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Why is my 1985 s 10 2.8 engine so hard to start ?



 
 
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  #1  
Old October 6th 17, 06:28 AM posted to rec.autos.tech
[email protected]
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Posts: 4
Default Why is my 1985 s 10 2.8 engine so hard to start ?

Ok,i have been searching for an answer to why my truck is so hard to start. I have done everything i know to fix this but no luck yet . I have put a re-manufactured carburetor on it.I have checked all the vacuum lines,replaced the fuel pump. manual pump. I have a clear fuel filter that look good. I have done a tune up,plugs,wires,cap,pickup module,exc... I have even done a compression test that passes easily. The engine runs good, its just hard to start. Im stumped !
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  #2  
Old October 8th 17, 12:42 AM posted to rec.autos.tech
Scott Dorsey
external usenet poster
 
Posts: 3,744
Default Why is my 1985 s 10 2.8 engine so hard to start ?

> wrote:
>Ok,i have been searching for an answer to why my truck is so hard to start.=
> I have done everything i know to fix this but no luck yet . I have put a r=
>e-manufactured carburetor on it.I have checked all the vacuum lines,replace=
>d the fuel pump. manual pump. I have a clear fuel filter that look good. I =
>have done a tune up,plugs,wires,cap,pickup module,exc... I have even done a=
> compression test that passes easily. The engine runs good, its just hard t=
>o start. Im stumped !


Fuel, air, spark, timing, and exhaust.

Is the mixture good? Is the choke closing down for starting and then opening
up once the engine warms up a bit? Look at the butterfly and mark where it
sits with a sharpie. If you block it partially with your hand or with masking
tape, will the engine start properly? The fuel mixture needs to be extra rich
for starting. The automatic choke sets it that way, if it's working, which
it often doesn't.

If you put the timing light on it while it's running properly, do the marks
line up? And then when you put the light on when you're trying to start it,
is the timing retarded or do the marks still line up? The timing should
shift severely back for starting and then the vacuum advance move the timing
up once the engine catches. Make sure it's moving the timing, don't spend
your time dicking with the vacuum system unless you verify that it isn't.

Is there a good hot spark when you pull a plug out and watch it? An awful
lot of "carb problems" turn out to be ignition problems.

If you disconnect the exhaust system, will it start right up? A partial
exhaust blockage may produce high back pressure at starting, but then the
blockage may be forced out of the way once the engine starts running.

Don't just replace things, check them out one at a time. Think about what
is different between starting and running... and three big things are the
choke position, the timing advance position, and the exhaust pressure...
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #3  
Old October 13th 17, 04:55 AM posted to rec.autos.tech
[email protected]
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Posts: 4
Default Why is my 1985 s 10 2.8 engine so hard to start ?

On Saturday, October 7, 2017 at 6:42:33 PM UTC-5, Scott Dorsey wrote:
> > wrote:
> >Ok,i have been searching for an answer to why my truck is so hard to start.=
> > I have done everything i know to fix this but no luck yet . I have put a r=
> >e-manufactured carburetor on it.I have checked all the vacuum lines,replace=
> >d the fuel pump. manual pump. I have a clear fuel filter that look good. I =
> >have done a tune up,plugs,wires,cap,pickup module,exc... I have even done a=
> > compression test that passes easily. The engine runs good, its just hard t=
> >o start. Im stumped !

>
> Fuel, air, spark, timing, and exhaust.
>
> Is the mixture good? Is the choke closing down for starting and then opening
> up once the engine warms up a bit? Look at the butterfly and mark where it
> sits with a sharpie. If you block it partially with your hand or with masking
> tape, will the engine start properly? The fuel mixture needs to be extra rich
> for starting. The automatic choke sets it that way, if it's working, which
> it often doesn't.
>
> If you put the timing light on it while it's running properly, do the marks
> line up? And then when you put the light on when you're trying to start it,
> is the timing retarded or do the marks still line up? The timing should
> shift severely back for starting and then the vacuum advance move the timing
> up once the engine catches. Make sure it's moving the timing, don't spend
> your time dicking with the vacuum system unless you verify that it isn't.
>
> Is there a good hot spark when you pull a plug out and watch it? An awful
> lot of "carb problems" turn out to be ignition problems.
>
> If you disconnect the exhaust system, will it start right up? A partial
> exhaust blockage may produce high back pressure at starting, but then the
> blockage may be forced out of the way once the engine starts running.
>
> Don't just replace things, check them out one at a time. Think about what
> is different between starting and running... and three big things are the
> choke position, the timing advance position, and the exhaust pressure...
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."


Thanks Scott, i have done all you have suggested. I am somewhat mechanically inclined,i fix all my own issues, but this has me stumped !
  #4  
Old October 13th 17, 04:59 AM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 4
Default Why is my 1985 s 10 2.8 engine so hard to start ?

On Saturday, October 7, 2017 at 6:42:33 PM UTC-5, Scott Dorsey wrote:
> > wrote:
> >Ok,i have been searching for an answer to why my truck is so hard to start.=
> > I have done everything i know to fix this but no luck yet . I have put a r=
> >e-manufactured carburetor on it.I have checked all the vacuum lines,replace=
> >d the fuel pump. manual pump. I have a clear fuel filter that look good. I =
> >have done a tune up,plugs,wires,cap,pickup module,exc... I have even done a=
> > compression test that passes easily. The engine runs good, its just hard t=
> >o start. Im stumped !

