Technical Crank, hard start, rough idle and dies, backfire through the carb

So I'm rewiring my truck, and I'm trying to make it run. It ran before I pulled all the wiring and it will somewhat run now, except after a few seconds of really rough running, it dies. It also backfires through the carburetor. I had to wire in a Mallory HyFire VI box because I have a unilite distributor, and everything worked before I took the wire out. I checked the wiring diagram and everything is where it should be. What should I be looking for? I desperately need to make my car run. It's a 454.

Thanks guys!

 

I hate to ask, but are the spark plug wires connected in the correct firing order? The only other thing I can think of right now is the timing. Did you move the distributor at all?

 

When a new problem shows up, go back to the last thing you fixed.

All you've mentioned is wiring, but what else is there?

I know you said it's wired right, but then not running problem is either something else or you're mistaken on wired things.

Go back to basics, start at square 1 and work your way up to the problem by process of elimination. That's what the pros do because it works every time.

 

X2

Pat

 

I may have by accident while wiring up the pickup but I didn't do it on purpose. It wouldn't shock me if it's timing,I hope it is because that's easy. Going through a ton of wiring isn't.

As far as I recall, I didn't mess with the plug wires at all, just pulled one or two to get to a hard to reach place.

 

Timing?
Did you move, remove or change the distributor

 

Sounds like the distributor is 180 degrees out... don't ask me how I know!

 

I had that problem before and we fixed it!

 

check that the plug wires are all where they belong.



As for the rest of the ignition system...hmmm....you said you had to install HyFire box, because it has a Unilite distributor. That doesn't make sense to me, because the Unilite is designed to work without a separate box.

Since we can't be there to look over your shoulder, and see problems that you don't even know to look for, maybe it would help if you could take some pictures of the engine.

 

I'll take some pics as soon as I get home from work.

I said unilite...I meant MSD. It's a points to Electronic conversion. The only thing I know about about the distributor is that the P/N starts with 855, and that it's in my 454. I couldn't even find proper instructions for it since I don't have the full product number. I didn't remove the distributor or make any intentional efforts to change the timing since I pulled all the wiring, and it ran fine before that. The pickup has a black and orange with and a black and purple wire I believe.

I will also check the order of the plug wires when I get home.

 

I'd put the points back in it...

 

well it sounds like you got a plug wire in the wrong place. but did you wire the dizzy at the same time you did other wiring? if so you might have a wire from the box to distributor wrong.

 

If I had the negative from the box going to the positive on the mag pickup, and vice versa, would it still send out a spark but at the wrong time?

Also, why points when I can just put in HEI?!

 

If the wiring from the box to the distributor were wrong, it could indeed act like that...maybe...

I say that because I once fixed an HEI equipped engine that had the two pickup wires reversed. But I don't know if the box you have is as picky as an HEI module about the polarity of the pickup wires.

There are some other things that could be wrong, such as the pickup being phased wrong relative to the cap.

Why points? well...why not? the damn things work. They've worked for a century.

 

Is Mallory made my MSD? All I know is it's a Mallory HyFire VI product number 685.

I feel like the Pick-up wires might be reversed...would them being backwards cause it to not fire when it should fire and fire when it shouldn't? Because that would cause it to backfire but wouldn't it not run at all?

Could it be a weak spark?

 

Try switching the pickup wires, and see if it helps.

But double check the plug wiring order first.

 

I will do both.

Just in case neither of those works, is it possible my box is fried? I'll also tell you what I wired each of the box wires to when I'm at break.

Thank you guys for all of the help.

 

Usually if the box is fried, it won't do anything. but not always.

Pictures really really help for troubleshooting things over the internet. Clear, in focus pictures that show all the stuff we need to see, from a few different angles. I highly encourage you to try to post a few.

 

well anything is possible but if the box is fried i dont think you would get anything at all. just the motor tuning over

 

I call timing the worst thing mr. Single did is run the dizzy thru the intake

 

I'm not sure how much pictures will help because the wiring is a mess right now, just trying to thrash on it to get it done and clean it up later. What would you like pictures of?

It's definitely sparking at least a little.

I'm not totally sure what you mean.

I messed with the timing retard on the box and it didn't do anything in either direction.

The red wire of the ignition harness on the HyFire VI box went to the coil positive wire. The black wire went to the tach. The green wire on the ignition harness isn't connected to anything. The yellow wire on the ignition harness went to coil + qnd the black wire of the ignition harness went to the coil -.

The green pickup wire on the box went to the orange wire on the pickup and the black and orange pickup wire on the box went to the black and purple wire on the distributor.

The long black wire went to the ground terminal on the battery and the long red wire went to the positive terminal on the battery.

 

Looking at some Mallory instructions on the internets, it looks like you need to connect the Purple wire from the distributor to the Black wire from the HyFire box. And connect Orange from the distributor, to the Green wire on the HyFire box.

http://www.manualsdir.com/manuals/3...tion-controls-685_6851.html?page=7&original=1

 

Take the box out. The Unilite does not need a control box.

 

he doesn't really have a Unilite. He has an MSD distributor.

 

Sorry, I misspoke. That's how I hooked it up

 

Sorry I was going off his original post.

 

61Chev454..Maybe if you posted your location on your profile page,someone here may live close enough to come by and give you a helping hand.

 

So we have a internet troubleshoot-

With a unilate that's really a Msd.
We got a detailed verbal on wiring that's really a dyslexia wiring description that may or may not be correct.

I'm just gonna watch this one. It will go 17 pages.

 

Thank you for essentially calling me an idiot. The wiring description was correct, otherwise, I'd either have no spark, I'd not have the box turn on at key on or I'd have smoke coming out of the box. I described the wiring how it was. I'll try switching the mag pickup wires when I get home but as far as I know, I made damn sure to put the green pickup wire from the box.to the orange and black wire on the two pin distributor connector, and the black pickup wire on the box to the purple and black wire on the two pin distributor connector.

I'm sorry I made a mistake about the distributor, it happens.

Also, I'm located in St. Louis.

 

Don't worry about the hecklers, they're just bored.