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Sorting electrical issues in an 280Z with 1990 TPI 5.7L


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Guys,

I haven't been active on this forum for over a year because I've been out in the garage building.  My 1977 280Z conversion to a 5.7L (350 cid) TPI V8 with World Class T5 is now complete, sort of...

After weeks of startup attempts and reading SES codes I'm not much closer to firing it up.  I did find a bad fuel pump relay and replaced that.  I temporarily relocated my battery from the cargo area back to the front to shorten the cables, just in case.  I verified 46 psi of fuel pressure at the rails, and spark at the plugs.  I've tried to start it so many times now I'm getting concerned about re-priming the oil pump.

 

I've been very careful over the two year build using the Helms and GM factory manuals as well as JTR Z V8 and TPI/TBI manuals.  My wiring connections were done well.  I've added temp-switch controlled electric cooling, Vintage Air AC, upgraded the suspension and brakes, and replaced the fuel and return lines with 3/8" steel tubing and AN-8 fittings.

 

Both cars ran when I started this project.  I think it is time to enlist the expertise of a professional auto electrician to figure out what I have missed, or what I may have wired wrong.  I kept detailed notes and made new wiring diagrams for everything I changed or added.  I kept the VATS, Resistor key, VSS, and all sensors. I've been back over all of those looking for any mistakes and don't see any.  But electrical work is not my area of expertise.

 

Can anyone recommend an electrical expert in So. Calif. (I'm willing to trailer the car) who really knows, and is willing to work on a Z conversion?

 

For those of you with years of experience, I know the 5.7L never came with the T5, so I swapped out the 5.0 for a 5.7 in the original car to sort everything out before starting the Z swap.  I even had to have it smogged that way before the swap due to bad timing (it passed).  The WC T5 is for insurance against excessive torque, but I did not use/test it before starting the swap.  It has no impact on my current problems.  I also welcome informed input from members of this forum who has successfully done what I'm attempting to do.  Any help is appreciated.

Thanks,

Steve

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sstallings:

 

What year is the TPI V8?  This will have to be known before someone is advising you.  Is there 12 volts at the distributor?  Does the fuel pump run for approximately 2 second when trying to start the engine?  Is there a 9th fuel injector for starting the engine?  Both fuel and spark are needed to start the engine.  The VATS can be disabled.  What part number is the engine computer?  All of these things need to be known.

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Rsicard,

Those are all good questions that I should have covered.  The 5.7L L98 TPI is from a 1990 Camaro using the 8-injector manifold, wiring and ECM with MAP air density calculation.  The ECM part number is 01227730 with a standard calibration ePROM.  It is not the older 9th start injector type with MAF air metering on 88-89 models.  This engine, wiring and ECM were first swapped into a 1990 5.0L L03 TBI Firebird with a manual T-5 transmission to make sure everything worked well together (since GM never offered the 5.7L and T-5, but I wanted the manual in my Z).  Then the entire engine, trans, wiring and ECM were placed in the Datsun 280Z.  I used everything but the fuel pump from the Pontiac, as a 1977 280Z already has an EFI pump capable of 46 psi.  I also used the entire JTR kit including radiator, and used a Ford Taurus dual-speed cooling fan and custom shroud.

 

Since I have to pass CA smog laws, nothing is bypassed or deleted.  It has full EGR, A.I.R., Dual Catalytic Converters, VATS/PASS, VSS, etc. all hooked up and functional.  Headers are ceramic coated Sanderson shorties, with full ceramic coated 2" exhaust to the Cats, and single 2.5" exhaust to the muffler in the stock location.  The Oxygen sensor bung was welded into the driver-side collector.  Edelbrock EGR/A.I.R. tubes were welded into the headers as well, before ceramic coating.  About the only thing I didn't re-use was the power steering -- no need.

 

I don't think I missed anything relevant this time around, but please ask more questions if I have.

Thanks.

Steve

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RSicard,

You asked a couple of additional questions that I didn't answer.  Yes I have at least 12.7 volts.  If it falls below that, I hook up my Optima smart charger to my Optima Red Top battery and top it off before continuing.  But, I moved the battery back to the cowl temporarily because I was getting barely 12.0 volts with it mounted behind the passenger seat.  I may have to get better quality cables in order to put it back there permanently.  And no, the fuel pump is not running for a couple of seconds before starting.  That is one thing that is driving me nuts.  The other is that sometimes it will crank over, and sometimes it will not.  When it doesn't, I typically get SES trouble codes, but after the 12 codes, it seems to be it seems to be gibberish that I can't interpret.  I've run through several pages of the GM manual troubleshooting an confirmed that I do have ECM grounds on the right circuits 340 & 439, and that 419 is not shorted to ground.  And I do get a constant SES with the ignition on, before starting.  But something is still keeping me baffled.

Thanks again.

Steve

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sstallings:

 

Go back to the wiring diagram for the 730 ECU and check that there is +12 volts on the proper power inputs of the ECU.  The fuel pump should be powered through a relay.  The relay should have +12 volts on one side of the relay coil.  The other side of the coil should be tied to the ECU output that turns on the fuel pump relay.  The high current normally open contacts should have one side wired to the fuse panel and the other (load side) should be wired to the fuel pump +12 volt input.  The other pump connection should go to ground (12 volt return i.e. negative side of battery).  Make sure GOOD grounds (returns) are being used or tie back to battery negative.

 

To you have a wiring diagram or hookup for the ECU?  I will see if I can find one for the 730 ECU so that I know the hookups.

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sstallings:

 

Found some wiring diagrams for 7730 ECU.  There should be two Orange (Circuit 340 Battery Feed B+) wires that have +12 volts hot from the battery.  There should be a pink/black (Circuit 439 Ignition Feed) wire from the ignition switch +12 volts when the ignition switch is ON.  Look for these color wires as they should go to fuses and to the battery and Ignition switch.

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From what I've read here it seems like your ecm is getting all the needed power and grounds since you are getting spark. The injectors get power from a separate fuse if I recall correctly. See if you have battery voltage to one pin on the injector plugs then measure resistance from the other pin to the ecm. Should be 8 pins at the ecm for sequential.

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  • 1 month later...

Guys,

Thanks for the reply posts.  Rsicard, you nailed it.  One of the two 10 gauge orange wires was not tied into the master fuse and red BAT wire.  So that was a huge help.  It now starts and idles for up to a minute before dying. I connected a fuel pressure gage to the shrader valve on the passenger fuel rail and I'm barely getting 38-40 PSI with the ignition ON before starting.  I have a brand new 60 PSI pump to replace the Datsun 46 PSI pump that had a slight leak at the casing halves.  I replaced the 16 ga. Datsun fuel pump wires with 12 ga. to match the gray wire coming from the fuel pump relay.  But, at any point before or after starting, I get a chattering (rapid clicking) from somewhere near the passenger fuel rail, and fuel pressure drops to anywhere between 20-35 PSI.  If it's running at that time, it dies. Even before that happens, if I blip the throttle, pressure drops quickly, and it may die before it recovers.  I'm assuming now I have a bad injector or fuel pressure regulator.  Does that sound right?

 

It's amazing how much can go bad on a good running engine when you let it sit for a couple of years. :)

Thanks.

Steve

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