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1987 R10 5.0L

Weird problem that has me stumped....

1987 R10 5.0L V-8 Auto. Trans.

Crank the engine and when it starts, the rpm goes almost full throttle (like the throttle is full open) and that is without the pedal depressed at all..

I did some prelimenary checks such as:

1: Watched the TBI injectors during start and the fuel is spraying with substansial flow..Disconnected the electrical connectors and verified no leaks(or flow) from injectors while cranking

2: Disconnected TPS, cranked engine and it still goes full rpm

3: No codes stored (jumped connector and SES flashes 12)

This one really has me stumped and I could really use some help. The truck is totally undriveable.

TIA, T.

Reply to
TM
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did you look and see if the throttle plates are stuck open some ? your Idle air controll might be stuck wide open ( they allow air to by pass throtttle plates at closed throttle and let ECM to adjust RMP , fast idle on start up...AC command ...stuff like that ..... also if air is sucking in from somewhere else ..call a vacume leak ..look for vacume hose off . if you got plyers , temporary pinch off hose to brake booster ..case brake booster screwed up ......also if you got cruise controll make sure its not hanging up , EGR could be stuck open but i doubt it , they usualy run like crap, dump black smoke out pipe , you can use water in a spray bottle with engine running , if RMP isn't 4000 and above .lol spray water around TBI gasket and Intake were it meet cylinder head , if RPM changes or engine stumble you may have found your prob.. .TBI on your year of truck were bad for sucking in the base plate gasket , Thats under the throttle body unit ...easy fix replace gasket ... if you got a can of air intake cleaner ( similar to carb cleaner ) spray around tbi gasket , or like i said up top water will work but dont spray into throttle body , and goes easy around base plate ...hope

hope this helps some

- "TM" wrote in message news:e5zwg.40116$ snipped-for-privacy@tornado.ohiordc.rr.com...

Reply to
Chevy

Tried most of these, but I'll go over the list again.

Thanks for the info, and I'll post what I find.

T
Reply to
TM

Rigid vaccuum line to the brake booster had rusted thru....Swapped it out and all is good now...

thanks for the help.

T
Reply to
TM

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