97 Chev Blazer Fuel/Injector Problem? HELP

I have a 97 chevy Blazer 4.3 that won't run worth crap now. I replaced the fuel pump unit, spark plugs, plug wires, cap/rotartor, and ingnition coil. The truck will start then stumble to a halt seconds later. I used starter fluid to keep it running by spraying in to the throttle bore, once I stopped the start fluid feed it stumbled to a shaking halt. I am thinking it is an injector problem or injector controller problem but don't know how to go about trouble shooting this problem. Also I tested the fuel pressure at the fuel line on the engine and it reads between the 60-66 psi like it is suppose to.

I also kept getting a P0300 code for the last couple of months but then it would go away. P0300 multiple/random misfire detection. When I pulled the plugs they were all black as coal so I am assuming it's been running really rich lately.

Any help would be appreciated.

Thanks, Mav

Reply to
Mav
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EGR valve is jammed open by carbon deposits

Reply to
TransSurgeon

Or it's time for the injector nut kit..................

Doc

Reply to
"Doc"

Nope not EGR, no flag on it since I replaced it a year....besides the truck runs good when I directly pour fuel into the intake or spray starting fluid in there also for prolonged moments...soon as I stop the truck comes to a stumbling starving stop.....

What is this nut kit on the injectors your talking about?

Reply to
Mav

The only "nut kit" required is for the OP....

I question anyone who uses starter fluid at the best of times. This sure didn't sound like a situation that called for it.

Reply to
Commentator

My bad, if it's starving for fuel it ain't the pressure regulator/injector nut kit. When they go it runs super rich.

Doc

Reply to
"Doc"

It was safer than directly pouring the gasoline in from a can......at least I can stand back a little ways when spraying into the intake. We do this all the time when we ran our race buggies to get them ready to start....

Reply to
Mav

Do you have any idea what that does to your engine though? As an FYI, it is one of the quickest ways to lose an engine warranty.

The ONLY time I have ever felt comfortable using that stuff is to start the pup engine on a CAT tractor that has been sitting in the field in -40 weather in Labrador. At least those pup engines are more or less disposable. Other than that, the biggest use starter fluid has ever been to me is cleaning my tools.

I appreciate your comment about the gas, but I have seen friends blow up their engines because they thought it was ok to use that stuff on a cold day.

Reply to
Commentator

I'm thinking something wrong with the injectors or the control for firing the injectors. It did look as though the truck was running rich for some time since the plugs were all nice and black coated all over. I just wish someone new how to test to see if the injectors were bad or what might be causing it.

Anyone know how to test using a multi-meter to get readings off the injectors or the sender for anything like that and what the output reading should be? I wish I had bought a helms book set for this truck already but I didn't think it would take a crap already at only 100,000 miles.

Mav

Reply to
Mav

It sounds like a fuel relay to me. They have a timer function that allows oil pressure to build up, then the system goes into it's normal operation. If the oil pressure is lost, the fuel pump is cut off. It sounds to me when the timer runs out, the pump is cutting off.

I'm not sure what the wiring looks like on the 97 blazers, but there is a test point on the fuel pump circuit. It's in the trouble shooting section in the Hayne's book, I know I've seen it. On the older TBI units, there was a test point in the ALDL connector, but that's gone now. It's now in a pigtail off the relay, IIRC. Anyway, put a voltmeter on the fuel pump wire, crank it, and watch for the voltage to drop after a few seconds, FOLLOWED by the engine quitting. If the engine dies first, THEN the pump loses voltage, that is normal (since there is now no oil pressure). If that's it, check your oil pressure switch wiring. If you haven't done so since it quit, pull the dipstick. The gauge on the dash has nothing to do with the computer oil pressure switch, BTW. Separate circuit.

Reply to
John Alt

The 97 also doesn't have that system. I haven't looked at my 2000 yet, but my impression is that the FI system is substantially different from that failure-prone system used in 92-95...

