DO-WORK-SON

So 97 civic ex about 112k miles I'm guessing original fuel pump, but problem is
every time I gets to about 1/8 tank of gas the car will start to stumble and hesitate, so i fill up and the hesitations get slightly worse then will run fine after a short drive, like the pump is having to get used to the better pressure of more fuel in the tank or something. i don't know is this a sign of fuel pump going bad or something else? injector issue maybe?
just thought of this also i have not changed fuel filter and not sure if its ever been replaced. suppose i could start with that?

98vtec

I moved this to an appropriate section.

You need to test fuel pressure and see if its within the spec needed

wwcrxww

I would start with a nice new fuel filter and put some Techron fuel injector additive in the gas tank along with a full tank of gas. a lot of pple dont believe in fuel additives but the techron brand is supposed to be proven.....but who the hell knows....

if nothing changes after that then another common issue is the fuel pressure regulator....you need to get your hands on a fuel pressure gauge and take some readings.

to me it sounds like you diagnosed it yourself....good chance that the fuel filter will cure your issue

good luck bud

DO-WORK-SON

Sounds good then i will start there, just unsure so wanted to see what other thought

wwcrxww

let us know how you make out

DO-WORK-SON

Ok i ordered a fuel pressure gauge and fuel filter, what pressure should the system be at ?

wwcrxww

40-43psi at idle

DO-WORK-SON

Ok so i got my fuel pressure gauge and filter in today got them installed, and gauge is only reading 30psi at idle. so is there a regulator that can be adjusted somewhere or do i just have to get a new pump?

And if new pump which one should i get, would it be worth it to go with the walbro 255 or is that over kill? walbro 190 instead?

kyden

pull the pump and check to see if you have debris in the tank.

DO-WORK-SON

you mean like check to see if i can just get away with replacing a clogged up pump sock?
Or that i should drain and clean the tank?

fcm

If your only getting 30PSI the fuel pump is weak or FPR is bad, replacing the sock is not going to change anything.

What is FP when vac line to FPR is pinched off, [ with engine running]?

Does FP stay at 30psi overnight or does it drop, if it drops, to what does it drop to and how long does it take? 94

DO-WORK-SON

That was kinda my thought too, changing the sock will do nothing.

Well im at work now so ill have to check that tomorrow.

What do you mean by does the FP change over night? Not sure Why night time
changes anything?

wwcrxww

Its your fuel pump.... if your fuel pressure regulator was no good it wouldn't only act up when you have 1/8th tank....

DO-WORK-SON

it kinda seems to be getting worse, now when i go to start the car it will run for like half a second then die, repet that like three times then idle fine. and that is happening when the tank is about half full its weird, but does run smoother and better now with the new fuel filter, the old one had like nasty black **** in it.

1998GsRIntegra

Keep in mind that the pump doesn't create any pressure, everything post fuel pump causes resistance which creates pressure. So either you have a fuel leak some where which is causing your drop in pressure because it would be a drop in resistance so to speak, or the pump is actually worn out to the point that it can no longer move enough volume of fuel to create the pressure you need.

DO-WORK-SON

never thought of it like that, i should have being what my dang job is. Brain fart
So what pump do i get to replace it, walbro 190 or 255.

1998GsRIntegra

Obviously dual walbro 400's BECAUSE RACECAR lol.

Is it a stock daily driver? If so, a stock pump will be just fine because you aren't asking the pump to do any more than it was designed to. I think stock pumps flow about 190lph, but don't quote me on that.

DO-WORK-SON

LOL heck yeah dual 400's !

but it is my DD and i dont really plan on doing anything to the motor, though with how my planning is i will end up spending alot on the little d16 because i get carried away with stuff.

I think i already know what people are going to say but are the pumps from a local parts store good or should i go with OEM.

fcm

I mean once you have the 30psi and turn off the engine, [day or night] does the fuel pressure stay at 30psi or does it drop, if it drops, how long does it take, [over night] and by how much?

What is fuel pressure when you pinch off the vac line to the FPR?

Answers to the above will narrow down the problem, or you can just replace parts untill problem is solved, although if you did not know when the last time fuel filter was replaced it needed to be replaced anyway.

Be a bit of a pain if you replaced the fuel pump only to find out it it was the FPG all along, not that a new fuel pump will hurt anything, but if you can afford to toss parts at your problem do the easy, [least expensive] ones first.94

DO-WORK-SON

Oh ok so over night the car lost all fuel pressure, not sure how long that took it was
about 10 hours later when i checked it.

And the FPR whn i pinch the top vac line nothing happens, the bottom one makes
pressure spike to around 55 psi.

And your right i could just keep throwing parts at it but id rather not do that.

fcm

The check valve in the fuel pump is not working, [stuck open] but not a big deal by itself, but if the check valve is bad in the pump what else is.

It is usually debris that jambs the check valve open.

When you pinch off the vac line to the FPR the pressure should go up, if not the FPR is bad.

You may have two (2) problems a bad FPR and a possible weak pump, replace the FPR first and see what happens. 94

1998GsRIntegra

That's because when you pinch the bottom line, you are pinching the fuel return line.

When you pinch the top line with the engine running, the fuel pressure should shoot up a little. The FPR works off of manifold vaccume to lower the fuel pressure at idle so if you pinch the vac line to it and nothing happens to the fuel pressure, chances are, it's bad(the FPR).

DO-WORK-SON

i guess i will just be replacing both then to be sure.

fcm

Do the FPR first, if pinching the return line increases pressure to above recommended, the fuel pump is doing it's job and it is the FPR that has failed.

The pump may be weak but still usable, if you have a permanently mounted FRG, just check it every once in a while, the pump could easily last a year or more, don't fix it if it ain't broke, spend the money on something else. 94

DO-WORK-SON

OK then, ill do that, thanks. to bad the car is down for a while now while im replacing all suspension bushings, so wont know how the FPR changes the way it runs for a while. LAME