stavros

I drive the car for about half an hour and everything is fine and suddenly the fuel pressure drops about 0.5bar at idle and 1-1.5 bar at acceleration. If I let the car to cool down, everything returns to normal until the next 20-30 minutes of running.
I have changed the fuel pump and the pressure regulator but the problem still exists in exactly the same manner.

I use a 20L fuel cell, Bosch in line fuel pump and Sard fpr.

Any suggestions?

Jolly Green Monster

iTrader: (4)

fuel pump over heating perhaps?

stavros

I tried that and when I touch the pump after the problem occurs it seems fairly warm, not too hot.

stavros

Come on guys, I know you can do better than that. I need your opinions.

R19KET

What year car, stock, or after market ecu ?

Also what pump, and have you checked what current it draws. Is the stock wiring getting hot ?


Mark.

stavros

The car is competition prepared (tarmac hillclimp) MY99 Type-RA with 2.5L engine and M800 ECU and custom wiring
I will connect a volt meter at the pump tonight and see what happens to the voltage when the problem occurs.

stavros

I have connected a volt meter directly on the pump and the voltage just drops from 14.2V to 14V during acceleration , which I do not think that this little drop causes the pressure to drop.

Any other ideas?

3barboost

pipe swelling somewhere

stavros

I use -8AN Aeroquip braided hoses throughout.

Jolly Green Monster

iTrader: (4)

coil packs? sorry private joke.

I think you are going to have to start pointing the finger at the Sard reg or the vac line to it..

You aren't using Samco vacumm hose to the reg?

stavros

I have swap the Sard with a new one but still the same problem.
I do use Samco vacum lines.

Cheers

Jolly Green Monster

iTrader: (4)

the samco vac lines inflat under boost.. especially when hot.. they are too soft imho..

I would be inclined to replace them for that reason alone.. it might also be causing the problem.. although unlikely if pressure is dropping on idle.

Simon

stavros

Thanks Simon,

I will try that too, I will change the vacum hose to some harder one.

stavros

Vacum Line to the regulator changed. No difference.
However the problem now occurs always not after 20-30minutes of running.
The fuel pressure flactuates while accelerating progresivly but when I try go full throttle suddenly, the fuel pressure goes down immediately.

Jolly Green Monster

iTrader: (4)

sounds like fuel pump is tired..

3barboost

what ecu are you running ?

the factory ecus run 33% on idle 99% on wot
perhaps your ecu is feeding a duff relay ? or your wiring is showing volts but not amps if you follow my logic

or else try a different pump and see if the same thing happens
thats what I would do

stavros

I have changed the pump to a new one, still the same problem.
I use MOTEC M800.
I will check the amp to the pump. It must be 13, isn't it?

Also tonight I will pressurise the fuel sustem with the engine off and give the regulator 1.5bar of boost and I will measure the fuel at the return line in a container to see what Litres/hour do I get.

stavros

Ok, with the engine off, I started the fuel pump through the Motec and with a tire pump connected with a T to regulator and boost gauge, I gave pressure to the regulator. The fuel pressure was 3.3 bar at 0 boost and gradually increased when I increased the boost pressure. I gave almost 2 bars of boost and the fuel pressure responded normally climbing to 5 bar, no flactuations, not drops. I had the headlights and fan on.

It is driving me crazy.

I have a question though... if the engine cuts off for a reason not related to fuel pressure, say faulty coil, does the fuel pressure drop during the cut off?

Maybe I have to look in other areas other than fuel related components???

Jolly Green Monster

iTrader: (4)

if it is a very quick misfire for example then no.. it will only drop off when the boost drops off.