Author Topic: Cold Engine Problem  (Read 10857 times)

Offline boll213

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Cold Engine - Update
« Reply #15 on: August 04, 2005, 02:01:00 PM »
Thought I would take a minute to post an update on my problem.  It wasn't a vac. leak.  It was/is a fuel problem.  It is lean, but it is because it isn't getting enough fuel.  I put a new Fram fuel filter on prior to installing the new engine.  After exhausting all of the possible vac. problems, I switched my focus to fuel.  I bought a new Wix filter and installed it.  About 80% of my problem immediately went away.  Still a little off on power when it is cold, but runs.  I cut the Fram filter apart and it was completely clean, just a bad filter.  I'm not a Fram fan!

The balance of my problem, I believe, is fuel pressure.  I'm only getting about 8 lbs. at idle,  I'd like to get that up to about 12 -13 lbs.  (read somewhere that was the target pressure).  Any ideas other than changing to an adjustable regulator.  I'm wondering if a stiffer spring or shimming the existing regulator would be options???


Offline roundedline

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Re: Cold Engine - Update
« Reply #16 on: August 08, 2005, 02:44:00 PM »
Are you getting 8 before or after the regulator?  How much are you getting from the tank.  It should be between 13 and 16 from the tank pump.  If you are only getting 8, that would be a little low.  GM recommends between 9-13.

I am not saying this is the problem, but it is one place to look.

Here is more info on GM TBI: www.cfm-tech.com/gm_tbi_f...essure.htm

This is a link that should assist in making the regulator adjustable.
www.thirdgen.org/newdesig...afpr.shtml
www.diy-efi.org/gmecm/faq/tbi_fp.html

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project


Offline boll213

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Cold Engine - Update
« Reply #17 on: August 09, 2005, 12:31:00 PM »
Thanks - I took the regulator apart this weekend and raised to pressure to about 12 (that's all I could get out or it without shimming or replacing the spring).  Runs a lot better, power is good, just a little surge at idle when cold, but runs just fine under load.

Thanks for all your help!


Offline 1911a1

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87 305 to 350 swap
« Reply #18 on: August 11, 2005, 08:35:00 PM »
my son and i are doing the same basic thing. go to tbichips.com for lots of info. the things different on the 350 from the 305 are: injectors,prom,electronic spark contr,and knock sensor. do the heated o2 sensor will stop the surging. good luck.


Offline boll213

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Cold Engine - Again
« Reply #19 on: August 24, 2005, 09:43:00 PM »
Do you have an application or a part number for a heated or 3 wire O2?  Also, how will this help - as I understand the way the computer works, it will not read the O2 until the engine reaches a pre-determined temperature - read by the temp sensor in the intake and will continue to use the "static fuel matrix" until then.  So, heating the O2 wouldn't really make any difference if the computer isn't in "closed loop" and using that information to adjust mixture, etc. would it?  Perhaps changing the computer is also necessary in order to make this fix work?