Car dies

BLACK SNAKE

BLACK SNAKE

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I have a 1997 mark viii when I drive on expressway on a warm day the car runs fine. A soon as I head off the expressway and slow down the car will go dead. If I wait 15 min. or so the car will start and run awhile be fore it does it again. Help!!!
 
sounds like a fuel filter or fuel pump. Best to change out the fuel filter first. Its located behind the inner fender pan on the passenger side. If that doesn't fix it, you'll have to drop the fuel tank and install a new pump/sending unit. My thinking on this is at revs, there is enough amperage being generated to force fuel threw a partly clogged filter. At low engine revs, the pump pressure is reduced with the less amperage being generated. Good Luck with it.
 
xtriggerman said:
sounds like a fuel filter or fuel pump. Best to change out the fuel filter first. Its located behind the inner fender pan on the passenger side. If that doesn't fix it, you'll have to drop the fuel tank and install a new pump/sending unit. My thinking on this is at revs, there is enough amperage being generated to force fuel threw a partly clogged filter. At low engine revs, the pump pressure is reduced with the less amperage being generated. Good Luck with it.
Click to expand...
 
New fuel pump and filter, I'm thinking some kind of electrical problem getting hot and loosing contact.
 
If it is a fuel problem I would think it would bog significantly if you stick it in first gear and floor it. I’d do this test with a hot engine, so the electrical components are hot too.
 
I had a 1973 Volvo 164 (fuel injected) that did the same thing as you described. The problem was the egr valve sticking open when it got hot after expressway driving. Check the egr valve for proper function; it should fully close when the engine is at idle, if not fully closed, the rpm will go to zero - engine dies.
 
Easy test for EGR, unplug the vacuum line and plug it. It will throw a CEL if you sustain cruising speed for several different instances but for getting to work/home it should not indicate. If your engine doesn’t die when you come off the freeway, there you have it.

I forgot to plug in my EGR a few weeks ago and it threw a code after about a day and a half. It went away within an hour of plugging it in.
 
LandYachts said:
Easy test for EGR, unplug the vacuum line and plug it. It will throw a CEL if you sustain cruising speed for several different instances but for getting to work/home it should not indicate. If your engine doesn’t die when you come off the freeway, there you have it.

I forgot to plug in my EGR a few weeks ago and it threw a code after about a day and a half. It went away within an hour of plugging it in.
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I will try it , thanks for the response
 
I'm going to guess your crank sensor is going bad, I've had a couple Mark VIII's with those exact symptoms and that was the fix.
 
This might help.

crank cam sensor.jpg


Changing it is fairly easy, you just need to get under the car and get the A/C compressor out of the way. I've uploaded the instructions from the workshop manual.
 

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  • Crankshaft Position Sensor.pdf
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Check the wire harness there too
They're known to fail too
Rock auto has bothered the harness and sensor
 
slowmkviii said:
Check the wire harness there too
They're known to fail too
Rock auto has bothered the harness and sensor
Click to expand...
The sensor hasn't show any codes I had it checked and my mech. said it looked fine, wouldn't it show a code if it was bad?
 
I would think he would see some sort of code with an event like this. VAC tee leaking? IAC valve sticky (black thing in pic).

IMG_E3148 (2).JPG
 
slowmkviii said:
Never seen a code for the Csps on the cars I've worked on
But there might be a code too
Click to expand...
This problem has been going on for over two years. I replaced fuel pump, ign. switch, drove with a code checker and nothing shows. Just a little frustrated.
 
It can’t be a fuel delivery problem because a greater volume is consumed at speed than when coasting down or making slow turns.

It can’t be electrical because it is speed dependent.

I’m a very OLD fashion mechanic (I started on 60’s Honda motorcycles). When speed becomes a factor in a problem I suspect:

Vacuum accessories
Timing advance mechanism
Charging system/battery
Idle throttle position
Idle mixture (to achieve appropriate idle throttle position)
So in your case IAC as well

I would check:
Irregular idle under varying loads (trans, A/C and PS movement) or other IAC symptoms
Voltage while driving vs while idling (use the cigarette lighter socket and some insulated leads)
EGR sticking

I suspect voltage only because old Honda’s had crap electrical systems. They barely had enough to run the headlight at night. It could start and ride all day on the highway, but if it was even slightly below nominal, the ignition wouldn’t have enough to continue idling.
 
Just my experience-crank sensors at speed are cooler since it gets a lot of air, but heat sink issue can cause it to get weird at lower speeds. No matter what, it is not going to throw a code and it is classic symptoms for a crank sensor-easy enough to do, if it takes a half hour you took your time. Worth a try.
 
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