Parked my car for a short time went to start it and it will not start

JACKKEP

MEMBER
1999 MERCURY MARQUIS
4.6L
V8
FWD
AUTOMATIC
160,000 MILES

A little over a week ago I pulled into my driveway and turned off my car. Later that evening I went to get groceries and the car just would not start.

Oil level fine.
No issues while it was running
I have not made any changes other than adding a new radio a couple weeks ago.
Worked fine before, the occasional hesitation starting, maybe once a week it would take a four or five seconds to catch and start, but it would always start on the first key turn.

What I know/What I have tried:

-Checked fuses

-Replaced the fuel filter

-I can hear the fuel pump turn on, I do not have a pressure gauge to test the pressure at my engine but if I press a pin into the port where I would put a pressure tester fuel sprays everywhere.

-The spark plugs do have power and they do work (we pulled them out and my friend held them and grounded himself while I cranked the car and he always got a big shock. Very scientific)

-If I spray engine starter into my engine it will start and run on the starter for a second then cut out.

-I checked power to the fuel injectors and they have power, but when I measure the ground to the injector and try to crank the power does not pulsate like it should.

-I called a local mechanic and he said to check the grounds for injector pins in the PCM, I opened the PCM and put my multi meter on ohms/continuity and put the positive lead on the battery and the negative lead to the PCM injector pins, it did not zero out. If I touched that negative pin to ground on the cars body the reading would zero out. I tried cranking the car while checking the reading on those pins and it fluctuated mildly but still did not pulsate like it should.

-He told me to check the grounding wires for the PCM but I have no idea where those are or how to do that. (My friend's 2001 Ford Escape has a grounding wire leading from his PCM wire bundle but mine does not and never did.

-The mechanic also told me to check my camshaft sensor, I checked that there was power to it and there is, but that is the extent of what I knew how to do.

1 Reply

CARADIODOC

MECHANIC
33,916 POSTS

The tests you are trying to do are not going to yield any useful information. First of all, digital voltmeters respond much too slowly to read the injector pulses on the "DC Volts" scale. The "AC Volts" scale is for reading a 60 Hz sine wave, which is house current. They are not accurate in injector circuits which are square waves and varying frequencies.

The first step is reading and recording the diagnostic fault codes. Unfortunately you can only do that yourself on Chrysler products. For all other brands, you need a code reader. The fault codes will indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. If there are no fault codes, fuel pressure becomes the next suspect. Many engines will not start and run if the fuel pressure is just a little low, so we need to know the exact pressure you have. Many auto parts stores will rent or borrow tools. They will have a fuel pressure gauge.