Cranks does not start

ROY PERRY

MEMBER
1997 MERCURY MARQUIS
4.6L
V8
2WD
AUTOMATIC
200,436 MILES

Ran fine the evening before. Went to start cranks but doesn't start, check engine light not on, checked fuses, and tried checking wiring harness to no avail.

Tuesday, April 9th, 2019 AT 3:45 PM

4 Replies

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

Okay, an engine needs three things to start. It needs fuel, spark (delivered at the proper time), and it needs compression. If these three things are present, then your vehicle's engine really has no choice but to start. So, if it ran good the night before, we can pretty much rule out compression. So, let's start with spark. I have included a link down below for you to go to:

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Please go to this link and go through the guide there and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

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Tuesday, April 9th, 2019 AT 8:00 PM

ROY PERRY

MEMBER
3 POSTS

No spark, no fuel. If I bypass relay for fuel pump I get 45psi koeo. No communication with PCM. Checked fuses again all good.

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Wednesday, April 10th, 2019 AT 4:34 AM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello again,

The problem probably is your vehicle's Crankshaft Position Sensor (CKP). Your vehicle's Power-train Control Module (PCM) use the input from this sensor to determine the speed of the crankshaft and for engine RPM's. The engine will not start if the PCM doesn't get this signal from the CKP.
I have included in the diagrams down below a factory troubleshooting guide for your vehicle's CKP. Please go through it and get back to us with what you are able to find out please.

Thanks,
Alex
2CarPros

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