how to check digifant ecu. for correct voltage

i have a 81 vw pu. i put a 1.8 with all of the wiring including dash from a 87 golf i also changed the grill. it looks so cool a golf truck. but one problem. it will crank only when i spray gas in the intake. someone before me had tampered with wiring harness trying to put in a alarm. i suspect. my unit is not getting voltage like it should. no voltage at injectors. but it fires at plugs. ineed help with checking voltage where it should be going in to the unit. thank you

An '87 Golf should have had CIS not Digifant. Digifant would have an electrical air flow meter attached to the air filter box w/no braided metal fuel lines. Or, is this a CIS or CIS-E system? CIS has a black fuel distributor, CIS-E has a silver fuel distributor.

no this is digifant 2 i am sure. it has mass airflow. the digifant controler is located by the wiper motor. i installed it all my self this truck had no wiring inside or out. i transfered all of it from the golf . i think digifant was put in the golf in what they call 87 and a 1/2 thank you.

An '87 Golf should have had CIS not Digifant. Digifant would have an electrical air flow meter attached to the air filter box w/no braided metal fuel lines. Or, is this a CIS or CIS-E system? CIS has a black fuel distributor, CIS-E has a silver fuel distributor.
it is digifant 2 i am sure

I have seen stuff about those strange Digi systems on '87's, There's not much info on them, I assume they're similar to later models. CIS (& E) went to '89 and Digi didn't officially take over until '90. Have you checked the fuel pressure? It's fairly simple on Digi, test port is on the end of the fuel rail w/7mm plug. I have had problems with the injector harness connector also. Power should be on the red wire with the same source as the fuel pump . Does the fuel pump run for a few seconds when the key is turned on? If it does you can wire them directly to be hot with the pump. By the way, that red wire may change to red w/black trace by the time it runs to the fuse panel.

I have seen stuff about those strange Digi systems on '87's, There's not much info on them, I assume they're similar to later models. CIS (& E) went to '89 and Digi didn't officially take over until '90. Have you checked the fuel pressure? It's fairly simple on Digi, test port is on the end of the fuel rail w/7mm plug. I have had problems with the injector harness connector also. Power should be on the red wire with the same source as the fuel pump . Does the fuel pump run for a few seconds when the key is turned on? If it does you can wire them directly to be hot with the pump. By the way, that red wire may change to red w/black trace by the time it runs to the fuse panel.
so the voltage to the injectors is not regulated by the system. i may be thinking wrong but it seems like if you wired 12 volts constant from the fuel pump the injectors would spray wide open. no mater where the throttle position was. i do have a mass air flow sensor and knock sensor but i will try anything to get it going. please reply thank you

The injectors are controlled by the ECM on the ground side, they have power at all times w/key in the on position. There are two ways the ground can be controlled: On Digifant I systems they are individually controlled by the ECM with seperate grounds. Digifant II uses one ground & fires all at the same time. An easy way to tell which you have is if there is an external ignition control unit it is Digi II. As I am unfamiliar with what system you might have keep an eye out for external resistors, some injectors operate on three Volts & you would not want to bypass the resistors.

The injectors are controlled by the ECM on the ground side, they have power at all times w/key in the on position. There are two ways the ground can be controlled: On Digifant I systems they are individually controlled by the ECM with seperate grounds. Digifant II uses one ground & fires all at the same time. An easy way to tell which you have is if there is an external ignition control unit it is Digi II. As I am unfamiliar with what system you might have keep an eye out for external resistors, some injectors operate on three Volts & you would not want to bypass the resistors. Sorry to keep bothering you. i tested like you said. i am getting 12 volts to fuel pump. 12 volts to injectors also when i ground my test meter to body. when grounded with other wire on injectors it lowers to about 3 volts and drops to nothing fast. do you think this could be my digifant 2 ecu. or should i try more test. i am getting fuel also good pressure. thank you

You can't test across the two pins of the injector with a test light, & probably shouldn't. You would need a "noid" light or injector tester if you wanted to see the injector pulses. You might be able to see the pulses with a LED test light. What did you do about your fuel pump? How much pressure are you running? Your old CIS system runs at different pressures (60-70 psi) than this Digi system needs (35-40 psi). I suppose the regulator will be able to handle it though & keep it correct. You still need to hook up a fuel gauge & see what your pressure is at. I'd still try to see the injector pulses to be sure they are geting signal when cranking.

You can't test across the two pins of the injector with a test light, & probably shouldn't. You would need a "noid" light or injector tester if you wanted to see the injector pulses. You might be able to see the pulses with a LED test light. What did you do about your fuel pump? How much pressure are you running? Your old CIS system runs at different pressures (60-70 psi) than this Digi system needs (35-40 psi). I suppose the regulator will be able to handle it though & keep it correct. You still need to hook up a fuel gauge & see what your pressure is at. I'd still try to see the injector pulses to be sure they are geting signal when cranking. ok i will see if it pulses when cranking i have a analog tester vu type meter it should pulse. i havent used a test light i wasnt sure myself if it was wise. but i do know what you mean about the noid light i will tinker arround with it tomorrow and probably write to you again thank you you have been a great help