Running ATR 7th full time (ala Bruce)

[tminer]

I set my ATR 7th (circa 1992) to run full time by bypassing the hobbs switch. The only problem is that it runs the injector static when I turn on the ignition. If I quickly turn the key from off to start then it works very well (fires the 7th with same pulse as one of the other 6).

Is this normal or is mine maybe defective?

Is there a +12v tap that is only on when the engine is cranking or running?

Any ideas? I don't like using the alternator charge cicuit and the oil pressure switch is wired in parallel with the fuel pump timed relay.

Thanks,
Tom

 

[KendallF]

Originally posted by tminer
I set my ATR 7th (circa 1992) to run full time by bypassing the hobbs switch. The only problem is that it runs the injector static when I turn on the ignition. If I quickly turn the key from off to start then it works very well (fires the 7th with same pulse as one of the other 6).

Is this normal or is mine maybe defective?

Is there a +12v tap that is only on when the engine is cranking or running?

Any ideas? I don't like using the alternator charge cicuit and the oil pressure switch is wired in parallel with the fuel pump timed relay.

Thanks,
Tom

I don't remember how those're wired normally, but what you need to do is leave the +12v on a normal circuit (keyed hot) and wire the ground for the injector into another injector's ground lead. Then it'll pulse just like the other 6.

 

[tminer]

Kendall,

Do you mean firing the 7th and one of the primary 6 with one driver? Can it handle the load?

The ATR is working off of the ground side of the trigger injector, it just fires the seventh constantly when there is no trigger. So at power on there is 12V at the seventh, but while running the DC voltage varies by ipw. I didn't drag out the o-scope, but since I only had to add 1/6 of the 7th's flow to my injector constant, I am convinced that during cranking and running, the 7th is following the trigger.

So without re-working the ATR circuits, I need a power source that is only on at crank or engine running, not Run or Start at the ignition switch. The only sources for engine running that I see are the alternator charging circuit and the oil pressure switch. Niether are acceptable as-is.

Tom

 

[bruce]

Originally posted by tminer
I set my ATR 7th (circa 1992) to run full time by bypassing the hobbs switch. The only problem is that it runs the injector static when I turn on the ignition. If I quickly turn the key from off to start then it works very well (fires the 7th with same pulse as one of the other 6).
Is this normal or is mine maybe defective?
Is there a +12v tap that is only on when the engine is cranking or running?
Any ideas? I don't like using the alternator charge cicuit and the oil pressure switch is wired in parallel with the fuel pump timed relay.

It's a richer prime signal with the addition injector, but it shouldn't be static.

The controllers I've taken apart all use a seperate driver for the additional injector, it not just run off the ecm injector, from what I've seen.

If your doing your own chips drop the BPW for the crank pulse down some. ie if you added 10% more PPH then drop the pulse 10%.

 

[tminer]

Bruce,

I just added 1/6 of the 7th to the injector constant and didn't even need to change my MAF or PE tables. It starts fine as long as I don't pause in run and flood the engine. It definitely is static (+12v across the injector connector) when key is in run position and engine isn't running.

I think that I can use an NC relay with the coil between a run/acc hot and the NC side of the oil pressure switch (assuming that it is not used in parallel with another grounding mechanism). Turning the key to run will energize the relay and turn off the ATR. Going to start will power it again and oil pressure will break the ground so that it stays on when the key goes back to run. Hopefully the oil pressure switch opens within a second or so of startup.

Tom