Need some engine diagnostic help:

[Graystroke]

1996 Suburban 3/4 ton w/ Vortec 454. Note:The 454's have Sequential EFI and not the central pod thingy on the Vortec 350's.

The symptoms: Every now and then when I try to crank the engine it doesn't want to fire. I have to give it throttle to get it to catch...which is no bueno in an EFI motor.
Also, when it does this as you start to drive it and you floor it it pings bad under load (not all the time). Has a miss a idle too. Not a steady one just every so often. My first guess is either ignition or fuel pump. Truck has 78,000 miles. All the wires, plugs, cap, and rotor have been replaced....so I'm thinking fuel? Maybe the pump is on its last leg? check valve is failing and the system has to reprime up to the engine?
The other thing I think is wrong is when it starts up it seems to really throttle up high at first. It revs to about 1800 RPM then settles down to a high idle (which I'm guessing is normal for when it's cold outside) of around a 1000 RPM until it warms up just a tad, w/in a few minutes-then drops to 750 RPM. I replaced the IAC, thinking this was the problem w/ the idle at start up and it didn't help any.
No check engine light....I'm figuring since there is no Check engine light that there wouldn't be any codes stored. Chevy fuel injection is a new one on me to what are typical problems. The Haynes manual sucks balls b/c they cover absolutely nothing when it comes to Vortec 454's...not even a pic in the book. The book pretty much reads: This is how you remove/fix problem "X" on a Vortec 350...If you have a Vortec 454 it's different and you're **** out of luck. :mad:

[agjohn02]

fuel filter? try it, then think complex stuff.

[Graystroke]

already did

[agjohn02]

timing? at 78,000 it shouldnt be the pump. make that your last resort since its the biggest pain to fiddle with. i dont think the high idle is a symptom, just a side effect of cold. my vortec 350 has 180,000 on it and i havent had to mess with it other than tune ups so im not familiar with specific problems.

[aggieblazer07]

to check the fuel pump you can use a pressure gauge, I'm not sure how much it needs I think it's around 26? but that way you don't have to take it off and check

[mudtoy67]

Sounds like the computer might be getting a bad signal somewhere. I've run into bad temp senders sending the wrong temp to the computer and throwing timing/fan control/ idle/ etc... out of wack. Even though you don't have a check engine light on I would hook it up to a scanner and just look at the values the different sensors are giving while the engine is running. You might find something that is wrong enough to throw things off but not wrong enough to throw a code.


I think fuel pressure on the port injected motors is 40-60 psi. Have you had your injectors cleaned with that pressure cleaner that goes directly into the fuel rail?

[uglyota]

what plugs did you put in it?
John a vortec 350 is timed by the comp, I imagine it's the same for a 454

[agjohn02]

John a vortec 350 is timed by the comp, I imagine it's the same for a 454


its got a dizzy doesnt it? if it gets twisted, the comp can't compensate with enough retard or advance.

[uglyota]

yeah but it's fixed. If it's twisted it's broke

[Graystroke]

yes it has a dizzy but it also has a cam sensor. you stab it in and just get it close and the computer is suppose to take care of the rest as long as the spark isn't jumping terminals on the cap. I thought it was weird to when it said do not adjust the timing and there was sitting a distributor. I'll try the scan and see what happens. It also cuts out sometimes at full throttle when reaching RPMS in the neighborhood of 4 grand.

[agjohn02]

that cam sensor is what id look at next as long as the dizzy is close to where its supposed to be. i dont know how the advance is controlled, but it prolly got some sort of comp controlled vacuum actuater or solenoid. might look for vacuum leaks or a bad actuater.

[BMFScout]

wtf's a dizzy?

[uglyota]

a british distributor...they run on petrols

[Graystroke]

i dont know how the advance is controlled, but it prolly got some sort of comp controlled vacuum actuater or solenoid. might look for vacuum leaks or a bad actuater.

It's all computer controlled. all there is is a plug on the side. The cap is one of those funky ones where the wires all come out in order on the side. one side is 2, 4, 6, 8 and a place for the coil and the other 1, 3, 5, 7.
I don't think there is a vacuum leak, what I initially thought. I've sparayed a whole can of Beriman's (sp) carb cleaner all over every vacuum port and all along the manifold.
Where can you get this "pressurized" FI cleaner. It plugs in the fuel rail pressure reading port, right?
Does it work?
I think I'll take a reading on the rail and see what pressure I got.

[robertf03]

is your tps adjustable?

how much throttle do you have to give it? do you just hold it open a little or do you have to hit it like your pumping a carb?

[Graystroke]

I just hold it open about half way.
I don't know if the TPS is adjustable

[mudtoy67]

Where can you get this "pressurized" FI cleaner. It plugs in the fuel rail pressure reading port, right?
Does it work?
I think I'll take a reading on the rail and see what pressure I got.

NAPA sells a 3M brand fi cleaning kit that comes with a can of throttle body cleaner, a pressurized can of injector cleaner, and a bottle of in tank additive. The whole setup works really good at blowing crud out of the fuel system. There is an adapter to hook the pressurized can to the fuel rail, I think they sell it but i'm not sure cause we had a FI system kit that had adapters for everything.

