Automotive Help Requested?

[TopCatGr58]

Hey Folks,

Okay, my sister-n-law that lives with "US", her car is a 2001 Chevy Blazer with a V6 FI....I think Throttle body style, has trouble starting after it's sat a few days, but with a STRONG BATTERY!

What I've done:
A few months back, replaced spark plugs, distributor cap/rotor.
Have run FI cleaner and Sea Foam in the tank when it would RUN.
Have had battery charged and used booster battery as well.
Recently rechecked for spark, have good spark "I THINK"... fat yellow spark!
Removed fuel filter, was flowing, could blow air thru with my mouth, but replaced with NEW anyways. Turned key on before completing fuel filter line connections, had fuel flowing into gas can, so fuel pump works!

Symptoms:
IT would turn and turn and turn with no sign of catching/firing for 20+ seconds! A few weeks ago, I learned to hold the throttle foot all the way down, that seemed to put enough fuel into it to get it to catch and finally got it to run. Once it was running, I drove it about 20 miles, no problems with accel, etc., and after stopping and turning it off, would restart easily!

I tried to get her to remember to start it every other day, but she's partially disabled, diabetic and bad foot, and we just would get busy, and it would sit for several days.

I've recently tried to start it, same symptoms, it occasionally acts like it wants to catch, but sometimes it would crank, rrrr, rrrr, rrrr, oomph, it would stop or severely slow down like it was firing during the upstroke of a piston's compression stroke??

Just recently the starter STOPPED responding to turning the key, so now I figured I've FRIED the starter motor, and will need to replace it, but this still brings me back to WHY it's behaving like this?

No warning lights had come on with the previous actual starts, no check engine light, etc.. I think it's got a throttle body FI design vs. individual port FI, which should be easier to use? I even poured some gas into/onto the throttle body butterfly, and tried to start it, but it still didn't help?

Regrettably, I don't have a MANUAL for it, I'll check the College online access we recently updated the username/password for, but would gladly accept and appreciate any other trouble shooting ideas!?
T.C.

[trbig]

Fuel pump relay...

After you get a starter, under the hood, there's a fuse box looking panel that has different relay switches in it. You can actually take one (if you see that it has the same number on it) such as for the A/C, unplug it and plug it in to see if that makes it work.

On Chevrolets, they have an over-ride for that Fuel pump relay to where if you build up enough oil pressure, (From cranking it a lot) it will override that relay and work so you don't get stranded somewhere.

Hopefully that will work for you.. @ $20 or so to fix. Cheaper than the tune up you did! lol.

Tod

[DGXSER]

Just a thinking out loud

Everything you suggest sounds like fuel issue. I always like to hear them crank to hear if it is fuel or not,but base dupon what you have described, fuel seems to be the issue. If you can hear it tryign to catch but wont quite start, that is usually fuel. If it were the pump, typically, that would not go away once started.

I have no lcue about the disable issue Tod mentioned, but it seems like that would return eveyr time you tried to start it after it sat for a bit. And IIRC you stated it starts fine after one start for the day?

Runs great once started, starts easy when hot or warm, wont start when cold. . Perhaps it is the fuel filter? Had that happen on a 94 Voyager.

Does the check engine light come on before you start it? Perhaps it is burnt out and it has some codes, I'd throw a code reader on it just in case.

[Dragonrider]

Also make sure your battery, when fully charged and at rest, is reading 13.4v or more...and that it holds over 12.5 when lights are on/turning over etc.

My wife's olds did that (before we traded it)...felt like the battery was strong...and it put out plenty of amps to turn her over...but the voltage was low due to a dead cell (under 11v) and the systems just won't come on line with that low a voltage.

[excessive1100]

Have you tried putting a booster battery on it right away when it has sat for a few days.

It may have be a battery or ground issue. My van will do this on occasion but will start just fine when hooked to another car using the battery and ground from the other car.

[DiverRay]

TC,
If you have access to a "fuel pressure gauge", use it. You may find the fuel pump is marginal, and isn't quite up to the 40 PSI it needs.

