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Starts for 2 seconds and shuts back off


Guest joelmartin

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Guest joelmartin

Fellow mechanics,

My new to me 89 Reatta has some starting issues. It starts and runs good for 2 seconds and then shuts back off. It had the famous cam sensor code so I checked into that which revealed the cam interrupter missing. I replaced that which did not fix the problem. The only current code is C339- loss of radio data. It seems like a fuel problem because it starts good but kinda sputters and dies. Sometimes it pops. I checked fuel pressure at rail and it was around 20. I changed the fuel filter to no avail. I put 12V to fuel pump test connector and the highest it went was 30. So I just got done changing the fuel pump and it still will not start. Now the pressure is within spec, 40-47. It does seem to start stronger, like if you use the throttle it will rev up, but promptly dies. Something seems to be shutting off the fuel. Some things to test or check? Could the security system be doing this? Thanks for now

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Still seems like a fuel pump problem to me. In your original post you said the pressure with your new pump was 40-47 psi. Was this with the ignition key on or with 12v supplied to the test connector? With 12v on the test connector pressure could be as high as 75 psi. Does pressure hold for a few minutes after voltage is removed? Another question: did you buy the cheapest pump? I'm not being a smart-ass, just speaking from experience. I bought the cheapest pump Rockauto had to offer only to have to drop the tank again 2 days later to put in a Delco pump.

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Guest joelmartin

It has 45 with key on and has held that for the last 1/2 hr without dropping. With 12V to test connector it goes up to 50 and I can hear something in the fuel rail releasing the pressure so it can't go higher. I assume this is the regulator. The pump is a Carter from Napa.

I just ohm checked the ignition coils and they are 11-12k.

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I spent total about 5 hours or more trying to find out why my Select 60 was acting the same way. ( this was last spring and I hadn't driven the S 60 since the previous summer ) Some of the things I did was I replaced the fuel filter, put a temporary fuel pump along side the car and had problems with that one. I then got another one and to make sure it was good tried the temporary pump on my sisters Reatta that was here at the time to make sure it was good. I then hooked it up to my gas lines and no change. I tried a different fuel pressure regulator, no change. My neighbor, a mechanic, came over with a tester for the injectors and they were operating correctly.

He then casually mentioned it could be the MAS. I unplugged the MAS and the car started and ran fine.

I put on a good MAS but left the connector off and started the car. Plugged in the MAS and the car hesitated for about a half of a second and has been running good since. Like you I was sure it was fuel related but turned out to be a simple MAS.

Unplug your MAS and see what happens.

I do have a good used MAS available from one of my several parts car.

Jim

Edited by Jim (see edit history)
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Hmm, the engine starts under ignition control from the Ignition Control Module/crank sensor combination and then switches over to ignition timing command from the ECM to the Ignition Control Module. The starting sequence also commands the injectors for the initial shot to start. Fuel pressure sounds a tad high, but gauge accuracy may account for a little of that. In any case, that does not appear to be the problem, regulator controls the upper pressure limits, not the pump, as you surmise. I believe one of the three items is turning off the spark and/or injectors when it goes to the run position, or more accurately, not keeping them going. Does the fuel pump run for a couple of seconds when the key is just turned to the run position?

I just read Jim's post and the suggestion is a good one (MAF?). In most cases if you suspect a bad sensor, simply taking it out of operation will help pin it down. I wouldn't think it would cause a stall, but we are finding out the "normal" failure mode does not always apply.

Edited by 2seater (see edit history)
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Guest joelmartin

Unplugged the MAS which didn't help. Yes the pump runs for a couple seconds when the key is turned on. I did some testing on the wires that go into the ignition module connector. There is 12V being supplied with key on and while starting it. The ground is good and tested both 3X and 18X crank sensor wires and they gave good signals. I also tested the A wire all the way to the right which is the one the ECM uses to take over once it goes above 400 rpms. Cranked the engine and it only got 1-2V. I think it has more than 400 rpms before it shuts off. So now I have to figure out why the ECM isn't putting power through that wire when it should. I'm expecting it to put 12V to that wire unless I'm mistaken.

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OK go back to Ronnie's post. The engine gets a 2 second shot through the fuel pump relay then turns off. Once the oil pressure comes up a switch is made in the Oil Pressure Sender to turn the fuel pump back on for as long as you have oil pressure. Those two circuits are in parallel and the second does not go through the ECM. I would put a voltmeter on the prime connector and see if it goes to 12v when the key is turned on, stays up for two seconds, then goes back to zero before the engine stops turning.

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Guest joelmartin

Yes at prime connector it gets 12V for 2 seconds and goes off. Then when you start the engine the Vs go right back up to 12 until the engine stalls. I don't think the ECM is taking over.

Yes I've read that tutorial.

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Yes at prime connector it gets 12V for 2 seconds and goes off. Then when you start the engine the Vs go right back up to 12 until the engine stalls. I don't think the ECM is taking over.

Yes I've read that tutorial.

Do you have another oil pressure sensor you can try? If so try it to see if that corrects your problem.
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Guest Mc_Reatta
Unplugged the MAS which didn't help. Yes the pump runs for a couple seconds when the key is turned on. I did some testing on the wires that go into the ignition module connector. There is 12V being supplied with key on and while starting it. The ground is good and tested both 3X and 18X crank sensor wires and they gave good signals. I also tested the A wire all the way to the right which is the one the ECM uses to take over once it goes above 400 rpms. Cranked the engine and it only got 1-2V. I think it has more than 400 rpms before it shuts off. So now I have to figure out why the ECM isn't putting power through that wire when it should. I'm expecting it to put 12V to that wire unless I'm mistaken.

Your expectation is off a bit. The white wire at pin A carries a spark timing pulse from the ECM to the ICM whenever the ECM receives the crankshaft reference signal from the ICM. So your measurement may be OK.

To switch the spark timing control from the ICM to ECM,(after 450 rpm is reached), a 5 volt signal is sent from the ECM to the ICM via the tan/black wire at pin B.

In either case the engine should start and run no matter which module is in control.

I'm thinking you might have a injector pulse signal problem that is causing your issue.

Do you have a noid light? (LED and resistor)

When the car is started, the fuel pump turns on for a few seconds and the engine cranks. The ICM monitor the sync signals from the crank sensor and generates a fuel control reference pulse which is sent to the ECM. When the ECM gets this pulse, it opens all 6 fuel injectors for a priming shot then turns them all off until two crank revolutions occur, and it gets a cam sensor signal. Then it opens each injector individually based on its calculations or defers to a default mode.

I'm wondering if something is interfering with the ECM from sending those individual injector pulses after the priming pulse. This would provide enough fuel for the engine to start for a bit until the priming charge is burned off and then die out from fuel starvation. A noid light would allow you to quickly determine if this is happening or not.

Not sure why a default mode isn't allowing the car to keep running though, but at least this would narrow down the areas to further troubleshoot.

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Guest joelmartin

I was working hard on it last week but have now got other things keeping me busy. A little update is my dad was looking through the ECM inputs outputs whatever they are and noticed the coolant temp was 23 deg. Changed the sensor and it started and ran a little longer than normal then stalled. I'm not done yet.

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