2000 454 fuel probs...

[Chuck L.]

Inherited a problem, that I can't ID.
2000 Chevy 3/4HD.
A used truck, that has had this problem since 2nd owner has had it.[He bought it w/ 160K on the odometer. Now at 236,000]
Truck starts easily when cold.
Starts easily, if restarted very soon, after warmed up.
Has prolonged start time, [say 10 secs of cranking], if it is allowed to sit for, say 10 minutes. When it does start, it throws black smoke, and nearly raw fuel out the tp's.
Clear flood helps to shorten the cranking time, and the resulting smoke show.
The long block was replaced in Jan 08, but the top end was off the orig engine. [@Approx 230,000 mi.]
GM tech scanned and said his findings were inconclusive. He did replace 1 inj.
New plugs, wires, fuel filter, have been put in. No cure.
I hooked up the scan program,[V2] and find:
A. A/F is constantly fluctuating from 2+, to 50.
B. Timing retard is constantly fluctuating from 2* to over 20*.
C. Idle is smooth @ approx 725.
D. IAT reads about 95*. Ambient was 75*.
E. Only fault code was for steering input theft det. Shown as "HC". I cleared the codes, and this 1 reset immediately.
MAP is steady at 36KPA.
**I found an air leak at the cleaner elbow. The mass air was dirty, so I cleaned it. No change.
**The owner changed 2 temp sensors. No change.[NAPA brand].
**The owner does not know if the O2's have ever been changed.
**Knock sensors are out of original long block. Maybe overtorqued??
I have a download of the tune file, and a datalog, but will have to have DFE1 post them, as my wireless router is on the fritz..

Now, the ?...
NE suggestions as to where I begin???:help2:

SORRY for the "editorial"!!:bawl:

[joecar]

Chuck,

Commanded AFR is fluctuating... PCM is computing the airmass wrong...

If in CL, the this would cause the trims to be wrong...

Commanded timing is determined from cylinder airmass...

Ideas:
- O2 sensors;
- ECT sensor;
- MAP/MAF;
- leaky injectors;
- leaky fuel pressure regulator (diaphragm ruptured);
- IAT sensor looks like it may also have a problem.

Don't take the customer's word about what sensors were replaced, and don't assume the new senors are good.

It's not long, it contains all the relevant info... :cheers:

[N0DIH]

#1 issue on these engines. Fuel Pressure Regulator. This is the EXACT problem I wrestled with for a long time. I refused to go on a parts swapping binge. I won't do it. To costly and fruitless. on FullSizeChevy.com we have seen a lot of people with and a 100% success rate of people with the same symptoms.

ONLY test that you can do is to connect up Fuel Pressure Gauge, pressurize fuel system, shut it off and if the fuel pressure drops down in a few min, even 10 psi, get the FPR out. Mine litterally had fuel puddled up in the intake it was so bad. I was seeing LTFT -18% almost always. And nothing short of 50% E85 would correct it. And still wasn't running right, but ran better. Now I run E85 (100%) and see mpg better than I got with gas and the bad FPR. Go figure, it was bad....

They are notorious for leaky injectors, toss some in while you are at it if you can. You can SEE if they leak when the upper plenum is off, just fire up the fuel pump once you have the FPR replaced or before, and look at the tips, you can see them on the L21/L29 454.

But the FPR is almost always the issue. You will see fuel come out the fuel line when it is disconnected, but you cannot get to the FPR or vacuum line without the upper plenum off.

Do the FPR first, and get it Autozone, it is the IDENTICAL part at NAPA, only NAPA charges 30% more... I bought both and even the boxes are the same size with the same printed label on the side.

Check out FullSizeChevy.com, we have a lot of BB threads running, this is one of them. I am on there, look for posts for FPR and 454 in the techincal forum.

Don't go into the craze of replacing parts blindly (JoeCar is right on the list I was working on testing on mine, he is for sure there on the right track), I did the O2's on this one and got some crap ones in there that are fussy, and my GM ones are still good (put one back in). Get GM sensors if you REALLY want to replace them. The key for them over non GM (AC Delco) is GM requires the SHELL to be grounded to Sensor Low, most aftermarket are NOT. Connected up a wire manually got my aftermarket sensors to work. I was ready to live a life of Open Loop over this thing, but fueling was still too ugly with the bad FPR...