>
> Fuel, air, spark, timing, and exhaust.
>
> Is the mixture good? Is the choke closing down for starting and then opening
> up once the engine warms up a bit? Look at the butterfly and mark where it
> sits with a sharpie. If you block it partially with your hand or with masking
> tape, will the engine start properly? The fuel mixture needs to be extra rich
> for starting. The automatic choke sets it that way, if it's working, which
> it often doesn't.
>
> If you put the timing light on it while it's running properly, do the marks
> line up? And then when you put the light on when you're trying to start it,
> is the timing retarded or do the marks still line up? The timing should
> shift severely back for starting and then the vacuum advance move the timing
> up once the engine catches. Make sure it's moving the timing, don't spend
> your time dicking with the vacuum system unless you verify that it isn't.
>
> Is there a good hot spark when you pull a plug out and watch it? An awful
> lot of "carb problems" turn out to be ignition problems.
>
> If you disconnect the exhaust system, will it start right up? A partial
> exhaust blockage may produce high back pressure at starting, but then the
> blockage may be forced out of the way once the engine starts running.
>
> Don't just replace things, check them out one at a time. Think about what
> is different between starting and running... and three big things are the
> choke position, the timing advance position, and the exhaust pressure...
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."


Thanks Scott, i have done all you have suggested. I am somewhat mechanically inclined,i fix all my own issues, but this has me stumped !
  #5  
Old October 13th 17, 10:26 AM posted to rec.autos.tech
Vic Smith
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Posts: 929
Default Why is my 1985 s 10 2.8 engine so hard to start ?

On Thu, 5 Oct 2017 22:28:26 -0700 (PDT), wrote:

>Ok,i have been searching for an answer to why my truck is so hard to start. I have done everything i know to fix this but no luck yet . I have put a re-manufactured carburetor on it.I have checked all the vacuum lines,replaced the fuel pump. manual pump. I have a clear fuel filter that look good. I have done a tune up,plugs,wires,cap,pickup module,exc... I have even done a compression test that passes easily. The engine runs good, its just hard to start. Im stumped !


I've had a starter cause hard starting. Running too slow to get good starting compression.
My celebrity 2.8 was injected and a bad fuel pump caused long cranking.
But on my Lumina 3.1 it was the starter causing it.
It failed after a few weeks of hard starting/slow cranking.
  #6  
Old October 13th 17, 08:35 PM posted to rec.autos.tech
ben91932
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Posts: 367
Default Why is my 1985 s 10 2.8 engine so hard to start ?

Everything that Scott said was spot-on accurate.
With the engine cold, did you look down the carb with the choke open and work the throttle several times to see if you get a solid stream of gas yet?
Let us know...
Ben
  #7  
Old October 13th 17, 11:17 PM posted to rec.autos.tech
Xeno
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Posts: 76
Default Why is my 1985 s 10 2.8 engine so hard to start ?

On 14/10/2017 6:35 AM, ben91932 wrote:
> Everything that Scott said was spot-on accurate.
> With the engine cold, did you look down the carb with the choke open and work the throttle several times to see if you get a solid stream of gas yet?
> Let us know...
> Ben
>

Nobody seems to have asked the pertinent question;

Is it hard to start *hot and/or cold*???

It makes a big difference as to where you start and direct your diagnosis

--

Noddy! Have you made that call, sent that email?
The number to call: 1300 304 064
The email address:


Xeno
  #8  
Old October 14th 17, 02:56 AM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 4
Default Why is my 1985 s 10 2.8 engine so hard to start ?

On Friday, October 13, 2017 at 5:17:53 PM UTC-5, Xeno wrote:
> On 14/10/2017 6:35 AM, ben91932 wrote:
> > Everything that Scott said was spot-on accurate.
> > With the engine cold, did you look down the carb with the choke open and work the throttle several times to see if you get a solid stream of gas yet?
> > Let us know...
> > Ben
> >

> Nobody seems to have asked the pertinent question;
>
> Is it hard to start *hot and/or cold*???
>
> It makes a big difference as to where you start and direct your diagnosis
>
> --
>
> Noddy! Have you made that call, sent that email?
> The number to call: 1300 304 064
> The email address:
>
>
> Xeno


its harder to start when its cold. but it still dont start right when its hot.
  #9  
Old October 14th 17, 04:08 AM posted to rec.autos.tech
AMuzi
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Posts: 418
Default Why is my 1985 s 10 2.8 engine so hard to start ?

On 10/13/2017 8:56 PM, wrote:
> On Friday, October 13, 2017 at 5:17:53 PM UTC-5, Xeno wrote:
>> On 14/10/2017 6:35 AM, ben91932 wrote:
>>> Everything that Scott said was spot-on accurate.
>>> With the engine cold, did you look down the carb with the choke open and work the throttle several times to see if you get a solid stream of gas yet?
>>> Let us know...
>>> Ben
>>>

>> Nobody seems to have asked the pertinent question;
>>
>> Is it hard to start *hot and/or cold*???
>>
>> It makes a big difference as to where you start and direct your diagnosis
>>
>> --
>>
>> Noddy! Have you made that call, sent that email?
>> The number to call: 1300 304 064
>> The email address:

>>
>>
>> Xeno

>
> its harder to start when its cold. but it still dont start right when its hot.
>


You mentioned 'rebuilt carb'.

I don't know and I don't know your vehicle but rebuilt
carburetors nowadays can have the wrong aperture(s) in the
venturi cluster. Rebuilders seem not so diligent about
matching these for each application (many port sizes in the
same part blank get mixed after cleaning and before
assembly). Tracking down the actual spec and wire-gauge
measurement are tedious but if you've eliminated all else,
compare that to your original. Drove me nuts until I checked
it and swapped in the original.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971


 




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