[SquishyPanda]

So I was pondering my fuel pump issue, wherein I lose fuel pressure during left turns at a little over half tank (120 miles or so), and I lose pressure during acceleration, too, at a little under half tank (after 200 miles).

Is it possible that the S tank (which I didn't bother to switch out during my engine swap) has no baffles in the tank, since the float bowls act as a reserve in case fuel sloshes away from the pump pickup? Does the Si tank have baffles? I want to go look, but I'm really nervous about sitting on top of a big open container of gasoline while it's starting to get warm outside.

If there are no baffles in the S tank, then I'm just hosed and have to continue putting up with refilling the tank every 150 miles. If there are baffles, then I goofed something up installing the pump (though I re-adjusted it twice since I discovered the problem 2 days after the swap) and I can fix it.

[GUESSMAN]

I still have the 91' Si tank sitting on my back porch and I can look in it when I get home from work and try to see if there are any baffles in it. My S tank is still on my car so I can't help you there. Sorry.

[SquishyPanda]

Cool thanks. You still have the carb motor in your S, though right? So you haven't had fuel pressure issues during corners?

[GUESSMAN]

Originally Posted by SquishyPanda

Cool thanks. You still have the carb motor in your S, though right? So you haven't had fuel pressure issues during corners?

No, I yanked the S motor out last summer. It was having all kinds of problems but that was not one of them. Idle problems is what I was having, but I just figured it was those pain in the ass carbs. Sorry man, I'm not much help there.

[preludegofast13]

IT does maintain fuel pressure with a full tank, or does it still drop?

[GUESSMAN]

I took the fuel pump out of my 91' Si tank and looked in there and I see where the fuel pump sits down into some sort of baffle. Just to let to know what I saw.

[SquishyPanda]

Originally Posted by preludegofast13

IT does maintain fuel pressure with a full tank, or does it still drop?

Everything is fine from full all the way down to almost half tank (about 120 miles on the odo). Then it starts cutting out on really hard left turns. Then as I use more fuel, it's more sensitive, as in it takes less lateral G's to cause it to cut out. The motor doesn't stall, so I guess it's getting some fuel, but it just bogs. When I get down to the 200 mile mark (usually just under half-tank) the problem starts showing up under hard 1st and 2nd gear acceleration. By 240 miles on the odo, it does it on the freeway in 5th gear if I stomp on it. If I roll into the gas, it's fine, since I'm not triggering the acceleration enrichment, I guess.

It never happens under hard braking or right turns, though, presumably because the pump is mounted forward and on the left side of the tank. I don't know if this is reversed for RHD preludes.

I originally thought that I had put just put the pump too high up on the bracket, but when I was at work this morning I was pondering opening the tank again when I got home. Somewhere in the train of thought the baffles idea came up and now it seems to make a lot of sense.

I've replaced the fuel pump before while the motor was still carbureted. The FI pump is the same size, and I'm still using the carbed bracket (modified to house a return line) in the carbed tank. Nothing really changed except the guts of the pump. It's not likely that I messed it up, especially since I opened it up to mess with it once already since the swap.

[jlude90]

so, did you change over to a high pressure pump?

i'm assuming you did. but i just have to ask

i never had this problem in my S, and i'm pretty sure the part numbers are all the same for all models, but i'll check

EDIT: well smack my ass and call me sally, they are different

damn, not you have me worrying...dammit

[SquishyPanda]

I do have an Si pump in the tank. Everything is hunkey-dorey until I get to that half-tank mark.

[jlude90]

damn dude, that sucks, i guess i'll have to see what happens when i get down there

how can you tell this is happening?

does the engine start to die out or what?

can you actually tell its losing pressure or how do you know?

[SquishyPanda]

the motor bogs but doesn't stall. It follows a pattern that makes sense with fuel sloshing away from the pump pickup (problem only appears during left turns and acceleration, starts at half tank).

The only variables at work are inertia and fuel level. I put my Sherlock Holmes hat on and deduced it, Watson.

