wont start

Bridget,

(You said) it has fuel pressure and spark

Post in detail the test and tools you used to confirm spark and fuel delivery.

Hint:

If you didn't use an In-line Spark Tester to confirm spark delivery, and you didn't use a Fuel Pressure Gauge to confirm fuel delivery, then you made two classically typical mistakes.

Another Hint:

When it comes to fuel delivery on a Vortec, if the PSI is off by only one that’s enough to keep the engine from starting. Post the static fuel pressure. Static means key on engine off. If pressure is below 65 PSI, there’s you’re No start reason.

Bridget,

Also, have you confirmed power to the injectors as well as ground pulse?

Bridget,

Still another hint :-)

If you have the proper fuel pressure and good spark then you should look for the possibility of a fuel injector problem. It's possible the injectors are not being pulsed by the PCM, which causes no power to the injectors or the PCM is not grounding the injectors. Also if you have proper fuel pressure, good spark, and injector pulse, then the injectors are stuck shut. The CSFI system uses a poppet valve on the end of the injector to supply fuel. That poppet is a mechanical ball and seat injector design (not my design of course) that WILL stick. Just a matter of time before it sticks.

AND THE HINTS JUST KEEP ON COMING :-)

Like are there any error codes set?
Like P1345?

they used the right equipment to test and the fuel pressure was around 65 at least i dont remember exactly we had a mechanic bring the computer thing and its not throwing any codes but suggests it has to do with the passloc system and I think the previous owner had aa remote start installed but i never even knew how to use it so there are some wires under the steering colum that look like they dont belong.I was thinking about lighting it on fire to fix it!

Bridget,

You stated that you don't know how to use the remote but do you have possession of it. If so, what brand name or symbols (if any) are on the remote.

Bridget,

Big Block asked if there were any codes and I'm curious myself. Also, do the mystery wires under the column lead to a little box (probably black)? If so, can you read anything on the box?

Bridget,

We’re tryin to help you, but you gotta understand that this is an online forum and we don’t have your Tahoe in front of us to test. With that being said you gotta post accurate and honest answers to the questions below so that we can help you further. Understand that these questions are basic and fundamental and must be addressed first. The first rule of successful auto mechanics and repair is to rule out the basics, before you go lookin for a different or bigger problem. In this case that's just it Bridget, the basic's have yet to be be ruled out, or ruled in for that matter.

(You said) they used the right equipment to test.

Well, you can start by tellin us who THEY ARE?

Then you can tell us the right equipment and tools that THEY USED for testin?

(You said) the fuel pressure was around 65 at least

Well around or at least is useless. What’s the reason that THEY could not come up with an accurate and honest fuel PSI reading?

sorry didn't mean to annoy you. My husband is one of them and our friend who is a mechanic is the other. the fuel pressure was 65 which was checked with a fuel pressure gauge and the spark was tested with an in line tester. these guys are not new to this. It is not throwing any codes but is suggesting something with the security system. The mystery wires under the dash do go to a small box with a switch on it I am not at the shop right now so i will have to look for any info written on it when we go back down. We are having another mechanic come tomorrow eve with the computer to have a look as he is more familiar with this vehicle.

Bridget,

Thanks for the response and we look forward to hearing more.

I would venture to guess that you didn't annoy Big Block. He's just an @$$ like that. KIDDING BLOCK! Seriously though. That's just the way he talks. It's a NYC Marine and mechanics thing.

Let us know what you find. Thanks.

Bridget,

Look the simple truth, is that you are just lucky that you happened to stumple onto a forum that has guy's like me and Drivability postin here. Wait the fun has yet to begin. In other words you have yet to wake up the sleepin giant (ASE MASTER). Understand that he's out there, and checkin in, and it's just gonna be a short time before he checks in, and rips us all a new one. Thing is for any one new one that he rips me, I'm gonna rip him 47 new ones. Bridget, you gotta start answerin all the questions that have yet to be answered. Again we're all tryin to help you here, and we need those answers. Forget about security system problems for now, and let's get back to basics here and the answers to those basics. Here's another basic question that we gotta have an answer to.

Have you replaced the modified cap and rotor yet? There is no timing bypass on a CSFI after 1995, so usin a timing light is gonna be useless here.

Bridget,

Is the security light on?

Also, please exlpain "they did have it off and did NOT use any kind of tool to put it back on".

Thanks

Bridget,

You're not annoying me, and now that I know your X-husband is a MARINE your gonna get extra special care in resolving this problem. Hell, you might even get a house call :-).