[The Lorax]

Fuel pressure can be a real sticky issue, some modern vehicles will not start if the fuel pressure is even 1psi low. apart from that, you say you replaced the plugs, cap and rotor, but did you put a set of wires on it. I had a vehicle years ago that I thought was on it's last leg (over 170,000 miles), replaced the wires and it ran like new again. Could be anything, fuel, air or spark. just a week ago or so, pulled my truck into the driveway, let it sit for a few days, would not start, put a set of plugs in it as my truck has a tendency to foul plugs (valve seals) and it still wouldn't start, ended up replacing the rotor and all was well. thought it was damn odd that it would fire up fine and a few days later, the rotor is shot. good luck, put new wires on it bu beware, thay can be a little pricey, new wires for my truck (v8) cost me $65.00......ouch. hope this helps some. have a nice day and ride safe

[Montreux_Blue]

I believe the psi should be in more the 50 - 55 range. Check your fuel pressure.

[ccogswel]

T.C.
I read what all you had done. I was thinking about fuel issue but when I read you poured fuel into the TBI and still a no go. It can be a pain to do, but inside the distriputor is a pickup coil. Replace it. I had one on a friends truck go bad. Done the same thing but in the reverse. It would start cold, but when hot it would not.

Tod my be on the right track also. There may be a oil pressure switch on it. If you can find it if it has it just wire it together. Or replace the sensor.

You know come to think of it. You might want to check the wiring from the starter. I don't know about this one being it's a 2001 model but I do remember on some other Chevy's there is a wire that goes from the starter to something in the ignition. Might be a fusable link kind of thing. Something to check if you can get a hold of a wiring diagram.

Could just be a bad relay somewhere too.

Good Luck!

[Montreux_Blue]

It would start cold, but when hot it would not.
Good Luck!

I had a Suburban that did that, ended up being the fuel pressure regulator. It could be a lot of things, but start with the simple checks before you start just changing parts.

[TopCatGr58]

Appreciate all the ideas so far!!

I did a little research, can't find any manual online without shelling out $$. Did find some troubleshooting sites, and among the first few steps of a cold no start scenario is checking the ignition coil. I had stated that I saw a "yellow" spark, but the guide stated that it should actually have a rich BLUE spark!? They suggested testing the ignition coils primary and secondary resistances just like we do for our bikes, but I don't have the SPECS, it's in the REPAIR MANUALs that I don't have, and she doesn't really have the $$ to spend on it right now. I normally buy manuals for all of my vehicles because I do most of the work on them myself. Yeah, when the fuel into the throttle body didn't do much, that steered me back towards looking at the ignition a bit closer.

I know a few of "us" are professional mechs, and might have access to a big reference book that could tell me the resistance values for this year/model of car/coil!? Chevy Blazer with 4.3l V6 SFI(sequencial fuel injection, not just a throttle body style!)

I'll be pulling the starter out tomorrow for testing and possible replacement!
I was monitoring the gauges during starting, the volts are at 12 during the cranking, but this friggin' suv comes with the AUTOMATIC ON headlights, so that adds an extra strain right from the beginning! The check engine light does work, along with all of the other dash warning lights, but did not come on at the last actual starting/running episode. I don't have a code reader, the T-shoot guide stated that a bad coil can actually trigger a T-code. Will check other things as well, and report what I find, fix, helped, etc.!
T.C.

[The Lorax]

Apply the parking brake, that should disable the daytime running lights. that's how it works on my '96 GMC (Sierra, sorry, no 4.3l for me). could be the coil for certain. my son has an s10, he doesn't have a manual for it yet, but will be looking for one soon. I wonder if the coil resistance on the 4 cyl is the same as the 6. I'll see what I can find out. you might be able to calculate the resistance ratio and get a REAL rough idea what the output voltage would be. it wont be exact as the wire gauge is different between the primary and secondary windings and will have a different resistance per foot but if you get say 10 ohms on the primary and say 50 kilohms on the secondary, it might be indicative of approximately 60kv output. like I said, it wont be exact due to the differences in wire gauge, but might get you in the ball park. I'm still betting on plug wires though as they seem to be more prone to failure than the coil, at least I've changed wires several times more often than I have coils. just a thought, have a nice day and ride safe

[Ivan]

If this is the famous "vortech" style V6 I am going to bet you have a bad fuel pressure regulator.

