[skidze]

hey,

i have a 90 lx hatch with a 351w that is carb'ed. i have been driving this car with no issues for the last year, and all of a sudden i have started having problems with the car bogging down terribly under heavy acceleration. as far as the fuel system this is what it has.

stock fuel tank
holley blue electric fuel pump
holley adj FPR
holley 650

for the last year my fuel pressure has been a solid 6 psi according to my fuel pressure guage. well yesterday is when the car first started acting up, so we raised the fuel pressure to 7.5 psi because i JUST installed some drag radials and some koni adj shocks.
well after we raised the fuel pressure and reset the floats, it seemed okay. or at least until i got to the track. same thing happened, bogged down really bad, and when i tried to accelerate it was as if nothing was there. hell even in the burn out box, anfter i burned out and started rolling the car died, and i barely got it started back up.

my fuel pressure for some reason has dropped to like 4psi and then fluctuates. sometimes it will hold 7.5, and other times it drops to 4, 5.5, etc. with the pump on, i checked for any poor or loose connections, and there was no difference. the pump at times seems like its barely on, when it does this.

can someone help me out here. i dont wanna replace the pump unless that is what it sound like it is. has anyone had this type of problem before??

oh, and this morning i decided to take it to work, (9 miles) and it held steady at 7.5 psi and drove fine.. i have no clue..

[trueblue01]

If you don't have a restriction or obstruction then it most likely is the pump. The Holley's are alright but I have had 2 blue pumps go bad over the last 5 years. They are rebuildable. Is the pump located at or below fuel level or do you make it pump fuel up to the pump. They are designed to have fuel feed gravity to the pump and then go up to the carb from there. Mounting the pump above fuel level causes accelerated wear on the pump and it will fail sooner.

[skidze]

hmm, interesting. well the pump was mounted up high in front of the gas tank right behond the diff. the pump pulls gas out of the stock fuel tank from up top, and then goes through the pump to the outlet of the pump and then the fuel goes to the fpr, and then carb. i see your point for sure. i wonder if this could be a intermittent failure where the pump is eventually going to go out fully one of these days. maybe this will help-

today at work i went outside and turned the ignition on only KOEO so the pump would run. it had a steady 7.5 psi for about 10 mins, and then it started dropping to 4, 4.5, back to 6, then 7 etc.

[trueblue01]

I'd have a spare on hand for when it quits

[skidze]

okay well guys i am still having issues. i checked for continuity to the fuel pump and it was getting a solid 12 volts, and this was when the fuel pressure was acting up. so i went down to oreillys and bought another holley blue and threw it on. much to my dismay, the fuel pressure was still acting up, and the car would bogg BAD if i put my foot in it and act like it wanted to die. so i figured i would replaced the fuel pressure regulator with the new one that is supplied with the pump, as well as the inline fuel filter i have that sits right after the FPR, before the carb. well i replaced those two things, set my fuel pressure, and float levels, and once again it ran like shit, and the fuel pressure is everywhere.
the only two other ideas i have is that it might have a bad ground for the pump, or the fuel lines going into the tank have sucked some junk up into them.
does ANYONE have any ideas, or has anyone had this similiar problem before??? any help would be appreciated!
thanks

[skidze]

anyone??

[GoodOleBoyzRacin]

check the lines. disconnect them and blow them out with air. if it still does it drop the tank and check in there. then blow the lines out again, if the trash is in the tank then it would have sucked it up again. thats if thats the prob....

[trueblue01]

Your not sucking through the original in tank pump are you?

[skidze]

no sir, today i re-wired the fuel pump and ground, and replaced the power valve in the carb. after that, it ran better but it still needs some fine tuning i guess..??

[skidze]

this is just an update to help anyone else out that could be having the same issue here. my conclusion-

replaced the holley blue fuel pump because it was weakening
replaced the FPR and inline filters
replaced the blown power valve in the carb (6.5)

after that and some fine tuning, the car ran alot better, but still had a slight hesitation. after making some fine adjustments to the carb and changing out the small 66" jets in the carb with some slightly larger ones we finally achieved a linear smooth power band, that the car never had before. im very happy with the car now, and hope to get it to the track very soon, so i can get some times for everyone.
i have always worked on fuel injection, so haviong this carb'd engine has been a whole new learning experience. i hope this helps someone!