(You Said) The mystery wires under the dash do go to a small box with a switch on it.

(You Said) When they put gas directly into the throttle body{ i guess what used to be the carb} it fires up.

That mystery box could be some sort of fuel cut off system that was installed for the purpose of being an anti-theft device. Get rid of the box, and the mystery wires, and make sure that all the wires under the dash are returned back to OE configuration. Even if the box is not a fuel cut-off just get rid and all those mystery wires under the dash. That could be the reason why the truck is not startin. But like I said, don't just simply get rid of the box and wires. You gotta restore all the factory wires that the was spliced into back to their OE configuration. Also how about an improperly installed distributor or incorrect cam retard number. Once you put the distributor in you gotta watch the cam retard on a scanner to spec it out. That spec is gotta be 0 + or – 2. You set the cam retard number by turning the distributor and watchin a scanner, not a timing light.

Bridget, It sounds like a timing problem to me. Are you sure the distributor was correctly installed? Was the engine rotated while the distributor was out? If it was did you find top dead center before installing the distributor and did you make sure the rotor was in the correct position? I hope this web page helps you.

http://www.ehow.com/how_6698478_test-csfi-fuel-injection.html

ok im writing this stuff down because we will be back down there tonight. when they put the distributor back in they SAID it was top dead center but no scanner was used. And I can remove the mystery box myself so I know it's been done! Ahh yes Marines, we once took a family vacation to guess where? Paris Island! Was actually interesting though and I shouldnt blame it on the corps, he was just not a nice person all around.

and yes when you turn the key the security light flashes a few times then goes out. sorry forgot that earlier

Bridget,

I would agree that removing an aftermarket alarm would be best. If and when you remove the box and you find that you need to splice wires back together, I would recommend using solder and heat shrink. If you don't solder and heat shrink, please at least use a solder butt connector that has solder and heat shrink built in. The link below shows you an example of a solder butt connector if you are not familiar.

http://cableorganizer.com/elelktralink-butt-splices/

PLEASE DON'T USE SOME CHEAP OLD SCHOOL BUTT CONNECTOR UNLESS YOU JUST LIKE WALKING. :-)

Let us know what you find. Thanks.

thanks! duly noted. will be heading there in a few hrs and will keep youns updated!hope we get this running before we actually get snow! need it to pull snowmobile trailer!!

Bridget,

If you would copy the info above I'd like to erase it. It appears obvious to me that you're not a car thief but I can't say as much for some of the readers in the past and those that will come in the future. It's not like they can't find the info on the web but I'd prefer it not come from me. Let me know when I can delete it. Thanks.

got it! and u r right im not a thief but I do understand where you are coming from! Thank you again!!

POOF! It's gone. Thanks for the quick reply and for understanding why we don't like catering to thieves.

Block Head,

If we’re making a house call can you give me some advance warning? I would like to change my socks for the trip :-).

Bridget,

(Quote) when they put the distributor back in they SAID it was top dead center but no scanner was used.

(Quote) When they put gas directly into the throttle body { i guess what used to be the carb} it fires up.

As it stands right (NOW) and until something (CHANGES) I’m inclined to (AGREE) with Pete in that this (COULD) very (WELL) be a (DISTRIBUTOR) problem (IN SPITE) of your (SECOND) quote. If the distributor (CHECKS OUT) then what I have written below (MUST) be put into (PRACTICAL APPLICATION) as a fuel (DELIVERY) issue. (DO NOT CONFUSE) fuel delivery with fuel pressure (PSI), fuel volume, or fuel regulation. All are (CONNECTED) via the (DOMINO EFFECT), but your (PROBLEM) is (MOST LIKELY) a (DELIVERY) issue. In your situation there (IS) fuel pressure but that (PRESSURE) is (NOT) being (delivered) to the (POPPETS).

The first step in diagnosing a hard start or no start on a GMC or Chevy CSFI system would be to check fuel pressure. If fuel pressure is less than the KOEO specification, you need to test the fuel pump and its voltage supply circuit.

Dead head pressure from the fuel pump should be 70 to 80 psi or higher, and the pump should be capable of delivering a quart of fuel in 30 seconds. If the pump is not delivering the required pressure or volume, check the pump’s voltage and ground connections.

You should see battery voltage at the pump when the key is on, with no more than a 1.5 voltage drop for the total circuit (ideally less than 0.5 volts). No voltage at the pump could be due to a blown fuse, an open in the pump circuit wiring or a bad fuel pump relay. If the relay isn’t closing, check the oil pressure switch. Power to the relay is routed through the oil pressure switch to kill the pump if the engine is not running. This is a safety measure to cut off the fuel in an accident.

