Loosing pressure as the engine running

[duduglanza]

Hi i got this problem i cannot solve.. I am having trouble with the fuel pressure as it is decreasing bit by bit while the engine is running. A new walbro pump and turbosmart fpr are fitted and still having same problems! any ideas what may happened? Can it be a bad injector?

 

[Texx]

How low does the pressure drop? Does the fuel pressure increase when you rev the engine?

 

[duduglanza]

If i leave the engine running it will go down to 10psi but never left it too long to stall... when i rev yes the pressure will increase

 

[Texx]

If you pull the vacuum hose from the FPR when the engine is running, what does the pressure gauge read and is the reading stable?

 

[duduglanza]

The fpr raises pressure and will stay stable..

 

[Texx]

What pressure have you set the regulator at? What does the gauge read with the engine at idle and the vacuum hose disconnected?

 

[duduglanza]

Set at 36psi but when disconnected 42psi

 

[Texx]

Have you replaced the fuel filter?

 

[duduglanza]

Yes new filter, pump , and fpr... I sending my injectors for a test now... They are the last thing i can check.

 

[Navi]

so without the hose connected the pressure stays stable?

but with hose connected to fpr it loses pressure slowly?

Sounds like a bad FPR to me.

 

[duduglanza]

No i only pulled of the vacuum hose for few seconds..

 

[wildchild]

did you check for leaking injectors at base as well as the top where it fixes to the injector rail? the small O-rings fail without a reason.
On the other hand it could be a blocked pipe or a dented pipe on the underside of car. maybe your fuel pump isnt getting enough voltage for optimum power. check fuse amperage.

 

[duduglanza]

How can I check the voltage? Normal Multi-meter? anyone knows whats the normal voltage so i can compare?

 

[wildchild]

easiest would be you start with the fusebox. check that all fuses are to the correct amperage by comparing with the amperage on the fusebox cover. 10, 15, 20 etc.
For the fuel pump its a relay as i remember. this is in the engine compartment fuse box.
maybe the earth/ground wire at the pump is loose. if pressure increases when engine is revved up means either low current to run the pump or else the fpr diaphragm is leaking. during idle check if fuel is leaking from the vacuum hose of the fpr when removed.

 

[duduglanza]

The fpr is fine.. no leaks at all. I was told that i can check the fpr by blocking the return pipe for split second and check the fpr gauge for leaks from the vacuum line. Still no leaks and the pressure gauge went up.

 

[wildchild]

one more test. remove the FPR and fix the factory FPR and check what happens.
thats the only remaining suggestion. else pump has to be replaced again..

(btw did you check ur MAP? when engine is about to stall, the fuel pressure will drop as well as ive seen. just a weird assumption but better to check you know)

 

[Evo]

Hi i have a similar problem but its my fuel gauge thats effected. It shows i have a full tank when driving and then if i let it idle for about 10 mins it goes down to my actual fuel level. Ever had this? know what the problem is?