is vented via the other set of vent tubes on the other side of the tank. I did some reading and it looks like the blocked off tube is used for a 1/4 return line from a 3 port fuel filter by the fuel pump. I dont think i have any return line at all


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