Sometimes the pump wires inside the tank can also overload and short out. The wires are a small gauge and were not designed to handle high amp loads (as can occur when a worn pump starts to pull more than its normal current). That’s why some aftermarket replacement fuel pumps now include a new tank wiring harness for these trouble-prone applications.

If the fuel pump is OK, the next thing to check would be the fuel pressure regulator. When the key is turned off, the pressure in the fuel line should hold for at least five minutes. If the pressure drops off, the fuel pressure regulator or fuel pump check valve may be leaking. If pinching off the fuel return line produces the same results, the problem is the check valve in the fuel pump (replace the pump). If pinching off the return line stops the pressure loss, the problem is a leaky regulator.

The next step would be to check the MAXI valve (CPI) or the individual injectors (CSFI), and the poppet valves. If the MAXI injector or CSFI injectors are not buzzing, check the power supply to the injector(s) from the PCM. You can use a noid light to see if the injectors are being pulsed, or connect a digital storage oscilloscope to the injector harness to see what’s happening in the circuit.

The MAXI injector can also be tested with an ohmmeter. The resistance specification is 1.9 to 2.1 ohms, and the coil voltage should be 3.3 to 4.8 volts. On the CSFI systems, injector coil voltage should be 5.4 to 7.5 volts.

If an injector or poppet nozzle on a CSFI system is bad and you have to replace it, make sure the poppet nozzle is securely locked in position in the lower half of the intake manifold.

General Motors has issued several technical service bulletins for the CSFI system that deal with hard and no start problems.

TSB 99-06-01-022 that covers procedures for cleaning CPI poppet valve spray nozzles

TSB 00-06-04-003B for cleaning CSFI poppet valve spray nozzles

TSB 56-63-06 and TSB 66-63-09 that cover diagnosing hard-starting/no-start problems with the CPI system

Master of Disaster,

Last time you changed your socks was Christmas Day 2010. What makes you think you gotta change them again?

wow. so many choices. up to this point I have not insisted that my husband sit and read all this but I guarantee he will tonight! Unfortunately I do not understand some of this but thinking if he can wire the USS Enterprise aircraft carrier he knows very well what you mean! He has a lot of electricl test things that I am not allowed to touch which is fine cause I dont know how to work them anyway! Between what you just said and the TWO mystery boxes under the dash, clearly an added exta, this is getting real interesting! And you can all come on over for a house call and I will wash your socks for you or better yet, buy you new ones!!

Bridget,

(You Said) you can all come on over for a house call.

Are you sure?
Do you realize what you're sayin?
How are you defining all?

Findin you is alot easier than you think, then one day you'll open your front door and find over 5000 MARINES standin there with dirty socks.

ALSO BRIDGET,

We posted a lot of information already, and if your husband is gonna sit down and read all that information he’s gonna need a lot of beer and whiskey. Even with all the booze the info is still gonna turn his brain into potato salad. I wrote this up for him to read because it’s gonna be easier and faster for him to follow than everything else we posted we posted so far. It basically sums up all we have said so far, so have him read this first.

GOD BLESS AMERICA AND THE UNITED STATES MARINE CORPS!!!!

Checking for Spark:

A reliable and safe way is with an inline spark checker; I use Lisle #20610, about $10 and available at most good parts houses. It simply goes in-line between a plug wire and the plug itself. If you're doing this test without a helper, you can experiment with positions to install it so you can still watch it through the gap between the rear of the hood and the engine compartment

If spark appears weak or erratic, remove the distributor cap to check inside it for moisture.

You can dry it out by spraying WD40 inside and wiping the excess out with a paper towel. On the big block, you may need to remove the coil/module bracket from the rear of the plenum to access the distributor. If the cap has moisture, it is probably cracked or was not seated properly. Be VERY CAREFUL re-installing, as the Vortec distributor body is plastic and it's easy to damage the places where the screws thread in. If you buy a new cap, use your old screws as often the new ones have threadlocker that makes the screw "fat" and easier to break the distributor.

If either or both cap mounting tabs are broken and you need to rig it to get by:

the easiest/best method I have seen is to use a zip tie (chain them together if you don't have one long enough) looped under the distributor body around the cap, through the gap between the centermost terminals to keep it the tie from sliding off.

If no spark, suspect the ignition module.

