2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

vacuum while cranking at start

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Old Oct 22, 2003 | 02:04 PM
  #1  
junior-coyote's Avatar
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From: Boston, MA
vacuum while cranking at start

I have a 91 NA with a no start condition.
I have good fuel pressure and spark.
I pulled the plugs and it seems to be making good compression by ear. I will put a compression tester on it next.

I put a vaccum gauge on the intake manifold and I'm only getting 4" of vacuum which drops quickly to 1". Throttle is closed. This doesn't seem right to me. What should I be seeing?

thanks.
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Old Oct 22, 2003 | 02:35 PM
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Honestly, I never looked at my vacuum while cranking...Have you tried unflooding?

http://www.rx7.com/tech/unflood-fc.html
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Old Oct 22, 2003 | 03:22 PM
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yes I have unflooded it after each failed starting attempt. My wife had it while I was out of town, and she said the performance degraded gradually before it died. Unfortunatly, now it just won't start.

She had a shop look at it (before I could tell her not to.) They put in new plug wires (bosch) and a new battery and they threw away my battery hold down. I love pros. Now I'm checking everything. For the trailing coils the front coil goes to the front rotor, right? For the leading coil, does it matter which rotor each wire goes to?

thanks.
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Old Oct 22, 2003 | 03:38 PM
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From: FORT WORTH, TEXAS,USA
Lead wires don't matter, as long as they go to the bottom plugs.

Trail coils......on the plastic piece on the coil assy...it has T1 and T2 embossed on there for ID.
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Old Oct 23, 2003 | 08:32 AM
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lots of spark and good fuel pressure. No error codes. Computer seems to be firing the injectors. I'm suspecting a vacuum leak, hence the vacuum test. I'm not sure what I should be seeing.

Its snowing here right now, so the real compression test is on hold.
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Old Oct 23, 2003 | 09:59 AM
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yep, snow today in Boston. That sucks.

if you have spark and fuel, and it does not start, it's gonna be pretty flooded at the end of the day. I would do the unflooding procedure with the oil or get somebody to push start you.
Make sure you don't do compression test on a flooded or partially flooded engine.

I understand your frustration though: pretty hard to take care of things when you have to worry about flooding and potentially something else on top of it.

BTW, was there any ECU error code when you wife experienced the decrease in perf ?

Hugues -
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