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Discussion Starter #1
My daughter is away at school with her '97 P38. About 3 weeks ago she was driving along at around 30 MPH when the motor suddenly shut down. Car electrics all worked, the motor cranked but would not start. Towed it to a local mechanic who checked and rest connections to coil pack, crankshaft sensor and fuses/relays. Without a solid diagnosis, the motor restarted and worked flawlessly, until this evening. While at a rest stop, she began to drive away and the motor shut down yet again. This time it won't crank when attempting to restart. Thankfully she's in a safe spot and is awaiting a tow home where I'll be able to have it properly sorted. In the meantime, any thoughts and suggestions are welcome.

Thanks!
 

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I would agree with TheoR about the CPS, however not even cranking is yet another issue. Possibly you have a couple of things going on. I know I sound like a broken record, but the electrical sticky is the first and best option. Also check the fuse box for burnt smell, get your nose right in there. it should not smell at all......
BTW, changed the fuse box on the Borrego this evening, and now the Rad fans do not run continuously. Issues in there can cause any number of intermittent headaches. Good place to start.
 

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Discussion Starter #5
My daughter has finally arrived home safely and I've had a quick look at the car. The motor is now cranking and it has spark, but no fuel at the rail and I can't hear the pump when the ignition is turned to on. Will need to dig in further tomorrow, but wonder if the battery is shorting out and/or the battery cables are buggered. Would not be surprised if the fuel pump failed although it was replaced 3 years ago. My '98 lost a fuel pump only one year after replacement. Will run through the sticky. Thanks for the advice.
 

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Yep, do check all the battery cable ends first. In 98 they ran Batt pos to the starter then to the fuse box. Stupid idea. First thing, clean the terminal at the starter motor, Battery terminals and earth points under the bonnet, then have a good long look at the fuse box, as what you are now describing sounds suspiciously like a burnt fuse box.
Test the fuel pump by using a small piece of wire like a paperclip to jump the pump relay output terminals (The 2 outside slots that are PARALLEL to each other at the relay socket,)
Listen for the pump, or check pressure at the rail after running it for a bit. Heck, Jump the relay and try to start it!
Good luck
 

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Really? What does the CPS have to do with fuel? There was spark, but no fuel.
I can answer that without being snappy about it.

It's a standard safety feature on gasoline powered vehicles.
As long as the engine is running the CPS transmits a signal that the fuel pump relies on to run.

If the vehicle is involved in an accident and the engine stops there cannot be a case where the fuel pump continues to pump fuel with potentially ruptured fuel lines spraying gasoline all over the place.


Of course the fuel pump relay could potentially stick in closed position causing the fuel pump to run continously causing the fuel injectors to drip gasoline into the engine and in turn causing the engine to back fire and blow the plastic plenum. Thats totally possible (happened to me once due to corrosion in the relay on a totally different vehicle).


Cheers.
 

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the cps transmits a signal to fuel pump,AS long as engine is running,if it does not transmit signal it wont run,that is why i suggest you test wiring to cps,if signal is intermitent ,it will start sometimes and some times not,if cps gets to hot as they sometimes do it wont start,if you squirt easy start into inlet manifold ,and it fires, it will tell you there is no signal,to cps?if the wiring is faulty,you can run a positive and negative wire from ECU to cps to check wiring,but do check to see if you have faulty cps,pin 11 and pin 12 ,on right hand side black plug on ecu,lookin from front of car,is where you ca n attach wires ,direct to cps,ask me how i know,hope this helps you,get going,good luck
 

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Discussion Starter #9
I can answer that without being snappy about it.

It's a standard safety feature on gasoline powered vehicles.
As long as the engine is running the CPS transmits a signal that the fuel pump relies on to run.

If the vehicle is involved in an accident and the engine stops there cannot be a case where the fuel pump continues to pump fuel with potentially ruptured fuel lines spraying gasoline all over the place.


Of course the fuel pump relay could potentially stick in closed position causing the fuel pump to run continously causing the fuel injectors to drip gasoline into the engine and in turn causing the engine to back fire and blow the plastic plenum. Thats totally possible (happened to me once due to corrosion in the relay on a totally different vehicle).


Cheers.
Does the CPS transmit to the fuel pump or the fuel injectors?

Is is the accident case not addressed by the inertia switch?
 

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Wooly is dead on about the relationship between CPS and fuel pump relay. ECM reiles on CPS signal to determine whether to turn on fuel pump relay or not.

Therefore, if CPS is not working right, you won't see fuel pressure at rail, as he said.

You mentioned that you have a Nanocom. What fault codes are you getting?
 

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Does the CPS transmit to the fuel pump or the fuel injectors?

Is is the accident case not addressed by the inertia switch?
My reply was a general comment as to why the CPS could interfere with the fuel pumps ability to run and the safety reason behind it. I haven't studied the actual diagram on the petrol version like wooly apparently has. I wonder what happended to his other posts....

I don't have a diagram here but I would guess the inertia switch adds another layer of safety making sure the engine is shut down on collision and fuel is stopped from pumping.

I'm glad you found the cause of the fault.
 
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