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Discussion Starter #1
I have an 87 5.7L TBI with a cold start issue. Once it is warm it runs perfect. However when I start it at ambient tempatures it will start and want to stall. Especially when I go in reverse. Any thioughts on what could cause this?

I have done a few things which did infact make the truck run better but this issue is still there.

I am curious if it is a vaccum leak that would cause this. Just finding the leak is the fun part.
 

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Today the cold start turned into a serious ruff idle and it now blows black smoke. Wondering if this could be my fuel pressure regulator. I just replaced the plugs today and that did nothing. The timing has been done, pcv and coolent temp have both been replaced.

not sure .. this is the worst it has ever run. Yesterday it was running like a dream. Today.. wah wah :grrrrrr:
 

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As I read your first post I immediately thought "vacuum leak" Did you test for it?
 

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I seriously dont think this is a vac leak. It seems more of a fuel problem. I just replaced the Fuel Pressure Regulator and that did nothing. All though the old one was not so good and was leaking, so it was a needed replacement but not the issue. It is still blowing black smoke and running like crap. My thoughts might be that the new plugs I put in yesterday are already fowled from the pressure regulator. The old ones where really bad. I also checked the MAP sensor and that is good. I am going to put another set of cheap plugs in and a cap and see what happens. The check engine light will come on then go off. Checked for codes and there are no codes coming up. I honestly dont know what is left that would cause this.

Vac leak
Pressure regulator
MAP sensor
Plugs

What else would cause this?

I know it is very hard to explain when no one else can sit here and look and listen to it run
 
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