[agjohn02]

the dealer is supposed to have some kind of complete fuel system cleaning procedure they do thats really good.

[Graystroke]

My long epic day:

Well, I'm up here in Fort Worth in town by myself and I decide to tow my Range Rover out to the shop in Granbury.
1st problem: My dad has all the straps, chains, EVERYTHING that I could possibly use to tie down my truck to the trailer in his truck. Call him up ( my parents are in Houston) he suggests to go buy another chain from Lowe's for $35 or to just wait 'till he gets home. I reject both those ideas.
I brainstorm and look at the trailer and the Range Rover and realize they both have winches on them. I run the RR's winch down to the front and the trailers down the length of trailer, hook a snatch block on the rear tie downs and hook it on the back of the RR. Cinch them both down. Problem solved.

2nd problem (mistake): It starts to rain and I had been fidling w/ the brake controller on the 454 burban (for you eric :D ) and apparrently I backed it off too far b/c I wasn't stopping and for some reason the front wheels decided to lock up and I was heading in a skid right towards the back of a Tahoe. I lift off the brake for a split second to regain steering and promptly came to rest into the side of a guardrail about two feet from the back of the Tahoe in front of me. I just new the whole side of my truck was toast and that that ****ty ass WAAG brush bar had wrapped around the front of my truck. I pull away and say to myself, "Well at least the wheel is still attached." I pull over and check the passenger side. THANK GOD for those wide tires that I swear at every time I get my truck washed and drive through a puddle! Apparently the entire impact (as evidenced by the marks on the tire) was taken on the tire! No body damage! ..and I hit it pretty hard. Hard enough that I knocked it out of alignment or bent a tie rod or something b/c the steering wheel is a little off...seems to track straight though.

3rd problem: As I'm pulling into the gate at the shop the truck decides not to turn. I'm like WTF?! I look down and see all the dash lights on. Engine died, kaput.? I tried cranking, it cranked but did nothing. I open the door and listen for the little whirring fuel pump noise. Can't here it. CRAP! I'm half-way out in the road. Past the turn b/c the lack of power steering and brakes was unexpected. I decide to unload the RR and use it to pull everything backwards. Did I mention I was by myself? RR runs like shat b/c of a hellacious exhaust leak upstream of the O2 sensor. Pull truck and trailer backwards, jump back in the burb and roll it and the trailer through the gate down towards the shop. Call my aunt to come pick me up.
4th problem: While I'm waiting on my aunt I decide I need to get everything in the shop to lock it all up. I unhitch the trailer, roll the burb out of the way. Grab the tractor out of the shop to get the trailer in there. Now I have to get the burb in the shop. Remember I'm by myself. I pull it back up the hill w/ the tractor and then roll it down the hill to line it up w/ one of the doors. Problem w/ this is that we haven't got the gravel delivered yet and the slab is about a 8" step.
So I hook up the tractor w/ a short choker strap and try to pull the burb over...no bueno...not enough ass in the little 4wd tractor.
So I get the RR and hook up to it. Pull the burb's front wheels over fairly uneventfully. The rear is a little different. I'm doing a four wheel burn out trying to get the thing over the lip and finally the thing comes over (remember: by myself and I have a ~6 foot strap) and BOY here it comes! WHAM! Right smack into the back of the RR. The ****ty WAAG Brush bar came in handy. No real damage sans a couple of dings in the bar.
SO....Back to the original reason for this thread: Im guessing my troubles were a failing pump all along.

5th problem: I had just filled up and problably have 35 GALLONS OF FUEL IN THE TANK! UGH!
I'm heading to the auto parts store now to buy a pump and grabbing every fuel container I can find. Oh what fun........

[uglyota]

One less daily driver 454 burban on the road...sounds like a good start! :flipoff2:
You couldn't find any rocks to stack?

[robertf03]

Did you try giving the pump 12 volts to make sure its really dead?

[mark]

I had a similar problem several years ago on the way to Las Cruces. Yep, the black Suburban I was driving crapped its fuel pump at the pump island after I filled the damn thing up. As I recall it was better than 40 gallons of regular unleaded. So, after pulling the Suburban out of the way with the attached Jeep, and spending the night sleeping in the truck, I borrowed a couple of floor jacks and lowered the full tank to the ground. I replaced the pump and all was good after that. Thanks to the Brothers Brune for help and general moral support.

The other time I got into that was when the fuel pump installed into my CJ’s tank by Bill Higgs and myself crapped out after I filled it up on the way through Colorado. David O and I emptied the tank, 22 gallons, into a hastily procured 25 gallon plastic trash can. We weren’t sure if the can would melt or not. We ended up borrowing the parts guys new Ford diesel to fetch the new pump some 30 miles away. We put it all back together, refilled it and left the empty trash can in the parking lot. Then just a few miles down the road we ran across a nasty one car accident and had to help out until the ambulance and cops arrived.

[BMFScout]

we towed the jeep out of the way with the dragula, trailer still attached. The tank was lowered with two scissor jacks b/c the hyd jack we borrowed from the redneck parts store was junk. 'twas a *****...