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Old 04-07-2013, 07:37 PM   #1
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Unhappy No Start Continuation

Previous thread: http://986forum.com/forums/general-discussions/43943-wont-start-dropping-oil-level.html

We determined the fuel pump was faulty as the plug itself had power to the pump, but when power was applied to the pump nothing happened.

After having Brumos overnight a pump for me (ended up being cheaper than Pelican), I installed it on Saturday evening. Success! Started up and drove wonderfully. Did a few startup cycles with no issues.

This afternoon I went to go buy groceries and... it just cranked. I only drove 13 miles between the new pump until it was parked in my garage and it's doing the same thing again.

Checked the fuel rail, no pressure. Fuses are good. Bypassed the fuel pump relay, nothing. Swapped the ignition switch, no improvement. However, the DME relay and fuel injector relay (#1 and 2 on the rear relay panel) get warm/hot when cranking. Swapped those relays to no change either.

I'm stuck, guys. What are the odds that there is a short somewhere and it fried the new pump (I hope not! )? Out of ideas on what else to really look into as the same issue (cranks but doesn't fire) came back so soon.

Update: Replaced sending unit (w/ internal fuel filter) and fuel pump with used examples, drained the gas tank completely, and refilled with fresh 93 octane. Problem solved. Old fuel in the tank smelled old, not as pungent as fresh gas does - likely a contributor to the failure.
Related threads:
http://986forum.com/forums/general-discussions/43943-wont-start-dropping-oil-level.html
http://986forum.com/forums/general-discussions/44258-still-doesnt-run-help.html

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Last edited by Deserion; 04-27-2013 at 08:50 PM.
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Old 04-07-2013, 10:27 PM   #2
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Could've been a faulty fuel pump. The only thing that could've fried the pump motor would've been a high surge, and that is very, very unlikely. The system doesn't produce enough power to fry it. With a dc system, the pump is only going to draw as much power(amps) as it needs and the voltage will not exceed 15v.

I would check for power at the pump and go from there. My guess is that you got a bad pump...hopefully under warranty.
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Old 04-08-2013, 06:54 AM   #3
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Failed fuel pumps are possible but relatively rare. Put 12VDC directly to the new pump to see if it runs. Now put 12VDC to the old pump and see if it runs. If they run, it's not a fuel pump problem and we are still missing something.
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Old 04-08-2013, 07:50 AM   #4
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perhaps not getting fuel - something jamming up the pump? the fuel lines in the tank get brittle and break with age. perhaps you are drawing air? perhaps bits of plastic up into the pump?
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Old 04-08-2013, 09:10 AM   #5
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Quote:
Originally Posted by The Radium King View Post
perhaps not getting fuel - something jamming up the pump? the fuel lines in the tank get brittle and break with age. perhaps you are drawing air? perhaps bits of plastic up into the pump?
The new pump has fresh lines to connect it to the fittings in the sending unit that connect to the lines to the engine. Also the strainer screen on the new pump was intact (incidentally, the pump is very similar to era Volkswagen pumps, just in a slightly different case).

Air is possible. Going to have it towed back to my dad's house again so he can work on it.
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Old 04-08-2013, 09:12 AM   #6
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Quote:
Originally Posted by Topless View Post
Failed fuel pumps are possible but relatively rare. Put 12VDC directly to the new pump to see if it runs. Now put 12VDC to the old pump and see if it runs. If they run, it's not a fuel pump problem and we are still missing something.
The old pump definitely failed the 12v test, repeatedly. When my car gets off to my dad's garage, we will test the new pump to see if it is still working. I would hope it didn't crap out already. Wonder if I should just go ahead and replace all of the relays for the DME/fuel system as a preventative.
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Old 04-08-2013, 09:13 AM   #7
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Quote:
Originally Posted by particlewave View Post
Could've been a faulty fuel pump. The only thing that could've fried the pump motor would've been a high surge, and that is very, very unlikely. The system doesn't produce enough power to fry it. With a dc system, the pump is only going to draw as much power(amps) as it needs and the voltage will not exceed 15v.

I would check for power at the pump and go from there. My guess is that you got a bad pump...hopefully under warranty.
From what I can tell the pump should be under warranty (new OE part), but with my luck it won't be covered. Going to re-check power to the pump connector (was good before) and power the pump separately as well.

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