injectors wont pulse
 

88 engine with N333 ecu.

injectors will not pulse


the ECU is telling the coils to fire so this leads me to think the ecu has power and ground, but it wont open up the injectors.

any advice?

I had a similar problem in my '89 GTU, which was one of the reasons I went over to a carb. it wound up being that a number of wires under the dash were frayed internally. I never bothered to test and find out which wires they were, but when I moved the wire pack while while the ignition was on, the pump would run intermittently. Under cranking either the injectors would pulse while rubbing the wire pack, or lose voltage completely.

First, check all fuses and relays related to the EGI system.

I would suggest starting at the injectors. Use a pigtail led-tester (a led light the goes between the harness and the injector), then test them for resistence. if they pass move up the harness to the ECU. IF there is a fray (which happens in old cars) you wont find it with a led tester or ohm meter. You'll need a special tool that reads electrical signal through shielded wire (available from the snap-on man for a coupl $$$). Otherwise you will only be able to narrow it down to the specific wire with the fray or break.

If you would like to check your ECU (just in case), it's pretty simple to look over for physical damage (shit happens). Dig it out from under the dash, and use your phillips screw driver to undo the retaining screws. A small flathead will suffice as a pry bar to get the plate loose. Observe the circuit board for anything unusual (ex. score marks, discolored capacitors, broken anything.) THe kind of damage most likely to occur is from heat damage. Unlikely, but it covers a base and is part of the troubleshooting method.

Most importantly, when checking the harness or any related components, make sure the connectors are not damaged.

Good luck man. Sorry I can't be real specific.

im actually thinking my fuel lines were crossed.


should fuel be able to pass all the way through if i am inputting where i should?

the way i had it before i could pressurize one side and nothing would come out the other, now when i pressurize one side it comes pouring out the other.

Fuel feeds from the fuel pump to the filter to the primary rail to the secondary rail, out the regulator and then back to the tank.

You can easily verify your injectors are pulsing by listening to them with a stethescope or through a long screwdriver.

Yes. It should flow. You problem MIGHT be that you put a JSPEC engine in the car. Those JSPEC have the pressure and return lines just the opposite where the lines connect to the engine. sounds like you just fixed your problem.

How do you know that?

i do not know it for 100% sure. but the injectors have power and fuel pressure..and im not getting any fuel into the engine. if they are pulsing they aren't allowing enough fuel for the engine to even cough.

have a loose plug that i beleive is for some sort of idle mixture screw
http://memimage.cardomain.net/member...08_67_full.jpg
it's unplugged at the moment, think it could have anything to do with it?

The only way to know if they're not actually being opened is to monitor them electronically or listen to them with a stethoscope or long screwdriver.

Have you checked that the fuel lines are around the right way? If they're wrong the FPR will block fuel flow to the rails. If they've been disconnected since the last time the engine ran, check that first.

Are the spark plugs wet or dry? Are you sure it's not just flooded? If it's cranking faster than normal, it probably is.

Are you sure you're getting spark?

Unplugging the variable resistor should not prevent starting. You should plug it in anyway...

A little background to your problems would help a lot. Has it been running? Did this problem just suddenly start? Have you installed a new engine?

And WTF did you do to your TID? Is that sealed?

this is all going into a 1st gen.

spark is present on leading and trailing, positive it isnt flooded..have fed it gasoline through a vacuum line and gotten it to run.

fuel lines are routed properly, entering the primary rail first.

the TID thing is..temporary haha

somethings grounded out in the injector system.... maybe....

Are the injector resistors present?

Do you have 12V at the injector plugs?

no injector resistors are in place. engine is 88 with red top injectors

12 volts at every injector

Tried a different ECU?

AFM plugged in? For sure?

yes afm is plugged in, even tried manipulating the door while cranking without any visible change.

only ecu i've got.

im going to leave a bunk ecu for one of the last things i try, i'm sure its something im missing or wired improperly before its hardware failure.

Here's something to try: REmove the small white plug for the lead coil assy and trail coil assy so they can't fire. You know, the plug that has the black/yellow wire that feeds pwr to them.

Now remove the CAS but leave the electrical plug on it.

Key to ON, NOT start, just ON.

Spin the cas's bottom gear. Even if there is no fuel at the injectors, you should be able to HEAR the injectors click as you rotate the CAS's bottom gear.

You disable the coil assy's so you don't mistake the firing of the sparkplugs for the sound of the injectors clicking.

Also, since you say you have 12v at each injector, you should get the meter out and ohm/ring out the other wire at each injector back to the ECU pin for that injector.

I guess you could just pull the ECU small plug off and just see if you have 12vdc at each injector pin and that would almost be the same thing. Yes, Do that plus the spinning cas.

If you still hear no clicking at the injectors by spinning the cas bottom gear and have a good circuit from the injector to the ECU.................you might make sure the three gnds for the ECU are good by pulling the ECU plugs off and reading the resistance with a meter AT the gnd pins on the PLUG on the harness. You already know the ECU ground connection is on TOP of the rear rotor housing and is in the form of a ring connector that goes into the EM harness. Gotta have that gnd . Can be verifiyed by reading the resistance of the gnd wires in the ECU PLUG hon the harness..

I'm talking series four engine and ECU.

ok, i have made quite a bit of progress of the past few days.

discovered the TPS was preventing the injectors from staying open very long so with a few adjustments i got it to crank.

however im at my next problem...it runs for around 1 second. its a sharp rev to 2krpm...then nothing. it will crank up and do the same thing yet again.

TPS adjustments dont seem to affect anything, tried blocking the BAC, no change, tried messing with the AFM door and there was a change..but it basically wouldnt crank.

what could cause the "death"? im going to see if i can figure out if it's pulling fuel or pulling spark that causes it...