Started last week of april dragster new k&r wiring new grid.programmed it started ran fine started 20 times at home went to track I had warmed it up at home . towed to track started it up ran litle bit then quit on alky primed it with gas fires again quits get it out of trailer no spark,has not ran since.took it home bad 7720??? borrowed my buddies spare still no spark sent mine back to msd,the said nothing wrong but they pd fgt back.bought crank trigger sensor new even though i have a spare put it on, spun motor over it tried to fire then nothing with buddies box while mine was at msd.Got my box back from msd put it on spun it hit ign and it gave great indication it would fire got excited blew a little rust out of the collectors,Then nothing tried 2 other hvc coils and my spare crank trigger sensor tried a different 7720 and 77303 tried different 12 prong harness out of 77303,Have had all duetch connectors apart and wired back together without plastic, hardwired another harness to the tri angle three prong connector to crank trigger ..Any ideas ????

Forgot to say rotor is phased

quote:

Originally posted by 3628:
Forgot to say rotor is phased

Also have jumped the relays on k and r board

Are the heads and block grounded? At one point I had some weird stuff before running dedicated grounds to all three.

block is grounded heads are not, but i will try it

Initial Troubleshooting with Grid help.

Turn ignition ON. Is Grid Green LED next to usb port ON?

If Green ON, does it blink On /Off when cranking. If Yes, remove spark plug wire at distributor cap from coil, insert a spark plug and ground to heads. Crank engine. Do you have spark? If yes, put coil wire back on distributor and take any plug wire, attach spark plug and check for spark from distributor.

If no blinking of Green LED, check trigger input from distributor or crank trigger.

Attach to Grid with a laptop, select the Monitor tab and look at RPM cranking, ignition timing. Check for any faults in Grid going to the VIEW tab on top and selecting Alerts.

You can test 7720 separately when it’s in the car. It’s explained at the end of the Grid posting in this LINK .

Here’s a recent 7720 bench test video that Greg Kelly posted . https://www.youtube.com/watch?v=UmPyfjpruw4

Green lite blinks when cranking .It does have spark at coil wire but no spark at spark plug end, going to plug laptop next will let you know on my next post

It has no active alerts

quote:

Originally posted by 3628:
Green lite blinks when cranking .It does have spark at coil wire but no spark at spark plug end, going to plug laptop next will let you know on my next post

Are you saying it has spark at coil wire end that goes into the center top of the distributor ?? If yes, and no spark from the 8 spark plug wires from the cap, then it’s in the distributor. Cap or rotor issue.... maybe even timing or phasing

yes will work on that now thanks for your help...

Check to make sure the button is in distributor cap in center that the rotor contacts

And make sure the tongue
of the rotor is tight and not moving around

Take the rotor off and check the square drive on the distributor.

Troubleshooting humor. A racer contacts me (10+ yrs ago) saying Grid not working properly with MFI. Idles poorly, no power and won’t go wot. Go through everything Grid related, meter crank trigger connections, ohm plug wires through distributor cap, check spark and more. Everything checks ok. Later he decides heads need a valve job, takes it apart, puts it back together and has exact same problem. Next he takes the nozzle jets out to change and finds 3 of them partially plugged up with trash. Funny how the easiest things to fix are sometimes the hardest to find.

Here is the story,Had 99 mullis cage to small went 4.75 90 degree weather last day I raced it Guy who fit in it purchased roller,by the next weekend I bought 2001 mullis roller 23 inch cage. put motor trans converter in by next weekend this car had a 7AL3 took to track went 5.08, while trying to figure out wtf was wrong within couple of weeks late Oct after making 8 runs 5.06 to 5.08 parked it. Called MSD told them I wanted to send red 7AL3 back to them, They told me they couldnt get parts for it. So I sent red box to the tech west guy and he said it was only putting 7000 hz and it needed at least 1300 hz whatever,Over winter I decided to have car rewired and buy new grid like other car, which brings to my oringinal post,by youputting sark plug in coil wire yesterday and seeing spark gave a hope got new cap rotor supposed to be delivered today plugs looked terrible, yes earlier fI checked spark but tied sticking a sccrewdriver by myself, when I put my post up and put grid on it I hoped you markemark would see thank you..ps in my initial check for cranking voltage at coil was at most 4 volts,I checked it on my nova which has a 7al2 it 12 volts Sometimes it no fun to be a dumba$$

The old 7al3 that are red pt# 7230 were introduced in the 1990’s by MSD. They were manufactured until 2012 when they were replaced by the newer black 7al3 pt# 7330. The new 7330 is an excellent stand-alone analog ignition. The older 7230 is poor choice to continue with if presently using imho.

Prior to placing the old plug wires on the new cap, meter them using the ohms scale. Most of the racing wires will be in the 50 to 200 ohms per ft range. Others could be more. Look for any that are dramatically worse than the normal readings given same length you find.

Also, prior to putting the new cap on, install the new rotor and then slowly drop the cap in place. You should feel some slight pressure from the flexible rotor tang engaging the center ball on the cap interior the last 1/8” – 3/16” prior to seating. This is important as if there’s any gap it’ll eat away that ball.

I coupled a Grid with a 7330 (the black digital 7AL-3) to make it easier and quicker to change the burn out rpm, the launch RPM and the RPM limit, this is all done with chips.

It simply takes too long to attach my lap top and a mouse to the Grid, connect the grid to a USB port, provide power to the lap top and make those changes. Using chips takes only a few seconds. Before installing them I check each chip with an ohm meter to be certain they are accurate. MSD provided me with the wiring schematic since it didn't come with the Grid instructions. The only two things I use the Grid for is the timing map and data acquisition.

At 83 I'm a one man band with no help, simple is the only way I can deal with complicated/cumbersome electronic systems.

Bob

are you sure the coil wire is good

I have tried 3 different coil wires .. When I said last week it had spark at coil wire with spark plug and green light blinking when cranking that was true then I got my new rotor and cap installed It has spark and couple cylinders trying to fire I just by passed the wiring out of grid to coil with another harness no spark tired another 8261 coil hit on couple cylinders ..I noticed now no green light blinking when cranking .That is inadvertent

have you tried a msd tester?if you dont have one I THINK you can place a spark plug in the dist end of coil wire and then tap the white wire on msd to ground .if all is working this should produce a spark on each tap.of course the spark plug would have to be grounded.not sure but unplug crank sensor to test with white wire.