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Chris, Technician
Category: Volvo
Satisfied Customers: 790
Experience:  20 Years Volvo experience, Based in Maine, Volvo certified Expert.
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1996 VOLVO 850 GLT: number 3 injector is plugged..smells..scanned

Customer Question

I have a 1996 VOLVO 850 GLT that when the number 3 injector is plugged up it smokes and smells like raw fuel, it also drinks gas ALOT but when it is unplugged it does not drink gas and does not can tell that it is unplugged but it runs alot better. I had it scanned and the codes I got were...P0303,P0137,P0201,P0203,P0204,and P1310. can you tell me what I need to do to fix it.
Submitted: 7 years ago.
Category: Volvo
Expert:  Chris replied 7 years ago.
It sounds as if the injector might have failed. The best way to know for certain, is to have a noid light plugged into the injector wires. Compare its flash signal at idle with that of the affected injector. If the affected injector noid flash is brighter, or constant...then you have a fault in the ecu or wiring, if its a normal flash pattern (as compared to another injector) then the fault is local to the injector.
Customer: replied 7 years ago.
that is what i thought but what about the other codes that i am getting....all of those could not be just because of one injector..or at least I wouldn't think that is the case.....the ecu is the computer....right? Also where can i get a noid that the same as a regular test light?
Expert:  Chris replied 7 years ago.
Yes the ECU is the main fuel computer. As to the other codes, we typically fix one problem, clear the codes then attempt repairs on other codes that repeat after the fact. A lot of times, the codes will be triggerd by another code (ie, fuel trim will be related to a mass air flow, misfire, vacuum leak, drippy injector etc etc...)

Ok I am thinking out loud right now. how about removing the vacuum line off of your fuel pressure regulator.... if you have fuel in the vacuum line then you have a bad regulator. For some reason the fuel might be getting more into injector 3 than the others.... simple quick test (do this with car running).

As to the noid light, its a test light, but it plugs into the injector harness and draws less amperage. I would not use a regular test light on it.
Customer: replied 7 years ago. more thing...where can i get a noid light.....also if the pressure regulator is bad would that cause the injector codes....and if I have the injector unplugged is that the reason I am getting a misfire.....I changed the spark plugs and I did notice that the number 3 plug was fowled out...probably because of all the fuel getting to it. One more thing.....when I pull out the oil dipstick it looks like steam coming out....what will cause that.
Expert:  Chris replied 7 years ago.
Yes if the injector is unplugged you will get misfire codes.... Yes a fuel pressure regulator can cause a number of codes, but most probable is the unplugging the injectors. Noid light can be purchased from your tool dealers (snap on, mac, matco) or most larger automotive stores can get or will carry them. As to the vapors coming out of your dipstick that is an entirely separate issue, you have too much crankcase pressure. You would have to remove your intake manifold, and replace the oil separator box, and service your pcv/flame shield.
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Customer: replied 7 years ago.
Ok...I will try your suggestions...Thanks
Expert:  Chris replied 7 years ago.
you are welcome, and thanks for accepting the answer.
Customer: replied 7 years ago.
ok....I put the noid light on the connectors and all the injectors except number 3 had the same flash pattern. The number 3 injector burned constant...and very brightly...I know you said it could be the ECU or the wiring.....could it be the injector wire!!!!
Expert:  Chris replied 7 years ago.

Well when you bypass the injector with the noid light, then you are removing the injector completely from the system.


I would look for mouse trails (droppings, food etc) The wiring is local to under the hood, from the box with the ecm down along the frame rail front edge then up by the transmission, then across the top of the injector rail. Look for where a mouse might have chewed through the wire. If you do not find such a place, the next step is pretty invasive and would require either getting an ecm out of a salvage yard, or performing a wiring overhaul at the ecm.


Just to let you know, all the injectors should have a full 12v.... they pulse with a variable ground.... the ECM provides that variable ground. So if you have a wire from injector number 3 that is.....shorted to ground then you would have a light on steady.

Customer: replied 7 years ago.
ok...i will start tracing.....question though....if the ecm is bad could that what is causeing the abs and traction light to come on sometimes and stay on for a while and then all of a sudden they go off.
Expert:  Chris replied 7 years ago.
2 possible sources for the abs light, first the ignition contact switch.... the spring is not allowing the key to rotate rearwards enough. You might notice headlights out, or turnsignals not working if that were the case though.

Second source, is a bad abs control module, these are VERY common to fail. If you need I can source a remanufactured unit. prices vary signifigantly between tracs and non tracs. Figure the parts price is about $400-$600 us dollars.
Customer: replied 7 years ago.
ok....thanks....I will try your suggestion on the injector problem...I figured it was the abs module or relay because everything else is working fine.
Expert:  Chris replied 7 years ago.
good luck.