F,I.L. has a 99 yukon 5.7 vortec. It will crank but will not start, Fuel pressure is 63lbs with key on and 68 while cranking. It has a strong spark on all cylinders. cant figure out whats going on. Hooked up an obdII scanner it has no codes. Please help , I need this thing out of my driveway.

Thanks

Did you check fuses in dash and under hood?

checked them all with a meter, all good. also checked to make sure timing chain wasn't broken. still at a loss here:confused: :confused:

checked them all with a meter, all good. also checked to make sure timing chain wasn't broken. still at a loss here:confused: :confused:
What kind of wires does he have under the hood?

autozone wires, I have spark at all 8 cylinders, also hooked up a scan tool, it has no codes

Lack of compression? Did you get it hot? I spent forever trying to get a car to start once, when it turns out my buddy had borrowed it and baked it, had no compression.

if you got spark, and fuel, and air, something should go boom boom

compression is good, He drove the car home at midnight, got up at 7:00am to go back to work and it wouldnt start. I cant tell if the injectors are firing because they are inside the intake. Im starting to think the injectors are bad/sticking. I just dont know for sure and dont want him to spend $350 on a maybe

the pop the induction hose off, and spray starting fluid down the throttle body tube while your cranking, it if tries to start you know its lacking fuel, dont do to much, I had a can light on me once, had to throw it QUICK lololol

What does the fuel press. do if you turn the key on and wait for the pump to shut off? does it hold or bleed down rapidly? If it has the goofy ces injection or whatever they call it, it may have a plastic hose in the "spider" leaking or a leaking regulator. Have seen them just leak into the plenum and real hard to start if at all. If pressure is bleeding off you will have to pull the plenum and see what is going on. Let us know what you find.

What does the fuel press. do if you turn the key on and wait for the pump to shut off? does it hold or bleed down rapidly? If it has the goofy ces injection or whatever they call it, it may have a plastic hose in the "spider" leaking or a leaking regulator. Have seen them just leak into the plenum and real hard to start if at all. If pressure is bleeding off you will have to pull the plenum and see what is going on. Let us know what you find.

checked this last night, the pressure held for 15 minutes with out dropping..

I think it may be something simple im just overlooking, but am so frustrated with the p.o.s. that I cant think straight enough to figure it out

autozone wires, I have spark at all 8 cylinders, also hooked up a scan tool, it has no codes
Theres your problem, trust me on this one. Those wires carry a lifetime warranty, go replace them at your local autozone, I guarantee she fires right up. Ask me how I know. If you've replaced the cap with autozone stuff, now would also be a good time to get a new one of those as well. I experienced the same exact symptoms with my 99 burban, went through all the usual suspects and changed my AUTOZONE wires cap, and plugs and the truck ran perfect afterwards. Absolutely no symptoms the day before, ran FINE. It didnt' happen to rain the day of or before the truck wouldn't start did it?

What does the fuel press. do if you turn the key on and wait for the pump to shut off? does it hold or bleed down rapidly? If it has the goofy ces injection or whatever they call it, it may have a plastic hose in the "spider" leaking or a leaking regulator. Have seen them just leak into the plenum and real hard to start if at all. If pressure is bleeding off you will have to pull the plenum and see what is going on. Let us know what you find.
If you get the momentary "prime" buzz with key on from the tank with that truck, the fuel pumps fine. My experience with tahoes and burbans, is that it's an all or nothing phenomenon

If your getting good fuel pressure at the gage. There may be problems after the gage then. These have a similiar port injection system to the 4.3, a sort of spider like assembly that has tubes running to each cylinder. It is located in the upper intake plenum. It is all part of the fuel pressure regulator assembly. Perhaps the nozzles are plugged up.

