Topic: Adjustable fuel regulators

[FourbangerYJ]

How does the FPR work on a OB1 system? Does the fuel pressure vary as the vaccume varies?

[sharpxmen]

How does the FPR work on a OB1 system? Does the fuel pressure vary as the vaccume varies?

you mean OBD 1? it's unrelated, there are obd2 vehicles that have a vac port on the FPR. The FPR vac port decreases the pressure in the fuel rail proportional with the vacuum in the manifold (which is the difference in pressure between the manifold and outside atmospheric pressure) - for YJ 91-95 closed throttle you should be at 31psi, wide open throttle at 39psi and in between for various stages of the vaccum level. The main goal for the vac port is to lower the flow when not needed so the duty cycle of the injectors is higher - some injectors have a limitation on low duty cycle, it is recommended to avoid something that is too low and lowering the fuel pressure is one way to address this (atomization is better above certain level of the duty cycle and if too low there could be a negative result).

[FourbangerYJ]

Ya I meant OBD1, I was in a hurry.
So how do you think a FPR that starts at 41 PSI and tops at 48 PSI would work? To much?

[sharpxmen]

Ya I meant OBD1, I was in a hurry.
So how do you think a FPR that starts at 41 PSI and tops at 48 PSI would work? To much?

it's all based on what you target - in your case i say it's too much - you'd end up around 19.3 static flow on the stock injectors and around 12.2 AFR which i'd say it's too low, but if it's a direct fit (if it's the same as the jeep one) and you want to test and see how it works you could, long term i don't recommend it.

[FourbangerYJ]

it's all based on what you target - in your case i say it's too much - you'd end up around 19.3 static flow on the stock injectors and around 12.2 AFR which i'd say it's too low, but if it's a direct fit (if it's the same as the jeep one) and you want to test and see how it works you could, long term i don't recommend it.

I had a feeling it would be a bit much. The Dodge/Chrysler ones I mentioned earlier in the tread look to be a direct fit. I am looking for long term so I guess it's out.
This had been a good learning deal for me. Thanks for the advice!

[sharpxmen]

I had a feeling it would be a bit much. The Dodge/Chrysler ones I mentioned earlier in the tread look to be a direct fit. I am looking for long term so I guess it's out.
This had been a good learning deal for me. Thanks for the advice!

if i get a weekend without rain i'll try to do a little writeup on my FPR and the wideband O2 install , just need some sunshine (been raining like crazy here the last couple of weeks and it's getting frustrating - forecast is not positive, rain till Tuesday next week and who knows what after that, hope we don't get snowed on)

[FourbangerYJ]

if i get a weekend without rain i'll try to do a little writeup on my FPR and the wideband O2 install , just need some sunshine (been raining like crazy here the last couple of weeks and it's getting frustrating - forecast is not positive, rain till Tuesday next week and who knows what after that, hope we don't get snowed on)

I keep telling the Mrs. she would not like living up there. We have so much sunshine here it's getting old. At least it's cooling down some. It feels sorta like fall.
That write up would be cool. Where are you working on this, outside?

With a higher pressure FPR I would think that atomazation (sp) would be a bit better. How about the 41-48 PSI FPR with a smaller # injector?
Like the 0280155703 or 705, or 706?