The module is riveted to the coil bracket next to the coil. On the big block it's difficult to see as it's bolted to the rear of the plenum, above the distributor. If you want to try another temporarily as a test, try hooking it up and use a nice heavy ground wire w/clips to attach the body of the module to the module/coil bracket. As of this time I am not aware if the parts house can test a Vortec module.

If spark is good, move on to fuel pressure.

Checking fuel pressure:

NOTE:

when you turn the key on, the PCM will prime the fuel system by running the pump for 2 seconds. If you don't start the engine, the pump will quit running. This can make it tricky to get a "key on" pressure reading by yourself, as the pressure can drop off before you get to read the gauge. Have a helper turn the key while you watch the gauge.

Do not assume

the pump is working because you can hear it, or not working because you can't hear it. Vortec pumps are usually noisy, but it's not necessarily an indicator of condition. Also do not assume that because there is residual pressure when you disconnect the lines or depress the test valve, that the pressure is good. It must be measured.

Vortec small block spec is 60-66 psi.

They are incredibly picky and generally won't start if it's a little low. You want to see at minimum 55 psi or so (varies.) Vortec big block spec is 58-62 psi. They will start on very low pressure, just run poorly. You want to see at minimum 50+ psi to run right.

If your pressure is low or zero, before replacing the pump:

If you haven't replaced the fuel filter recently, you should try this first.

Fuel pressure regulator could be bad, or poppet valves (small block) could be leaking. Replacement requires intake disassembly.

Fuel pump fuse or relay could be bad; check the fuse and relay (under the "convenience center" cover under hood); if fuse is blown the pump is likely bad or there is a short in the wiring. The pump relay on Vortec engines is often a sore spot with burnt contacts and melted socket.

On the fuel pump/sender assembly (old style, with separate pump mounted to sender) the short piece of hose or the pulsator unit joining the pump to the sender can crack or slip off.

Semper Fi! contacted the owner before us of this tahoe turns out he bought it used from a local dealer who purchased it from BUFFALO! So it's Hillarys fault! House call meaning you guys fix the tahoe and Ill cook you dinner and supply the beverages!!

And we never run out of beer!!

Bridget,

It looks like you were posting, while I was editing my answer. Just go back to my last answer and read what I added.

And a good time was had by all! Turns out the first spider we put in was defective! Changed it and she fired right up! Thanks again for everything the conversations were fun! Planning a trip to tug hill to ride soon that is as long as they have snow!!

Bridget,

(You said) Turns out the first spider we put in was defective! Changed it and she fired right up.

Read my bio Babe :-).

It doesn't matter how many spiders you install (and or) how many spiders are defective. If you’re gonna stay with the GM designed CSFI spider system then you’re screwed for sure. In other words, you can expect the same thing to keep on happenin over and over and time and time again. In other words just get used to changin out spiders. You may as well carry a few spare spiders with you :-). The time has MORE than come to seriously consider a CSFI to MFI conversion. Here’s a helpful link.

http://www.gmpartsdirect.com/results.cfm?singlepart=1&partnumber=PK93441235

I did read it and it's quite impressive! Actually we did upgrade i just still call it a spider all i know is it works!! ( could have used your aim during hunting season)

Bridget

(You Said) Turns out the first spider we put in was defective.

(You Said) Actually we did upgrade i just still call it a spider.

Thanks Bridget. No problem I understand the above. Thing is that’s a new one (even for me). Done thousands of these conversions and never had a defective part, but I’m glad to hear its runnin and that our advice helped

(You Said) could have used your aim during hunting season.

I've never hunted, and when my friends go huntin I don’t go with them. You’d figure bein a MARINE SNIPER it would be the other way around, but there’s alot of MARINE SNIPERS that don’t hunt. We’re trained to defend and protect AMERICA, and we do both usin one simple philosophy.

WE SIMPLY ANNIHILATE THE ENEMY!!!!

For me and countless other MARINE SNIPERS hunting animals just goes against our sense of reason and purpose. We just don’t see animals as a threat to AMERICA, and we don't kill for sport.

understood. I only hunt deer to put safe meat in the freezer and thank God for the Marines and the many others or I would not be able to do that! The first spider was not new but a "friend" gave us one he thought was ok, apparantly not! But i now know more about that vehicle than I ever thought I would thanks to you guys!!

Bridget,

(You Said) But i now know more about that vehicle than I ever thought I would thanks to you guys!!

You're very welcome, and thank you for the opportunity to teach you.

SEMPER FI !!!!