What would cause NO injector pulse?
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Have you checked the fuses? You might need a noid light to see if the injector harness is pulsing. I have used a light tester and found that it will show when the injectors pulse. The distrubitor sends pulses to the ECM inturn send it to the injectors depending on RPM and engine load/sensors.
Team Owner
Joined: Jan 2003
Posts: 20,253
Likes: 219
From: Summerland B.C. Canada
Melting Slicks
Joined: Aug 2003
Posts: 3,377
Likes: 387
From: Lakeville MI
Wide open throttle, or stuck or failed high tps.
Crank Fuel Pulse Width Multiplier vs TPS:
%TPS Multiplier
0 1.00
12.5 1.27
25 1.27
37.5 1.39
50 1.53
62.5 1.64
75 1.80
87.5 0.00
100 0.00
Note the 0.00 multiplier at 87.5 and 100% TPS. This is intended to help clear a flooded engine, if you open the throttle.
Crank Fuel Pulse Width Multiplier vs TPS:
%TPS Multiplier
0 1.00
12.5 1.27
25 1.27
37.5 1.39
50 1.53
62.5 1.64
75 1.80
87.5 0.00
100 0.00
Note the 0.00 multiplier at 87.5 and 100% TPS. This is intended to help clear a flooded engine, if you open the throttle.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
If this happens.
then
Is not the issue.
Did you follow the steps I pm'd you?
Originally Posted by DrEvil11417
the engine cranks - there is fuel pressure, spark, and voltage to the injectors
Originally Posted by redrose
vats
Did you follow the steps I pm'd you?
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Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 14
From: backwoods upstate ny
vats module does two things:
1) circuit ''a'' closes ''enable starter'' relay.
2) circuit ''b'' generates 30 hz sink of ecm signal to enable injectors.
an input error to the vats module (wrong key resistor,etc.) will result in both ''a'' and ''b'' circuits not going to ''permit'' mode.
an internal failure of the 30 hz generating circuit can leave the injectors grounding transistors inactive....with ignition key on, check dark blue wire between vats module and ecm (need to know year to get ecm pinout)...should be approximately 2.5 vdc, if its 5.0 volts or less than 1.5, there is an issue...
1) circuit ''a'' closes ''enable starter'' relay.
2) circuit ''b'' generates 30 hz sink of ecm signal to enable injectors.
an input error to the vats module (wrong key resistor,etc.) will result in both ''a'' and ''b'' circuits not going to ''permit'' mode.
an internal failure of the 30 hz generating circuit can leave the injectors grounding transistors inactive....with ignition key on, check dark blue wire between vats module and ecm (need to know year to get ecm pinout)...should be approximately 2.5 vdc, if its 5.0 volts or less than 1.5, there is an issue...
Thread Starter
Racer
Joined: Jul 2004
Posts: 389
Likes: 2
From: Howard Beach, NY
there was no dark blue wire from the VATS to the ECM that i saw, but there was a white one that reads "MFS/VATS" that has about .650 volts at the computer pigtail when the ignition is in RUN (labelled as PPL or WHITE on diagram)
...though the diagram shows a purple wire coming off the VATS decoder module going to the ECM. i didnt see any wire coming off the theft deterrant module to the ECM
...though the diagram shows a purple wire coming off the VATS decoder module going to the ECM. i didnt see any wire coming off the theft deterrant module to the ECM
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 14
From: backwoods upstate ny
like G. K. sez--there are errors in the service manual--86 red cover, page 6E3-A-4 and 6E3-A-7 call for a white wire...pages 8A-133-6 thru12 call it purple....whatever color, it runs to ecm pin B6 on the -165 ecm.
my apologies, i currently have a 90-91 ecm -727 on breadboard and that one has dark blue , runs to ecm pin B6 there too.
been doin nasty things lately to bench test ecm's, smoked several so far...i've found that around 2.5 volts on the wire from pin B6 to vats sink will pulse the injectors, no injector pulse below 1.5v, 5.0v indicates my vats signal generator is not awake....this correlates with the info in the service manuel.
my ''final'' vats simulator design just did 100+ hr shakedown on breadboard , if you have a soldering iron and want the diagram, pm me....there are also recently a couple on-line vendors , apparently they also use the good ol 555 chip too (i can't recommend them until i try one tho)
my apologies, i currently have a 90-91 ecm -727 on breadboard and that one has dark blue , runs to ecm pin B6 there too.
been doin nasty things lately to bench test ecm's, smoked several so far...i've found that around 2.5 volts on the wire from pin B6 to vats sink will pulse the injectors, no injector pulse below 1.5v, 5.0v indicates my vats signal generator is not awake....this correlates with the info in the service manuel.
my ''final'' vats simulator design just did 100+ hr shakedown on breadboard , if you have a soldering iron and want the diagram, pm me....there are also recently a couple on-line vendors , apparently they also use the good ol 555 chip too (i can't recommend them until i try one tho)
