Stock FPR Problems: Who else...

[stylEmon]

Has anyone had problems with the stock FPR? I am curious because I am having issues with Fuel Pressure. I have an new filter, new lines from filter to rails, stock rails, 1600cc Bocsh secondaries, no pulsation dampener and stock fpr. (Walbro Hi Flow pump)

I noticed pressure issues, and took off the stock fpr. Replaced it with another stock one and am having the same issue. It's possible that both fpr's are faulty. I would even say it's probable.

Anyone have any insight or similar problems?
Obviously I want to upgrade to an Aeromotive with braided lines and AN fittings, but I don't want to spend the $600 on that right now..
Thanks

[Ender]

I don't have any personal experience with something quite like your situation, but I suspect you could have fuel flow issues when two of your injectors are rated for ~3 times the flow of the stock injectors. Are you seeing the pressure drop under light load or just when you're under boost? More specifics would probably help.

[stylEmon]

not sure why that would be a problem. I have a stand alone.

The main problem is at idle. The fuel pressure is 20 psi higher than it should be. Under load it raises a little more.

[classicauto]

Hmmm.

When did you first noticce the issue? Anything else changed/going on in that time period?

[TehMonkay]

It's either not bypassing enough fuel or there's a clog in the line or your fuel tank is very pressurized.

[stylEmon]

I think its always been a problem since I had this car running after the engine build.
It was masked by other problems, or unfinished tuning... make sense?

So what causes the tank to be pressurized?
We are suspecting that my walbro is faulty... I dont want to have to buy another one (since they offer NO warranty on it) but this may be the culprit...

[jgrewe]

Take the top off of one of your stock FPR's and put an adjustable top that is made for a Honda on it. B&M makes them, they are about $50 from Summit racing.

[classicauto]

So what causes the tank to be pressurized?

Poor venting. Are you running a charcoal canister?

[stylEmon]

no...

[TehMonkay]

So, do you just have a cap on the line on the firewall going to it?

[stylEmon]

pretty sure its all capped... not positive. I'll have to check it out.
So high fuel pressure is a symptom of this? What other ill effects from running no canister? or capped off lines?

[classicauto]

Capping the vent for the tank will do some things......I'm not sure if high fuel pressure would be one of them, although its ENTIRELY possible.

All that vent's doing is essentially what the "vent" hole on a gas can does. It allows air to replace the space occupied by fuel once you start suckign fuel out. Does the reverse when you start pouring fuel in.

Its vented through the charcoal canister to keep fumes down, other wise you'd probably smell fuel coming out of the hole.

I've seen gas tanks collapse inwards from a plugged vent + heavy duty fuel pump.

[stylEmon]

yikes. makes sense tho.
Will look into that.

[stylEmon]

it is not capped off, so thats not a problem.
It is the fuel pump. I've been having issues with this pump for a while. Sometimes the pump would be really loud, other times not so loud... and it didn't matter what the fuel level was. I should've returned it months ago but now I am stuck buying another walbro!!

[SpooledupRacing]

loud pump = bad pump.. sorry to hear looks like a new pump is in order.

[Max777]

Take the top off of one of your stock FPR's and put an adjustable top that is made for a Honda on it. B&M makes them, they are about $50 from Summit racing.

i would like more detail on this? How is a Honda adaptor going to fit? Have you tried this yourself? I'm currently reading on zilvia about a DSM FPR adaptor that will fit nissan regulators, but nothing about the RX-7...

[stylEmon]

Thanks Dave, it's shitty that this pump has been acting up since day one.. I should've taken care of it long ago. I hate having to redo stuff that I've already done!

[jgrewe]

i would like more detail on this? How is a Honda adaptor going to fit? Have you tried this yourself? I'm currently reading on zilvia about a DSM FPR adaptor that will fit nissan regulators, but nothing about the RX-7...


The part number for the B&M part is #46057. It fits the '88-'00 Civic and '90-'00 Integra and NSX.

I have two race cars running these. You just grind the largest diameter rim of metal off to remove the non-adjustable cap. The metal is pretty thin but its good to keep it cool by dunking it in some water as you go, there is a rubber diaphragm that is inside that holds the fuel in. Just gently spin the FPR as you grind and peel the top off when you can. You will see when you get through the first layer of metal. The B&M top just clamps on the now "headless" stock unit with 4 allen screws and a C type lower piece.

Turn the top screw to set your pressure and then lock it down with the locking nut.

[TehMonkay]

Or you could tap the stock rail for 3/8" npt and get a barb fitting adapter and go to an aeromotive pretty cheap.

[Max777]

Well, if I have fuel issues, I think I will get the B&M unit. Thanks for the info, this was an informative thread, and hopefully someone will search it in the future. :D

[Whizbang]

when i got my one turbo running for the first time i had bad fuel pressure issues. Turned out the fuel pressure reg. was stuck.

[stylEmon]

thanks for the testimony. I thought that was the problem. There was actually visible gas leakage coming from my stock fpr... So I replaced it with another stock unit, same problem... that's when I finally 'admitted' that I got a faulty fuel pump.

[classicauto]

FWIW, the nippon denso pump is more money - but IMHO far better the the 255.

I'm running the rx7.com version, which is just the denso pump with some parts to help the install in an FC, but its a great pump FWIW.

[SpooledupRacing]

I had a fuel pressure reg leak externally on me before and I never found out from where.. got another one from Alex and it was fine.. this was when I did my T2 swap

[SpooledupRacing]

yeah I sell the denso pump, more money but I agree much better.

[stylEmon]

what is better about it?

[SpooledupRacing]

I know the longevity of the pump is better (plus here we give denso pumps a 1 year warranty from time of purchase)

I have heard they they continue a consistant flow better then the walbro pump

[classicauto]

what is better about it?

I had two walbro's die on me in less mileage then I've put on this denso pump.

I've never personally flow tested them or anything like that - I've just had bad luck with walbro's dieing. Doesn't seem to be the case with everyone though, ltos of people have luck with them. J-Rat just made 550+whp on his old single walbro.......so hey :dunno:

Just throwing my 2cents out there

[SpooledupRacing]

I have seen a walbro next to a denso on a flow tester and the walbro after abotu 20 minutes was getting inconsitant numbers.. now these were both new units however I am with Classic.. it has never happened to me personally just stuff I have seen/heard

I have a walbro on my car with under 800 miles and I am going to swap it out before next year.

[Whizbang]

does anyone have the stats on a viper pump

[SpooledupRacing]

viper brand or as in DODGE VIPER?

[Whizbang]

dodge viper.

[SpooledupRacing]

I dotn have a listing on the pump, I bet a google search will net u some info.