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Post by unioncreek on Apr 22, 2019 8:58:49 GMT -6
I have a 2001 Aurora with the 3.5 in it. A little history, about 6 months ago the dash/gauge just stopped working for about 5 minutes and then everything was good. Car ran fine when the gauges were out. About a week ago it quit on the way to work, coasted into a pull out, it started right up. But the tach was saying 5K while the engine was idling. When I drove home that night everything was OK, tach worked. This past Friday on the way home, I was on a straight stretch and I wondered why the battery light was on, well the engine had quit. It would not restart so I pulled onto a road and walked home. We pulled it home later that evening, it wouldn't start. I was hoping it was the fuel pump, but it must have just shut off there was no chugging or anything associated like when your running out of fuel. I check the fuel pump pressure yesterday and it was at 35 pounds, and still doesn't start. When I pull it home I tried to start it and it acted like it wanted to start, but it was like it had no gas.
Does anybody have any suggestions of what I should look at?
Thanks,
Bob
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Post by paulaurora on Apr 22, 2019 9:47:45 GMT -6
most common issue with 3.5 when tech shoots up to 5k or so is the TPS . There is a gasket around the TB and when it brakes the coolant gets in to the sensor and it brakes. Did you try to start the car while pushing gas pedal at same time? or idle sensor can be issue as well.
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RCA1186
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Rob
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Post by RCA1186 on Apr 22, 2019 10:14:31 GMT -6
35 PSI seems a little low. Have you tried turning the key just to "on" and priming the pump a few times before starting?
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Post by unioncreek on Apr 22, 2019 13:29:48 GMT -6
Yes, tried starting it while stepping on the gas. Is there a diagram somewhere on the location of the TPS (I can probably find this one) and idle sensor? Initially when I turn the key on the fuel pressure reads 45 PSI until the pump shuts off then it reads 35 PSI
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Post by paulaurora on Apr 22, 2019 14:16:16 GMT -6
The TPS and Idle solenoid are both on throttle body.
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tigger
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Post by tigger on Apr 22, 2019 15:29:23 GMT -6
Tach and stalling issues sound like crank position sensor to me. Any codes?
45psi is still on the lower limit, FSM calls for 47-51, iirc. And it definitely shouldn't leak down immediately after the punp stops running.
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Post by unioncreek on Apr 22, 2019 15:57:01 GMT -6
I'll check the TPS and IAC when I get a little time. The only codes I get are the gas cap and hard shift one occassionally. Even with 35 PSI it should still run. If it was the crank sensor would it run for months at a time with no problems?
Bob
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Post by unioncreek on Apr 22, 2019 20:50:28 GMT -6
Tonight I looked at the car. I put my fuel pressure gauge back on and turned the key on. It pressured up to 45 PSI and then dropped to 35 PSI. I then pushed the pressure relief valve on the test gauge and gas just barely came out of the hose. I would assume that when pressure dropped the pump would start up and pump gas out of the hose. Am I assuming right. The pump never started up and I would have to cycle the key to get the pump to start. Does this mean that the pump is bad?
Bob
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tigger
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Post by tigger on Apr 23, 2019 0:09:24 GMT -6
The pump only primes once per key cycle. That's why Rob suggested repeating this cycle a few times to build pressure.
But again, it should take several minutes to leak down 10 psi at the rail.
Sounds like you have a leak. Check your FPR, injectors, and there is a anti drain back valve somewhere...
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Post by unioncreek on Apr 23, 2019 8:28:46 GMT -6
I'll try cycling the key a few time and see what the pressure does. Shouldn't the pump come on though if I release the pressure on the rail with the gauge? If not what triggers the pump to come on?
Just trying to understand how the fuel system works. I probably won't get to check the FPR or TPS til this weekend.
Bob
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RCA1186
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Rob
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Post by RCA1186 on Apr 23, 2019 8:41:38 GMT -6
Pump gets triggered once at key on to prime it. It won't run again unless you shut key off and re-prime or start the car.
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Post by unioncreek on Apr 23, 2019 14:24:21 GMT -6
RCA1186,
Thanks for the info.
Bob
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Post by unioncreek on May 18, 2019 10:41:06 GMT -6
I replaced the pump, pressure goes up to 45 then drops to 40 and holds there. I looked at the fuel pressure regulator and there is not gas in it, but it's been setting for a while. Is there a way to check if the spark plugs are firing? Disconnected the battery and pulled all the fuses to check them and they all looked good. I'm at a loss as to where to look at next.
Any suggestions.
Bob
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