jstnbyd5595

So I have an 88' s10 pick up with a 2.8 TBI, and I seem to have some sort of ignition problems that I can't figure out. It started with the truck running poorly, lack of power and rpm, until one day it just died and has yet to start again. I've replaced ECM, Distributor, Ignition Control Module, Knock Sensor, Fuel Injectors, Fuel Pump, Relays, Throttle Position Sensor, Map Sensor and it has a spark and fires off starting fluid, the fuel pump is delivering adaquate fuel, but the injectors are not opening/pulsing to let fuel through, I even tested them with a tester, and no power to them. The only thing thing with the truck that is not hooked up, because it was blowing the ecm-b fuse, would be the oil pressure switch, which after it was disconnected the truck still ran perfectly fine. Something i don't understand is there is a module called a Elapsed Timer Module, I have no idea what it does, and I can't locate it on the vehicle, but it is connected with the ECM.

Any ideas out there would help!!!

shawnvw

find the short in the ecm b fuse circuit. That fuse feeds power to the ECM, Fuel pump, and injectors.

jstnbyd5595

Actually the ecm-b fuse short was fixed a long time ago, there are no short to grounds at the moment.

Fletch359

I'm Interested to see what you figure out. I'm having almost the same exact problem with my 86 2.8 tbi. Did you try using a Noid light as a testor? My Noid won't light up at all but yet on the hot wire I have a constant 12v.

jmch

i had that issue when i made a swap form the 2.8 to a 3.4, hired a mechanic to make it, it ran great, but when still at the shop the engine suddenly stopped running, everything was checked, nothing unusual just for the fuel pump not working, the guy told me to change the pump, did it, oopss it didn't work as well, checked voltage, merely 8 V, then he told me to change the distributor module because maybe was fried, oooopsss didn't work either, then we checked Voltage at the injectors with the engine cranking, no pulse at all, then the guy told me let's change the ECM 'cause is fried up, then i said hell no buddy, ain't gonna let you play Medical Doctor with my pocket so, what i did was to look for the wiring diagram is at autozone's web site and i checked the harness, what i found was that the ECM B fuse wasn't passing enough current that same fuse feeds the pump relay so i ran a hot wire from the same fuse box to the ECM B fuse and tried, voilá!!! engine started right away, so i planned to run a properly isolated cable with a 10 amp fuse to bypass that fuse at the fuse box but lazy i am and recently started having and issue: with engine running when turning headlights the engine stalled to a stop and the pump relay was making funny noises, after a while it would start, then i noticed a funny smell and guess what the cable that supplied the current to my ECM B fried up the receptacle, so that was it, replaced with the wiring i should have done from the start and now is running nice, by the way, when having that problem RPM's were going low, engine misfiring, smoking , so it should maybe the same with you guys, check that current, by the way, the pin is C16 in my 87 S-10, orange cable and has to be hot at all times same at the fuel pump relay (same cable) and the elapsed timer is right next to the ECM under the dash, and when measuring pulse at the injectors, its a negative pulse from the ECM not a positive current ok? everything is in the diagram from autozone. if there's no current at the ECM no matter if you have a running fuel pump or spark, ECM will never send the pulses to the injectors, greetings from chihuahua mexico

jmch

by the way when i made my swap i noticed the harness going to the ECM at the firewall damn too close to the left exhaust manifold, that could cause a serious problem so what i dis was to pull it fartest possible away and isolated with aluminium tape, that harness has everything going in to the ECM and out to the injetors, relays etc