efi conversion help
#1
efi conversion help
Everything is pretty much complete. I have the efi dash harness, engine harness, fuel tank. This is all in an 85 4x4. It cranks and fires bit will only run for a second. I dont think its getting fuel through the injectors. It has fuel to the rail and the cold start. What could be my problem? Thanks!
#4
Contributing Member
make sure you have 12v to the single plug on the injector resister with the key on. Since its running on the cold start injector, this tells me that the fuel pump is working when cranking at least
#6
We checked the injector connector and got .01 volts. Then we checked the same wires at the ecu plug and got 12 volts. Any ideas? Maby some wires got cut somewhere in the harness.
#7
Registered User
The injectors are fired by pulsing them to ground. They're actually a single bank of injectors altough the ECU indicates two different banks.
Are you getting cranking RPM on the tach when hitting the starter?
Sure you have fuel pressure?
One way to test for injector trigger is to put a test light across the terminals of the injector connector. Crank the truck. You should see that light go on and off very fast - it might be best to use an LED test light.
ECU needs cranking RPM to know to trigger the injectors... i'd suspect that it's not getting cranking RPM indications from the ignitor if you have no tach deflection and no injector trigger.
Trending Topics
#8
Ya i'm pretty sure i'm gettting fuel pressure it reaches the cold start and the rail ive cracked both lines. We checked to see if the tack works and it does it jumps up to about a 700 rpm's when it starts for a second.
#11
Registered User
If so - that would indicate that your ECU isn't getting cranking RPM. If you have access to a FSM, I'd go through the "no fuel" diagnostic procedure - but what I'd be looking for is the signal out of the ignitor coming into the ECU that tells the ECU that the truck is cranking... I can probably detail out which pin that is if you need me to. The input is either a 12v or 5v square wave.. I forget which.
You can simulate cranking if you've got spare distributor. Just turn the truck "ON" connect the distributor and give it a spin. I've hooked mine up to an electric drill before to check tach and other operations.
#14
Registered User
#16
Registered User
I don't understand the question.
The ignitor isn't passive (unpowered). It's job is to take the VR signal out of the distributor, translate it to a square wave and send it to the ECU. The ECU then makes decisions about timing and tells the ignitor when to fire the coil.
Here's a photo of how it works.. Just assume the megasquirt in the photo is the stock ECU:
http://lakebox.dnsalias.com/photos/1...igncontrol.htm
The ignitor isn't passive (unpowered). It's job is to take the VR signal out of the distributor, translate it to a square wave and send it to the ECU. The ECU then makes decisions about timing and tells the ignitor when to fire the coil.
Here's a photo of how it works.. Just assume the megasquirt in the photo is the stock ECU:
http://lakebox.dnsalias.com/photos/1...igncontrol.htm
#17
ok well there seems to be 3 plugs on the ignitor, one smaller one, and two bigger ones, one of the bigger ones goes to the distributor, the smaller one plugs into the harness right by the ignitor, the other one that doesn't have power thats supposed to runs across the valve cover and ties into the harness under the upper intake plenum. I checked this plug on a 4 runner and it had power to 2 of the three terminals with the key on. Mine has no power at any of them with the key on.
#18
Registered User
You really need a wiring diagram from the right year of truck. You can't just hook up a 12v probe or volt meter to various wires and decide what needs power, especially since the signal wires generate 12v square waves (which can show as 12v or 0v depending cranking / engine position).
My advice is to get the FSM, map out the wires to the ignitor - there should only be one "power" wire to a switched ignition source.
My advice is to get the FSM, map out the wires to the ignitor - there should only be one "power" wire to a switched ignition source.
Thread
Thread Starter
Forum
Replies
Last Post
live4soccer7
84-85 Trucks & 4Runners
3
05-11-2016 06:52 PM
runnermedic
95.5-2004 Tacomas & 96-2002 4Runners
13
09-21-2015 05:20 PM