I just purchased this truck and it starts and idles just fine, no
roughness. But about 30 seconds after you start it, it just dies. It also
does this at nearly every traffic light, twice at longer lights. If I
punch the accelerator as it is dying, it will come back to life. It runs
just fine as long as I don't stop. It stalls less often if I put it in
neutral while I'm stopped, but it eventually still stalls.
The seller says that this just started happening after he let it sit for a
month or more without running. This engine has trottle body injection TBI.
It seems like a fuel problem to me. I guess I need a plan of attack.
Here's what I plan:
1. Add some Iso-HEET to the tank to remove any water.
2. Install new fuel filter.
3. Check for fuel pressure. I'm not quite sure how to do this - even after
reading the Chilton manual.
4. Install new pump if the pressure was bad, otherwise look to the
Am I heading in the right direction? Can you help with some suggestions?
Will Seattle make the playoffs?
Check the alternator. It has been my experience that the symtoms you
describe have been because of low charge. When you come to a stop and
put on the brake lights it draws so much power that the ignition
suffers and dies.
Check it out and you will see. :)
Thanks Gordie but this happens even if the truck is idling. It only
seems to happen after it is warmed up. I can put it in park, start it up
and it will die after about 5 minutes. If the engine is warm it will die
sooner. It will die more often if it is in gear, like at a stop light.
I've checked the throttle position sensor, the idle air control valve,
the MAP sensor, I replaced the oxygen sensor, I disconnected the engine
coolant temperature sensor and the rpms increased so I assume that it is
I look at the injectors when it dies and they are continuing to spurt
right up to the last, which indicates that it probably isn't a fuel
supply problem. Under normal conditions when you turn off the key, the
injectors stop immediately.
This has the guys at the local parts store stumped, not to mention me (I
only know what I read in the manual, and that ain't much).
I'm starting to think that it might be ignition system related because it
acts like someone just disconnected the ignition system. But if I give
it some gas, it comes back and if I keep the rpms up, it doesn't happen -
which doesn't sound electrical to me, but I'm a novice. I'm starting to
think maybe the ECM (brains) is bad.
Any more advice? Anyone? If I haven't fixed it by Monday I'm taking it
in to the shop.
Not sure if you did this or not, but have you checked the plugs and wires?
I had an AMC Eagle a very long time ago that didn't want to stay running if
I didn't have my foot on the gas (can't remember if it had anything to do
with it being warm or cold). Gave it a tune up, and never had a problem
Thanks Bill. I know how to pull the plugs and check them out, but I'm
not sure how to check the wires. The way I used to do it many years ago
is open the hood on a pitch dark night. If I saw a lightning storm on
top of my engine, I knew it was time to get a new set of wires.
First I think I'll check out the knock sensor. Someone suggested that if
it gives a false knock, the computer might retard the timing until the
Thanks Ed. Checking the EGR valve is involved and requires a vacuum
tester that I don't have. Before I do it, could you give me a short
description of how EGR valve failure would cause the engine to die only
while idling? Meanwhile I'm going to check the timing.
if it sticks open, exhaust gas gets into the plenum and dilutes the A/F mix
to a point that is barely burnable. above idle, the ratio of exhaust gas
to A/F is much smaller. A properly functioning EGR valve is more or less
octane adjustment on the fly. it does this by diluting the A/F mix at
cruise to slow it's rate of burn (the Octane rating is a comparison of the
burn rate of gasoline and pure octane gas, less than 100 octane and the
gasoline is burning faster, higher than 100 and the gas burns slower) so
more timing can be run to get better gas mileage.
Thanks Bret. Some of that is over my head, but I get the drift.
Just to reiterate (if I didn't iterate already) the engine doesn't idle
rough, it just dies all of sudden, as if someone disconnected the
distributor or pulled on the choke.
I located a stripped thread on a distributor cap screw, actually on the
distributor itself, (I didn't do it, honest!) so I'm going to take care
of that now. I guess I'll just ream out the dist cap hole and tap the
screw hole in the dist to the next size screw. Someone tell me if this
is a bad idea.
Off to the hardware store.
Well on Saturday I took it to a mechanic who was nice enough to take a
look at it for nothing. I told him everything I did and he couldn't
figure it out, but suggested replacing the timing chain if there was too
much play. I checked the play and it is 10 degrees - a lot. So I'm
replacing the timing chain and I've got down to the crank pully. I've
got the 3 bolts off and now I'm trying to get the center bolt off (the
damper bolt) but I can't keep the crank from turning.
Thanks Bret! I solved that problem by taking the fan belt, wrapping it
around the existing pullies and doubling it back on itself at the crank
pully so that it binds on itself - sort of like a huge strap wrench.
That's about the best I can describe it. It worked. Then I about
screwed up my pulling tool and the center threads on the crank when I
tried to pull the damper without a bolt in the center hole. I ended up
forcing the center post of the puller into center hole on the crank.
Luckily the threads on the puller were big and deep enough that I could
recarve the threads with a Dremel tool. Crazy. You'd think they'd make
a nice big cone shaped focrum for the puller.
