1988 4.3 S15, feels like it's cutting out

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Tom Taylor - 14 Nov 2006 00:39 GMT

I have an 88, S15, 4.3, Auto, 4x4, with 197,000 miles that's driving me
crazy (crazier??)......It runs fine when cold. When it reaches operating
temp and it's driven at around 40 to 50 mph, it feels like it's cutting out
electrically. It happens for a second and then will be ok for another
minute or so, then it does it again.

It's not setting any codes. I've used WinALDL and see all the sensors
responding as they should. Timing has been checked and it's fine. ESC is
working because when I disconnect it I see the timing change........It has
new injectors (Standard), plugs, wires, rotor, cap. My mechanic also
changed the pickup in the distributor - since that was original. Also
changed some vac lines that were dry-rotted.....All this, yet I'm still
experiencing the problem. I'm stumped - and so is my mechanic.

I'd appreciate any help you can provide.

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Repairman - 14 Nov 2006 12:47 GMT

Coil's bad.
My '89 Blazer drove me crazy with a intermittent miss/power drop out. Mine
would run fine unless climbing a hill or stomping on it. Will not set a code
either.
One night I got lucky and heard it arcing and then I saw the coil arcing.
Remember it's intermittent and I just happened to be in the right spot with
the hood up.
If you look close at it you'll see the grey arc mark where it shorts from
the coil to the laminated frame.
Get a quality repl. coil , I cheaped out an put a AZ one it, lasted 2 weeks
and same problem again until I put the NAPA coil then problem free after
that.

>I have an 88, S15, 4.3, Auto, 4x4, with 197,000 miles that's driving me
>crazy (crazier??)......It runs fine when cold. When it reaches operating
[quoted text clipped - 11 lines]
>
> I'd appreciate any help you can provide.

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kneedeep_4 - 14 Nov 2006 21:06 GMT

check your fuel pressure...9 to 14 psi with key on engine off..not within
the specs replace pump..

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Tom Taylor - 14 Nov 2006 21:43 GMT

I should have said in the original posting that the fuel pump was changed
about 40,000 miles ago and is within specs. Please excuse my error of
omission.

> check your fuel pressure...9 to 14 psi with key on engine off..not within
> the specs replace pump..

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kneedeep_4 - 14 Nov 2006 22:38 GMT

check your engine coolant temp sensor...

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Mike - 15 Nov 2006 04:56 GMT

I have a 88, K1500 with a 5.7L and it just started doing the something like
that.
It only cuts out after its warmed up, mostly after a short blast on the
highway.
It will miss and/or has no pwr at idle and at lower speeds. I can hear it
ping badly and a few times it backfired into exhaust manifolds. It will do
that for a minute and then run fine. It will not do it all the time, I can
drive
it 20 minutes, it will miss for a bit then run fine. Like you, no error
codes.
I don't think its a fuel pump problem, in that if the pump is actting up it
it would miss longer and at all speeds, hot or cold, ( IMHO ). I am betting
something with the ignition. I 'm just starting to look into it, and will
let you know what (if) I find.

Mike

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Tom Taylor - 17 Nov 2006 22:45 GMT

It turned out to be a bad set of wires. Sprayed the wires with a misting
bottle and it almost stalled. Replaced the wires and she's running like her
old self.

Thanks to everyone who offered assistance.

>I have a 88, K1500 with a 5.7L and it just started doing the something like
>that.
[quoted text clipped - 30 lines]
>>
>> I'd appreciate any help you can provide.

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littleblue - 30 Mar 2007 23:35 GMT

Iam having the same trouble , have you had any response? The only
difference is that mine is a 1989, with about $2000.00 worth of new parts
under the hood, plus ECM change and new fuel pump and tank.

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