Fuel pressure woes

Hi guys need some input. I've been fighting my lean running conditions and eventually fitted an aero motive fpr. I set it to 3 bar without a vac source to start with and took her for a run. I saw my afrs pushing 12 so had a look at the pressure gauge and she was back at 1 bar. So reset the fpr to 3 and ran again, all without restarting he engine after a good run I saw it was sat at 3.5 bar. I've done a search on here and seen that heat soak can cause a fluctuation of about .5 bar so I thought it was fine.

Pulled the supe out tonight for a wash a spotted the fuel pressure was up at 7 bar!! So wound back down to 3.5.

My jets are 440s I have a fuel pulsation bypass fitted, aeromotive fpr, walbro 255 pump.the filter was changed ack end of last year, I've deleted the charcol canister.12v fuel pump mod and checked pump sees 12v constantly.

Why would my fuel pressure vary by soo much?

Alli can think of is there a blockage somewhere maybe but it seems to come and go and means I have to manually set fuel pressure every start.

Just thought this really shoud have been in technical...sorry

Is the hose from the fuel pump securely attached?

Perhaps the new flow rating has indeed clogged the fuel filter. There is also a small gasket in the afpr that will go bad is over psi is experianced. Mine was acting strange onec. So I took it apart and found that that gasket was bad. I ordered one dropped it in and bamm!!! good to go... I hope this helps. Oh and my filter had extra crap in it due to the fuel that is was getting from the 255.

I take it you mean static fuel pressure? If so flow has no bearing on it.

Thanks guys will check those bits over. Yes swampy I'm talking about static fuel pressure at idle

Its not static if its at idle, static is pump on, engine off. Dynamic is engine running

Ahhhhh I shall have a look at both later tonight then. Thankyou for enlightening me.

I would say you have a leak between pump and fuel rail, or between pump suction side and pick up strainer. Is the pump in tank, or external? What pump? I also do not use or recommend Aeromotive stuff, I would only recommend Bosch pressure regulators. You won't find an Aeromotive regulator on any serious race car, you would find plenty of Bosch ones. I find them much more reliable.

If the engine is turbo charged you should not, NOT, never, ever, run under boost without the vac / pressure reference port connected to the intake.

Hi Chris and thanks for your input. Its an in tank Walbro 255. I will pull it out and check that the connections between pump and strainer are not leaking or there are any leaks on the pump setup itself.

I havent ever run the car with the pressure port unplugged i have only ever un plugged it to set a base pressure and then refitted. I will check all the connections between pump and fuel rail to make sure nothings leaking.

Surely if there is a leak the pressure would stay low and be pushed back to 'normal' when changing the settings on the FPR rather than it being really high sometimes and really low others?

First of all i will check for leaks and dig the pump out again.

Without a pic or two I'm lost, but think it worth asking if you've removed the charcoal filter and replumbed the fuel system with one of the Old Wives Tale cock ups?

David that is very possible with the various different methods out there. Ile get some pics up tonight.

From the guide...when you remove the chrcole canister you are left with 3 tubes. 2 at the top and one that goes through the bulkhead and into the wheel arch.

The smaller of the two is a vac source and could just be capped, The second was a return to the tank and could also be capped. the lower has been left open.

yes done as per that guide. Just not made very clear by me. i will check everything over later on

I suspect a slit or leaking pipe between Walbro exit pipe and the pump hangar hardware. If it's the pump itself that's faulty I have a 1 hour old one to sell. See the For Sale section.

Thanks for the input today guys. I got home late so didn't have time to dig the pump out to check the connections. I did set the static fuel pressure. Engine off. And took some pics of my canister delete.

Ile check the pump tomorrow.

the two top tubes capped they will be deleted later

Cannister delete isn't pretty yet correct. I'd have a pipe-clip over the petrol-hose blanking-bolt, old hoses split easily when asked to do a new job.

Where's the boost/vacuum hose from the FPR plumbed to?

Basically where the stock fpr source came from. I have a t for the fpr and boost controller

As long as it's behind the butterfly where it's getting both vacuum and boost it'll be fine, I like to give each components hose it's own tail and you have an unused spare, yet that's not your problem.

Chris's diagnosis is your first job.

Is that a stock N/A MAP sensor?

Yes with a t for a greddy 3 bar map sensor I will look over the pump and hanger tomorrow but thanks yet again for your input

Whilst you're taking the pump out and in, you could block the cannister breather pipe at that end with a bolt and clip, where it's out of sight.

Why/how are you running both 1 Bar and 3 Bar MAP sensors?

Im running the three bar for the emanage, i thought that was the idea so the existing sensor doesnt see anywhere near 1 bar and throw a wobbly. could i just unplug the stock map sensor vac source?

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the hoses in the picture from the canister are usually out of sight just put where they were for demo purposes. tbh i could just remove it from the tank end!

...in addition im running them both with the map clamp value set to 4.9 V so the stock one doesnt see boost as suggested and the 3 bar fitted to reference the fuel/ ignition maps against.... that reads a bit better than the above.

God knows how the e-manage could use two sensors, I am not familiar with it, and don't really want to be, but I'd be surprised if you *SHOULD* be running *BOTH* MAP sensors!

If the 3 Bar sensor is feeding to the same place as the 1 Bar Map sensor, then that's going to cause problems.

I'm amazed your "Engine Tuner" didn't pick up on that.

Unplug the stock 1 Bar and give it a try.

chris i dont think the emanage uses both sensors as the stock is running to the standard ecu and the 3 bar running to the emanage. I thought the whole idea was to set the map clamp to avoid the stock toyota ecu seeing boost and then utilise the 3 bar with the emanage to tune whislt in boost. Need someone like fosta/noz to confirm this