The regulator is part of what we used to call the "spider" which had an injector, a regulator and six lines with poppet valves on the ends, and was contained inside the intake plenum.

Usually what happens is the engine starts hard and idles rough because the regulator leaks extra fuel into the plenum. In turn, the O2 sensors end up making the engine terribly lean to compensate. The fuel leaks on one side of the engine only, so three cylinders get flooded, and three are overly lean.

The fact that you could hold the throttle open while cranking supports my theory, since GM has what is called "Clear Flood Mode". If the ECM sees WOT (Wide open throttle) while cranking, it doesn't fire the injector(s). This would eventually allow the fuel status in the three flooded cylinders to stabilize enough to start.

The easiest way to check this problem is with a bore scope, even a cheap one, with a light. One side of the plenum will be normal, black looking, and the other side will be washed clean. In the absence of a borescope, pulling the top half of the plenum isn't difficult at all, and gaskets are cheap. If you do see the one side washed clean from a leaking regulator, get ready because your wallet is going to shrink several sizes. The device it's self is very easy to replace, so save your self the extra labor costs.

Unfortunately, this failure was way to common on these engines. Back during the time I fixed these (97-02) the price on the spider was almost $500. I am sure it is much more now.

As for the coil, if it still has a distributor, there is a coil in the bottom of the distributor with two wires that hook to the ignition module. Pull the two wire connector off and back probe it with a multimeter set to AC. During cranking you should get a minimum of .4V AC. If you don't, replace the coil, you have to pull the distributor, and the gear off the end. This is the triggering coil not the ignition coil. If you do, the coil is fine, which I suspect to be the case. The actual ignition coil was pretty solid on these and rarely caused a problem within the service life of the vehicle.

Also, if you don't want the DRLs (Daytime Running Lights) on while you are working on the vehicle, set the parking brake. If it has auto dimming, read the manual, there is usually some way to turn them off. On my Yukon you push the dome over ride button four times within a few seconds.

[JWilly163]

If you're positive that your fuel system is sequential port fuel injection than the vehicle should have an individual injector for each cylinder, possibally connected by a split/common fuel rail. Central Multiport Fuel Injection has a single injector and individual poppet nozzles (spider).

Sounds to me the problem has to do with the injector(s) not completely closing and letting fuel leak into the ports over a longer period of time(over night), possibally caused by gummed injectors (most likely) or a broken pintle return spring (highly unlikely). Either way you need new injectors - SORRY - unless they can be cleaned somehow. That would explain why hot starting works fine as there is no time for the engine to flood. Also, on newer FI systems, a wide-open-throttle start doesn't completely turn off the injectors. Instead the air/fuel is kept at a very lean ratio of approximately 18/1, significantly leaner than the stoichiometric ratio of 14.7/1.

As for the electrical problem theory, the hot start leads me to think against resistance issues. Resistance increases with heat, therefore a hot engine compartment would worsen the problem. I wouldn't rule it out, but I'd focus on the injector problem first.

Unfortunatly I don't know of a quick way to check for this. Though it may be possible to remove the injectors and fuel rail after letting the vehicle sit for a long period without running, then check for flooding.

Until then, I recommend running Shell Premium gasoline as it actually has helped many vehicles of mine, Family and friends.

As for the info, I consulted a textbook and knowledge gained at Nashville Auto-Diesel College from which I have recently graduated with honers. All the other ideas are great and I appologize if I steped on anyones toes. I know my opinion may lack experience but two cents is better than nothing! Good Luck!!

[tarzan]

I had a friend with a 98 or 99 that did that .It had spark and even when you spray gas in the intake it wouldnt start.It turned out to be the fuel pump.If that is the problem .He paid like $800 to have it fixed.I think he said the pump itself was around $400