It will gain significant more power and drivability, as well as mpg. You'll love it....

http://www.fullsizechevy.com/forums/general-discussion/technical-maintenance/275591-7-4-hard-starting.html

[Chuck L.]

THANKS guys, for the help!
I'm on my way to fullsizechevy, now..

I just registered and read that thread.. LOTS of good info on that site!!
THANKS, again.

[Chuck L.]

THANKS guys, for the help!
I'm on my way to fullsizechevy, now..

I just registered and read that thread.. LOTS of good info on that site!!
THANKS, again.
Have been shopping for parts.
Have:
Fuel reg, filter, plugs, gasket, air cleaner element, batt cables.
Went to the "stealership", to get the air cleaner elbow. Ran into the "Goodwrench tech" that had worked on this truck.
He had some interesting "feedback".
Says the truck is JUNK, and not worth fixing it.
He said the problem was the timing, and a bad inj. He checked the injs, and found 1 leaking. [Replaced it]. He then returned the next nite, and had his timing lite with him.
He said timing was off 2-3*. He reset it to the factory spec of "0", at idle. The truck was running just fine when he left.

What do you guys think? Should I look elsewhere, since those items are now "OK"??:help2:

[joecar]

Check the FPR...

Key on several times to build pressure, the FPR has to hold pressure, if it doesn't then it or the inj's may be leaky;

if you remove the ait hose to the FPR, it should not have any gas in it, and with a vac hand pump it should be able to hold vac.

[N0DIH]

Well worth fixing for sure. The 454 is an animal tuned and with good injectors/FPR. BRUTE force for sure. Sure a 6L or even a 5.3L might beat it in a drag race, but you won't stand a chance with 10K or 12K on back....

I have towed 10K with mine (99 Burb 454) and it was very much at home towing heavy and got 9-10.5 mpg towing (even cold out with a bad FPR at the time!).

Hard to test them FPR's, one they have to have the intake off to see them, and 2, you can't get 4 bar with a vacuum pump, mine tested perfect and 100% the same as a new one on the bench, but leaked gas out the line. 4 bar vs -0.7 bar isn't the same. I think mine was good to 20-30 psi, still in the near 2 bar range or over.

Yeah, the timing offset needs to be right. My LT1 I think can set for it software, but the L29/L30/L31 need it be dead on.

Can you test that with EFILive?

[97K15004WD]

He had some interesting "feedback".
Says the truck is JUNK, and not worth fixing it.


Sounds like he is trying to buy your truck!! ;)

[N0DIH]

sorta what I was thinking!


Sounds like he is trying to buy your truck!! ;)

[hquick]

Yeah......

And yes, you can check the timing with EFILive...log GM.CMPRET.

[Chuck L.]

He holds himself out as a "tech", and tries to tell me that he set the timing w/ a lite???:muahaha:
The truck belongs to a customer, that tries to make them last to the very end!!:eek:
The FPR is getting replaced, and the injs cleaned, and flow tested, yadda, yadda..
DFE1 is going to bring his timing lite over, and we're going to do a "tuneup!!:grd:

[dfe1]

DFE1 is going to bring his timing lite over, and we're going to do a "tuneup!!:grd:
We may have to postpone the tuning session. My digital timing light is being fixed, and I don't think we can use an analog light because it's not compatible with the digital control system. I'll do some checking to see if we can find an analog-to-digital converter, but I hear when you use one, you have to use the timing lights when it's completely dark because when you convert analog light to digital light, you lose a lot of brightness.

[Chuck L.]

We may have to postpone the tuning session. My digital timing light is being fixed, and I don't think we can use an analog light because it's not compatible with the digital control system. I'll do some checking to see if we can find an analog-to-digital converter, but I hear when you use one, you have to use the timing lights when it's completely dark because when you convert analog light to digital light, you lose a lot of brightness.

