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1984 Crusader 454/350hp coil pertronix puzzler

M

MichiganTrooper

New member
Three years ago we converted the original Mallory YL distributors with Pertronix drop-in magnetic points. They worked well.

This year both engines started to run rough and slowly lose power when they were warm. After about 10 minutes of declining power the engine will stall and not restart until cool.

Pertronix suggested their Flamethrower Coils. Did that. Same result. Replacing the coils (with any cool coil) solves the problem -for about an hour of run time.

Our small harbor has a good mechanic who is back-logged for 5-7 days. Suggestions for what to look at?

Thanks
Todd
 
Yes we used resistors with the standard coils: measured 2 to 4 ohms resistance. (I think greater than 1.5 ohms is Pertronix spec.) We used no resistor with the Flamethrower coils that are marked internal resistor. We did use a 12V by-pass wire from the battery to the + side of the coil once to get us home. Read somewhere this is not good practice.
 
Are both engines drawing from the same fuel tank? If so, run one engine on a portable tank, OR, loosen the filler cap a few turns and run with that for a few hours.
 
Thanks Dave, The gas good. The problem CAN be solved by switching coils out every 30 to 60 minutes. A cold coil = no problem. I have a pile of different brand and type coils and resistors we have tried.
 
MichiganTrooper said:
Thanks Dave, The gas good. The problem CAN be solved by switching coils out every 30 to 60 minutes. A cold coil = no problem. I have a pile of different brand and type coils and resistors we have tried.
Click to expand...

I was headed down the road of the tank perhaps developing a vacuum after 45 minutes of running. So, if you change out the coil every 30 minutes, a problem never develops? Resistors don't usually come back to life. Neither do coils of wire. There is that one in a thousand chance that normal heat will expand an electrical connection and cause an open, but you tried many coils, etc. Note that a bunch of things may happen during engine cool down. A 99% tank vent clog will untimately pass enough air into the tank to allow running to when it all happens again.

When you say "gas is good". You can see 5psi with a gauge just before the carb? That's the best way to see if, in fact, enough fuel is getting to the carb.

ps. the mention of "10 minutes of loosing power until stalling" does not usually mean ignition issues.
 
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Wow ! We all need to know when this gets resolved. Sounds like fuel more than electrical, but if changing coils heps, you just took it out of my league.
 
Repeating my Mantra: Replace the carbs. Those you have don't owe you anything and after all these years they cannot be fully functional. While you are at it replace all the fuel lines filters cap rotor wires plugs belts.
 
Carbs on both engines were rebuilt and gas pressure was checked: $800. down the drain (dont ask) This happens to both engines - though not always at the same time. It seems to me that it is extremely unlikely that a wire is faulty, a rotor or cap is cracked etc. We have put in a spare pertronix unit - no difference. A cool coil makes an engine (that WILL not even START) run STRONG (4000rpm under full load) again for 30 minutes....then comes gradual power loss, backfiring (I forgot to write that earlier) and eventually stall. Another cool coil will make it run like a top again.
 
Hi

I would make sure that you are getting proper voltage to the resistor. Somewhere in the vicinity of 13.5v with the engine running. I would also check the condition and gap of the spark plugs, if the gap is to wide your coil will have a tough time, also check your cap and rotor condition and make sure both engines are grounded properly.



Good Luck,
Jon C Allen
 
I've had a bad distributor cap give somewhat similar actions, including loss of power and backfiring. Still having a tough time with the "keep the coil cool" issue, though. How old is the distributor cap? Over 2 years, put on new ones.
 
I'm with DD I had a issue where the screen in the pickup tube from my fuel tank was getting packed with crude but the engine would run for about 20 minutes before it would loose RPMs and shudder and die. After 20 or 30 minutes the engine would start right back up no problem for another 20 -30 minutes. Check to see if your pickup tube in the tank has a screen in it if it does get rid of it. The filters will get the crude.
 
Thanks everybody. We have replaced spark plugs and wires once and caps and rotors twice. No change.

Though it DOES sound that way, the problem is NOT gas or tank related. We chased that idea for several days. We have cross-over valves on the tanks and can run BOTH engines from ONE tank at cruise speed...until the coils heat up:

The engines will only run well with cool ignition coils. This is probably a symptom of some other problem but we cannot figure it out. I just counted - we have tried 6 different coil/resistor combos (X two engines = 12 coils) argh.

We have had great luck with pertronix in our Jeep, truck and past boats. However, I am going to put the points back in tomorrow.
 
This just in from the previous owner of the boat: "I had Mallory Unilite ignition conversions installed - they were unreliable...the points are a pain, but they are predictable".

T
 
I had a similar issue with my Chrysler 318 and found it to be voltage related, too much. With a voltmeter check your battery voltage at 3000rpm don't trust your dash gauge. Also check your voltage before the resistor and after the resistor running 3000rpm as well. Turned out my wiring connections were a little corroded and the voltage regulator wasn't seeing enough voltage and kept cranking out too many volts.
 
"I just counted - we have tried 6 different coil/resistor combos (X two engines = 12 coils) argh."

I'm sorry but the above statement indicates quite strongly that the problem is elsewhere.

Could be faulty ignition wiring back, i.e. high resistance or bad connection, in the engine harness or all the way back through to the ignition key switch. Could be also fuel related. Perhaps running off a portable tank will show something.

Best wishes,

Tom
 
Ditto on the "not a coil issue".

I'd vote with DD - fuel supply. Put a vacuum gauge in the suction line feeding the pump and see if the vacuum increases when the "power loss" occurs. Another quick check would be to check the float bowls when the engines stall out. I'd bet the bowls are empty. (You can probe the float level thru the forward bowl vent tube. Measure it with a coffee stirrer when cold and idling - that should be full. Measure again when it stops running. If it has dropped, it will be significant {> 0.25"} and it means no fuel supporting the float.)

After 25 years, I'd think it is reasonable that the tank has accumulated some sediment.
 
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