Diagnosis Needed

GMAN

GMAN

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Ok everyone. I need all of your collective minds. My buddy has a 96 Mark he recently bought last month. Before he bought it, it sat for about two years, being started once a month or so. He drove it around for about two weeks fine, then all of a sudden it wouldn't start. It just kicks over like it is starved of fuel. So he has it in the shop now. First the tell him it is the fuel pump. They replace that, now it still don't start. They think the computer is fried. I don't think it is the ECU. I think it could be the VRCM. That is my 2 cents. All of the maxifuses are good. We need some other avenues to explore.
 
Before we shoot in the dark again (although replacing the fuel pump would probably have been needed anyway soon), can you get a pressure reading of the fuel. Low side, 32 psi to start with up to 40 psi.

I am thinking fuel pressure regulator.

And how about a voltage reading? Even a battery that "looks" good can make a non-start issue. That is the lights and stuff seem ok, but not enough juice to get it started.

You try unplugging the crank position sensor?
 
unity said:
can you get a pressure reading of the fuel. Low side, 32 psi to start with up to 40 psi.

I am thinking fuel pressure regulator.
Click to expand...

I would hope that the mechanic would have tested the pressure at the rail to diagnose the fuel problem and then confirmed it after he installed the new pump. I agree with the crank sensor though. Isn't there a cam sensor that will give you the same problem?
 
This is a good information. I don't think that they've check the CPS. I will pass that on to him, as well as the fuel pressure regulator.
 
GMAN said:
This is a good information. I don't think that they've check the CPS. I will pass that on to him, as well as the fuel pressure regulator regulator.
Click to expand...

I don't think the fuel pressure regulator has a regulator? :p sorry, couldn't resist
 
Thanks GMAN for getting the ball rolling.:) :feedback

The mechanic tells me that the car is not firing (has no spark) but is getting fuel. The engine turns over fine, but had only started a couple of times after replacing the fuel pump. They drove it about 300 yards to the painter, and it hasn't started since.

The original reason it was at the mechanic was an oil leak on the oil filter adaptor where it meets the block. (Is there any wire or sensor in that area that could have been damaged during initial diagnosis and repair that would cause this problem?):confused:

No check engine light is coming on at anytime, even when turning the key to the run position. He says that the car is not communicating with his Snap-On scanner. (I think that is the basis for his "bad computer" diagnosis) But the computer didn't communicate with the computer at the state inspection station when I bought the car and had it state inspected, and it ran like a top for about 2 weeks starting several times a day and logging about 300 miles.:mad:

To answer the previous question, I don't think he tried unplugging the crank. pos. sensor.

I humbly bow to The MarkVIII Gods and ask for their guidance and wisdom.
Thanks:feedback
 
Crank position sensor :) Cam position will allow the car to start, crank will not. Unplug and plug back in and see what happens. Takes two seconds and if its a no go we can move on to something else.
 
O.K. the mechanic (and I type that last word grudgingly) says it's not the crank sensor.:mad:
 
Are we SURE we are not getting spark? At first it was no fuel, or so we thought.... Was the fuel pressure checked?
 
How did he check if it was the CPS or not? This is "almost" always the problem with a cranking no start... The other would be a blown fuse... (Just ask GMAN about that one...) ;)

Mike
 
Well, we've check everything, and we've come up with zippo. All of the fuses are good, the computer is good, the VRCM is good, the crank position sensor is good as well. On thing we noticed is the Anti-theft light blinking rapidly when we crank the car. Any ideas?
 
GMAN said:
Well, we've check everything, and we've come up with zippo. All of the fuses are good, the computer is good, the VRCM is good, the crank position sensor is good as well. On thing we noticed is the Anti-theft light blinking rapidly when we crank the car. Any ideas?
Click to expand...

you just answered your own question. The alarm is disabling the car. Its probably malfunctioning. Disconnect it and see if it works
 
Get behind the glove box. On the right side you will see a module with 2 plugs going into it. On my 96 the module has plastic covering it. You just unplug the two connectors going into it. If I remember correctly, the module is mounted horizontally.
 
Unplugged the anti-theft module, and car still didn't start. So now we are going to replace the crank position sensor. All clues lead to it being defective.
 
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