Burned Q2 Q7

[dart73]

Hello folks,

the engine was running.
After some starts the engine started to flood completely;
I´ve realized that I had always 12V @ the injectos connectors;
Them checked that INJ1 and INJ2 in relay board had cotinuity to chassis ground;
Checked harness/wiring and everything looks ok;

When opened the module Q2 and Q7 was completely melt. Any guess on what could be caused that? I dind´t use heat sink on that neither any dissipator;
Any shorts, bad injectors or just the heat itself?


thanks and Br,

[DaveEFI]

What is the resistance of each injector?

[dart73]

Hello Dave, just measured and all the 8 injectors around 10.5 OHMs.

Br,

[dart73]

Hello all,

after changing the transistors I realized that HEI module and distributor it´s not triggering RPM anymore (so no spark).
Have changed HEI for a new one and checked all the wiring with no success.

Any guess on what should I look for? I really appreciate any help.

[Matt Cramer]

Can you get an RPM signal on the Stim?

[dart73]

Hello Matt,

just rebuilt my stim here and yes there are RPM on stim. So no 4N25 problem right....

I´m using a HEI-8 to condition the locked distributor. Already bought a new module and nothing changes. Checked wiring and everything looks fine.
Any way to check the tach output pin 24 without an osciloscope?

[dart73]

Well, forget about last post.. I figured out that one of the wires coming from VR was cutted. So MS started to read tach input / RPM.

Probllem is that still not firing the coil. I see 12V on both sides of the coil but it´s not firing the plugs. Using a test light on C pin (-) of coil It´s steady.
It should blink right?


Br,

[DaveEFI]

If you've had components burn out, there's always the possibility of damage to the PCB. Sometimes this can be seen, sometimes not.
Refer to the schematic, and check continuity between each component on your coil driver circuit. In other words, check those PCB tracks are all good.

[dart73]

Thank you Dave.


What kind of tension should I look for on Spark A and Spark B? If I´m not wrong after 300rpm Spark A led turns off.
Need to check it on pin 25 (E) and 27 (B).

[dart73]

Ok, here again.. so frustrated and sad with this..

today went to my test bench again... and for my surprise no RPM again... checked wiring again, changed the HEI module, changed distributor to test the VR and nothing changes... tested with stim and RPM is working fine. Does it means that there are no problems with RPM circuit or could de a different problem for the HEI?

Checked the HEI mods and everything seems fine. One thing called my attention. Doing continuity test between X11 and X12 they have contact. Is this right?

Any help are very welcome.

[kjones6039]

Curious here.... Are you using the Opto or VR circuit for HEI? Several years ago I ran an HEI setup and had much more success using the VR circuit.

Ken

[dart73]

Hi, this is VR trigger. V 2.2 board.