1990 GT No start No Spark
#1
Rennlist Member
Thread Starter
1990 GT No start No Spark
Knowns:
With ignition in the start position:
Starter spins - plenty of juice
Injectors click
No spark
Fuel smell from the exhaust
No needle bump
9-10 volts at the coil with ignition on
New CPS
New front engine harness
Injector harness ends all replaced including CPS harness end
Verified continuity from computer to the CPS harness end
Swapped in new 53 for EZK relay (one with fuse tester)
12 volts go to the CE panel
11ish volts at the EZK relay - 87 and 30
Swapped computers for known good GT computers
New coils - swapped in used one same results
I always assumed for fuel to be present and injectors to click meant the CPS was ok.
With ignition in the start position:
Starter spins - plenty of juice
Injectors click
No spark
Fuel smell from the exhaust
No needle bump
9-10 volts at the coil with ignition on
New CPS
New front engine harness
Injector harness ends all replaced including CPS harness end
Verified continuity from computer to the CPS harness end
Swapped in new 53 for EZK relay (one with fuse tester)
12 volts go to the CE panel
11ish volts at the EZK relay - 87 and 30
Swapped computers for known good GT computers
New coils - swapped in used one same results
I always assumed for fuel to be present and injectors to click meant the CPS was ok.
#2
Rennlist Member
Thread Starter
We also swapped the two ignition amplifiers for known good ones.
#4
Rennlist Member
Thread Starter
#5
Rennlist Member
Thread Starter
Verified wiring order on the replacement CPS harness end. Matches an 89 parked next to the GT.
#6
Former Vendor
Did it run before the work was performed?
#7
Rennlist Member
To add more details, this car hasn't ran for at least 16 years. The engine was out of the car and the bottom half had been put in an S4. There was no LH/EZK harness in the car. It literally came in about 10 boxes, and we have spent last year putting car back together. Has a Sean Ratts 14 pin harness, all engine connectors on LH/EZK harness were replaced. CE panel was gone thru and deoxit used, all fuses and relays replaced. All grounds were cleaned, and new hardware used. It also has "new" MAF.
I am leaning to something simple that we are overlooking but of my 4 928s, i have never started from ground zero without some level of known good.
I am leaning to something simple that we are overlooking but of my 4 928s, i have never started from ground zero without some level of known good.
Trending Topics
#8
Addict
Rennlist Member
Rennlist Member
Join Date: Oct 2003
Location: Gone. On the Open Road
Posts: 16,572
Received 1,687 Likes
on
1,096 Posts
What’s in relay slot XVII and XVIII?
#10
Rennlist Member
Thread Starter
#11
Former Vendor
To add more details, this car hasn't ran for at least 16 years. The engine was out of the car and the bottom half had been put in an S4. There was no LH/EZK harness in the car. It literally came in about 10 boxes, and we have spent last year putting car back together. Has a Sean Ratts 14 pin harness, all engine connectors on LH/EZK harness were replaced. CE panel was gone thru and deoxit used, all fuses and relays replaced. All grounds were cleaned, and new hardware used. It also has "new" MAF.
I am leaning to something simple that we are overlooking but of my 4 928s, i have never started from ground zero without some level of known good.
I am leaning to something simple that we are overlooking but of my 4 928s, i have never started from ground zero without some level of known good.
Even if the relay board is from the original car, I'd still verify the part number...the '89, '90, and '91 boards are all different.
If that is correct:
I'd start in the middle and make sure that there is 12 volts coming out of the fuel pump, LH, and EZK relays (on the "87" posts of each relay) when the engine is cranking...and move in whatever direction you need to move, from there.
#12
Addict
Rennlist Member
Rennlist Member
Join Date: Oct 2003
Location: Gone. On the Open Road
Posts: 16,572
Received 1,687 Likes
on
1,096 Posts
Well, that was my Hail Mary pass. Baring the not-so-obvious-but-obvious(*), I would probably go to the basics ...
(*) the not-so-obvious-but-obvious is basically making sure you have everything plugged-in, fastened and/or connected. Visually follow all the connections from computers to injectors and plugs. Did you forget something? Engine ground strap? Coil wires to caps? Etc.
You can rule out the CPS since having injectors firing means that the CPS is sending a signal to the EZK that is sufficient for it to tell the LH to begin fueling ops..
#13
Nordschleife Master
No clue what is causing the issue, but you might think about yanking either the LH or fuel pump relay while trouble shooting. If you are cranking and getting fuel but no spark, you are going to wash off the cylinder walls and get fuel in the oil.
Neither are good things.
Neither are good things.
#14
Rennlist Member
Thread Starter
We pulled the fuel pump relay once we knew we have fuel and injector pulse.
#15
Nordschleife Master
Glad to hear it. I tend to make 'Captain Obvious' comments.
All to often, I get a "Thanks, I didn't think of that'" in response.
Not trying to say you don't know what you are doing, but we can all miss stuff like that.
All to often, I get a "Thanks, I didn't think of that'" in response.
Not trying to say you don't know what you are doing, but we can all miss stuff like that.