90 replies to this topic

[blue_sniper_fox]

OK so here is an update, Finally got my parts in, installed the new injector, bracket and gasket. Threw everything together, double checked all the connections to make sure wiring was hooked up and fuel lines were tightened. After all that was done, double checked fuel pressure and then proceeded to crank and nothing. She still won't start unless you feed it down the intake. I took the Fuel pump out of my buddies truck to double check on maybe I was getting some Effed up problems out of mine. Still nothing, we also put mine in his and she purred like a dream so its not a fuel pump issue. I'm going to pull this fuel filter off which had recently been changed off and get a new one. I am running out of ideas on what it could be.

[N2O_ZR2]

Bad ECM or security system problem?

[Bobbing]

Listen for clicking or buzzing that would indicate the injectors are working. No noise? Check for voltage and ground at the injectors. Loss of signal from the cam sensor could prevent the system from functioning. Did you plug the cam sensor back in? Its located on the distributor.

[blue_sniper_fox]

Listen for clicking or buzzing that would indicate the injectors are working. No noise? Check for voltage and ground at the injectors. Loss of signal from the cam sensor could prevent the system from functioning. Did you plug the cam sensor back in? Its located on the distributor.

Yea I've checked everything a hundred times now. Maybe the sensor is bad and needs replaced?

[Bobbing]

Is the check engine light on?
A massive vacuum leak could be preventing the engine from starting. A large enough vacuum leak will lean out the air/fuel ratio to such an extent that the mixture won't ignite. An EGR valve that is stuck wide open, a disconnected PCV hose, loose vacuum hose for the power brake booster, or similar leak could be the culprit. Check all vacuum connections and listen for unusual sucking noises while cranking.
The timing chain may have broken or slipped. Either type of problem can be diagnosed by doing a compression check and/or removing a valve cover and watching for valve movement when the engine is cranked.

[Bobbing]

Is this only happening when cold? I was wondering if it will start after its been warmed up. That would indicate the ECT sensor is not working.

[blue_sniper_fox]

ok changed the Throttle Position Sensor, Crank Sensor, Distributor Pick-Up Assembly, Ignition Control Module, re-checked all the vacuum lines, fuel pressure, spark, and still nothing. I'm going to recheck and see if maybe its out of time. I'll have to take a day and tear into it and see. Does anyone know how I could check the EGR valve and see if thats my problem?

[rustyg]

I haven't found a way to bench test the egr yet, but I don't think it would prevent the truck from starting

[blue_sniper_fox]

I haven't found a way to bench test the egr yet, but I don't think it would prevent the truck from starting

I'm thinking its out of time, I'm getting bad back fire a lot now. It will randomly try and start but then dies out after a few seconds. I just need to take the time and break it down to make sure it didn't jump time.

[Bobbing]

I haven't found a way to bench test the egr yet, but I don't think it would prevent the truck from starting

I'm thinking its out of time, I'm getting bad back fire a lot now. It will randomly try and start but then dies out after a few seconds. I just need to take the time and break it down to make sure it didn't jump time.

Yeah could be a timing chain problem. Distributor is in correct?
The MAP sensor has an effect on timing and will cause the vehicle to die as soon as started.

Edited by Bobbing, 12 December 2011 - 10:19 AM.

[blue_sniper_fox]

I haven't found a way to bench test the egr yet, but I don't think it would prevent the truck from starting

I'm thinking its out of time, I'm getting bad back fire a lot now. It will randomly try and start but then dies out after a few seconds. I just need to take the time and break it down to make sure it didn't jump time.

Yeah could be a timing chain problem. Distributor is in correct?
The MAP sensor has an effect on timing and will cause the vehicle to die as soon as started.

I swapped out the MAP sensor on my buddies Z and still nothing and he even ran his with mine no problem. I'm getting a lot of back firing when I try and start it now so I'm running out of ideas except for a timing issue. The distributor was never removed or anything just replaced the button and cap as well as new plugs and wires. The motor does have a lot of miles so I'm hoping maybe the guide or tensioner may have broke. I'm going to have to take a warm day and break into it and check my timing. If anyone has any other ideas let me know I'm up for trying anything.

