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View Full Version : Mercury Tech Injectors won't fire



skeeter91
01-23-2018, 08:17 PM
1998 200 EFI
fresh rebuild, injectors cleaned and calibrated
Brucato ECM
Injectors will not fire! I've got good fuel pressure(39 psi)
Got good spark on all cylinders.
12 volts at the injector plug on harness, but not getting closed ground on multimeter when I turn it over. I've even changed the harness to a known good one, no change.
I've checked all the grounds, but I'm missing something!
Anybody got a good suggestion?

vnemous
01-23-2018, 08:21 PM
Try your old ecm if you still have it. How many injectors had to be calibrated?

skeeter91
01-23-2018, 08:24 PM
Yep, tried the stock one too, same thing. I had Rich at Brucato's clean and calibrate all six injectors.

Steve Pope
01-23-2018, 11:47 PM
sounds like the ecu is not getting ignition command from switch boxes ???

skeeter91
01-24-2018, 06:33 AM
sounds like the ecu is not getting ignition command from switch boxes ???
that was my line of thinking as well,which led me to switch the harness. if the system is firing the coils, would the signal be going to the ECM as well? i was sure i missed a ground somewhere, but havent been able to find a loose one.i've built a couple of these EFI motors and never had this issue, im stumped?!:confused:

patchesII
01-24-2018, 06:38 AM
I would double check your wiring at the switchboxes, especially making sure you don't have an active ground on the black/yellow post. If you have a kill switch disconnect it. I've seen them go bad

skeeter91
01-24-2018, 09:49 AM
I would double check your wiring at the switchboxes, especially making sure you don't have an active ground on the black/yellow post. If you have a kill switch disconnect it. I've seen them go bad
Will go over the entire system again when i get back this afternoon.

flabum1017
01-24-2018, 06:31 PM
use an onhm metere and check for continuity betweem the ground and ecu case.

skeeter91
01-24-2018, 09:04 PM
What a difference a fresh set of eyes make!
Upon entering the shop this evening, i set my eyes upon the starboard side of the motor and there it was, tucked under the wire loom, loose purple wire(12 volt supply for the ECM)! I knew I missed something! Damnit man! I hooked it up, bolted the EFI unit back on and it fired of on the first hit! Thanks for the replies and perhaps this will help someone else out down the road!