If your getting good fuel pressure at the gage. There may be problems after the gage then. These have a similiar port injection system to the 4.3, a sort of spider like assembly that has tubes running to each cylinder. It is located in the upper intake plenum. It is all part of the fuel pressure regulator assembly. Perhaps the nozzles are plugged up.
chris, if the fuel injection branches were clogged the engine would throw 2 conditions:1 single, or multiple cylinder misfires, or 2 Lean condition.
I know you said you had spark at all 8, and plug wires sounds very trivial. I had the same issue, and spark at all 8. change your wires, that's your problem

8 plug wires didn't go bad overnight. You must not be getting any injector pulse. You will need to start checking the harness. Get a subscription to Alldata so you can have the wiring diagrams. I know you said that you checked all the fuses, but double check them again( I have missed a blown fuse before, swore that I checked them all) I believe the ECM fuses are in the underhood dist. box. I don't really know much about this system, but if you get in on alldata there should be enough troubleshooting info there for you to figure it out. Good Luck

Do you have a ground problem? Some guys might disagree with these but i've taken a screw driver handle to the ecm and just tapped on it and hit the key and the old van fired right up, replaced the ecm with no problems afterwards. Also ck the crank sensor and wire.

I dont know were you live but if its possible your buddy put some bad gas in it or you have water in the lines/tank. Take starting fluid like stated above and spray it in the air cleaner tube and see if it fires. How old are the plugs?

changed plugs and wires, still will not start. I did get a backfire out the throttle body and exhaust. Ill start checkeing the harness and fuses again

You can also, cheaply, get a noid,l a clear plastic thing that you plug the injector harness end into, it will flash when it gets the pulse.
So no flash, no pulse, flashes, its working

Easier to simply spray starting fliud down the throttle body, it it starts to start, you KNOW its fuel related

Otherwise your doing a lot of looking and research on the fuel system for possibly nothing

You can also, cheaply, get a noid,l a clear plastic thing that you plug the injector harness end into, it will flash when it gets the pulse.
So no flash, no pulse, flashes, its working

Easier to simply spray starting fliud down the throttle body, it it starts to start, you KNOW its fuel related


Otherwise your doing a lot of looking and research on the fuel system for possibly nothing



tried starting fluid, thats when I got the back fire. I dont think the injectors are firing. I think im going to pull it to a friends garge and have them scope it

I have a theory, it has spark, it has a good chance of getting fuel, you should be getting some kind of firing. Also when you tried the starting fluid it backfired through the TB, which sounds like it's not sparking at the correct timing. How about the crankshaft position sensor? I've heard quite a few guys that have had troubles with them, and it would make more sense to me. One sensor went down, engine doesnt know where the crankshaft is and when to fire the plugs so no firing. That idea sounds more plausible to me, but I'm no expert. Might want to try this over at www.ls1tech.com , they will have you figured out in no time!

had some fun a little bit ago, went a little crazy with starting fluid, it backfired, then a large ball of lames shot from under the hood. singed my neighbors arm caught the airbox on fire. unfortunatly the fire went out before the truck was consumed, so no damage. Just read that the security system can wig out and disable the injectors. (with out the security light coming on). They said a dealer can reset it was wondering if anyone has heard of this or knows a way to reset it??????????

Unhooking the battery for a few hours should reset it. If you are still fighting it I would definately head over to www.ls1tech.com though, this is kinda like asking about a gen 1 big block build question on a honda forum.

I'm not positive on this but I think if the "passlock" system kicks in, it will start but then die right away when the injectors are disabled. This may be something to look into though.

Not getting any response on LS1tech. Checked the timing again, it was off abit adjusted it now it tries to start but just wont kick the last little bit to run. Getting close but just not there yet

I would look close at the dist. cap & rotor. Had one do the same thing I checked the cap and didn't look real bad but not the best. Replaced the cap&rotor and it fired and ran great. I was going to same don't use starting fluid but I guess thats to late. I would use carb cleaner instead. To adjust the timing it will have to be running at 2000rpm and adjust until the cam retard is 0 degree's on a scan tool. It won't set a missfire or lean code until it's running. Also check to see what the ect sensor is reading. If you crank it and leave the key in the run position does the security light stall flashing or does it go out?

the security light goes out, the cap,rotor, plugs and wires are new. ECT says 54* which is close to what outside air is so imguessing its close


EDIT-- My scanner shows 0.0 degrees timing advance while cranking. it never changes, that doesn't seem right. does anyone know how to check the crank position sensor???????????

