Hey guys, Went to test and tune last night and the car shook really bad in the burnout (car only has a 468 with iron heads and track was really good). The car died after it shook like it lost spark and wouldn't restart. I towed back to the trailer and got the test light and checked msd and it had power. Tried to start it immediately after and it started right up. Went and made another pass really quick and it went ok. The car has been breaking up about 400' to 500', which I thought was a fuel pressure issue initially. 4th pass I went back up and the car died in the burnout again. Towed back again and checked MSD and it has power, but won't start now.

Any ideas??? It has fuel, but no spark. I have a brand new coil, plugs, wires, dist. on the car. The crank trigger is older, but that's all I can think of. Is it possible the wiring is coming loose inside the plastic exterior for the main MSD power wire and is only connecting intermittently?

Last question. When MSD's go bad they typically are just bad right? They don't just work intermittently?

Thanks

If it shook, every wire connection and routing is suspect until physically inspected and checked off .

Then use this or borrow a spare box.

https://www.holley.com/product..._testers/parts/89981

my guess is floats too high/flooding

wiggle all battery cables,i had soldered connections inside heat shrink at one time.it would do the same thing.one cable unsoldered and made bad contact like yours.if not battery something similar

Thanks guys. I'll try all this stuff tonight after work and see what happens

Check ALL electrical connections, especially the ones going to your MSD box. Make sure the shake isn't shutting off your master shut-off switch...
Put a carburetor return spring on the lever of your switch that holds it towards the open position - adjust it so that it takes a firm push to shut the power off but a very light pull to turn it on.

Fire it up and gently tap on MSD box with soft faced hammer and see what happens and what model box if has screw on terminal could wire led light into power and ground mount light where you can see it and watch to see if it goes out when car dies

That's usually the cutoff switch, shook closed.

Man..wish I would have posted this stuff up last night. Now gonna have to look at everything and wait until next thursday to try it all.

The weirdest part is I got towed back 2 times and MSD always had power when I tested it with a test light. It has a junk pro systems fuel pressure regulator on it. Could it be bad, and fuel pressure fluctuation be burrying the floats??? Seems like if it sits a while it fires which would seem like its flooded right?

quote:

Originally posted by Holytown:
Man..wish I would have posted this stuff up last night. Now gonna have to look at everything and wait until next thursday to try it all.

The weirdest part is I got towed back 2 times and MSD always had power when I tested it with a test light. It has a junk pro systems fuel pressure regulator on it. Could it be bad, and fuel pressure fluctuation be burrying the floats??? Seems like if it sits a while it fires which would seem like its flooded right?

That would be pretty easy to check with a helper. When it dies look and see if the fuel is above the windows or with the pump on is it running over into the booster?

It only floods after burnout if thats what is infact happening. I have a 3 step on it so it goes to 6400 in burnout at wide open throttle. Dies as soon as I lift off the gas. Wonder if it loads up at that point and dies

is the fuel pressure gauge dry or liquid filled?

If it's liquid filled, take it off and throw it in the weeds, replace it with a dry gauge and set the fuel pressure to 6.5 as a baseline.

Next take both fuel bowls off, turn them upside down so the float is hanging. Now take a 7/16" drill bit and adjust the float so it just touches the drill bit when you slide it between the hanging float and what is the roof/top of the bowl. Once done, it ain't fuel related if the pump and regulator are working correctly.

I would also run a piece of fuel line from vent to vent cut opening in center

And work on your burnout procedure to avoid the shake as much as possible. Even if you figure out this issue, constantly shaking the tires in the burnout will cause all sorts of other issues and broken stuff, especially in a hardtail where there is no suspension to absorb anything.

check all your main power supply terminals to the ignition box and grounds , I had a problem like this and under the heat shrink it had broken the terminal. while it was sitting it would be fine, but on launch and run it was breaking up real bad and sometimes just die. due the the connection being broken. just check all the connections, wiggle, pull etc.

Buck gave good advice....Inspect the wires going to the coil very closely....we had a wire break at the terminal on the coil..intermittent failure
drove us crazy,,,We had a weather pak connector near the coil to ease R&R the motor....The connector worked great but the wires going to the coil through shaking broke down inside the insulation. the continuity of the wire was positional...I found it by checking for power with a test light as I shook wires..the wires were secure and heat shrink was used over the terminal connections but there was a break..GM used to call this the jiggle test...

After this happens, do you have to hold you foot down on the fuel pedal to get it fired again?
May be fuel level too high. Like 355X stated. Do the hose deal. Vent to vent. Open on the top bend.
If in fact the level is too high it will bleed out of the boosters also.



This is a Bowl vent balance on a set of 1450's.

This message has been edited. Last edited by: TD3550,

Ignition box took a dump.

What kind of switch panel? I had one shake loose as described and lost contact. Then after the tow of shame back to trailer it started back up. Bad switch and bad connection loose/opening when it got hot. Cost me money twice.

quote:

Originally posted by JPosey:
What kind of switch panel? I had one shake loose as described and lost contact. Then after the tow of shame back to trailer it started back up. Bad switch and bad connection loose/opening when it got hot. Cost me money twice.

That is also a possibility. I would say it is the ignition box but a loose ignition wire is possible.