getting there.

[clutchdust]

finally figured out a drivability problem i've been fighting off and on for the last couple months. turns out the electric fuel pump i installed can't pull fuel from its current mounting position. at least not adequate fuel.

i was having a problem in that the engine would start idle and free rev fine but as soon as i would drive it, the thing would fall flat once accelerating into 3rd gear. i determined it was a fuel delivery issue and played with the float bowls. i noticed that if i turned the engine off immediately when the engine went flat, i could pull the plug from the bottom of the float bowl and it would be just about bone dry, even after adjusting the floats to practically full open.

i reconnected the mechanical fuel pump and viola, problem gone. now i feel stupid. i am pissed that i bought an electric fuel pump that won't do the job but i think it might be more position than anything. it's mounted in the engine bay at roughly the height of the top of the tank. after doing more research, it appears these cheap pumps claim to work best if mounted at or below the level of the bottom of the tank. also, they don't like to pull very far either so i have two things working against me there.

at least i have that part of the problem licked. now if i can just get these things tuned up correctly and the headlights working....

[clutchdust]

o.k. can somebody tell me why we like these cars again?

after screwing with this thing all afternoon yesterday, i'm having the same problems. AGAIN! it just doesn't seem to go away. i have a feeling it's going to go away. just as soon as i yank those freakin' SUs off and drop a single holley four barrel in there.

<GRRRRRRRRRRRRR>:mad: :mad: :mad: :mad: :mad:

[240ZX]

Gary, Have you looked into possible problems upstream from the SUs? Alot of time on these old Zs, the gas tank has accumulated some rust and it tends to flake off and will plug the fuel pickup line in the tank. I know it a PITA, but if your tank has some rust, and I'm guessing it pobably does, pull it out and have it flushed.

[zman525]

sorry to hear about all ur problems man.... but from what ive heard Holly 4-barrel carbs are no good on Z's. Some have managed to tune them properly but ive mainly heard complaints about em. They dont deliver fuel to all cylinders properly, i believe its because of the design of the intake manifold. If ur lookin to get rid of the SU's ill GLADLY take them off ur hands :-P im lookin for a pair to swap out my Fuel injection with.

[2-4-T-Z-MAN]

Doesn't sound like a carb problem. Sounds like a fuel flow problem. 240ZX is correct with his thought. You could also look at the PSI of the pump. Is the pump a pusher or puller. The metal fuel line could have a build up of crud. Some fuel pumps have a built in filter screen that can get clogged. Good luck.

[clutchdust]

thanks for the replies. maybe you can see why i'm banging my head on this one since one of the first things i did was drop the tank and have it flushed. the main fuel line was so gunked up with varnished fuel, i just ran a new 5/16" rubber line all the way to the fuel pump. the fuel pump was disassembled and all the funk was scrubbed out with a toothbrush in a solvent tank.

it's even more frustrating when you know you've done about all that you can to ensure you have adequate fuel and still having these problems.

i swear, maybe i'll put one of those 300gph holley electrics on there to make DAMN sure i'm getting fuel.

<grrrrrr>

[=Enigma=]

Good suggestions. Based on what I've read on the forums here, it's important to make sure, as 24tzman pointed out, that it's a puller or a pusher, depending on where you plan to mount it. On my 73' 240Z, the electric fuel pump is mounted down low by the fuel tank and is therefore a pusher. I believe it was added to assist the mechanical pump up front with it's job. Moving this pump to the front of the car would probably not work very well. Perhaps simply mounting your elec pump lower would help things.

[clutchdust]

well, i read somewhere recently that the words you speak should be soft and sweet, just in case you have to eat them.

so i thought i might as well see exactly what's going on. i pulled the fuel line from the fuel pump and tryed to blow backwards, almost gave myself an anurism. drained the (freshly hot-tanked) fuel tank and separated the fuel line from the tank. tried the fuel line by itself and it was clear. tried the fuel tank pick-up tube--nothing.

long story short (kind of), i ended up using a piece of weed trimmer line to bore a hole through the crud in the pick up line. it was blocked right about at the flange where it passes through the tank shell. feels as though there is a burr in this area that acts as a natural catch for debris.

i put more fuel back in the tank in hopes that it would help flush the debris out the drain but i saw no significant particles come out. i hope that breaking the crap loose will allow small particles to pass through the area and get caught by the filter rather than collecting there. we'll see. at least if i start running into the same problem, i know where i'll start looking next time.

[=Enigma=]

Glad to hear you got it figured out. Did you have the tank lined? If so, so you think it's possible that some broke loose and was blocking the outlet?