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Engine Not Starting/idle Rpm Up, And Down,etc.

knnhon

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knnhon Enthusiast

knnhon

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Well, I'm too lazy to try to find where the guy had BIG trouble with engine starting, or idle RPM going up, and down.

 

Well, i did some investigation---like CHIEF Inspector Clouseau!!![my apologies to Peter Sellers/Blake Edwards], and because i had quotes as high as 400 bucks to fix my problem...I decided to theorize[HA!].

 

I went about it like this: first went to Advanced Auto Parts[not Autozone-they don't sponsor any NHRA car], they read the code, said i needed a new MAF sensor.... NAH, that's too easy[any problem I've had-it NEVER was that easy!-in 50 yrs!]

So i got out my Haynes' books[YUK!]; i have 2 old one and newer one for '94-'98 Chevy trks. You know these are NOT that good[Yes, Virginia, I've gone to Ebay to find a USED Service manual-now]. Funny thing, there is an upgrade in newer Haynes' about the screen on MAF.... why would they go to that much trouble to reprint book.... so that got my curiosity up, AND playing around[because they say there a 4 PRONG conn. for MAF-there is only a 3 prong plug]. i decided to check for 12 volt supply... there was NONE!-AND NO pink wire!

 

My truck would start-U had to turn key on, and wait 10 seconds before cranking engine, or it would not start. Then the idle speed would go up for 3 sec's, then come down,etc. until warmed up. Then it was reasonable driving, except, if you were in light throttle at 50 mph-then there was a SLIGHT miss....My initial thought was that fuel pump was going bad[starting condition]. i used press. guage, and it said 40 psi.That was low[52-62 is normal]. Also in newer Haynes', it says idle psi will be lower-so that satisfied me that my 3 yr old Carter pump-#714467 is OK. Then i inadvertently forgot to hook-up my MAF plug-in... The truck started, and did what it had been doing for 4 weeks[starting,etc.!] IT RAN!--- with NO MAF input!!!.... So CHIEF Inspector Cloiseau did what he is famous for----- BLUNDERED RIGHT into the cause and cure!!!! NO elec. supply to MAF-AHA!! Took voltmeter, and probed, and found 2 blown fuses next to PCM... one a 30 amp, one a 10 amp. they didn't look blown from top[don't ya HATE these LITTLE fuses?],

.... i disconn. pos. terminal[to clear codes-& kill 'Chk eng.' light]. re-attached MAF plug, and Voila[wanted to impress ya wit ma 'Frog'...er, my French pronounciation]... I'm GOOD-To-GO again... NO prob's with start-up,idle[cold, or hot], and no miss at 45. Saved 400 bucks.... BUT, have no idea what caused fuses to blow, so i'll be on the look-out if prob. returns--- let ya know

knnhon Enthusiast

knnhon

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Posted
Excellent. Glad you figured it out. :cheers: Which fuses were blown?

 

uses were to MAF... one was a 30 amp, one was 10 amp. both located in '96 under hood fuze box[hard to see if blown]. Disconn. batt. and just started going one by one...What i don't know, is why they blew in the first place... i didn't reply right away to y'all, wanted to see if they blew again... Everything is GREAT, EXCEPT now, i couldn't open door from inside![130,000 mi.]I'm not complaining... just went to Junk yard, got a 30,000 mi. latch!]30 bucks[Rock Auto does not carry this part!]. Had to drill out inside door panels, that was only time consuming part of fix

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