No injector pulse please help

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Joined
Dec 25, 2016
Messages
23
Reaction score
8
Location
South central pennsylvania 16650
Hello and thanks in advance. I have a 92 c1500 with the 4.3L v6 and a nv3500 trans. I bought the truck cheap as a no start. So far I have replaced the cap, the rotor, the sparkplugs, the ignition control module. I have checked the wires going to the injectors and have the constant 12vdc on one side of each plug. I have continuity back to the ECM on the ground wires for the injectors. The injectors will work if given an auxiliary ground source so I know I've got good injectors and good fuel pressure. It's just that something is not letting the injectors fire I've got 12vdc on the orange wire to the ECM and ground on the black wire to the ecm. The ECM is a 4288 and has the soldered in Cappadocia and prom so I would have to get a complete ECM if that's the issue. Is there anything else I should look at ????
 

Chewy1576

I'm Awesome
Joined
Jan 14, 2013
Messages
950
Reaction score
302
Location
Ogden, UT
The pickup coil on the distributor maybe? The one my '90 original distributor went out not long ago. You can either take the distributor apart to replace just the coil, or new distributors usually come with one installed.
 

sntrym

I'm Awesome
Joined
Sep 9, 2015
Messages
244
Reaction score
126
^^ Common failure item. Check the electronic components of the dizzy. The ECM will not send injector pulse without a distributor reference signal.
 
Joined
Dec 25, 2016
Messages
23
Reaction score
8
Location
South central pennsylvania 16650
Sorry guys forgot to include I tested the pickup coil and its testing good resistance is good and it puts out correct AC voltage when cranking the engine the ignition control module is brand new and the truck will run if given a shot of fuel down the throttle body I'm at wit's end on this thing I have to replace the computer ECM though knowing if it's even going to help. I just put $150 into the ICM, cap, rotor, new sparkplugs, new fuel lines, fuel filter. Hoping it would make a difference but no luck. The only thing left is the ECM so I guess that's the next step. Problem there is mine has the calpac and prom chip soldered in so I need a complete 4288 ECM the ones sold at parts stores and rock auto need to have a calpac and prom installed from the old ecm. I have soldering tools but this is not something I feel I can do I'd have to ruin it attempting to try. Any info on what ecm's interchange with the 4288
 

Ruger_556

I'm Awesome
Joined
Jul 22, 2013
Messages
4,741
Reaction score
179
The 2 wire harness that connects to to the ICM can fatigue and cause a voltage drop (Mine cracked right where they connect to the pickup coil). Dead in the water. Use an ohmeter, unplug the ICM and test between the two wires in the connector while moving them, resistance value should stay the the same, if it bounces around they're junk, throw a new distributor in it.
 
Joined
Dec 25, 2016
Messages
23
Reaction score
8
Location
South central pennsylvania 16650
@ skylark...Yeah good fuel upto the throttle body just no spray. If I apply an auxiliary ground to the injectors they will spray. But they don't pulse like this and just dump fuel in. So I know my injectors work and the truck runs but the dang injectors just won't spray

@ ruger_556.... I have tested the pickup coil inside the distributor and all seemed to be in order but I will try again while moving the wires around

I'm going to get a new-used ECU on Monday I hope this fixes it if not I'm at a loss. I've tested the harness alot and cannot find any problems. If the ECU don't fix it I will move onto a new harness
 
Joined
Dec 25, 2016
Messages
23
Reaction score
8
Location
South central pennsylvania 16650
Up and running. I ended up getting a new ecm at the u pull it for $10 it had a 4288 ecm i had to get a 7747 its running but i get a vss code 24 vehicle speed sensor because the ecm came from an auto and i have a manual but it works the truck runs and drives.
 
Top