Monitor the engine rpm on the scan tool while cranking and see if it shows any rpm.

checked engine rpm while cranking it gets up 850 or so. Still need help This thing is driving me nuts HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :( :(

If your getting good fuel pressure at the gage. There may be problems after the gage then. These have a similiar port injection system to the 4.3, a sort of spider like assembly that has tubes running to each cylinder. It is located in the upper intake plenum. It is all part of the fuel pressure regulator assembly. Perhaps the nozzles are plugged up.

I still think this is it. LOTS of problems with the CPI units. Could very well be a combo of several things, though.

you will have to determine if it has the CES system or multiport,
get a wiring diagram and check for power to the injector unit or injectors
with key on, then check for the computer switching the ground for the injectors while cranking. You can get a subscription to alldata or a good book and it will give you all the "pinouts" for the ecm

looks like pink should be common power and pcm controls the ground side for each injector.

The next step is to see if you have a signal to the injection assembly. Try getting ahold of a noid light kit. They are cheap set of light connectors that plug into injection connectors and will tell you if you have a signal at the unit itself. Crank and watch to see if it flashes. You may have to have a partner crank while you watch, its not easy to bend your head around the open hood and see if it flashes all the while your reaching in to turn the key.

Just another possibility.

its being towed to a friends shop today to be hooked to a diagnostic computer. This is the first time in 30 yrs I have had my butt kicked by a car, I dont think I like it:mad: . told wifey I want a $5000 scanner for our anniversary so it never happens again. her response-- :noway:

thanks for all the help- Ill let you know what the verdict is

computers aren't always that smart, it may still have to be trouble shot with a good old ohm meter, wire by wire. Hope they get it figured out for you. Let us know what happens.

Even though you had it towed to a shop already. We once had a Vortec 350 in our shop that was in a companys full size work van that wouldnt start. It was an full size Express van. Cranked and cranked and we had all the basics. Fuel, air, and spark.

We discovered the gear on the distributor was pretty chewed up, but the rotor still span when cranked. Seen it one other time since then on my very own 1997 Tahoe, 5.7 vortec engine. I did the intake gasket job last month and found my distributor gear is starting to wear but was not bad enough that it will be a problem just yet. But one thing is for sure, it will certainly need attention sometime in the future. This could be another possibility.

last thing I did before towing it in was pull the distrib and check the gear, it looked fine. mild wear no missing teeth etc. this truck has always been well taken care, frequent oil changes and tune ups etc. Im going to stop by the shop this morning to see what they've come up with. Im sure its something silly and obvious that my frustration caused me to miss. Thanks for all the help:beers:

The shop called today, Apparently the timing is 180* off!!!!!!!!!!! My father in laws still says he did not pull the distrib!! so either he is not being truthfull or the new rotor button he bought was made 180 off. Your guess is as good as mine ( i know what im leaning towards, Im glad hes paying the bill)

If the rotor button wasn't made 180 degrees off, I think I would be dis-owning the old guy for not having come clean... :clonk:

I guess at least this is on his dime!!

It's highly unlikley the rotor was molded backwards. They typically have the molds keyed to accept the metal insert in only one direction prior to shooting the resin.

All the more reason to mark the distributor housing, and mark the rotor someplace on the engine or firewall before you remove the distributor. Or even before you go to loosen it.

All the more reason to mark the distributor housing, and mark the rotor someplace on the engine or firewall before you remove the distributor. Or even before you go to loosen it.

I marked it before I pulled it to check the gear and am 100% positive it went back exactly where it was. I have to assume either my F.I.L pulled it and screwed it up or an alien landed and played a practical joke!!

Would seem more likely that the rotor mount has slipped on the dist.shaft.