Finally got the "L's" head repaired plus they said I should get the
new ECM " CUX2" cause they say my CUX1 was shot. Since then
put in new plugs as it ran like @#it. Seemed ok for half a day of
riding around. Then a misfire or cutting out under part throttle in
3rd gear. Got worst as time went on. So pulled couple of plugs
and they are fried ? Ceramic is white and ground electrode looks
white also. Installed new fuel filter, not much if any better at all.
I think its starved for fuel, possibly fuel preasure is low? Now
what else might be screwed up. No chip in yet either! Need help
before @itchin at Dealer when I take her in for repair??? Oh Dealer did S/C recall at same time head was changed..

 

Robert,make sure your gas tank is under e and drop it and check the clamps that hold the fuel pumps..99's are known for this problem.
Do it yourself and save a buck as i dropped mine on my 00 last year but found mine were in good shape.
I only wish i would have had some 255's to throw in there then...now i have to drop the tank again...doh.

Greg

 

ib fast,

O.K. will do tonite. But not sure as to what " 255's " are? Different fuel pumps ? If so I'll aquire them before dropping tank,
then install pumps.

 

Robert, the 255's are hi volume fuel pumps that you would use for nitrous or with big pulleys or a bigger blower.
The time to install these would be the first time you drop the tank...even if you don't plan on doing any of these mods in the near future.
I beleive the whole kit can be bought for around 300.00 and the install would be easy.
Greg

 

I don't think it's the fuel pump clamp problem, because that usually results in about 10-15 psi of fuel pressure when that happens, barely enough to run the truck. However if you want to upgrade to the twin 255lph pumps, we have them in stock.


It sounds to me like you have some other problem, but related to being too lean. Either a bug vacuum leak somewhere, or maybe the fuel pressure regulator is not hooked up to vacuum. Whatever it is, it sounds like you are running way too lean. You're not running the 90mm MAF by any chance with no chip, are you?

 

Sal, if you would answer your phone,i am looking to purchase the 255's
Greg

 

Sal,

Nope no 90mm installed yet. Just your filter kit, CUX2, full
Bassani exhaust ! Your idea on vacuum is most likely right, now
Boost gage needle is at bottom of gage not near the 0 anymore.

 

What codes is it throwing? Local owner had a rough running truck after an engine install and it turned out that the intake air sensor up near #8 cylinder wasn't plugged in(difficult to see.) He also had the boost problems you were reporting. Very rough running.

He also 2 vacuum lines reversed. These were I beleive a pink and green ones above the #7 cylinder. I don't remeber exactly which ones they were.

 

easterisland,

No code yet but have Check engine lite, but it reset when I
took off neg. batt cable while working on it. Vacuum line idea is
great, and will check intake air sensor too!! This is really buggin
me, thanks for idea's!!!

 

Yeah the hose loose or blown off the in tank pump would only allow my 99 to idle along barley. I just had some lean issues with my X motor. Be careful. If yo had some monkey do the work you may want to check behind him. Even good mechanics can make a mistake.

Good luck.

 

I'm am having the exact same problem with an '01 that I have been working on...the first engine actually leaned out to the point that it scuffed all the pistons and froze the rings on the RH bank (#4 was the worst). All the plugs were still intact but very white/grey. If your truck is misfiring and running rough now, the damage is probably done.

I just finished installing a new engine with all the Manley hardware and we're still having the same problems. If you do find the problem please post what it was. I will do the same. Whatever you do, DON'T RUN IT AT WOT anymore!

I'm not sure the truck has a vacuum leak concern as it runs perfect and the plugs look great if you just drive it around normally. The instant you get on the gas over 3/4 throttle it goes way lean. I'm going to drop the tank and verify the pumps and lines. I've heard of a split "Y" connecor between the pumps as well. That or possibly a defective fuel pressure regulator or MAF meter.

 

DrTriton,

Pulled front plug on each bank, put originals back so I can
show plugs around and seems to run alittle better?? Will check
if I may have been givin wrong ones for testing things out!! Will
put NGK's TR-5 in tonite then see whas up??? Hope its not as
you say!!!!! Thanks , REALLY !@#$!!!!!!!!!

 

TTT...I've dropped the tank and checked the pumps and lines - they pressure test and hold to 80PSI before the blowoff's open up, verified the pressure regulator at idle with and without the vacuum line connected (32 PSI w/ vacuum @ idle, 40 without, 40+ as the boost goes up), MAF seems to follow throttle opening, swapped injectors, and I'm still scratching my head...maybe one of the tuners will chime in again...any news on yours, Robert?

 

DrTriton,

Well I think maybe I found something that has to do
with the fuel rail assembly on the left side of the engine above
cylinder # 7. It's somekind of sensor that has two 5 mm bolts on
each side of itself holding it to the fuel rail mount (black) and has
a three wire plug going to it. After I pulled it to look at it, there's a 5/16 diameter or so hole sticking out with a blue O'ring around it and thats it ????????? Looking at these 4.6 Mod Motors here they put in the Town Cars that sensor plugs into the fuel rail and to me would be like a pressure sensor or something like that ? Need to find out what it is and if it is all there ?????? I don't think so Will go back to dealer Monday and find out if not before from looking at another "L" and comparing
the two. More to come when I KNOW!!!

 

Robert, that's the BAP sensor. It's supposed to be going to nothing. It reads atmospheric pressure.