Combustion but no start

[bjblock]

Attempted first start today and looking for some debug help. Blueprint 347 with Sniper. After running the Sniper Setup Wizard, I cranked it up and it fired up immediately, but stalled out right away. This happened consistently several times in a row. In the Sniper startup guide it says the monitor should show the RPM as “stall” until cranking starts, then should switch to “syncing” and then show the RPM. However, the monitor continues to show “stall” when cranking. We confirmed the sniper yellow wire was connected to coil- and that the pink wire was powered during cranking, although the voltage did droop a bit.

Any ideas what would cause this? I haven’t verified fuel pressure yet so that would be my next step, but the fuel pump is definitely running and priming to get the initial combustion.

[burchfieldb]

I had issues with mine and my Atomic MSD EFI, turned out to be the oval air cleaner I was using, it was picking up EMI from the distributor cap. Try removing the air cleaner and see if it will start. Could also be timing or ground. I would assume that BP had it running before shipping. Have you change anything?

[bjblock]

No luck without the air cleaner. It was dyno’d by Blueprint and I haven’t messed with timing or anything like that post-delivery.

[burchfieldb]

You could try the Holley tech support. I had good luck with them helping to track down the issue. The guy stayed on the phone with me for an hour while I was trying different stuff to get it to run.

[bjblock]

A bit of progress - I pulled the yellow "coil -" wire off the coil and found that there wasn't a good connection in a butt connector I used to extend the wire to reach the MSD blaster. I re-wired that with a soldered connection and hooked it back up. With that fixed, I fired up the engine and the Sniper monitor was registering RPM this time, but the value was jumping all over the place and it stalled out after 5-10 seconds. The RPM signal jumping around rapidly seems like it could be an EMI-related, so I tried removing the air cleaner again, but got the same result.

[F500guy]

I got a filter from Speedhut, settled out my RPM reading really well.

[John Dol]

Did BP install the Sniper and ran it or did you?
I had to do a bunch of shielding to get rid if the interference. I used Faraday tape on the oval air cleaner bottom. Made a shield between the distributor and the sniper body as well.

HTH

John

[burchfieldb]

I got a filter from Speedhut, settled out my RPM reading really well.

This was going to be my next move as well, if a carbon fiber air cleaner base does not solve my issues. I need to make one anyways to get the hood clearance I need. I was looking at these from Digikey, easy to snap on and test. Our electrical engineers use them all the time for EMI issues.

https://www.digikey.com/en/products/detail/fair-rite-products-corp/0431178281/8594004

[bjblock]

I finally had some time this weekend to do some more debugging and turns out it was another electrical issue. I must have been having a bad day when wiring the coil - the coil +12V ring terminal didn't have a solid crimp so once the engine fired up, the vibration was causing an intermittent connection and it would stall out. After fixing that with a new ring terminal, a better crimp, some solder and heat shrink, the first start milestone is complete!

[burchfieldb]

Nice! Congrats on the easy fix.