Intermittent Power Loss in 1989 Chevy G10 Van with 305
For 10K the van loses power intermittently for 1 to 10 seconds then comes
back to normal power. It happens at all speeds from thruway to idle. A
variety of shops including a Chevy dealer have failed to eliminate the
problem. The following have been checked or replaced: fuel pump pressure
checked, fuel filter replaced, spark plugs and wires replaced.
Does anyone have experience with this specific probem on this vehicle engine
or similar?
Any guidance would be appreciated.
187 - 08 Sep 2006 03:56 GMT
sounds like a throttle posotion sensor.
does it idle good, or does it go up and down?
i saw u replaced plugs and wires, what about dist. cap and rotor button?
really sounds like TPS though.
hope this helps
matt
unr - 08 Sep 2006 11:36 GMT
Thanks for your idea.
We also changed the distributor cap and rotor.
It idles fine when not experiencing the problem. Then when it happens it
dies at idle and needs to be started again. The idle doesn't go up and
down.
Do you still think we should try TPS or is that only a suggestion if the
idle goes up and down.
We really appreciate your suggestion because everyone who has looked at it
has failed to find the problem and that has never been mentioned.
Thanks.
> sounds like a throttle posotion sensor.
> does it idle good, or does it go up and down?
> i saw u replaced plugs and wires, what about dist. cap and rotor button?
> really sounds like TPS though.
> hope this helps
> matt
Ken - 08 Sep 2006 12:22 GMT
Intermittent problems can be the toughest to figure out. Has the
problem been recreated by any of the shops you take it to? Often an
intermittent problem cannot be figured out because it cannot be
recreated by the technician.
> Thanks for your idea.
> We also changed the distributor cap and rotor.
[quoted text clipped - 15 lines]
> > hope this helps
> > matt
unr - 08 Sep 2006 13:10 GMT
No, the van often works fine for many days or many hours. Sometimes we go
weeks with no symptoms.
We haven't been lucky enough to have it happen in a shop.
And it isn't getting more frequent. This has been going on for over a year
and we still haven't hit a consistent period when we can get it into a shop.
Thanks
> Intermittent problems can be the toughest to figure out. Has the
> problem been recreated by any of the shops you take it to? Often an
[quoted text clipped - 20 lines]
> > > hope this helps
> > > matt
George - 08 Sep 2006 14:07 GMT
I don't know what that engine has, so this may not apply. But, we had a
Buick of (IIRC) 1980's-vintage that acted like that. The problem was a
bad intake airflow sensor.
Other vague memories: EGR? vacuum leak?
G
>Intermittent Power Loss in 1989 Chevy G10 Van with 305
>
[quoted text clipped - 8 lines]
>
>Any guidance would be appreciated.
unr - 08 Sep 2006 18:33 GMT
I just checked the records and both the throttle position sensor and the air
control valve *were* replaced. Neither of these fixed the problem.
The fuel pump has not been replaced but the pressure checked fine in the
Chevy dealership.
The coil has not been replaced.
> Intermittent Power Loss in 1989 Chevy G10 Van with 305
>
[quoted text clipped - 8 lines]
>
> Any guidance would be appreciated.
George - 08 Sep 2006 19:11 GMT
What does it do when it fails? Any backfire? Does it just abruptly
lose all power, or gradually slow down, or ...? When you give it more
gas, do you get any response? Do you hear anything?
And, for how relatively little it costs, I'd probably replace the coil.
>I just checked the records and both the throttle position sensor and the air
>control valve *were* replaced. Neither of these fixed the problem.
[quoted text clipped - 17 lines]
>>
>> Any guidance would be appreciated.
unr - 09 Sep 2006 02:36 GMT
When if fails it just cuts out with no backfire, no sputter, no gradualness.
If you then give it gas there can sometimes be no power at all or, other
times, much reduced power, almost enough to maintain speed but no
possibility of accelerating. There is no unusual sound.
I have been carrying both the coil and the computer which I will now replace
but am trying to collect a list of all possible options to do them all at
once. This issue has been such an aggravation in its tendency to reappear I
really want to try to put it down once and for all.
Thanks for the guidance.
> What does it do when it fails? Any backfire? Does it just abruptly
> lose all power, or gradually slow down, or ...? When you give it more
[quoted text clipped - 23 lines]
> >>
> >> Any guidance would be appreciated.
jeffcoslacker - 08 Sep 2006 19:22 GMT
Not getting pinging associated with it when it happens, are you?
The HEI distributors' centrifugal spark advance would sometimes hang
fully advanced intermittantly (rusty), usually after a hard
acceleration, then when you stepped down on it again, you'd get flat
reaction and hard pinging...
Not sure if '89 still had the mechanical advance either...
Is that carb'd or TBI?

Signature
jeffcoslacker
http://www.automotiveforums.com
unr - 09 Sep 2006 02:37 GMT
There is no pining or other remarkable sound but thanks for the perspective.
It is an early fuel injection, not carb.
Thanks for thinking about this. We are beyond stuck.
> Not getting pinging associated with it when it happens, are you?
>
[quoted text clipped - 6 lines]
>
> Is that carb'd or TBI?
unr - 09 Sep 2006 23:11 GMT
Today, installing the coil and then an ignition module I looked carefully at
the connectors, as various Chevy shops had claimed to do. In fact the
connectors to the latter were corroded. I suspect this will resolve the
problem and most components are replaced anyway.
> Intermittent Power Loss in 1989 Chevy G10 Van with 305
>
[quoted text clipped - 8 lines]
>
> Any guidance would be appreciated.
silicon212 - 09 Sep 2006 23:39 GMT
unr Wrote:
> Today, installing the coil and then an ignition module I looked
> carefully at
[quoted text clipped - 21 lines]
> >
> > Any guidance would be appreciated.
This to me was coming across as an ignition module issue, hopefully
cleaning the corrosion fixes it!

Signature
silicon212
http://www.automotiveforums.com