North American Turbocoupe Organization



What causes the injectors to pulse
Littlehoe Offline
Junior Member
#1
I have a new to me 87 turbo coupe. I bought it not running but don't know why. I have spark and fuel to the rail, however when I test lighted the injector I was only getting a very faint and not steady pulse. So what tells the injector to fire/pulse/open?
1987 Turbo Coupe, Auto and running... Yippeee
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boboli Offline
Member
#2
Injectors are grounded by the ecm. Ecm determines when to ground based on signal from the tfi on the distributor. Do the injectors have 12volts @ them with key on? Maybe a bad fusible link or the ignition switch is falling a part. Check the ignition switch no matter what. They are notorious for problems. Change it for cheap insurance
1988 turbo tbird, 5spd, 140k, all stock except boost control valve.
1986 dodge omni glh turbo, 111k, my money pit.
1989 mustang Lx 5.0 convertible, tropical yellow/ tan interior, 1of only 144 made, 164k, aod, all stock including overheating TFI!
89 Jaguar XJS convertible, LT1 conversion, now fighting the prince of darkness (aka Lucas electronics)
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zip Offline
Member
#3
Welcome to NATO!

The injectors are controlled by the computer. They are supplied ground from pins 58 and 59. Have you checked the signal with a noid? When you checked fuel pressure did you use a gauge? If not did fuel shoot out of the valve as if there was good pressure or did it just run out a bit?
Matt
86 TC 5spd:QH/SD,Walbro190,CFI 52#, AFPR,WB,FMIC,3"dp to axle, .63 T3, E6,Stock Longblock.
Shelf:N/A 2.3, Die grinder, Carbide Burrs.
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Littlehoe Offline
Junior Member
#4
No gauge on fuel pressure, but I can hear the pump cycle when you turn the key on, as well there was a spray of fuel that came out of the Schrader valve when I pushed it. As for the injectors, I have 12 volts on the red wire and then I used a test light and had a minimal bleep of light when turning the car over.

I have spark at the plugs, so I am at a loss. The guy I bought it from thought maybe the timing belt jumped and that is why it died on him. But he really had no idea. I lined up the crank pully to the tc and the notch on the cam pully lines up with the middle mark however when I removed the distributor it appears the rotor is possibly just before the number one position however it appears very close. The odd thing is I don't get any sputtering, no backfires, nothing just turns over and over.
1987 Turbo Coupe, Auto and running... Yippeee
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Pete D Offline
Administrator
#5
Welcome to the board.
Pressing the schrader valve to gauge fuel pressure is not a valid way to do it.It may have pressure but not enough. It takes around 20 psi just to run the engine You really need to put a gauge on it and go from there. I would recommend you run the fuel system diagnostics:
http://turbotbird.com/techinfo/Fuel_Syst...ostics.htm

You could also try a couple shots of starting fluid. It should at least fire/sputter if timing is close.



Pete Dunham


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Littlehoe Offline
Junior Member
#6
Well I tested it with a gauge and fuel pressure is good, so I investigated more... and... turns out the timing jumped. after disassembly I found the timing belt has a couple teeth missing and a few near it just fell off when I rubbed my thumb on them. So a new timing belt and tensioner is on order and should be here tomorrow.

Thanks to you all for the help.
1987 Turbo Coupe, Auto and running... Yippeee
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