[N2O_ZR2]

It may be a long shot that probably wont work, but you could try a can of seafoam in the gas tank. I had a 95 blazer that if it sat for more than a couple weeks it wouldn't start, only thing that would make it run was a can of seafoam in the tank. One of the wierdest things I have ever seen.

And the 4.3 doesn't have a guide or tensioner for the timing chain. A worn or cracked distributor gear could also be a possibility.

[blue_sniper_fox]

It may be a long shot that probably wont work, but you could try a can of seafoam in the gas tank. I had a 95 blazer that if it sat for more than a couple weeks it wouldn't start, only thing that would make it run was a can of seafoam in the tank. One of the wierdest things I have ever seen.

And the 4.3 doesn't have a guide or tensioner for the timing chain. A worn or cracked distributor gear could also be a possibility.

Ah there has been plenty of foam ran through this one. I drained the tank and put 5 gallons on 93 and a can of foam in her when I was trying to figure out my injector problem.

So there is no guide or tensioner? hmm then why the f*#k does advance auto sell one lol. I'm gonna get on checking the main timing first before I tear into the distributor. I sure as hell hope that is not the problem because it is in a crappy place to get to.

I'm getting to the point where I am about to just get another 4.3 and drop in there or get a bare block and throw all the new crap over on it. When I finally discover whats wrong I will be sure to let everyone know what the culprit was.

[jwwaldschmidt]

If you decide you need a bare block, I've got the one from my '99 that would be a great rebuild candidate. I'd be more than happy to ship it to you and make you a heck of a deal on it.

[rockininthezr2488]

Have you considered replacing the CPI/CSFI, as apparently it is also known? I am having similar troubles with my truck right now, but my truck is getting TOO MUCH fuel. I have been dealing with this for about 3 weeks now, on and off. Truck wouldn't start. Took her in for a check-up; they took her in for a tune-up, replaced plugs, wires, ran fine for about two weeks, now I'm right back where I started. I've heard a LOOTT of people talk smack about the CPI, but have rarely ACTUALLY seen or heard of an actual case where someone's "CPI" failed them. It sounds like you've put a LOT of work into your truck, and are ready to get it fixed. I am too. Let me know what you think, and we'll talk some more. It sounds like you've got a "lean" condition, so our cases may be different, but from what I've read, it sounds like the only thing you HAVEN'T replaced is your CPI. I am Thinking, and hoping this may be where one of our problems lies.

[rockininthezr2488]

did you check to see if pressure is holding for a couple of minutes. 60 is good to start, but it may be bleeding off right away.

It stays at 60 for about 15-20secs then it drops back off....Could it be the fuel pressure regulator?

The Fuel Pressure Gauge's needle will drop 5 PSI only and remain steady for at least one full minute.
In a system where the Fuel Pressure Regulator or Fuel Lines are not leaking.. the pressure should hold steady (not dropping to zero) for about 5 minutes.

CASE 1: The Fuel Pressure Gauge's needle DID NOT drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that the Fuel Pressure Regulator and the other components that are part of the Fuel Injector Assembly are NOT BAD.

CASE 2: The Fuel Pressure Gauge's needle DID drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that there is something leaking inside the Plenum. More than likely, it'll be the Fuel Pressure Regulator

Are you SURE, this is the case, Bobbing? I have read much information regarding fuel pressure and am tired of seeing misinterpreted information. I checked my fuel pressure a few weeks back, and found no indication of this being the problem with my truck. Makes me wonder if my trouble is elsewhere, like possibly in my non-functioning 4-wheel drive, potential inconspicuous, vacuum leak.

