Hello everyone,

I own a 1969 L36 427. I had the unfortunate problem of an old dry rotted hose becoming disconnected and wrapping itself around the header on the passenger side of the vehicle. There was a small fire which I quickly put out. I had the car towed back to my house, T replaced the hose (It was a vacuum line coming from the wiper actuator down to the headlight actuator in the passenger side wheel well.) and it ran fine for a few weeks. Seemed to have a weaker vacuum than normal but the engine fired right up, ran hard, shifted well, and hit 5k RPMs without issue. Recently I was driving and it just sputtered out and died on me, took about 3-5 seconds from the point I noticed the engine going down in RPMs to when the engine cut out. I have attached two videos but will also explain my dilemma.

In the first video, you'll see my attempts at starting the car the morning after getting it towed. The battery sat at about 12.8v. The engine would fire on a few cylinders but would not sustain an idle. Starting with fuel I disconnected the fuel line to the carb and cranked the engine over a few times which showed a few large pumps of fuel into a bottle, next I checked I was getting spark on all plugs, and finally I plugged the vacuum line off of the intake to "eliminate" a vacuum leak somewhere within the system. Didn't seem to make a difference. I decided to charge my battery thinking maybe it was too low. Well, after charging the battery and having the volts settle at about 13.05v I tried starting it up, and to my surprise, it ran... for about 90 seconds then sputtered any died. In the second video you'll see I start it, check voltage at the terminals and at the alternator. I'd like to also preface that at the beginning of the video you'll see I show ~12.5v at the battery terminals and ~14.2v at the alternator (kind of hard to see my shirt was sort of in the way). But after the video ends, I checked the voltage at the terminals again and it read 13.8v - 14.2v as well. Not sure why it took so long for the voltage to get to the battery, I would have thought it would have read the same as the alternator nearly right away. I'm stumped for what I should be checking now. Distributor, coil, bad connections, grounds? Why would it seem to run when the voltage is high enough on the battery? It made me think the alternator but then the output is 14.2v...

First video:
Second video with 13.05v battery:

 

Seems to be running fairly well in the second video, no apparent shaking so probably not missing, and probably not an electrical issue (unless it is too intermittent for us to see)
Was the engine hot or cold during these incidents?
I'm going to lean towards a fueling issue. Either a dying fuel pump, dirty fuel filter, dying accelerator pump, or something along those lines.

 

Thank you for the reply!
Here's a video of fuel coming up to the carb:
I just find it odd that if I overcharge my battery to 13.2v then it'll run for a couple minutes. The engine was cold for both of these videos, they were about a day apart. The engine was hot when it sputtered and died on me driving. Are there some good ways to diagnose a dying fuel pump or accelerator pump? To my knowledge the hardware on this vehicle is original to '69 + 20 years at most. It mainly sat since the 90s but has been a beauty driving the last 2.5 years. I was going to hook up my timing light, recharge the battery, and see if I can check spark when it sputters out.

 

I'd think that even a weak fuel pump would supply enough volume to keep the engine idling. To test the fuel pump, you could hook a pressure gauge to an outlet hose (like you have in the video thumbnail) and measure psi. I'd guess a minimum should be about 4 psi but I'm sure others will correct me if I'm way off base.

 

In the first video engine sounds like it wants to run on just the start position. I would take a look at the wire feeding the coil, or the Ign. Sw. The coil is powered differently during start and run positions of the Ign. Sw.
Start Pos.uses a resistor bypass to power the coil.
Run Pos. uses a resistor wire to power the coil.
Check the resistor wire it's insulation is usually a white braided fabric w/blk dots. It's fragile though, being so old.
Better yet, as a test, just run a jumper wire from the Batt to the + coil and start. If it runs better, then it's the wire.
Test for 5 Min. only.(Or you will burn out the coil)

Second video, As for the voltage difference, could be a bad ground, poor connection.

 

If you have the canister filter in the fuel line before the carb then your getting enough fuel to at least idle the engine. If you have the small filter in the carb inlet then I would replace it it may be dirty or clogged.
Pat

 

So I see you’ve mucked with the OE distributor. These cars OE are alittle different being with points the coil only gets a full 12 volts during starting. When the key goes to the run position the coil is fed power through a resistor wire. Basically it’s a red braided wire that has higher resistance. Basically under load the amperage pull from the coil steps the incoming voltage on the wire down to about 7-8 volts. This was done to give the coil a “boost” when starting but you would burn the windings up in the OE style coil running on 14ish volts all the time.

Where I’m heading here is what is the coil you’re using now rated for? If it’s designed to be externally resisted like the original then ignore everything I just said. If it’s INTERNALLY resisted or in the case of a lot most performance coils not resisted at all then your starving it for voltage. This is assuming the original resistor wire is in place.

It may have run before being wrong because you had a healthy charging system. You should be getting alittle bit better of a charge than that. Being your seeing only 12ish volts at the battery I’d start there. With that said it should run all day on a 12.5 volt battery.

I’d unhook both the resistor wire and yellow wire from the coil and connect a bypass either to the alternator lug or the battery + and see if it still does it.

Somebody will have to back me up here but I think the resistor wire is red and the booster wire is yellow from the solenoid.

 

The battery charging issue and the voltage issue points to dirty, corroded or just plain bad grounds or bad ground lead wires. Clean the battery connections the frame connections and ohm out the ground wires frome the battery to the frame and the engine to the frame. All should be zero. Check the wiring on the starter, you could have burnt up the starter wires and the starter has wires that power the coil during cranking and provide the charging path and the electrical for the interior


You have fuel to the carb and squirming a tiny bit of fuel down the throat would tell you if you filter or the carb is clogged.....I don't think so

 

Thank you. I'm not sure how to do a multi reply but thank you to everyone that replied. I'm going to make sure my electrical connections are cleaned and reading zero resistance. I did replace the ignition coil yesterday just out of curiosity and it seems to be running well now. I cannot definitively say it was the ignition coil without doing some testing, but so far it seems like a culprit. I'll have a better idea once I test all my grounds and electrical connections to see if there is any impedance.

So far so good. Thanks everyone!

 

Just click on the "Multi Quote" button for all messages you want to quote but select the "Quote" button for the very last message. All of the messages will be quoted in a single reply message.

 

No problem. Make sure you have the right coil for whatever your application is.

Also zero resistance means nothing with no load on it. You’ll want to put a load on the whole charging system and do a voltage drop test where several of the grounds terminate.