I have an '88 n/a 327ecu and harness that came out of a running chassis.
Engine is out of same car but has S5 intake installed.
Receiving chassis is an '87 GXL.

receiving chassis is fully assembled and wired.

When I turn the engine over, it does nothing. Spray brake clean in the Afm and the engine comes alive.

You can hear fuel flowing in the fuel rails and hear the pump running. Spark has been confirmed on both leading and trailing coils plus injectors are clicking when spare cas is spun by hand. I've re-stabbed the cas countless times and am confident the timing is right (both current and spare cas have been used).

Spare ecu has also been used.

I've replaced the injectors with known working high impedance injectors.
Checked all grounds and injector clips.

The only thing that has come to mind now is fuel pressure. But I am at a loss as to why I get nothing when I turn it over. Not even a sputter.

Thoughts?

Thanks!

 

Have you confirmed the presence of fuel w/key to on and key to start or just one of the two?

 

when you say it has an s5 intake,do you mean that it now has an s5 AFM wire into the s4 harness?

 

- check connection to AFM
- check AFM operational and compatibility with ECU
- check vacuum and FPR
- check grounds (main ground from ECU that connects to engine especially)
- jump the fuel pump, turn the key to ON, and check fuel pressure

 

Yes. It has a priming pulse and when you start, the flapper in the AFM moves and the pump turns on.

No. I have the lower/mid/upper dynamic chambers from a S5. All peripherals and electronics are S4 (AFM TB ALT etc etc).

- AFM is working or at least the flapper is moving and turning the pump on
- AFM is a 327 which matches the ECU, map sensor etc.
- Will do today.
- Checked! The ground under the intake for the ECU is clean and has good continuity as verified by my snap-on circuit tester.
- I'm going to pick up a brass fitting to check fuel pressure today.




If it is bad fuel pressure, wouldn't i get a sputter as the fuel dribbled into the housings?

 

Just because it hasnt been asked yet, did you try swapping the fuel lines?

 

+1

are the fuel lines swapped?
and just because you hear the pump running and some noise in the rails doesn't mean squat, do you have fuel in the tank and fuel in the lines? put some gas in the tank.


you'll be kicking yourself in the *** for a week if it is either of these.

if you drained the tank and only put 2 gallons in it for example, it takes about 1.5gallons to even get the sock on the pump barely wet with fuel. with the fuel circulating through the system you have about a .2 gallon buffer which could have easily evaporated in a few days or sucked into the engine with only a few cranking cycles. i see this a bit, 2 gallons in a dry tank is not 2 gallons that the engine has available to it.

 

Did you grind the block to get the intake to fit? If not, the interference will cause a large vac leak.

Also, are you using the 87 injector resistor pack with your high impedence injectors? You should only be using one or the other.

 

the S5 lower intake will bolt right up to a S4 block without any modification. the EGR port may be a little iffy to try to fit under the UIM though. that could be the issue with the LIM to UIM not seating properly. i'd grind the UIM to make sure it is clearanced versus modifying the block.

another trick would be to use a inset phillips screws to mount the block off plate, that may give enough clearance.

 

And I believe clicking injectors don't always translate into flowing injectors.

 

I double checked the fuel lines and this is how they are routed (i do not have the rats nest):

Fuel filter to front of primary rail
Rear of Primary rail to Rear of secondary rail
Front of secondary rail (@FPR) to return line on firewall

You're right. I do not know how much is in the tank. There was fuel in the tank and I added some fresh fuel but not a whole lot. I do have fuel in the rails as when i switched the injectors, it poured all over the place.

One thing i haven't done yet tonight is pull the lines and see how much pressure i have. Someone has mentioned to be that the sock might be dirty and be starving the pump causing low pressure.

Yes.

It is an '88 N327 ECU and harness that does not use a resistor pack.

The second set was bench tested before they were installed.


Thanks for everyone's comments thus far!
Cheers.

 

Vacuum during cranking at FPR is about 3-4 in-hg

Max fuel pressure is around 60psi

regulated is about 29 or so during crank. (gauge bounces with inj pulse)

What i have found is that when i went for max pressure, i decided to turn it over and see what happens. the pressure dissipates with each inj click so i now know the injectors are firing...still perhaps not at optimum performance.

I'm going to try and start it with a mix of tranny fluid tomorrow in case i flooded it with the ether and now it has fuel wash.

I am also going to redo my compression test. I did it before i put the engine in the car but stranger things have happened.

 

if you're seeing pulses then you have a severely low volume output issue from the pump, or it's mainly pumping air.

 

Ok, i've been meddling around with this for a couple weeks. I'm ready to throw in the friggen towel already.

I pulled the pump out to check the pickup and it all looked fine. pulled the screen off, it was clean with no residue or gunk. slosh bowl was clear of debris and is free of rust.

put the pump back in the tank, turned the key and voila. it fired up.

that's it. no other changes from our discussions above.

So i run it off and on all weekend. no issues. starts runs and does it's thing. Left it for the work week plus a few days...go back to start it...nothing. back to square one.

Replaced the pump with a pump out of another car that runs...no dice.

Replaced the AFM with third one i have. no change...

What am i missing?

 

I'd check the wiring between the chassis harness (probably a plug clipped to the shock tower) and the fuel pump, especially the transition through the bulkhead to the pump itself.

Your problems seem too random to be mechanical but are exactly the sort of "hide 'n seek" bullshit that electricity really goes for.