EFIDynoTuning Forum

Alright I've been fighting the nonstandard and misfire issue for awhile now. Today I changed the fuel pump thinking that was problem, didn't fix it. I changed the distributor and module, that didn't do anything. I swapped the coil thinking it could be going bad, nothing. Luckily all these parts that I swapped were with parts good known parts I already had so no money was spent. What I've discovered during all of this is the car will not even attempt to fire. When you turn on the key the electric fan, which is wired into the factory harness and I'm using the QH to control, runs constantly. It'll run then act like it loses power for a split second then. Like it's cutting in and out. I'm lost at the moment and need a little direction on this. I'm not sure if I have a wiring issue or a tune issue. Anybody have any ideas?

And the fuel pump runs constantly.

pump runs constantly then the j3 port isnt communicating

The only time I've ever run into a constant pump running was me corrupting my tune. Is your battery dead on your quarterhorse?

I put a new battery in it today and done the same thing. I guess there's a chance that the new battery I installed is dead or low. I'll pick up another battery and try it. I'll also build a new tune in case my tune is corrupt.

If the battery was bad, it corrupted the tune so you world need to reload it after replacing the battery.

Also wouldn't be a bad idea to clean the j3 connector on the board with a ScotchBrite pad

I had an issue with the fuel pump in my car running constantly and the car not wanting to start. Turned out to be the caps in the computer were due for a replacement. Once changed the car fired right up.

id suggest the caps also-
another thing when that QH battery is removed it wipes the memory so the tune is gone I would bet

I think I have several things going at once here. The first being the capacitors going bad, which is funny because i actually replace these as a side gig but havent done my own. The second I think the battery couldve been going bad on the QH, not a 100% sure though. The third is my factory wiring harness has some of the tabs the that keep the pins from pulling out of the 60 pin connector are broke, which allows some of the pins to work themselves out. So when i get time im going address all the issues above.