trochoid

iTrader: (6)

I have a 88 that had a small engine bay fire and toasted some of the ecu harnes wires. After I got the car unflooded, it started, burnt wires and all.

Yesterday I put everything back together, after changing the harness with a pre-87.5 one. The gist is, I installed the low impedence harness, on a motor that has high impedence injectors.

I cannot get the motor to start. I have spark, but the fuel pump will not come on. The engine will fire when spraying carb cleaner into the intake duct. Pump will not come on even when the afm door is propped open. I have power at the fuel sending unit, but not the pump itself.

The obvious difference between the 2 harnesses is the plug for the ballast resistor. (I no longer have the burnt harness for comparision) If that is not plugged in on the pre-87.5, low impedence harnesses, I'm pretty sure the engine wouldn't start.

Put simply:

1. Do I need the post-87.5 harness for the high impedence injectors?

2. Or would it be just as easy to add the ballast resistor and change the injectors. Will I need to change the ecu and or afm also to do this.

I don't have a post 87.5 harness, changing over to the pre-87.5, for me, would probably be easier, I have those parts. (injectors, afm, resistor, ecu)

Thanks, Scott.

JLa

iTrader: (8)

The only difference on those 2 harnesses should be for the injectors, so yes you would need an 87.5+ for the different impedence injectors. Your afm should be ok so long as it reads n326, I would check to see that your ecu reads n326 as well. It sould be pretty easy to find someone parting an NA, just check the classified section and get the resistor pack, and matching injectors, and you should be good to go.

trochoid

iTrader: (6)

Funny you should mention the ecu #. I just went out and compared the 88 to my 87. The afm's are the same. both 326. The 87 has a 326 ecu, the 88 has a 327. I also found out that I installed low impedence injectors on the 88. Some days I just don't know any better.

I ran across a thread the other day that stated that if the first 3 alpha/numerics of an ecu match, then the are compatable and interchangeable, so I may be good with the n327.

I've installed a a spare ballast resistor, now to go through the FSM to figure out how to jumper the fuel pump, before I try to fire it up.

I've been working on 1st gens way too much lately and have forgotten a lot of the 2nd gen stuff.

The following link is what I have been doing since Thanksgiving weekend.

https://www.rx7club.com/build-threads-293/unvieling-12a-bp-widebody-462184/

Thanks, Scott.

Kingbob

if you are running high imp injectors on a low imp harness you just jumper the wires that go in the balast. (ECU Out (to resistor) <jumper wire> (from resistor) To Injector) You just basicly bypass the resistor because the high imp injectors basicly have one built in

HAILERS

You go to the SOLENOID RESISTOR package. You cut the SOLENOID RESITOR package wiring in half. You splice ALL FIVE wires ogether and reinstall the SOLENOID RESISTOR plug MINUS the RESISTORS (they are in the other half of the wiring you cut off). You put the resistors on the shelf in the garage for possible later use.

A N332 or N333 work in high or low resitance injector cars.

trochoid

iTrader: (6)

I have the low impedence injectors and the ballast resistor installed. With the n327 ecu. I'm not getting any fuel pressure, I do have voltage to the pump now. I don't know if it is from the jumper wire, or because I had the jumper connector plugged into the ACV.

The car has sat for 3 years since the fire and the fuel is, shall we say, skanky. Time for some Sta-Bil, Heet and fresh gas.

I found the old ecu harness, and it is not as badly burned as I thought. With some minor rewiring. I may be able to use it. Just didn't want to take off the intake, again.

trochoid

iTrader: (6)

So am I to infer that the n327 will not work with the low impedence injectors? If not can I change it out to the n326? That will be much simpler than pulling the intake and changing injectors (low impedence currently). I'd rather not slice up the only resistor pack I have left.

HAILERS

The ECU has not much to do with the problem.

The ECU sees the resistance coming from the injectors.

It cares not if that resistance is from a built in resistance in the injecotors themselves or if that resistance comes from a Solenoid Resistor Package.

See what I mean? It's not the ECU, it's the injector circuit that has to show approx 12-13 ohms (NOT an exact figure).

Either ECU will work just fine whether their in a 1986 low impedence car or a 1988 high impedence car.

Again, it's the resistance in the injector circuit BEFORE the ECU. Make any sense?

If you cut the Solenoid Resistor harness in half, there will be plenty of wire left on each half to later resplice each wire to make it whole once again.

I put some high impedence injectors in my early 87 car. I cut the Solenoid Resistor harness in half......spliced all five wire to each other......put the resistors on the shelf........plugged in the five spliced wire part of the Solenoid Resistor and lived happily ever after.

HAILERS

A N326 that you find in a low impedence car will work just fine in place of a N327 that was in a high impedence car and vice versa. More clear? Clearer?

HAILERS

Oh! Your problem is with the fuel lines most likely. Crossed? The AFM will make no difference nor the ECU.

You NEED to jumper the Fuel Pump Check connector and see if the pump runs with the key to ON.

The fuel line from the fuel filter goes to the most fwd connection on the engine (pressure and return lines).

EDIT: OOPS. I re-read your original post about the fuel pump. No power on the large BLUE wire at the fuel pump connector???????? Even with the fuel pump check connector jumpered????? Try this. Reach under the car and pull the small wire off the starter solenoid. It's a blade connector and you pull it straight off. Now put a meter on your large BLUE wire at the fuel pump connector.

HOLD the key to START. You should have battery voltage at the large BLUE wire. No voltage? Check the Circuit Opening Relay above the steering column. See if someone has installed a Fuel Cut Switch there.

No Fuel Cut Switch installed there? Then pull the relay out a see if there is 12vdc at the black/white wire with the key to ON and also see if there is battery voltage to the Black/Red wire when the key is held to START only.

trochoid

iTrader: (6)

I'm wondering if the pump hasn't died on me. I have 12v at the pump now, but it is dead quiet, even with the jumper in place and the key on.

So if the n327 along with the low impedence harness and injectors, and the resistor pack are hooked up correcly, the engine should run, Correct? If that is the case, then I need to look at the pump.

When I had the car apart, I removed down to and including the uim, I did not remove the lim nor the fuel lines. The fuel lines should be connected correctly, but I will check just in case.

I still have a few wires on the driver's side, below the spark plugs, that are toasted. The funny thing is the car did start, after the fire and before I took anything apart. Looks like another long night in the shop.

Thanks for the help, it is greatly appreciated.

88 GTU

woohoo!!!!!!!!

HAILERS

******So if the n327 along with the low impedence harness and injectors, and the resistor pack are hooked up correcly, the engine should run, Correct? If that is the case, then I need to look at the pump.******

YES!

Voltage on the large BLUE wire that connects to the Black/White wire on the pump harness means it should have run. IF you also have a good GROUND on the fuel pump connectors BLACK wire. If you have both, take the pump out of the tank. It might be rusted up. That's what I'd do in a heart beat.

trochoid

iTrader: (6)

Got ya. I have a spare pump I will switch out. Thanks again.

Yes, it is your future car that I and a friend spent 12 sweaty hours working on yesterday. I hope you appreciate it , my back doesn't.

I'll give you a call tomorrow with a parts list. So far it looks like calipers, plus all the associated hardware, including the mounting bolts, and a left front rubber brake line. Probably need the pins for the brake cables too.

88 GTU

sweet let me know what i need and i'll get the stuff together

trochoid

iTrader: (6)

Success. Fuel pump was doa.

Thanks for the help gentlemen.