340 Slowly Shutting Down ???

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Cruzin

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Hi Guys, I have friend with 340 duster that is having a weird electrical problem I think. The car starts up and runs great for about 15 seconds. Revs fine and goes back to idle. Then, all the sudden the engine slowly just starts slowing down , erratic timing sound, and shuts off. Plenty of fuel still pumping (5 lbs.) from manual pump. Its like the ignition is slowly loosing power. He has a MSD 6 box and MSD dizzy. The car caught fire (small fire) a few months ago. He replaced the wiring that was burned. But, now it will not run for more than 15 seconds or so. Starts fine, then comes to a slow creeping shut down. Any help would be appreciated. If I missed something that someone needs to know, let me know and I will try to fill in the blanks of what I know.
Thanks again.
 
Sounds more like it is running out of fuel even though you say it has 5PSI. Is there a fuel filter after the gauge? If so replace it. Next would be checking the carb.
 
I tend to agree with MD. Any chance the fuel is contaminated? Does it idle good for a bit? What might have overheated in the fire, IE the MSD, etc?

Does the carb make noise, IE can you hear fuel dropping into the carb? Does it start back up? What is the situation on restart?

Nother thing you might try is scaring up a simple ignition, IE points dist. and rigging an ignition as a quick substitute.
 
Mad Dart: the carb was completely rebuilt and from what I was told is functioning properly. I kind of thought that too. But he insists its pumping fuel into the carb when it starts to slow down and just before it shuts down. He said he looked in and can see the fuel being sprayed without a hitch. I am not for sure on the filter, as I have not seen it personally. I will show him this thread. I am trying to get him to join the forum so he can learn some things from the gurus on here. I appreciate your help. Will check this out.
 
67Dart273: Here are the answers to your questions.
1) once the car shuts down, he tries to start it immediately. No crank at first. About 15 minutes go buy and it starts right up and runs great for about 15 seconds or so. Then dies off.
The fire was pretty hot and could have damaged the MSD box. I know he said he had to replace wiring from the dizzy. He did mention something about a white wire from the MSD box that goes through the firewall to somewhere???

2) The carb does not make any noise that he mentioned. He just knows there plenty of fuel. He did show me a video of a device hooked up to the ignition wiring he borrowed from someone. It looks like a tube that shows the brightness off the spark during the running of the engine. I have never seen one of these items before. Its really bright when the engine first starts and runs for about 15 seconds, then the light starts to flicker and slowly fades away and the engine obliviously shuts down.

3) I tried explain that to him as another member on the forum told him that over the phone. I don't have a spare or V8 dizzy laying around to try it. The car was pre-wired when he got it, so alot of the mopar wiring seems to have been compromised to a certain extent.

I wish I knew more. I wish I could get him to post the video so somebody could see it. The video is good enough to see and hear everything that is going on. I am perplexed over it.
 
As it is starting to die, did he try spraying some ether into the carb to try to revive it? That may eliminate a carb issue! Just thinking out loud! Geof
 
You said something about "spraying" fuel. Make sure it's not FLOODING. Does it smoke black, hard to start, or smell rich when restarting?
 
If the carb was just rebuilt and the float bowls were never adjusted they could be low..... it will run out of fuel and have the symptoms you are having. Your Fuel Pressure could be @ 5 psi but that still don't matter if the bowls are low.
 
Mad Dart said:
If the carb was just rebuilt and the float bowls were never adjusted they could be low..... it will run out of fuel and have the symptoms you are having. Your Fuel Pressure could be @ 5 psi but that still don't matter if the bowls are low.
Click to expand...

Excellent observation!!
 
Guys, thanks for all the help. After checking all the above mentioned items, my friend finally removed the
complete ignition system and took it down to a local shop we have here and the guy that runs the shop performed a test on the whole system. The test basically emulated the engine running against the ignition system. Lo and behold the ignition system did exactly what was explained earlier. It slowly died.
The culprit was the actual MSD 6 controller. When the system was first put under test conditions, it was fine. Then in about 20 seconds, the controller started shutting off and you could see on the testing equipment each cylinder was shutting one by one, then the MSD 6 box just shut down.
The main controller was probably damaged originally by the fire in the engine compartment causing a short and damaging the unit. New one on the way and all should be back to normal. Thanks to all that have helped out. When all else fails.... take it to the shop. The guy who runs the shop was very nice and did not charge a penny to test the unit. He is also a mopar head like a few of us on the forum too.
Thanks again for all the help.
 
That's awesome you found the problem... Somewhat strange symptoms though, in my (limited) experience ignition systems either work or they don't, I haven't heard of one that would work fine at first then slowly deactivate. EENteresteeng lol...
 
I admit that "came to mind" but I wasn't sure ......thanks for updating.
 
Just to make you aware that there was a recent HotRod Magazine article 2
-3 issues ago on phony MSD boxes that look identical to the real ones which have inferior internals. Maybe you have one of those counterfit boxes?
 
Yea Rob............imagine that....Somebody mentioned something about it might be a faulty MSD Controller box. LOL
 
Thanks again everyone for chiming in. I just wanted to reply back and let people know what the outcome was.

Scatpackbee: I have heard of some of those reproduction copies of controllers, tachs, and such. Unless I know where it came from....I tend to stand clear.
 
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