Bus

OK, quick rundown:

80 US 5 speed 42,000miles. Sat for years with blown head gasket, came back to life a couple of months ago when it got an engine swap to a good 120k engine. I've been fixing items along the way, then went to SITM earlier this month. Ran great, and on the way home, I filled up with fuel, drove three blocks, had lunch came out and it cranked, started and died after a second. Towed home, been knocking out items one at a time:

Condition now, cranks, starts and dies after running for a second. Will do this two or three times and then doesn't start at all. Typical running on the cold start valve?

-Timing belt checked good, timing correct.
-Good Spark
-Battery charged,
-Fuel pump checks good, had some concerns about the supply side, had tank cleaned (and welded cracks that showed up, but that's another story). Fuel appears good.
-Fuel pump relay works properly,
-AFC relay was bypassed, no change, replaced it because I damaged the housing during removal.
-Bypassed alarm system (because I had a few inadvertant alarms go off.
-Cleaned the grounds for the injectors on both sides of the front under the headlight bar.
-cleaned contacts for sensor harness, and temp II
-checked for power at the injector harness. This is where things get weird.

I understand L jet has power to the injector and sends ground to fire. I have 12 volts on both terminals at the injector... and I can not find it going to ground ever.

My guess is a short in the FI brain, which is my plan to remove and search for proper flow into and out of the brain in the morning... but I thought I would ask for the help of the mighty listers, because, you all have helped me much in the past... and I've learned there were things I probably should have done differently already, if I'd just asked... so any advice on fixing if found bad like I suspect? Anyone ever run into power on both injector wires before? I didn't see that in any search I could think up.

a4sfed928

If the control unit is not trying to fire the injector you will have +12Vdc on both sides of the injector. Did you try this while cranking the engine over? You should try a noid light to test for a proper signal to the injector.

Imo000

Sounds like the ignition relay is fried!

a4sfed928

I think this sounds like a result of some other improper or missing signal to the EFI control unit. I would not open up the control unit until all other input signals have been verified.

Mark

What he said....

You can get noids at places like HF for cheap!

Rich9928p

Could be something totally unrelated to the fuel injection. My '83 had similar problems and it was due to a vacuum leak. Mine was an A/T - but your 5-speed could have a similar problem. There are two very large pipes out the side of the throttle body - with your 5-speed there is a vaccum diverter valve. If the valve diphraghm or the small hoses break, you will have exactly the problem you're experiencing.

Bus

Thanks for the notes, heading out to work on the shark now... I really need to get this thing on it's feet, as I've been spending too much time on my back under it and not enough driving it...

I appreciate all help, keep it coming!

hacker-pschorr

Mine did that the other day all of a sudden (after I took the plenum off). I took it back off, snugged the air valve and AFM connection, then it fired right up.

PorKen

Distributor pickup wire (AKA green wire)? Should be green, otherwise it's probably original, and should be replaced.

Jack Riffle

Check the ground for the fuel injectors. It is located on the passenger side cam cover underneath the air injectoin hose. Without this ground the car won't run. But........you have all the classic signs of a failed AFC relay. I know you said you replaced it, but getting a bad relay is not unknown. Try this.....make a 3-way jumper wire. Remove the AFC relay. Insert one end of the 3-way jumper into the #30 terminal and each of the other 2 ends of the jumper into the terminals marked #87. Turn the key and start the car. Every single time I have heard these symptoms, it has been a failed AFC relay. Doesn't hurt to try. My money says it fires up. Good Luck.

Bus

Rechecked the green wire... had a crack in the connector, but good continuity and no short to ground. inspected it and no frays or spots.. Insulated the connector and reattached.

pulled the ignition module, because I was right there and I was looking for the ground under the jump terminal. The boot was off, but the connector looked clean, reinstalled and got the boot on right.

Pulled the FI controller, checked all the grounds into it, and checked power back to the AFC relay, all good. Didn't have a way to jump the brain and check for the ground going out to the injectors though. Since I was there I pulled the cover off to look for any suspicious issues... all looked good, cleaned and reinstalled. Tested, same symptoms.

Wanted to triple check for vacuum issues like many have suggested, especially the area around the decel valve. hard to reach, so I pulled the airbox and MAF and got a good handle. The hoses are a little swelled from oil wicking into them, but they are sealed well, and the clamps are tight.

Since I have the MAF off, I'm gonna search on how to check and ensure it's correct. Then, I'm gonna go buy that noid light unless my method of checking with the DVOM was not a good way to check for switching ground... I'll double check those ground wires on the pass side cam cover, I thought I cleaned them during the engine install, but it's worth another check! THanks!

I'm off to work on it again!

Bus

Oh, and I had jumped the 30 to both 87's on the AFC relay without any luck before. Since I have 12v on both wires at the injector, and that supply comes through that relay, I'm confident that the 12v + supply to the injectors is a good circuit.

Thanks for all the help guys!

Bus

Ok, just wanted to get a few more numbers thrown in here.

MAF (or is it an AFM? barndoor type), tested exactly in spec for all test, the door moves very smoothly and there were no problems found.

Temp II checked at 581 ohms... It was about 93 degrees out there, and I think that is probably close for the temp. Checked it on the terminals, and the sensor, the info is getting through.

Cleaned and inspected grounds on the valve covers again, they're 100% fresh too. Went ahead and installed my fuel pressure gauge... I had ruled out fuel pressure after ealier checks, but it's still good to know what's getting to the engine. it's 38psi at the rail. Buttoned it all back up after a fixing a gauge related leak, and checked, same conditions.

I'm gonna go pick up that noid like, like I mentioned... but I'm 99% sure it will show no injector pulse.

Any advice?? Anybody got a spare brain they can loan me?

Michael

Bus

Picked up the noid light set this morning... nice tool.

Plugged in and confirmed that no signal is being sent to the injectors. When I had checked this before with my DVOM, I found 12v present on both pins in the harness, and neither one ever dropped to ground to fire the injector.

So, I'm at the end of my t/s tree... except for the injector brain.

One question, how can I confirm that the signal coming from the distributor for engine speed is present? Is it a voltage or an intermittant drop to ground on the green wire that gets sent to the FI controller?

Michael

Bus

Oh, and I had the Temp II readings wrong, it was something like 1830 ohms at around 85 degrees, which sounds good according to the chart.

So, going down the t/s tree in the WSM, the only thing remaining is:
Wiring harness problem, or Injection Control Unit.

I'm checking the harness by measuring all the same sensor values at the injection controller, and the one I'd like to verify is the engine speed signal (pin 1 iirc). How can I check this without an oscilliscope? maybe send the output to a universal tach?

Does anyone have an L-jet brain that they'd sell me cheap? Wish I had someone local... it might be worth driving up to see Airosey and seeing if he'll put my controller in his car... although, it's about 2.5 hours drive. Probably a unit I could buy for half the gas cost in my truck?