Anyway I got the sloppy, old chain and gears off and now I have the new
ones on - most of the way. The crank gear doesn't seem to want to seat
all the way (and I'm not sure where "all the way" is). This doesn't
surpise me since the old one was so hard to get off.
How am I supposed to get the crank gear to seat all the way? I tried
putting the old gear on top of the new one and banging it with a hammer -
so I wouldn't mar the new gear. It helped but it still seems like it
needs to go another third of an inch or so to seat all the way.
It is an old problem with an old solution.
Merely jam a rag into the balt and pulley and you will be able to get
the bolt loose. The lump of rag cannot get around with a tight belt
and it is incapable of harming anything. Try it - it works on blets
and also on chains.
what you may have a valve on your fuel rail for testing your pressure
if not youll have to run the gauge inline if you think your pump is not
putting out enough pressure sure you can change it but you also have a
fuel pressure regulator that might be the prob also check your vaccume
lines i had one that did the same thing and i went crazy changing this
and that but it ended up being a line disconnected is your truck
equipted with a MAP sensor sometimes this can cause the problem when
your truck stalls try pulling the codes from the pcm more info on this
if needed.it may just be a bad sensor Id pull the codes check the fuel
pressure and take a look at the vacuum lines before i went and spent
money changing parts i didnt have to
Sorry I haven't checked in sooner, it's taken me 2 days so far to get the
new timing chain/gears on. I should know this AM if it solves the
As far as stopping the crank in order to break loose a center bolt - the
suggestion about a rag won't work if you have the water pump off, which I
did. My idea about using the belt as a giant strap wrench worked well,
but a mechanic gave me a better idea that also involves a rag. At the
starter, remove the cover that exposes the flywheel - mine was already
exposed. Clamp a pair of vice-grips onto the flywheel using a rag in the
jaws to prevent maring the flywheel. Now either way you turn the crank,
the vicegrips will eventually be stopped by the housing and you will be
able to loosen or tighten the center bolt.
This thread is a bit jagged, but I'm trying to restart it when the
situation changes - also to prevent the posts from getting too big and
the responses from extending too far to the right. Probably violating
some rule about that.
It turns out that the auto supply store sold me the wrong damper puller
for my engine and it darn near messed up my center crank threads. I got
the right one and it works like a champ. I then had a problem getting
the new crank gear on. Someone suggested heating it in a 200 degree oven
for 30 minutes, but that didn't work. Someone at the auto supply store
suggested getting a longer bolt and using spacers/washers to pull the
gear on using the center bolt. This worked, but the side effect of
torking on the center bolt was that the two gears were no longer aligned.
I eventually got them so that the dots lined up. Then I scraped the old
gaskets off and got the new ones ready to install. I discovered that I
couldn't put the timing chain cover on, due to the way the oil pan gasket
was installed. Eventually a mechanic told me that I'd have to drop the
old pan, which I did. Out of daylight.
So that's where I am now. I think I'll replace that oil pan gasket while
I have it off. I suppose it is leaking at least a little because there's
fresh oil on the outside of the pan.
Also, before I took this apart, my timing light said that... I won't get
into that, just let me ask, what is the time supposed to be at idle for
an 88 Chevy 305 pickup? My book says 4 degrees BTC if I read it
DAMN!!! THAT WASN'T IT!!!
I finally got it back together and it runs pretty much the same as it did
before - only it doesn't seem to stall as often - and never in park. So
it wasn't the timing chain!
In the process of closing things up, I found a sensor that was
disconnected on the lower right of the block, right near the bottom -
about halfway back. I connected it after I got the truck running again
and of course it didn't solve the problem. Anyone's guess as to what it
might be? If it's a crank sensor, I don't think I tested it. I couldn't
find a crank sensor and the guys at Schuck's said that this model didn't
have one, but the manual says yes. It looks more like an oil pressure
sensor, but I'm pretty sure that's on the right side. Anyone know for
sure what this is?
My next plan is to adjust the timing. The numbers on the scale weren't
visible before, but now they are. Apparently I got 14 degrees BTC on my
old timing light, but the mechanic with his timing light said that it was
right on. He didn't say what the spec was, but the way I read my manual
the spec is 4 degrees! Could my timing light be off? It is pretty old
but it doesn't seem like it would fire late under any conditions. I'll
try adjusting the timing and see what happens.
After that, I'll run it by a trany guy. Sometimes it shifts hard
(whiplash kind of hard). He can at least tell me why that is and maybe
come up with an idea about the stalling problem.
If that doesn't work, I'll take it to the repair shop - like a normal
person would. "Normal" - what a dismal fate!
Steve, thanks for your input! I don't think this is fuel supply problem
because when it fails, I can see the injectors spitting fuel right up to
the time it finally stops. Also the plugs indicate that it is running
rich. If you still think it could be a fuel supply problem, let me know.
I've checked all the vacuum lines multiple times - I even checked the EGR
system per Ed's suggestion. The MAP sensor checks out (as does every
other sensor I could find). The PCM or computer does not return any
codes. If I disconnect the MAP sensor while it's running, the computer
will return a code, so I know that it is returning codes.
Thanks everyone for you inputs!
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.