No Injector pulse on 7/8 injectors
02-06-2015, 01:40 PM
#1
Junior Member
Thread Starter
Join Date: Jun 2014
Location: Minnesota
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
No Injector pulse on 7/8 injectors
I've swapped a 7.5 in place of a 5.0 in my truck. 5.0 5spd, 4x4. 7.5 came out of 89 F350, 4x2 C6 auto. 8800 GVW. I put it into this 6800 GVW truck. I swapped everything, ECM, but not wiring harness. I also installed a C6 auto for 4x4. I have 12 volts at every injector with the key on. (red wire) Spark at all plugs, but only #6 fires. I'm leading to an issue with wiring harness, the difference between the 2 trucks. Any Ideas? oh the o2 sensor is not hooked up. I also tried a different EMC from a 95 E350 van. and I had the same results. firing on #6. I only used the screw driver test to check for pulsing while cranking engine. I'm back to searching for an Answer. Any Help would be appreciated.
Thanks.
Thanks.
02-07-2015, 07:55 AM
#3
Junior Member
Thread Starter
Join Date: Jun 2014
Location: Minnesota
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
1989
its the same model year. as the donor. 1989. I tired a different ECM from a 95 7.5L and have the same issue. only fires on #6 I did check the ohm's on a couple of injectors and they were at 14.6 ohms. I then swapped the TPS just for the hell of it. same result. do you think there is a wiring issue between the 2 trucks? I pulled the harness out of the old truck. just to look at but if I don't know what to look for?? I may have to buy the wiring diagram and diagnosis manual. I just don't under stand why #6 fires.
02-07-2015, 09:03 AM
#4
89 should be speed density (no MAF) which (at least on the small blocks for sure) means it has a "bank fire" system. That should fire 4 of the injectors at once, then the other 4.
The only S/D harness I've taken apart was for a 94 4.0, but it had the 3 and 3 wires coming singly from each injector but they all joined together in the middle of the engine harness (3 to 1 wire, the other 3 to another wire).
Later MAF systems had individual wires from each injector all the way to the computer.
The only S/D harness I've taken apart was for a 94 4.0, but it had the 3 and 3 wires coming singly from each injector but they all joined together in the middle of the engine harness (3 to 1 wire, the other 3 to another wire).
Later MAF systems had individual wires from each injector all the way to the computer.
02-07-2015, 03:13 PM
#6
Saw your other thread too. Putting all that together, I'm wondering if your problem isn't maybe related to going from this computer to that engine compartment harness hooked up to a different engine harness. Lots of room for wire to pin changes there. Maybe google up some wiring diagrams and start comparing.