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Old 04-10-2021, 02:02 AM   #1
Msliwa24
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Exclamation 1971 142E she will not run for the life of me.

I've got a 1971 142e she's not perfect or even close, im planning to do alot but want to get her running as a starting point but I'm stumped. She turns over and even makes a little pop and bang from the exhaust. I've replaced battery,spark plugs, plug cables, injectors, fuel pump, dizzy rotor, dizzy condenser, and dizzy contacts. I'm getting spark and fuel pressure I assume fuel as the injectors are freshly rebuilt and tested as well as they are receiving voltage. Also compression is good as well. I got her to start once with starting fluid through the intake manifold but that's it. I suspect timing but have gone through it twice now. Any ideas I'm open to anything even if I've already checked it.
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Old 04-10-2021, 05:22 AM   #2
283SD
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If it runs on starter fluid, then check the system for the fuel injection, It might be at fault.?
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Old 04-10-2021, 12:36 PM   #3
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Have you checked the wiring for the contact trigger points?
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Old 04-10-2021, 04:32 PM   #4
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Quote:
I assume fuel as the injectors are freshly rebuilt and tested as well as they are receiving voltage.
How did you confirm fuel delivery? The most direct way would be to pull the fuel rail out with the injectors attached and then crank the engine for a second or two to confirm fuel delivery at each injector. Obviously you will have to make provision to catch the fuel from each injector so that you don't precipitate a disaster.

How did you confirm voltage? Did you use test lights on each injector while cranking the engine and see them flash? The D jet has the opposite injector supply arrangement of more modern injection systems. Modern systems typically ground switch the injectors so there will be 12 v on one of the injector terminals when the key is switched on. The D jet switches on the + side. If you measure 12 v at the injector terminals with the key on; but, the engine not running then you have a wiring problem or a problem with the controller.

I agree with the comment that if you can get it to fire on starting fluid then the problem is more likely to be on the fuel delivery side. Remove the spark plugs and inspect which may give you a clue as to what is going on. Are the plugs clean and dry (no fuel delivery) or are they wet (over delivery). Since the engine will not run I assume that the plugs will be clean with no combustion products residue (soot) which would be a further indication of what the problem is.
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Old 04-11-2021, 12:35 PM   #5
Msliwa24
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Quote:
Originally Posted by 142 guy View Post
How did you confirm voltage? Did you use test lights on each injector while cranking the engine and see them flash? The D jet has the opposite injector supply arrangement of more modern injection systems. Modern systems typically ground switch the injectors so there will be 12 v on one of the injector terminals when the key is switched on. The D jet switches on the + side. If you measure 12 v at the injector terminals with the key on; but, the engine not running then you have a wiring problem or a problem with the controller.
I tested the injectors with a test light but am going to retest them as I may have tested them improperly. Just to clarify on the system in the 142 with one end of the test light grounded I should get a 12v signal for one pin in the injector plug while cranking but only while cranking because on this old system it's actuated by sending power rather then completing ground connection.
Thankyou for your help
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Old 04-11-2021, 05:33 PM   #6
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Yes, one terminal in the injector plug is grounded at the connection on the intake manifold. The other terminal receives switched power from the controller. ON my 1971 142 E, each wire in the D Jet harness has a number that is repeatedly printed along its length (you may have to pull the harness covering back a bit to spot it). If you have a Volvo factory service manual and you look at the section covering the D jet which has an external wiring diagram for the D jet (not the complete wiring diagram for the whole car) which indicates the number of each wire and its function. With this info you should be able to figure out which terinal at each injector is ground and which terminal is switched power.

The D jet injectors are low resistance injectors, about 2.3 ohms as I recall (or maybe 3.2 ?????). The controller has an internal 6 ohm resistor which drops the voltage so that the injector receives about 3 - 4 volts when it is switched on. If you do your voltage measurement with the injector connected be prepared to only measure about 3 - 4 volts at the injector terminals. If you disconnect the injector to do the measurement and measure on the correct terminal you will see a short 12 volt pulse when the controller fires the injector. The voltage is high because there is no injector current flowing through the internal voltage dropping resistor. During cranking, the injector pulses are probably in the order of 0.002 - 0.003 seconds long which makes the test light the preferred tool for checking injector operation. Just select the test light voltage on the basis of how you do the test. Injector connected - you need a 4 volt test light. Injector disconnected - you need a 12 volt test light.

As an aside to the injector testing, have you confirmed that the ignition is correctly set up, particularly that you haven't got 1 - 4 and 2 -3 reversed. More people manage to do that than let on! If you have a timing light, that is probably the easiest way to confirm that #1 is firing at the correct 10 deg BTDC mark on the front pulley.