[blue_sniper_fox]

Have you considered replacing the CPI/CSFI, as apparently it is also known? I am having similar troubles with my truck right now, but my truck is getting TOO MUCH fuel. I have been dealing with this for about 3 weeks now, on and off. Truck wouldn't start. Took her in for a check-up; they took her in for a tune-up, replaced plugs, wires, ran fine for about two weeks, now I'm right back where I started. I've heard a LOOTT of people talk smack about the CPI, but have rarely ACTUALLY seen or heard of an actual case where someone's "CPI" failed them. It sounds like you've put a LOT of work into your truck, and are ready to get it fixed. I am too. Let me know what you think, and we'll talk some more. It sounds like you've got a "lean" condition, so our cases may be different, but from what I've read, it sounds like the only thing you HAVEN'T replaced is your CPI. I am Thinking, and hoping this may be where one of our problems lies.

Yea I order the kit from gmpartsdirect and it took them forever to ship it. Yea you save a pretty good deal but I would have rather spent the extra 200 and had the part within a few days then almost a month. I get strong fuel pressure all the way up to the fuel rail, you can jump the pump over and keep it at a constant 60psi, when you prime the injectors you can hear a rush of fuel. I need to make a new parts list or parts I've checked to eliminate the problem of suggesting the same thing over and over. I appreciate everyone's help and can not wait to get my Z running again so keep the suggestions coming.

[blue_sniper_fox]

did you check to see if pressure is holding for a couple of minutes. 60 is good to start, but it may be bleeding off right away.

It stays at 60 for about 15-20secs then it drops back off....Could it be the fuel pressure regulator?

The Fuel Pressure Gauge's needle will drop 5 PSI only and remain steady for at least one full minute.
In a system where the Fuel Pressure Regulator or Fuel Lines are not leaking.. the pressure should hold steady (not dropping to zero) for about 5 minutes.

CASE 1: The Fuel Pressure Gauge's needle DID NOT drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that the Fuel Pressure Regulator and the other components that are part of the Fuel Injector Assembly are NOT BAD.

CASE 2: The Fuel Pressure Gauge's needle DID drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that there is something leaking inside the Plenum. More than likely, it'll be the Fuel Pressure Regulator

Are you SURE, this is the case, Bobbing? I have read much information regarding fuel pressure and am tired of seeing misinterpreted information. I checked my fuel pressure a few weeks back, and found no indication of this being the problem with my truck. Makes me wonder if my trouble is elsewhere, like possibly in my non-functioning 4-wheel drive, potential inconspicuous, vacuum leak.

I had problems out of a bad 4wd acutuator. If you have the money go with a bravada front end or SFA. Then theres the cheap way and remove the battery box and manually lock it in 4wd then cut a piece of wood to fit the gap. Install everything back and boom 4wd when you need it and you can still lock in lock out.

[Bobbing]

did you check to see if pressure is holding for a couple of minutes. 60 is good to start, but it may be bleeding off right away.

It stays at 60 for about 15-20secs then it drops back off....Could it be the fuel pressure regulator?

The Fuel Pressure Gauge's needle will drop 5 PSI only and remain steady for at least one full minute.
In a system where the Fuel Pressure Regulator or Fuel Lines are not leaking.. the pressure should hold steady (not dropping to zero) for about 5 minutes.

CASE 1: The Fuel Pressure Gauge's needle DID NOT drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that the Fuel Pressure Regulator and the other components that are part of the Fuel Injector Assembly are NOT BAD.

CASE 2: The Fuel Pressure Gauge's needle DID drop down to 0 PSI immediately after the Key was turned to the Off position: This tells you that there is something leaking inside the Plenum. More than likely, it'll be the Fuel Pressure Regulator

Are you SURE, this is the case, Bobbing? I have read much information regarding fuel pressure and am tired of seeing misinterpreted information. I checked my fuel pressure a few weeks back, and found no indication of this being the problem with my truck. Makes me wonder if my trouble is elsewhere, like possibly in my non-functioning 4-wheel drive, potential inconspicuous, vacuum leak.

Did you start a thread for your problem?
Yes that is correct info BTW

[Bobbing]

Here is some literature for you guys that have a no start condition

Diagnose no start