Sorry if someone already mentioned this, but this is a long thread
and I may have missed it.
These symptoms sound almost exactly like my car did a while back,
What I found was that during the "no start" periods, I had little to
no fuel pressure, while other times the fuel pressure was fine. It
ended up being the fuel pump.
What appeared to be happening was that after the fuel pump ran for a
while, it would heat up and start binding. If the fuel pump turned
off, like parking the car, and I then tried to restart it, sometimes
it would start, sometimes not, as the fuel pump would not pump
because of it binding or such. If I let it sit another hour or
three, it would start right up, as the fuel pump had cooled
completly and would rotate freely. (I'm not saying this is really
what was happening, but it's what it SEEMED like.)
Do your troubleshooting during the "no start" periods. You may have
two problems, one bucking and stalling the other not starting, or
they may be from the same thing. The not starting is easier to
diagnose, so start with it, get it fixed, then see if it still
Check the basics. You need fuel, spark, and pressure (compression)
to start an engine. You can narrow down the possibilties with some
basic procedures/trouble shooting.
Does the engine sound like it usually does when you turn it over
with the starter? If so, your compression is probably close enough
not to be an issue.
On the fuel rail, just in front of the throttle body, there is a
connector for a fuel pressure gauge that looks sort of like a tire
valve stem end. In the absence of a pressure gauge, you can take the
cap off (if it still has one), use a key, small screwdriver, or such
to depress the pin in the middle (like letting air out of tires)
BRIEFLY. Protect your eyes!!!! (I like to put a rag over it to
prevent spraying gas everywhere.) If you have little or no pressure
during your "no start" periods, then it's going to be something in
the fuel line. (Electrical, pump, filter, etc.) Checking out the
fuel injectors is a little more difficult, and can be left for later
if you don't find anything else.
Spend a couple of dollars for a spark tester. You put it in-line
with the spark plug with the gap set at about 1/2", and when you
turn the engine over you should get a good, healthy, spark. Check
one plug from each coil, you should get a healthy spark from each.
(No need to check each plug, as the two plugs fed from a coil work
together. Spark at one means spark at the other.) No spark on any
coil could be crankshaft position sensor, ignition module, computer
module, etc. A spark on any coil shows the crankshaft position
sensor is good. No spark on one or two coils, with spark on one or
two indicates a bad coil, ignition module, plug wire, or plug.
These are the basics. If you want to do a more efficient and
thorough job, buy yourself a scan tool
, NOT a code reader (a scan
tool does so much more for not much more money), and follow the GM
shop manual troubleshooting charts that I've posted on my website at
You want Chart A-3, pages 1a
through 3b. This WILL find out why it doesn't start.
If you or anyone else wants to buy a good used scan tool, I can sell
my AutoXray XP-240 for $50. I just bought a used Vetronix Tech 1A
scan tool (which is the one the dealers use) for $400. I just bought
a 1995 Bonneville, and needed a scan tool that was compatable with
--- In email@example.com
, Kerry Donahue <fixn6000@...>
> Hi - - I have a 1990 Pontiac 6000 LE with a 3.1 v6 engine.
> About a week ago, I started having a stalling problem.
> The car will run fine for about a day (sometimes) then either
one of two things will happen.....
> 1. it will stall while driving and it is then very hard to
> 2. it will drive ok... I will park it and then after about an
hour or two if I try to start it, it just won't start - just cranks -
with no hint of starting. In this case, if I leave the car alone
for a few more hours, the car will start right up.
> I installed a new fuel filter - but still have the same issue.
> The service light has not come on and I had my local mechanic
check for codes and he said that there were no codes present.
> When I turn the key, I do hear the fuel pump "whir" - - think
that is an indication that is is OK.
> My local mechanic said that we should drop the tank and replace
the fuel pump and flush the tank. I really don't have that much
confidence in him...he's made some mistakes before when "guessing"
to fix a problem.
> I was hoping that someone might recognize these symptoms and
point me in the right direction before I start spending money on a
wild goose chase. Could some sensor cause the issue (I had my O2
sensor replaced about 6 months ago)
> Thank you in advance for your assistance,
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> [Non-text portions of this message have been removed]