[Jake]

Installed a FAST crank trigger kit on a vehicle with a 7531 box. Came with a pigtail to plug the sensor right into the MSD harness. No fire. Can plug the harness into the dist and fires right up. So that should narrow it down to the pickup I think. I've got the pickup darn near centered and have had the gap from .030-.060 with no luck. We had powdercoated the pickup mount so I tried externally jumpering a ground to see if that could be an issue with no luck. Any suggestions? Thanks.

 

[ls7camaroguy]

which wire color do you have the red wire going to on the MSD box???

 

[whitelightning]

we have swapped them around and still no fire. I even went out and bought a new pick up and still no luck.

 

[TYDO]

Does it have the magnets in the wheel?

 

[Jake]

Does it have the magnets in the wheel?

No. The wheel is steel and the magnet is in the pickup Mark.

 

[Jake]

which wire color do you have the red wire going to on the MSD box???

Red/positive. Sorry. The harness has a green and violet wire and so does the FAST pigtail. I even swapped the pins to flip the polarity with no luck. Even though that shouldnt matter to it actually working I think, only timing and stability. Absolutely no effort to fire doing everything. Checked the pigtail for a wire break, flipped pins, external grounding, new sensor, tried different gaps from .030-.060. The pickup it REAL close to center on the wheel maybe .040 off center at most. I really wondered if there was a pigatil to snip on the box or a function to switch in the box to get it to work since the FAST works backwards of MSD's.
Thanks!

 

[ls7camaroguy]

Does it have the magnets in the wheel?

Mark, it's the same one that is on my car in your shop. It uses a steel wheel with a raised portion to trigger the sensor. The magnet is in the sensor, and it is the same sensor as a cam sensor off a 4.6 mod motor, jw

 

[ls7camaroguy]

Red/positive. Sorry. The harness has a green and violet wire and so does the FAST pigtail. I even swapped the pins to flip the polarity with no luck. Even though that shouldnt matter to it actually working I think, only timing and stability. Absolutely no effort to fire doing everything. Checked the pigtail for a wire break, flipped pins, external grounding, new sensor, tried different gaps from .030-.060. The pickup it REAL close to center on the wheel maybe .040 off center at most. I really wondered if there was a pigatil to snip on the box or a function to switch in the box to get it to work since the FAST works backwards of MSD's.
Thanks!

It should matter as they both provide a IPU type signal. I do know that when. The engineers at fast were designing this unit, they had a 7al box on one of their spntron engines to measure timing values at every rpm. JW

 

[whitelightning]

is yours with a digital 7 box

 

[Jake]

It should matter as they both provide a IPU type signal. I do know that when. The engineers at fast were designing this unit, they had a 7al box on one of their spntron engines to measure timing values at every rpm. JW

So what do ya think it could be? We're pretty lost and so are all the engineers and tech's.
Thanks.

 

[ls7camaroguy]

is yours with a digital 7 box

yes, 7531 box, but it is EFI. I will see what i can find out and let you know Nick.

JW

 

[ls7camaroguy]

Jake / Whitelightning, make sure that nothing is near the same OD size as the crank trigger wheel, such as balancer / crank pulley for the blower. If so, this will cause a solid signal and the sensor will not be triggered from the trigger wheel. JW

 

[Jake]

Jake / Whitelightning, make sure that nothing is near the same OD size as the crank trigger wheel, such as balancer / crank pulley for the blower. If so, this will cause a solid signal and the sensor will not be triggered from the trigger wheel. JW

Thank you, I think your on to something.
The closest things would the balancer and blower pulley which are 8" diameter to match the wheels smaller OD(minus teeth diameter) that its supposed to be designed for. I even machined the back teeth off the pulley to be sure. At this point I'd say this is the case-. The sensor is "too sensitive" and cant deal with a mass of material. The sensor can only deal with the very thin smaller OD of its own wheel. Therefore I feel they need to redo a wheel that 9" diameter for the 8" diameter balancer and so on or extend the tbas ont he wheel and shim the pickup back. I put a ton of machining in all this blower drive stuff to use this setup and now it wont work. We cant risk another spark problem and knock another head off the engine.

 

[ls7camaroguy]

Thank you, I think your on to something.
The closest things would the balancer and blower pulley which are 8" diameter to match the wheels smaller OD(minus teeth diameter) that its supposed to be designed for. I even machined the back teeth off the pulley to be sure. At this point I'd say this is the case-. The sensor is "too sensitive" and cant deal with a mass of material. The sensor can only deal with the very thin smaller OD of its own wheel. Therefore I feel they need to redo a wheel that 9" diameter for the 8" diameter balancer and so on or extend the tbas ont he wheel and shim the pickup back. I put a ton of machining in all this blower drive stuff to use this setup and now it wont work. We cant risk another spark problem and knock another head off the engine.

I believe any sensor that is that close would do the same as far as seeing a constant signal from the blower pulley/balancer. Here is a trick that you could do to resolve this issue and still use your wheel. Take the crank trigger wheel, and on each tab, put a couple of weld beads on each "tab" to extend it out past the blower pulley/balancer. If you can get it above the pulley say .125 it should work fine. Just a thought, later JW

 

[hostile]

Jake is that blower pulley really made out of steel?

I would have thought anything that big on a race car would be aluminum.

 

[ls7camaroguy]

I believe he said it was aluminum, but aluminum will block the trigger if is it interrupted.

 

[Jake]

Jake is that blower pulley really made out of steel?

I would have thought anything that big on a race car would be aluminum.

No Sir, its aluminum.

 

[whitelightning]

It sound like talking to Jake and some of the tech guys from FAST that they are going to send a engineer up to find and fix the problem. Will keep you guys posted on what happends next.