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Join Date: Oct 2006
Location: Chas, SC
Posts: 981
Hot Start Problem

1986 930, all smog and cat removed, O2 disconnected and CO is approx 2.5%, otherwise stock. I have checked cold and warm control pressures and they are within spec. I have also checked system pressure, and also within spec (min of 1.6 bar after 10min, 1.4 bar after 20min) I have approx 2.0 bar after 10min, and 1.8 bar after 20min. I would assume that the above test rule out the WUR, Fuel pump check valve, and Fuel accumulator. What else could I check?

Tim
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Tim
1986 930
Gone:71,2,4 914's, 70T, 71T(RS),77S

Last edited by timc; 10-21-2007 at 03:58 PM..
Old 10-21-2007, 03:10 PM
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Hard to start hot

2 hours later and system pressure is still 1.5 bar, well within spec. Just thinking, since my cold and warm control pressures are right in the middle of spec, what if I tap the plunger in a bit to set the control pressures on the lower end of spec which would richen cold and warm. Just can't think of anyting else to try.

Tim
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Tim
1986 930
Gone:71,2,4 914's, 70T, 71T(RS),77S
Old 10-21-2007, 06:25 PM
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Acceleration Junkie
 
Join Date: Aug 2007
Location: Laguna Beach, CA
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Hot Start Problem

Even with good pressures, pumps, accumulator, if there is significant heat buildup in the engine compartment, it will vapor lock. I speak from experience here.
Does '86 turbo have a fan force feeding ambient air into the engine compartment? Vent that opens/closes with speed? Are they functioning properly? Are engine sealing tin pieces and associated gaskets in place, sealing the compartment from below?
Can the engine be restarted immediately after shutting off hot? Immediate meaning within a few seconds. Or, will failure to start occur after being off 5/10 minutes?
Good luck finding the problem.
Regards,
Chris
Old 10-21-2007, 07:35 PM
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Hot Start

I was thinking vapor lock also, but engine really does not have to get that hot, just warm. Yes, I can restart without problem up to approx 5-10 min after shutting down. This afternoon when I was checking fuel leak down times, with the engine just barley warm, after the 20 minute mark I had difficulty starting. Maybe it is vapor lock just don't know yet...

Sorry - Yes, all engine tin/seals are in place.

Tim
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Tim
1986 930
Gone:71,2,4 914's, 70T, 71T(RS),77S
Old 10-21-2007, 10:28 PM
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How fast does the engine crank when it doesn't start. Normal, slow or fast?
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG.
Fitting - New service kit.
Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head.

1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods.
Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit.

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Old 10-22-2007, 02:16 PM
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Hot start

normal, no difference from when cold.
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Tim
1986 930
Gone:71,2,4 914's, 70T, 71T(RS),77S
Old 10-22-2007, 03:56 PM
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