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-   General Q & A (https://www.offshoreonly.com/forums/general-q-20/)
-   -   Whipple 496 stopped running - scanner says no ECM (https://www.offshoreonly.com/forums/general-q/383122-whipple-496-stopped-running-scanner-says-no-ecm.html)

underpsi68 07-18-2024 11:40 AM
Originally Posted by ICDEDPPL (Post 4903332)
If you have no tach signal then ECU doesnt command fuel pump, spark etc ...IE no start .
If your tach doesnt move while starting you have no tach signal.
If you have a distributor with a module , module is most likely dead.
No dist on 8.1/496.

Brad Christy 07-18-2024 12:14 PM
Originally Posted by ICDEDPPL (Post 4903332)
If you have no tach signal then ECU doesnt command fuel pump, spark etc ...IE no start .
If your tach doesnt move while starting you have no tach signal.
If you have a distributor with a module , module is most likely dead.
Dan,

I'd have to watch the next time I hit the key to confirm, but I don't believe my tach moves while cranking until the engine fires.

Thanks. Brad.

Don_Juan 07-18-2024 01:27 PM
Thanks guys! Talked to Whipple and they suggested PCM has an issue. Sending it in today.

Brad Christy 07-18-2024 01:36 PM
Originally Posted by Don_Juan (Post 4903349)
Thanks guys! Talked to Whipple and they suggested PCM has an issue. Sending it in today.
Originally Posted by 87MirageIntruder (Post 4903326)
If you can't figure it out I would highly recommend John Mosetti at Boats Unlimited in Texas. He's the guru on the 496, especially electrical, and rebuilds the PCM555s constantly.
DonJuan,

Take this to heart....

John Mosetti - Boats Unlimited

Thanks. Brad.

Don_Juan 07-18-2024 02:18 PM
@Brad. Thanks. But they originally programmed it for the Whipple charger and repaired it for the IAC driver a few years back. Plus they are only a few hours away and say they can repair it in a few days.

Ryan00TJ 07-18-2024 09:02 PM
Originally Posted by Brad Christy (Post 4903340)
Dan,

I'd have to watch the next time I hit the key to confirm, but I don't believe my tach moves while cranking until the engine fires.

Thanks. Brad.
It should. With the Rinda/Techmate you can perform a crankshaft position sensor test. The PCM will send a 3k rpm signal for 10 secs. If all ok you'll see it at your tach.

Ryanw10 07-19-2024 02:30 AM
Do you have an ignition Relay somewhere? Not a fuse or a breaker, a RELAY

Don_Juan 07-19-2024 10:18 AM
Originally Posted by Ryanw10 (Post 4903398)
Do you have an ignition Relay somewhere? Not a fuse or a breaker, a RELAY
Yes, ignition and fuel pump relay next to PCM. I replaced both. It cranks strong, but fuel pump doesn't prime and it won't start. Fuel pump fuse is good. There is also a harness next to the PCM that has triple blade fuses. They're all good. I understand the PCM creates ground to power up the sensors, etc. The scanner gets power, but it won't read the PCM .... it's not getting data from PCM. Rinda said it's likely the PCM and so did Whipple. I sent the PCM off to Whipple, we'll see what they say.

Swamplizard 02-01-2025 01:29 PM
any resolution?

Don_Juan 02-02-2025 09:57 AM
Yes. The PCM was fried and unreadable. I had to buy a new one. $$$


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