Last edited by 142 guy; 04-11-2021 at 05:41 PM..
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Old 04-13-2021, 02:12 AM   #7
Msliwa24
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I will have to look into these trigger points as well

Last edited by Msliwa24; 04-13-2021 at 02:19 AM.. Reason: Double posted
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Old 04-13-2021, 02:16 AM   #8
Msliwa24
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Quote:
Originally Posted by 142 guy View Post
If you have a Volvo factory service manual and you look at the section covering the D jet which has an external wiring diagram for the D jet (not the complete wiring diagram for the whole car) which indicates the number of each wire and its function. With this info you should be able to figure out which terinal at each injector is ground and which terminal is switched power. If you disconnect the injector to do the measurement and measure on the correct terminal you will see a short 12 volt pulse when the controller fires the injector. The voltage is high because there is no injector current flowing through the internal voltage dropping resistor.
This was all very helpful thank you. As an update I found time between work and haveing daylight and found the injectors are not getting power I used the factory service manuel to trace the injector power wires back to the ecu and also tested it at the pin there and still had no voltage while cranking and then ran out of daylight.

My thought is that either the ecu is not getting power, the ecu is toast (not impossible my any means but I've heard these old ecu can stick out the test of time), or there is something that is stopping the ecu from sending power to the injectors.

I am curious if these old ecus would stop injectors based on reading from a specific sensor ie. Pressure sensor, air temp. In addition I also whent through all the timing again and it all appears to be hooked up correctly but will still have to check the trigger points following through the manuel.

Thank you again for all the help and information and I apologize if any of this comes off as stupid questions I just want to make sure I'm going in the right direction.
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Old 04-16-2021, 01:27 AM   #9
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When you turn the ignition key to the run position does the fuel pump start up and run for about 2 seconds and then shut off? That is the fuel pump prime cycle to pressurize the fuel system before attempting a start. If the fuel pump is going through that prime cycle then the controller is getting power. If the fuel pump is not going through its prime cycle, check to see if there is +12v on both controller terminals 16 and 24 when the ignition switch is in the run position. If you don't have +12 v, chances are your main relay is dead or you have a broken connection some place.

If you do have +12v on both terminals or your fuel pump is going through the prime cycle then you may have a problem with the portion of the controller that controls the main injectors. Clearly, if the pump primes then that portion of the controller works and if the pump runs when you crank the engine I think that indicates that the contacts in the distributor and the RPM input circuit in the controller is working (I have to double check on that). The 1971 140 has a cold start valve that is controlled by the controller. That cold start valve should inject enough fuel into the manifold that you should be getting some kind of 'start' activity (it won't run because the cold start shuts off when you stop cranking). Perhaps check to see if your cold start valve is operating during cranking. If it isn't, then that could be a sign that something is up with the controller.

If you determine that the controller appears to be dead, give planetman @ High Performance Auto a call. He may be able to set you up with a replacement controller or he may have the original Bosch tester for the controller and can check it out. As an observation, the controller is usually the last thing that dies on a D jet system so don't be in a rush to toss it in the garbage.
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Old 04-16-2021, 03:47 PM   #10
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You've gotten a TON of great advice here, but if you're a little more of a visual learner, pictures and a workflow can really help. Here's a link to the Volvo Fuel Injection Fault tracing handbook. It has cartoon illustrations and very short, clear explanations. It's helped me many times.

best of luck
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Old 04-16-2021, 04:18 PM   #11
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Another quick check you can do is to turn the key on, don't start it (not a problem in your case hah, sorry). Then go stand up by the motor and open the throttle by hand. It's not really a TPS like normal (although there is a switch that closes at idle) - it just slides across an alternating set of contacts as it opens and fires off injector bank fires/cycles. In normal use, these are 'extra' injector firing cycles, normally supplied by the contacts in the distributor base - and they act as a sort of simple 'analog' acceleration enrichment.

So as you open the throttle, you should be getting injector fires. With the motor off, nice and quiet, you should be able to hear the injectors clicking. As mentioned above, the way D-Jet injectors hook to the fuel rail, you can pull the whole rail off the head, leaving the wires and hoses all attached - just undo the sheet metal collars that hold the injector base to the aluminum mounts on the head, give the all the injectors a little twist to break the stiction, and then gently pull the whole thing off. Set up something to catch the fuel (like the bottom of 4 aluminum cans?) and then try it again.

You want all 4 of them to be making nice little spritzes, relatively equal in pattern and volume. My last D-Jet car had a habit of having the injectors stick if it sat around for a couple of months at a time. Everything else would be fine, but they'd just be mechanically stuck a bit, too much for the electrical windings to overcome. I'd pull the rail off the head, then *gently* press on the pin/pintle at the nozzle/tip. Once that was broken free, they'd be back in business, and fresh fuel flowing through them would clean out the residual gunk that was sticking them in no time.

And then there was the one time that I spent an embarrassingly long time diagnosing this and that (I suspected the pump! or the pump relay!) before I noticed that the main power supply wire (attaches right to the 12V+ battery terminal) had come undone. Yeah, no power to the ECU, not much is going to happen. If you get a priming pulse of the fuel pump, however, then the ECU is firing up.

I did have a D-Jet ECU die once. Just driving along, 1/3rd of a mile from my house, no problem, running fine, then dead as a doornail. I checked various things, nothing seemed wrong, pump still primed, just no injector firings (either while cranking or when opening the throttle). We happened to have a parts D-Jet car then, so I swapped ECU's, started right up.
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Old 04-24-2021, 07:44 PM   #12
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thanks jrv6a for that info
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