[Gmecm] Re: Warm start problem

[Brett Richards]

I had a similar problem with my LS1. I have an aftermarket thottle body
and the hole for the idle air control is bevelled, whereas the stock
throttle
body the hole is straight. Once we found the right size o-ring for it the
problem went away. Sounds to me like there is some sort of similar leak
somwhere with your setup. I'm not that familiar with the TPI setup, but
I hope this may help
Brett

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org]On
Behalf Of DOZIERHC at aol.com
Sent: Friday, 13 July 2007 5:52 AM
To: gmecm at diy-efi.org
Subject: [Gmecm] Re: Warm start problem



Mike...

It could be the fuel system leaking down.

Try putting a fuel pressure gauge on the Schrader fitting and watching the
fuel pressure decay.
A good system will hold pressure within about 10psi for 24 hours.
If your decays off to near zero in a few hours, I would then try and
isolate
if it is leaky injectors, or a leaking check valve in the fuel pump, or  bad
pressure regulator.

As for cranking fuel PW, the system experiences hottest fuel at about 20-30
minutes into a hot soak, after that, the temperature decays back towards
ambient.  So Hot starting vapor lock would be at that time, if it is going
to
happen (fuel flash to vapor in the nozzle of the injectors, therefore
effectivly
blocking injection PW).

IF that is the case, you might have to bump your cranking fuel PW for
higher
MAT temperatures, NOT ECT, to try and alleviate the fuel  starvation.

BTW, do you have a Wideband in your system to see what the post crank
fueling Lambda profile looks like?

Hank

Date: Wed, 11 Jul 2007 18:28:14 -0600 (GMT-06:00)
From: Mike Frels  <mfrels at ix.netcom.com>
Subject: [Gmecm] Warm start problem...
To:  diy_efi at diy-efi.org, gmecm at diy-efi.org
Message-ID:
<29180054.1184200095220.JavaMail.root at elwamui-milano.atl.sa.earthlink.net>

Content-Type: text/plain; charset=UTF-8

I am trying to  diagnose a hot or warm start problem. I've got a gm TPI 350
running $8D for a  305 that has been modded to work with my setup. Morning
starts she fires right  up. Hot starts if she's only been sitting for less
than
10-15 minutes also fine.  A restart between 15 minutes to 5 hours sitting
takes
some cranking. Looking  through my tables I've got various Start Up
Enrichment
and Crank Fuel Pulse  Width settings that I am thinking I need to adjust.
Can
someone enlighten me on  what the differences between Start Up Enrichment
and
Crank Fuel Pulse Width? BTW  I have acquired this summer time problem since
I
switched to LS1 injectors last  year.

Mike


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