fuel system questions

90pony302 · Oct 27, 2004

I did a search and couldn't find the info im lookin for. What does it mean when the fuel pump runs constantly no matter if the key is on or off. Is it grounding out somewhere. It's also very noisy; more than usual. I'm going to drop the tank tonight and check everything out. I'll prolly get a new pump. I've got an aeromotive FPR to install and was wondering if aeromotive made a 255 lph pump or if i should go with a different brand. Also what kind of fuel pressure guage do you suggest and about what pressure does the regulator need to be set at for my mods. Any tips on the install would be nice to. Thanks for all your help guys.

P.S. I still have stock heads (no port work but with five angle valve job and milled .030) Just installed msd 6AL.

5spd GT · Oct 27, 2004

90pony302 said:
I did a search and couldn't find the info im lookin for. What does it mean when the fuel pump runs constantly no matter if the key is on or off. Is it grounding out somewhere. It's also very noisy; more than usual. I'm going to drop the tank tonight and check everything out. I'll prolly get a new pump. I've got an aeromotive FPR to install and was wondering if aeromotive made a 255 lph pump or if i should go with a different brand. Also what kind of fuel pressure guage do you suggest and about what pressure does the regulator need to be set at for my mods. Any tips on the install would be nice to. Thanks for all your help guys.

P.S. I still have stock heads (no port work but with five angle valve job and milled .030) Just installed msd 6AL.

I think that means a "messed" up fuel relay...can't remember for your year model but I beleive they are located underneath the driver seat or under the hood on the passenger side...

I have a Walbro 190lph fuel pump ($90) bucks and works nicely and quitely...

I bought a fuel pressure guage (for the schrader valve) for $40 bucks (liquid filled) from 50resto.com or you can get the same one at www.maximummotorsports.com ...

I would set your FP at 38-40psi...

90pony302 · Oct 27, 2004

Thanks for the info 5spd gt...much appreciated! Also what set of heads should i get for my combo (no issue on price)? Ill be s/c sooner or later

jrichker · Oct 27, 2004

87-91 models - fuel pump relay is under the driver's seat.

92-93 models - fuel pump relay is under the mass air meter. Don't mistake it for the A/C WOT cutout relay, as they are very close together.

5spd GT · Oct 28, 2004

90pony302 said:
Thanks for the info 5spd gt...much appreciated! Also what set of heads should i get for my combo (no issue on price)? Ill be s/c sooner or later

Well are you going to keep your stock bottom end (302)...when you start to add heads/cam/intake/supercharger...the bottom end can get worn out pretty quick or fail on you...but many do it with no problems...

Good Luck

jd351 · Oct 28, 2004

Fuel pump relay is fused. Happened to both of my '90 'Stangs... hmm wonder if there's a pattern here. Anyway, relay is under the seat as stated.

BTW, Ford has discontinued that relay and has superceeded it with a different unit... wonder why. Yeh, it's common, and I'm sure many of us know that.

The reason why: The original unit was undersize (amp rating) for the load of the larger pump, increased size in '89, that came with the mass air change. Problem becomes really apperent when you go to an even larger pump. Found out the hard way, dead battery, the first time. If you change to a 255 pump it would be advisable to run an aftermarket relay like a Bosch 40A, and even better if you run this with a larger dedicated power line to the pump.

90pony302 · Oct 28, 2004

no the bottem end will be made to handle the power of course....just asking for suggestions that go with the intake.....a new cam will prolly be ordered along with the s/c (custom probably).

5spd GT · Oct 28, 2004

90pony302 said:
no the bottem end will be made to handle the power of course....just asking for suggestions that go with the intake.....a new cam will prolly be ordered along with the s/c (custom probably).

Well what bottom end you going to get because that effects what heads/intake you will want...

90pony302 · Oct 28, 2004

a forged 331 or 347 bottem end most likely.

5spd GT · Oct 28, 2004

90pony302 said:
a forged 331 or 347 bottem end most likely.

Minimum of AFR 185's if your going with that bottom end and a blower...I might consider going to a AFR 205...but I would probably stick with the AFR 185's...

I would do the bottom end first...and build it up with the heads and all...so you don't have to do the "install" twice...

90pony302 · Oct 28, 2004

5spd GT said:
Minimum of AFR 185's if your going with that bottom end and a blower...I might consider going to a AFR 205...but I would probably stick with the AFR 185's...

I would do the bottom end first...and build it up with the heads and all...so you don't have to do the "install" twice...

do you think a bigger maf and TB would be necessary

P.S. thanks again for your help guys and 5 spd gt

5spd GT · Oct 28, 2004

90pony302 said:
do you think a bigger maf and TB would be necessary

P.S. thanks again for your help guys and 5 spd gt

Definatly...

A stock MAF (calibrated for stock 19lb injectors won't even run right if at all)...and the stock MAF and TB size will kill/choke your stroker/heads, cam, intake, and supercharger...

You will NEED a bigger MAF calibrated for your new injectors and a bigger TB to provide you with the power and driveability...

Do you have a local dyno tuning place...that is almost a must also with what your planning so they can get your car running safely and efficiently...

Good Luck man...sounds like you got some big power plans for it...

90pony302 · Oct 29, 2004

well i got 75mm maf calied. for 19lb injectors and a 70mm tb. Thats better than stock but prolly still not enough. yah i need to do somethin' radical cuz im tired of the bolt on scene thanks again for your help.

5spd GT · Oct 29, 2004

90pony302 said:
well i got 75mm maf calied. for 19lb injectors and a 70mm tb. Thats better than stock but prolly still not enough. yah i need to do somethin' radical cuz im tired of the bolt on scene thanks again for your help.

That was my mistake for not looking in your sig. (I'm usually a stickler about looking before posting )...

So is your 75mm a Pro-M...if so you can get it sent off and have them recalibrate the MAF to the bigger injector you get later...if you have to save some money...if not just buy a brand new one for you new injectors...

Your TB wouldn't be so bad either...but you can upgrade that (when you get the engine done) and get some more power out of it...

How are you funding all this? What kind of time frame you talking about

90pony302 · Nov 1, 2004

as soon as i get out of school (im an engineer major). Im planning on going to Uni. of MO Rolla; im almost guaranteed a job when i get out....so Ill prolly have some extra money lyin around . Time frame 2 or 3 years tops. I could prolly get the heads and short block done before then tho. Thanks again for your help 5spd.

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