P: Loosing fuel pressure and cutting off

Hi all and best regards!
I hope somebody will help me with my longtime issuee...

Well, I have Coupe 20VT with some engine modifications:

-new Garett T3 Trim 60 (possible up to 370HP)
-new exhaust system SuperSprint
-new FPR Bosch (up to 3.8 bar)
-new fuel pump Walbro 255
-all inox air intake with new FMIC
-bov Bonalume
-and upgraded new Unichip Q+
-Blitz Dual SBC Spec R Boost controller with new solanoid

:::and there goes the story,i took the car for the first time mapping and that trial was failure. Mechanichals said to me that car on higher accelerate load lose fuel in engine mean the air-fuel mixture is poorness with fuel and the car on boost higher than 0.7 bars cutt-off or tremble without fuel. Mechanichals take suspicion on fuel pump (also used Walbro before this one new)....
so I replace used Walbro with new one, also fitted another one airflow MAF sensor, check all fuel housing wires in back, clean injectors ultrasonically, try with another one valid water temperature sensor, took a car to data analyse diagram and there is no any ECUs errors, try with plugging out unichip but, without or with him is the same thing always the same problem. When the engine get warm and operating temperature the car can't boost and can't give the horsepowers, just cutt off or tremble. I tried go to second run mapping but the problem presists.

What else can be??

Thanks a lot to anyone who even take a look about this topic!

Hi,

It can be very annoying trying to find the cause of fuelling problems. Have you upgraded the wiring to the fuel pump including the earth? Also the yellow connector block which connects wires for the fuel pump in the drivers foot well next to the main fuse board could be giving poor contact so worth checking.

Other sensors worth looking at are the fuel pressure regulator and connections to it also the throttle position sensor.

Good luck I hope you find the problem soon!

Cheers
John

PS.
A few people have had problems with Walbro fuel pumps might be worth trying the original pump with the upgraded wiring, have a look in the how to section for the guide.
Oh and if its happening when the car is hot it could be one or more bad coil packs, also check the wiring to the coil packs for any breaks/cracks especially under the coil pack cover.

Are the injectors up to the job at 370 BHP?

Thanks but i wrote that the capatibilities of turbo is about 370 BHP, my problem starts at about 0.7 bars which is not more than stock horsepowers even and less, otherwise I have also prepare Siemens 440cc new injectors which planned to upgrade for more than 300HP later but for now i have first to solve this problem.

@ Coupe_Don
--problem is probably in fueling. Tunner when mapping the car on dyno reads out lack of fuel in his program (thats how he said it to me), so it's probably not the coils.

I will also check all earth point and that yellow connector block you say.
Thanks a lot!

To be honest, join the club and get access to the workshop manuals, or check EPER and look at the whole circuit, and cross each bit of it off one by one. That's what I tend to do, did the same with the cooling system. A logical approach in theory cannot fail.

guys I tried many of these possible solutions but nothign, car still making problems but only when is engine temparture up....and when is about 90 C sometimes the KEY CODE turns on and car turns out, so i have to a couple of times start engine again to back him in stable work.

Does that anything mean about mymain problem? Could there be a connection about that at all?=

Few months later I join in with worthless info, however it may help.
I had the same problem. When mine got hot it didn't like to boost & I had to pull off to put back on again. After an eventful hour on Albert Bridge (whilst raining may i add) my radiator blew with steam pouring out of it.
Whilst getting the radiator re-done loads of holes were found. Never had the problem again so I always assumed that this was the problem from the start.
Don't know if this will help.

Forget about the last comment it was put on the wrong topic. Sorry!

Have you checked that the fuel pump is getting full voltage, that the fuel filter is not blocked, and maybe try putting a different fuel pressure regulator in?

Or a possibility that you could have a bad batch of fuel in the tank?

I've read about other cars recently losing pressure up the revs but i can't remember where or why.. Useful info from me!

Have you measured the fuel pressure?

I tested my car on rolling road last year. After first run I had really bad lambda=lean mixture. So I adjusted the fuel pressure regulator (Malpassi 1:1.2). After second run I still had bad lambda. My friend checked the fuel pressure during the run and saw that it didn't rise when I was on boost. Still the turbocharger managed to get 1.58 bar. Conclusion: crappy fuel pump.

We changed the fuel pump to a Walbro 255 and after RR I saw that fuel pressure and lambda was okay.
Result.
Wheel Torque: 421 Nm @ 4900 = 310 lb/ft
Max boost pressure: 1.67 bar


So I think you have bad fuel pump or bad FPR.