Can we use my digital to analog converter??:eek: :D
Or, I have to goto the stealership for the part I ordered. Maybe they'll rent me that lite??
Will advise..

[dfe1]

Yeah, see if you can borrow or rent the one from the dealer. The GM digital timing lights are really good.

[Chuck L.]

Yeah......

And yes, you can check the timing with EFILive...log GM.CMPRET.

The timing on the log matches the timing map, at the KPa/rpm I checked it at.
Since the dlr tech set the base at "0", should I recheck it
B4 proceeding?
Is "0" correct for this application?

[Chuck L.]

found the problem[s]...
Seems as tho the FPR couldn't leak into the manifold... The vac hose had rotted off, and was not hooked up at the intake end.
7 of the 8 injs were leaking so bad, that the Fp dropped from 55, to less than 30, in 3 minutes, and down to 10 in an hr.
The fuel leaks had washed the inside of the runners to a spotless condition.
Next: The regulator is getting changed, anyhow, as are the plugs, cap and rotor. The injs are getting pulled and cleaned. I'm not doing this again! The guy that put the components under the intake, is likely the same moron that designed the ZR1, and the Caddy Northstar...:mad:

Anyhoo, thanks for the help!:)

[N0DIH]

I talked to the guy who runs Witchhunter Performance http://www.witchhunter.com/ and he said that no amount of cleaning will fix up the 454 injectors. Get some LS1 or LS6 injectors, update the injector size and you are set.

Don't waste $$ on them at all. They are 19l injectors, so if you want to NOT tune the truck, toss in some TPI 305 or Ford 302/4.6L 19 lb/hr injectors. They are drop in. Even the LT1/LS1/LS6 injectors (they all fit but are larger flow so you need tuning). The stock 454 injector is dead on exact for 300 hp, so any mods and it is way out of injector flow. And any mods to the 454 respond with big power gains. Ed Wright got 35 hp and 60 lb/ft torque out it on 87 octane. Over the stock 290/410 lb/ft torque. Now add free flow muffler and straight intake like a CAI and modified air box, and you are up even more power.

And YES, the LS1/LS6 injectors will fit. I used to have blueprints on them somewhere, they are the same.

[Chuck L.]

I said:
"The injs are getting pulled and cleaned. I'm not doing this again!"
Witchhunter said:
" that no amount of cleaning will fix up the 454 injectors. Get some LS1 or LS6 injectors, update the injector size and you are set."
He is right!:)
I have an ASNU bench. I leak tested them. 5 of 8 leaked. I cleaned them for 4 -10 min cycles, put them on the bench, and they "appeared" to be OK. I then re-installed, hit the key, and whamo 5 leaked. NOT! :mad:
The new injs are $95.00/ea. The customer nearly had a stroke when I quoted him the cost!!
I have a couple sets of 19# firds, from a 302. I recall they are 19# @ 3 bars. At 58psi, they should be really close to the 24PPH I got when I flowed the originals...[22#]. Do those numbers sound close??

Thanks for the headsup!...;)

[N0DIH]

Sorry I missed this one! Yes, the Bosch 19's used in the Ford 302 and 4.6L's are common replacements in the Cadillac 4.5L/4.0L, TPI 305's and the L21/L29 454's.


I said:
"The injs are getting pulled and cleaned. I'm not doing this again!"
Witchhunter said:
" that no amount of cleaning will fix up the 454 injectors. Get some LS1 or LS6 injectors, update the injector size and you are set."
He is right!:)
I have an ASNU bench. I leak tested them. 5 of 8 leaked. I cleaned them for 4 -10 min cycles, put them on the bench, and they "appeared" to be OK. I then re-installed, hit the key, and whamo 5 leaked. NOT! :mad:
The new injs are $95.00/ea. The customer nearly had a stroke when I quoted him the cost!!
I have a couple sets of 19# firds, from a 302. I recall they are 19# @ 3 bars. At 58psi, they should be really close to the 24PPH I got when I flowed the originals...[22#]. Do those numbers sound close??

Thanks for the headsup!...;)

[ls197gmc]

The fuel pressure regulator has a leak, guaranteed thats your problem.