Reply to
Mike Levy

Think the 'test point' is called fuel pump prime lead. A trip to the local library to look at a service manual might be required to find it's location. Generally it's a lead from an underhood wiring harness with a single blade connector that seems out of place. Applying 12v to this lead will run the fuel pump. He should be able to hear it running. I haven't looked at the circuit in awhile but IIRC, it by-passes the relay and oil pressure switch and supplies 12v to the pump. In any case if the engine doesn't stall with

12v to the prime lead, then the problem is likely related to the pump stopping after the initial 2 sec. when the key is turned on.
Reply to
DonW

I replaced the fuel unit in the tank already, and it does run after the truck quits. It also has the correct pressure when I used my fuel pressure gage. The pump is good and so are the plug wires, distributor cap, rotor, plug wires, plugs, ignition coil. All changed already with nice new parts.

So what does that leave me with now?

Something with the injectors, injector controller. She runs good when I directly feed fuel down the throttle bore and quits almost immediatley after I stop. It is a fuel starvation problem for sure. Like I said I get good pressure at the fuel rail test point by the intank manifold, so I know the pump is good and fuel filter isn't clogged. That makes me believe the injectors are not working or something that controls the injectors. Problem is I don't know how to test the injectors to see if they are working or not.

Mav

regulator/injector

Reply to
Mav

Mav you might pose your question(s) via email or phone call to:

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I just bought a set of rebuilt injectors for a 3.4L engine. Shipping and all was around $160. I had a situation where a single cylinder would misfire. Then a couple weeks would go by and another one would misfire. With the equipment I have about the only thing I was able to measure was the resistance of the injectors. All were within spec at about

12ohms however don't know about the flow rate as the temperature goes up or their state of being plugged. Have you tried Chevron FI cleaner? or had the injectors cleaned? In any case the folks at lindertech could give you some hints on the susceptibility of the injectors in the 97 to plugging.
Reply to
DonW

is the security light flashing while the key is on>?.. I don't remember what year they started the passlock, I think it was 98, but it may have been

Reply to
Bobo

When you test the injectors with a test light or meter your just testing fo pulse to see if the injectors are getting power......You need to do a injector power balance test to test each injector.on a single basis to see which one drops durning the misfire.....Which you need a pressure gauge and a scanner of which can shut down the injectors one at a time.But it needs to be running...As BoBo stated its could very well e passlock...But you beed to pull the codes out of the BCM not the PCM for passlock...Do you have a scanner that can do that ? Ya sure you cat isnt clogged up restricting flow? It will cause multiple misfires usually in one bank or the other unless its completely clogged up.....Go into your history codes see i there are any other codes stored from the past also check BCM for passloc codes....Could be as easy as a key cylinder and ignition switch..... Steve C

Reply to
S C

Like I said before, Truck runs when I directly feed it down the throttle bore, I just pour a little bit of gas in and she idles okay and throttles up okay until the gas I'm pouring in is gone.

Truck has no passlock. Truck also started just running really rough then just stopped running for the most part. She'll sort of start up but then stumble really bad as the computer is trying to keep it running then it just dies out.

I also have a AutoX-ray 6000 handheld scanner and it shows cylinders misfiring on the 1, 2 , 3..... if you read my other updates on this thread you'll see the other conditions that exist and what codes, and items I have replaced.....

Doesn't anyone have a Helms book for this truck?

I'll be trying to see if the injectors are firing at all tomorrow when I get home from work. It's a fuel issue for sure and it lies within the injectors not giving any fuel, whether the injectors are bad, computer is bad, or some sensor that tells the injectors something is bad I don't know.

Mav

Reply to
Mav

OT of the thread.

Steve, can you please set your newsreader to mark what lines it is you are replying to? Without that mark, all lines of text show up as your posting and it's difficult to find where your post starts and the "replied to" post ends. See how mine was done, was done automatically by your newsreader, and if you have trouble I'm sure someone here will help you if you tell us what reader you're using.

Reply to
Mike Levy

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Did you happen to replace the fuel filter? Did you check the pressure while trying to start/run it?

Reply to
Scott M

Mav.I had a similar problem and it turned out to be the Air Flow Meter was sticking[after 200000 miles] and the computer was getting false signals and starving the engine of fuel.I don't know if your vehicle even has one but oif it does it's a simple job to remove.I don't know how to bench test one so I bought a used one that came from the factory pre set{some do not and you have to adjust} This totally cured a problem that none of the experts could figure out.I was lucky I guess,and I don't advocate replacing parts unless you know they are bad,but I thought this info might help.

Reply to
Brian Orion

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