roaminbmw

This one boggles me, I thought I was a decent weekend mechanic. I need help from the Chevy world. I like my truck, the wife says if it doesn't run, it must go.

The truck ran fine before repair (120k). The repair was Intake Manifold Gasket. I was losing coolant. Since then the Truck never ran again, it cranks only. I gone through alot and replaced lots of parts trying to get the truck to run someday. Yes the distibutor was disturb and set accordingly (checked many times). Since the problems I was having I bought the GM Manual (two Volumes)

Some Vidals:
- Fuel Pressure is 58psi
- Compression avg 150, one low cylinder of 135, and high of 155
- Spark present

Parts Replaced New (AC Delco)
- Battery
- Starter
- Cap / Rotor
- Spark plugs / Wires
- Coil
- Cam postion sensor
- Crank Sensor
- Ignition Module
- Fuel Pressure Regulator
- Fuel Filter
- Distributer Helix Gear

Still no Start

I thougth I could of Hydro locked... I pulled engine and conducted a minor rebuild. There was nothing wrong with the timing. While there I replaced the timing chain and gaskets galor....

all back together Still no Start

Please Help .... Give me ideas

RickCoMatic

If you disconnected the battery and did work on the ignition system ... there is a good chance that you might have tripped the Vehicle Immobilizer Circuit.
Nothing is going to start that Vehicle until the Immobilizer Circuit is reset.
You should call the Dealer (a Dealership) and tell them what youare going though and ask them if they think your vehicle is Immobilized.
If you double and triple-checked your work and the Vehicle gives NO hint of it wanting or trying to start ... it's Immobilized and you can't start it without a new key and the secret recipe fromm a Dealer!

roaminbmw

Vehicle Immobilizer Circuit? I'm positive the truck is not equiped with a security system. Its a basic truck, no Alarm, nor does it have power locks, Unless your not talking about a security system.

I wonder if the computer cuts fuel after the crank rotates one or two revs. I useally smell fuel in the air, I know the oil is fuel soaked, but all aside has anyone seen this happen. Could I bench test the spider fuel injection? Take the plenum cover off, have the injector out(exposed) contained buya rag, and crank the engine to see what happens

ehhget

I know its a long shot but I just picked up a new set of plugs for my truck and was informed that AC Delco changed the gap from 60 to 40 so if you increased the gap back up to 60 that could be a problem.

golfer

That isn't correct .... GM's Passlock II system doesn't work that way.

roaminbmw

cut-n-pasted email message

-----Original Message-----
From: hardhitter from Chevrolet Forum [mailto:x]
Sent: Sunday, February 03, 2008 5:21 PM
To: x
Subject: 4.3 won't start

rominbmw, I know you said you have checked many things, one thing that bothers me is you say you smell fuel in the oil? I have had something like this happen to an older 4.3 where the fuel line inside of the plenum actually had a crack (from the metal line going into the back of the outside of the plenum, the line inside of the engine going to the spider was plastic and had cracked) and was pouring fuel inside of the plenum area itself. So each time the ignition was turned on it pumped raw fuel into the plenum area and drained into the oil pan contaminating the oil.

You also say the fuel pressure is 50 some lbs, does it hold stedy after the ignition switch is turned off? If not check this fuel line inside of the plenum. But there should be a set of checks in your manual dealing with fuel pressures, check these out carefully step by step.

Also check the plugs, are they even wet or are they black looking? You said you had spark, but it must be a nice blue color.

I assume the fuel pump is working? If you do get fuel pressure it has to be so this can be taken out of the picture.

One thing right off of the bat you may try, get a can of start fluid and shoot a small amount into the throttle body hose (hold the butterfly open when doing this). Then make sure the hose is re-attached, and then try to start the engine. Did you get anything at all? If so it's a fuel problem.

Just a few things to check out, I hope they help some. If not P.M. me and I'll try to help you out.

Good Luck,
hard hitter

roaminbmw

Hardhitter,

Thanks for your email... I wanted to respond sooner, This weekend I check out a few things & reconfirmed a few things. I'm really stumped.


1) Re-confirmed spark... It a strong spark (blue), the plugs are fouled though (blackened) from trying many time to start. Remember they are still new.

2) Re-confirmed Fuel pressure... its 58psi, after 4min +/- it drops to 50psi, and a week later it holds 10psi. This pressure loss is in line with the GM manual.

3) I took off the plenum cover to test the spider injector system, throttle body set aside and hooked up all sensors, Cranked the engine with each injector valves exposed, each injector activated and shot fuel. This test confirms fuel pump, injectors, injector control module, wiring, is all Okay. I follow the GM book as closely as possible, but I'm limited in the special tools they refer to. But this test should say it all. This is the reason I have fuel in my oil, It's not being burnt

While the plenum cover was off I shot starting fluid, cranked the engine, shot more fluid and the engine stumbles a little.

None of this makes sense, the truck should fire up, as I'm writing this something bothers me from what I saw this weekend. Each injector shot fuel but not a fine mist,as thestarting fluid does, I'll check tonight, while everything is still apart.

northey87