Thread: fuel pump's fauiling on me??

did a few test runs on the highway whenever there was a clearing. once i did i noticed i was getting alot of KR such as 5-7*. i left off soon after. then i pulled off an exit ramp and onto a less used straight way and did a low roll at ~20mph to 100%. i noriced once i was at 100% throttle, i was getting KR and after looking thru the scan i logged my IPWs were like 14-16ms [X(][:'(] and this was with 10-12* of timing. after that run i slowed down to a complete stop.

since i have no back seat i can hear my fuel pump, but it was making various pitches from a high squeel to a low squeel. the pump only has like 30K miles on it and ed said it was from a wrecked L67 and supposely the fuel pump he sold me was a 'race' fuel pump and said it worked alright. well thus far it has, but i dont know if the fuel pump's either dying already on me or its not pumping enough fuel for the mods i have(has a vs cam in the car now thanks to dubob).

so do u think i should get a higher flowing, 255lph fuel pump? bare in mind i recentyl swapped fuel filters and running 42.5# lucas injectors.

if there is a way to borrow someone elses fuel pump assembly and test it.....from the sound of the pump..I would say it is switching between high and low output.

depending on the noises....I'd say it is having volatge flucuations....

well my voltage hasnt been up to par lately even with zzp's stage 1 voltage booster. b4 the voltage booster ym voltage via LS1M was around 14.5-14.7 and after adding it it tayed the same but lately the voltage was also dropping down to 13.8 every so often at idle. alternators a lower mileage and the battery's a bit over a year, but its not a high-powered battery like optima, just a generic one. i got the alternator rewire as well but i guess thats not doing the job either.

it would be the alternator's voltage regulator. the battery is only used to start the car, after that..it pretty much becomes useless in the electrical system.

all the electrical systems are run off the alternator. If the voltage has dropped to that even with the ZZP volt booster...I would say your alternator would need to be checked out....or the volt booster is a little wacky. take the volt booster off and see what your LS1M says you have for voltage after...if it improves....the booster is bad. if it doesnt improve and actually gets worse....your alternator would require replacing.

your pump may not be getting the required current to power it.

well the alternator i have on now is a lower mileage that i bought from a fellow member on CGP. the original alternator i had was making grinding noise(prolly the bearings) and with the voltage booster even on the old one the voltage was about the same. the voltage booster i have was bought from ZZP(i'll e-mail them to let them kno). i did noticed when i installed the lower milegage alternator the voltage was above 14.9 for a day or so(did a cam swap) and my radio was working w/o issues/interference because i got the low beams only HIDs.

After looking through my logged scan this is what I noticed, please let me know what you think would be the issue:
-from 1st to right before 3rd shifts, the O2s go from 950 and leans out to 880
-my minimum IPWs at the top of the shifts is approximately 15.5mS
-my injector duty cycle hits a max of approximately 75%
-the MAFF hits only 10.6K
-I get a max of 5* at the top of the shifts
-my WB was going from 11.0 up to 12.5

I didn’t log the voltage if I was loosing power being drawn and caused the fuel pump to not power on very much. For what its worth my idle voltage averages 14.3-14.7 even after adding in the ZZP’s stage 1 voltage booster.

from your O2's, and Injector duty cycle.......you are definately running lean. you should not even be close to that duty cycle with your setup.

would have to say your pump is not getting proper voltage...or possibly have a wiring issue

Originally Posted by archemedes

take the car to advance or auto zone and have the alternator tested it's free

yea that might be an idea. rather im gonna take my original 140K mileage one and see if thats bad or not since i was getting the same voltage with the one i have now

just got back from alot of driving and alot of testing. heres what i have done and come to realize:
took oof s/c belt and had no KR, maybe a blip, but none at all
reinstalled belt but unplugged BBV and limited boost to ~4psi. no KR at all from 1st to a bit after 3rd shift
threw on the 3.4" pulley and hooked up my fuel pressure gauge and did one last spin b4 night came. from a 15mph roll i got barely no KR and my fuel pressure from 1st to mid 2nd gear hit a max of 61PSI but as i progreesed thru 2nd gear the pressure dropped and b4 i had to slam on the brakes(road was coming to an end), fuel pressure was at ~54-55PSI.
the fuel pump, like i statred, was a lower mileage pump i got from ed. so is it possible that my curernt fuel pump isnt enough to fuel anything below a 3.3/3.2 pulley with the VS cam? i need some input on this as im drawing onl only one possible scenario, that being the fuel pump.


edit-b4 all of these runs i ran a few runs on the 3.2" pulley at full boost and no matter how much fuel i increased in the AFC, i still would get as much as 8* of KR in mostly 2nd gear and 3rd gear. i even tried to richen the PE_RPM vs TIME table and still the same effect.

any suggestions?

I'd shoot Ed an email, see if he would be able to send you another pump.

I am still thinking electrical...

the pump would only loose pressure if it were failing....or low voltage. is there a way you could hook up a voltmeter to the pump harness to see if there is a power drop?

well i think i forgot to mention on some of the runs earlier b4 i took off the belt and such, i scanned via the LS1M and scanned for the IGNV or the ignition voltage for a run. I got the KR but the voltage was showing a steady 14.6-14.7 across the WOT run. So I ruled that out.

Originally Posted by fst

well i think i forgot to mention on some of the runs earlier b4 i took off the belt and such, i scanned via the LS1M and scanned for the IGNV or the ignition voltage for a run. I got the KR but the voltage was showing a steady 14.6-14.7 across the WOT run. So I ruled that out.

Well the scanner may show an ignition voltage of 14.6, but thats not necessarily what is getting to the pump. The voltage losses to the fuel pump are well documented and I think along the lines of 2 volts or so was about the norm.

i see what u mean guys, so how would i check if the voltage is dropping from the pump? i would get either a voltmeter or multi-meter, but would I need to have somebody in the back probe the wires while I go wide open throttle?

Ive never had to check the voltage there (I was preemptive and installed a re-wire kit and larger power and ground wires up front), so I may not be the best authority on the way to do it. However, a voltage drop is a voltage drop for all practical purposes and the resistance in the wire is not going to change due to vehicle speed or load.

So I would just let the car idle and then check it. If you have a good multimeter, they make probes that are designed to clamp onto a wire and pierce the insulation enough to take a reading. So in that regard, it would be possible to take a measurement while going WOT, you would just have to have the meter up front with you so you can read it or someone riding with you to do that.

hmm sounds like an idea, but a hassle. would a higher flowing fuel pump with larger than stock wires such as PRJ or a racetronix fuel pump kit take care of this problem? lol....

If it were the problem, then I imagine so. But thats quite the expense to go through only to find out it wasnt (not saying it isnt, just playing the flip side of the possibility). Its going to be easier to take the voltage measurement at idle and by yourself, so start there. If the voltage drop is significant at idle then I guarantee you it is worse at WOT with the demands made of the ignition/voltage system at those load and speed levels.

Another quick way that migh prove it is if you know someone with the ZZP Stage 1 or 2 voltage booster. Ask them to let you borrow it long enough to do some WOT runs and see if the problem goes away or at least improves significantly. If it does then we will have another piece of information from which to work from.

did i mention i currently have a zzp stage 1 voltage booster on the car now as well as the alternaotr rewire?

You may have, but I didnt read through the whole thread, to say nothing I didnt look at your signature, sorry.

Hmmm, now that is interesting then. Because I would personally be under the impression that you have enough voltage there to run that thing. But you mentioned at one point your fuel pressure dropping, that does not seem normal to me.