EFI holley sniper

[victorguarrera]

I have rebuilt the engine and up graded to EFI Holly Sniper Hyperspark, My question is it starts very good once it warms up on idle it can run for a while then just cut out , with the timing light on when it cuts out no spark to the plug, rerouted the wiring and now it does it when out on the road for about 5 minutes it will cut out and then hard to start due to excess fuel I think, then it will run again and do the same thing again. I have a 73 Mach 1 and how do you get the original tacho to work. Has someone else had a similar issue, any help is appreciated.

 

[Kilgon]

First things first - did you have a Holley Sniper and added the hyperspark or did you do the entire system at the same time. If you already had the Sniper efi and it was running fine until you added the hyperspark distributor, then I would be looking at the wiring there and possible the hyperspark unit itself. If you installed it all at the same time then you need to make sure that ALL the sniper wiring is as isolated from the rest of the car wiring as possible. That means no wires touching or crossing. It doesn't take much interference to cause problems.

I had a somewhat similar issue after I rerouted my alternator wiring. The Snipers hot lead from the battery was touching the alternator wiring running from the voltage regulator and causing my engine to stall. Took a couple of days to figure it out but if you run a log and see any spikes that would be a good indication of ri problems.

There are several good sources to get info from that I have listed below. As far as your tach not working, what kind of ignition box and coil are you running - msd, holley or other. This will determine how to wire the tach. Beside the wiring diagrams that are with the hyperspark instructions I have also listed below a link for wiring of different types of boxes. You need to remember that our tach's are current operated so look for those diagrams that list current driven. You may need to add a tach adapter. In the Holley site choose you model from the list on the web page. In the link for the efi system pro site go to the EFI Pro Hangout up on top left when you open their site.

https://forums.holley.com/
https://www.efisystempro.com/

https://documents.holley.com/techlibrary_9615_wdtn_2011.pdf

 

[victorguarrera]

thank you very much, I have installed it as a complete unit and my positive lead does run with the alternate leads

 

[Kilgon]

thank you very much, I have installed it as a complete unit and my positive lead does run with the alternate leads

Odds are that is your problem. Run your leads by themselves and use a wire loom to wrap them in. Clamp or zip tie wherever needed to keep them in place and from moving around when driving. You might also want to check about a rfi shield if the problems persist and all your wiring is isolated. They sell them or you can make your own. Here is the link to the one I made. Even though my system was running fine I decided to add it as a safeguard. Disregard the section on the throttle linkage unless you are willing to change your cable and make other modifications.

https://7173mustangs.com/threads/holley-sniper-info-and-resources.40174/