[tweety-lude]

Hi, I have 4 Prelude in pieces and one I use. My husband try to put a new fuel tank but inside was not the same than the original. In my 4 Prelude, I have "S" and "SI". I use an "SI". So the fuel tank for "S" and SI" are not same. The fuel pump doesn't go deep anough in the "S" model. I hope you understand me ...

[tsiah]

metal man had to swap tanks on his S>Si conversion...
the car would die at "1/2" tank (I say "1/2" because he'd only driven ~80 miles and the gauge read half...) after we swapped the tank over, no more problems with the fuel level reading incorrect or the car dying after 80 miles of driving

[jlude90]

crap

[project88si]

i had the same problem with my swap for a while i just kept it above half a tank but i think its because i think the carb fuel pump bracket is straight and the fi fuel pump bracket is bent and doesnt make it to the bottom of the tank

[SquishyPanda]

Hmm... guess I'll just put up with it for now, then. I'm pretty sure it's not a depth issue, though, because I'm using an S bracket in an S tank. The bracket is curved and a pain in the balls to snake in. But apparently there are differences all around. Maybe some combination of goofy shit I did to put this car together just isn't working.

When I've got some money (someday) I'll keep an eye out for a 3g Si part-out and pick up the tank and bracket.

[jlude90]

yeah, my Si pump was an absolute bitch to get in but i got it, so i figured i was golden

[tricken]

the si tank has baffles like things makes it a pain in the ass to do a pump swap

[SquishyPanda]

OK so we've established that the Si has baffles. What I need to confirm now is whether or not the S tank does.

[89vtec]

nice i not the only one that had that problem.....

after the b18c swap in the car it did exactly what you are saying... my car is an s model .
so originaly it was carburated but now it s fuel injection.
i went to the honda dealer for some help and we looked at the diagrams for the fuel tanks and the s model has no baffle to retain the gas in the curves...
im running with the gsr gas pump and the si model gas tank for 2 years with no problem....

[preluderguy]

i would say IMO, that the fuel pump is overheating at that point when it is not fully submerged in gas... probably just a bad pump.... i had a cadillac that stalled when taking onramps too fast... and in extremely hot weather at idle with a low gas level...

i would start simple.... just throw a new pump in there... i bet thats what it is....

i mean it makes sense.... the motor is made up of a coil of wires....and if it shorts out... it creates heat.... and when there isnt gas surrounding it, it cannot disperse the heat....so when your fuel get too low it over heats and the coils expand (hence, binding the motor)

like i said ... in my opinion

[SquishyPanda]

Originally Posted by preluderguy

i would say IMO, that the fuel pump is overheating at that point when it is not fully submerged in gas... probably just a bad pump.... i had a cadillac that stalled when taking onramps too fast... and in extremely hot weather at idle with a low gas level...

i would start simple.... just throw a new pump in there... i bet thats what it is....

i mean it makes sense.... the motor is made up of a coil of wires....and if it shorts out... it creates heat.... and when there isnt gas surrounding it, it cannot disperse the heat....so when your fuel get too low it over heats and the coils expand (hence, binding the motor)

like i said ... in my opinion

that's a valid point, but I'm 99.9% sure that's not my issue. It's been doing this for a while, and the pump would have completely burned out by now. The pump also wouldn't overheat and seize instantly when the fuel sloshes away. My motor bogs, but doesn't stall, and it happens as soon as I go into a left turn at the right speed. It comes right back when I straighten out, though, so it's sucking in enough dribbles to keep the motor alive. The baffle issue just makes more sense with what I'm experiencing. Especially now that there's confirmation that the S tank doesn't have any.

Oh well. I'll just put up with refilling frequently.

[GUESSMAN]

I have that 91' Si tank on my back porch if you want it now. I just got my 88' Si car with a tank still on it.

$150.00 plus shipping and it yours. It cost me that much at the junk yard.

[SquishyPanda]

nah I'm good. I gotta spend all my money on school right now, because I transfered late and missed the financial aid deadlines Gotta find $3k for this quarter somewhere.

[GUESSMAN]

No problem at all. Just a heads up. good luck with your schooling.

peace