Hey guys, I’ve been rebuilding an 86 244 DL and I’m so close! I’ve got a lot of details so I’ll try to give a thorough rundown.

• New computers, ECU and ICU
• New Distributor (w/ Hall effect sensor of course)
• All new external engine electronics (oil pressure sender/coolant temp sensor/fuel injection temp sensor)
• New spark plugs, touched to block and visually confirmed spark during cranking.
• New fuses. Confirmed good resistance across fuse above fender.
• New fuel system (tank/fuel sending unit/in-tank pump/main pump/fuel filter/lines/cleaned rail/ injectors). While cranking, main fuel pump runs and confirmed fuel after the rail at the fuel pressure regulator. (The fuel gage will not measure fuel in tank. It used to when I first replaced the sender).
• If you spray starting fluid in the throttle, the engine runs until it burns up the starting fluid.
• I’ve tried cranking it with the MAF unplugged, attempting the “limp home” mode I’ve read about in case the MAF is bad.
• I put voltage across pin 13 on ECU and a fuel pump relay pin to simulator injectors firing and the injectors opened *audible click*
• I’ve measured resistance across pin 1 of ECU and RPM Signal pin on ICU and it was 0.3ohms. I attempted to measure voltage across the same wire while cranking and found none. I’ve read you need an oscilloscope to see the square wave, so this may not indicate anything.
• I’ve also tried to read voltage across the injectors while cranking and found nothing. Again, I’ve read you need an oscilloscope and this may not indicate anything.
• I’ve read voltage across fuse #4 while cranking but I don’t remember what that voltage was though.

This is one of those “I’m losing my mind at this point” posts, so any help would be appreciated. I feel like I’m just missing some single key detail that I don’t know to look for.

 

It's hard to diagnose a problem after such extensive renovations--many new parts may be substandard or faulty. What got my attention was the fuel gauge not reading, but it did at first? Obviously it is a fuel issue; have you measured the pressure at the rail?

 

1986 was in the middle end of the 'biodegradable engine harness' years. has the main engine harness been replaced ?

 

I am looking into the fuel level gauge not reading. No I have not checked pressure on the rail. I’ll do that next week when I come back from out of town when I get a gauge.

Pierce, the main harness has not been replaced but I’ve inspected it and no damage seems to be on the harness inside the cabin. The insulation of the wiring within the engine bay has degraded and I’ve replaced accordingly with equivalent wire. Four wires on the engine harness were biodegradable and they were replaced (oil pressure sender/coolant temp sensor/two positive alternator wires). No wires were damaged or replaced on the ignition harness.

 

its primarily the engine harnesses that get damaged accelerated due to heat... and the individual wire insulation often fails inside the outer black casings where you can't see it.

all 4 fuel injectors should be getting power from the fuel system relay on one pin, and the other pin of each of the injector connectors are tied together, and run to the ECU... the ECU 'grounds' that signal to fire the injectors.

the fuel level gauge is wired pretty much straight to the instrument panel... the sender is a variable resistor to ground, the instrument panel applies a voltage to it and measure the resultant current.

 

I’ve pulled the complete engine harness, cut into the black casing, replaced those four wires, and rewrapped the harness.

I have seen the four injectors tie into the single pin on the relay. As I mentioned, I sent a voltage through that pin on the relay with the “ground” on Pin 1 on the ECU and the injectors opened.

 

but you said you saw no power at the injectors when cranking with it all hooked up normally ?

 

Yes. Again, it was a multimeter and I have heard that you need a specific setting / multimeter or an oscilloscope to see the pulses on the injectors.

 

yeah, best way to 'see' injector pulses is a thing called a 'noid light'. these come with various pinouts, so you can plug them directly between the injector and the harness, and they blink when the injector is fired. these are Bosch injectors, and I'm pretty sure most all bosch injectors use the same plug... the kits aren't expensive, https://www.autozone.com/test-scan-a...ece/948078_0_0

 

the other thing about biodegradable insulation... the more it gets disturbed, the more likely it will crack and fail after its started to go brittle from age and heat.

and all that part swapping, phew, thats a lotta cable disturbing.

the good news is, Dave Barton, a volvo enthusiast who's turned his hobby into a parts business, has high quality custom made new harnesses made for many of these models, including yours
https://www.240turbo.com/volvoharnes..._240_non-turbo

and the ignition harness,
https://www.240turbo.com/volvoharnes...ml#240ignlater

 

Update:

I bought a fuel pressure gauge and attached it to the fuel rail output. Manually firing the fuel pump, the fuel pressure got up to 50psi. I turned the key to “on” and one half of the fuel pump relay kicked on like it should. I cranked it and the other half of the fuel pump relay didn’t close. Neither the fuel pump nor the injectors ran. I’m confused, because the computer has been running the pump every time I cranked it until now. Again, if I manually close that relay, the fuel pump runs.

I went back and checked a few things like the fuses, including the one above the fender, the air flow meter, the TPS, and that I’m getting spark.

I still can’t confirm the ignition computer is communicating to the ECU.

 

the fuel pressure for a LH2.2 240 with the pump on but engine not running should be around 36 PSI, I think. if its higher tahn that, the fuel pressure regulator isn't working properly.

 

I removed the fuel pressure regulator and attached a fuel pressure gauge in its place so that I could regulator the pressure manually with the gauge relief valve. I wasn’t sure if the regulator worked. My point of saying it reached 50psi was to say the pump could reach the proper pressure, but I had to fire the pump manually.

I’ve heard there are several reasons the ECU won’t fire the injectors/pumps.

 

You say you have spark, so the ICU is seeing the hall sensor and generating timing for the ignition coil...

the ICU sends a signal to the ECU with this same timing, and the ECU uses this to decide the engine is turning, so it can turn on the fuel pumps, and fire the injectors... looks like its a grey wire from ICU pin 8 to ECU pin 1 (per the Volvo 1986 greenbook for 240 w/ LH II EFI and Chrylser ignition)

 

I'm having a very similar problem on my '86 245. A rodent chewed through a wire to the distributor. After I fixed that the car still wont start. If I squirt a little gas into the intake, it will run for a second, so I know it has spark. The resistance of the injectors is 8 ohms; manual says it should be 4. I'm not getting voltage to the injectors when I crank. I listened with a stethoscope and couldnt hear them clicking. I've run tests at the ECU connector and things seem to be working properly. Any suggestions? I'm thinking about pulling the harness out and cutting it open to inspect it.

 

I just went out and tried another test. with all injectors unplugged, the resistance from 13 to the relay wire is zero. I plugged in the rear injector: 20ohms. plugged in the next injector: 12 ohms. Nextinjector 12ohms. last one: 9 ohms. So I know the wires to the injectors are not broken or shorted. but the manual says resistance should be 4 ohms. I've applied 12v to each injector and heard a click so I know they're all working.

 

I've even tried another ecu I have lying around and it doesn't start.

 

turbo and nonturbo have different injectors. the turbo injectors are low impedance (resistance), and there's a series resistor pack near the front left fender on turbos thats in series with the injectors.

 

Take a small tack hammer and lightly tack each injector 3-5 times. Try to start. If that doesnt work try again. I bought my 86 245 from a guy who literally had done every thing you have and could not get it running. I had it for 5 days and it was purring. Previous owner was kinda pissed..