12v mod required?

[LordLo]

Anyone here running a walbro on stock wiring + 9/12v relay? Can you adjust your fuel pressure above 40 psi?

Well I just installed my walbro today and the fuel pressure cannot go above 40 psi; if I try forcing it above 40 with my aeromotive afpr the needle will just bounce from 40-43 psi and it also starts clicking (sounds to me like the pump isn't flowing enough).

The only way I can get it to go above 40 psi with the walbro is if I jump the B+ and FP terminals on the diagnostic box. Does this mean the open circuit relay is bad or simply just the wiring?

 

[Angry7M]

Anyone here running a walbro on stock wiring + 9/12v relay? Can you adjust your fuel pressure above 40 psi?

Well I just installed my walbro today and the fuel pressure cannot go above 40 psi; if I try forcing it above 40 with my aeromotive afpr the needle will just bounce from 40-43 psi and it also starts clicking (sounds to me like the pump isn't flowing enough).

The only way I can get it to go above 40 psi with the walbro is if I jump the B+ and FP terminals on the diagnostic box. Does this mean the open circuit relay is bad or simply just the wiring?

Above 40 psi??? Do you have an idea of what the stock Fuel Pressure is suppose to be stock?

 

[TurboStreetCar]

well if your running more then 10psi of boost it could be an issue too......

 

[primercrx]

well if your running more then 10psi of boost it could be an issue too......

I have a similar problem with mine only I haven't replaced the pump yet.I discovered Sunday that my fuel pump is bad on Supra. The car is turbo. I was considering an OEM replacement but have heard that walbro's were a fairly good alternative to OEM. However, I feel that the reliability of the walbro's are not up to par. I guess my question is, would it be alright to use an OEM replacement or should I purchase an upgraded fuel pump? I'm not planning on anything above 10 psi. Suggestions? Comments? Anything would be appreciated. Thank you.

 

[TurboStreetCar]

The stock pump has nothing to do with the 10 psi of boost. if your running a factory pump and your air fuel ratios are good then continue with a factory pump unless you plan on upgrades. i would personally go walbro because there about 100 dollars and good insurance.

The 10 psi of boost comment is that fuel pressure raises 1:1 with boost. If base fuel pressure with no vacuum is 33~40 psi (as per TSRM) at 10 psig of boost it would be 43~50 psig fuel pressure. So if your fuel pressure can only reach 40psi you have a little bit of a problem once the car is in boost, Though the TCCS will switch the pump to 12v when it deems necessary but i would investigate further as it could cost an engine if something is wrong.

 

[grimreaper]

so if your pump is able to hit 40+psi with fp and B+ jumped (12 volts) whats the issue since the stock setup will switch to 12 v under wot?

edit: however mine doesnt have this issue at 9 volts or 12 volts.

 

[thevork]

I have a walbro and did the 12V mod however there was no problem whatsoever without the 12V mod regarding the fuel pressure.

 

[LordLo]

Well it's supposed to be set at 40 psi with the vac line off; but the thing here is that the gauge just bounces from 40-43 if say, I try to set it to 50 psi. I know it's not necessary to run 50 psi of base fuel pressure, but the fact that I can't set it there at idle means there is something seriously wrong with my fuel pump wiring or relay.

I was just curious if anyone had the same problem too and if it was normal at 9v.

Above 40 psi??? Do you have an idea of what the stock Fuel Pressure is suppose to be stock?

 

[jetjock]

Pump relief pressure is easily checked by jumpering the fuel pump on and pinching the return line closed. Don't do it for longer than necessary. If it won't do 50 under those conditions something is wrong. That something doesn't have to be the fuel pump either...

 

[LordLo]

Well guys I guess it's normal. At idle the fuel pump only gets 9v so it can't flow enough fuel to support 40+ psi. At WOT, the fuel pump switches to about 12v so it has no problem flowing.

I also had a buddy who has mk3 supra with the same setup (stock wiring, walbro, aeromotive afpr). He also couldn't get his base fuel pressure up past 45psi; the gauge needle just started bouncing between 40-45psi.

 

[Doward]

Did you try JJ's test?

 

[jetjock]

Sigh. I knew it was a waste of time so I'll leave it at this and move on: my 22 year old *stock* pump with 160K miles on it pressure relieves at 60 psi when running on 9 volts. Just checked it...

 

[TurboStreetCar]

Sigh. I knew it was a waste of time so I'll leave it at this and move on: my 22 year old *stock* pump with 160K miles on it pressure relieves at 60 psi when running on 9 volts. Just checked it...

more proof of checking it out further. maybe pump has bad ground, test for voltage drop across ground and voltage at pump to rule it out......

I pointed out the issue as something that could become a problem at an inconvenient time not that there it a complete issue now.

If the pump is in fact weak and dying out, it would be nice to find out when idling and testing rather then at WOT and full boost.

 

[LordLo]

Well my 7mge fuel pump which was run on my 7mgte had 180k miles on it. And yep, before I removed it I was able to hit 60 psi of base fuel pressure too at 9v; the walbro on the other hand can't unless I bump it up to 12v.