Funky Fuel Injectors?-*UPDATE*

[TYRODD]

OK, been smacked with more crap. Have very wacky cold start up problems like bad flutter, stalling, and other fun things. Truck hiccups like crazy until after 2000RPM-then things are smooth. After the truck runs for a while, even after completely warmed up(it can take a WHILE), the problem completely dissapears even the crappy idle. Ive replaces the plugs, wires(with delco's), MAP (this was bad), cap, rotor, and just about everything else that could cause ign. probs. I have checked things very thoroughly. I suffer from the Huge vac leak from the TB shaft-which really shouldnt cause a real problem. As far as Ive checked, the vac. system is tight as a drum otherwise.

Back to the subject at hand, I just got through checking injector pulses with a tester, this is what ive found:

All tests were done with key on, fuel pressure a 43psi (base), and tester set at 50 pulses. The injectors are stock.

#1 dropped to 22#
#3 dropped to 28#
#5 dropped to 22#
#6 dropped to 22#
#4 dropped to 30#
#2 dropped to 23~24#

I have very little experience with injectors, but #'s 3 and 4 seem pretty funky. Could anyone agree and or give me some help.

-RJ

 

[psych-lone]

Only feasable option I can think of would to have the injectors flow tested. Other than that, find somebody to swap a set with. Try clearing the codes as well, also sounds like a dirty IAC. Good luck.

 

[TYRODD]

Bummer, I live in nowhere, you know where thats at right? The only other ty in town is owned by a dude that could care less, its garnet(rare) he also owns a GN which also looks like feces. The IAC is new and everything was cleaned thoroughly. No codes either. I have a feeling I will be pulling them all out soon, as well as the upper intake, so I can give them a good cleaning.

Danke,
RJ

 

[psych-lone]

Well, if you think the vaccum leak at the TB is a problemo, try squirting it with some brake cleaner while the truck is running. If the RPM's shoot up a bit, there is a defenite vaccum leak. These trucks just seem to be a little cold blooded to boot. Did the problem arise suddenly or gradually over a period of time? What other symptoms does it have? Checked the timing? Possible that its a bit retarded.

 

[TYRODD]

Well, the location of the leak would probably cause more of a boost leak rather than a vac. leak, I cant suck carb cleaner in to check. Timing is fine, its a problem that fixes itself the longer I drive it, like if the injectors fix themselves. Asked a GM tech about it today, and he said it was definitily a prob. and that it could cause the symptoms I have. Prolly need to clean the injectors, but hard to find time to do something like that, especialy since its a DD. If it was a vac. prob. or ign., I dont think it would fix itself.

 

[Ian Turgeon]

grab a stock set off a board member, and ship those out to be cleaned/matched.

oh yea, and i have some for ya, your $ so you tell me how much their worth to ya.

 

[TYRODD]

Well, I ran a few more tests tonight, and found some more mysteries. With the fuel rail primed to 43# and key off, I lose 10psi of fuel in ten minutes. I also noticed it leaks very slowly from 43-40, but at ~39 it drops off fast enough to watch the needle move. I tested this several times, and actually on the first test, engine cold, I lost 10# in twenty minutes. After starting it and letting it run for a few, I was losing 10# in 10. Also the needle on my FP guage flutters pretty bad, at Idle it flutters about 4psi either way, even when I get on the throttle a little. FUN FUN FUN!!!

 

[TYRODD]

Lost a little momentum today. I was going to have my injectors cleaned and flow tested/matched, but no one can do it here in this hell hole. Looks like I'll be buying 2 or 3 new stock injectors @ $85 apiece. I'll have the upper to lower intake gasket in tomorow so if I can get the injectors then, I will be having fun tomorrow night. This shits adding up fast, I guess it comes with the territory. :-? :x

 

[TYRODD]

Well., I installed the two injectors, cleaned the others as well as the entire upper intake and throttle body, IAC, MAT Sensor, well everything above the lower intake and all I can say is WOW, it was durrrrrty. Appears that all this has fixed all of my known problems, the idle is as smooth as a babys butt now so dats cool too.

The Injectors I replaced had no physical damage to them, the "nozzle" er...the plastic/ceramic hoodis was fine as well. All the injectors are now flowing equally as far a I can tell with a pulsator and FP guage.

Yay for me :lol:

 

[Ian Turgeon]

good to hear.

 

[smeagol]

FWIW, or for others' benefit.. i would have just sprung for Delphi injectors from PTE or Mike etc. Methinks they are in the range of 300 bucks or so for 6 brand new matched ones.

 

[TYRODD]

Yeah, I though about the Delphi's, but feared the cost. Dammit, wish I had known about those earlier, it would have been about $250 cheaper than a new set of stockers($547)

I was surprised at how little time it took me to do this all, only about 3 1/4 hours, the cleaning took the most time, used 2 cans of BG (having to go get the second mid job as well as a few other "arrands")and a wire brush(not on the injectors! ). FYI this was my first time ever to take the Upper/fuel rail/injectors off the typhoon.