Fuel Pressure Dropping

[Anthony]

hi guys,

A wile ago I made a surge tank and fitted a 044 with a larger fuel rail and aeromotive rising rate reg installed and installed it and tuned according. all has been working well however in the last week I have noticed a power decrease and harder to start. I have also noticed when I prime the car before I start the fuel pressure drops of within 3 seconds. I have clamped of the return to the surge tank and the pressure still drops indicating the pump is losing the pressure. my question is: Does the bosch 044 hold pressure like any std pump would or for some reason are they designed to loose this pressure. There is not fuel leaks so the fuel cannot be going any were else. Oh I brought the pump on ebay came in bosch box all sealed and some paper work.

Regards

Anthony

[PHANTMXR6]

Judging by your description it could be the pump, or a leaky injector maybe?

Do you get a heap of exhaust smoke on initial startup?

[Ralph Wiggum]

no they don't hence why they are normally installed with a check valve on the outlet side

[mic]

+1 for a check valve, if your car is dropping power though that indicates a prob with the reg. I know aeromotive leak a bit but thought only over night when the car is switched off. maybe check the fittings are thread taped.

[Ralph Wiggum]

umm I would strongly suggest thread tape is NOT use in the fuel system. any tape that winds up in the system could cause major problems from blocked fuel regs too a blocked injector!

The check valve also help extend the life of the pump as it stops the pressure in the system from draining back throughout the pump.

[mic]

thread tape allows u to put more pressure on the fitting/tighter. u can buy special fuel safe stuff though aswell. if u have a look around u will c most with aftermarket regs use tape

[Ralph Wiggum]

so do liquid sealant that won't clog your fuel system.

Have you ever seen what a loose piece of thread tape does too a high pressure fuel pump?

and if you need to use thread tape on jic or npt fittings too get then too seal they have already been overtightened. tighter doesn't mean more leak proof with mechanical seal fittings

[mic]

of course injecting thread tape into the reg is not recommended, im sure this gentleman will make the right decision.

[Smoke them tyres]

JIC or AN fittings seal on the flare, so thread tape would be useless on them anyway, particularly the threads.....fuel would just leak out around the sleeve under the nut. Fuel system contamination is far more likely than successful sealing once the turning action of tightening is done. Thread tape is only useful on the interference type fittings.

Besides, these 37 degree fittings will seal far better than an NPT fitting..... JIC fitting - Wikipedia, the free encyclopedia

Spot on Hiddeous. If I were to use anything, I would use Loctite 567 on the flare faces.......

Loctite ® 567â„¢ - Henkel

and then give it some time so that it can "go off" before applying fuel pressure.

or reface or replace the fittings.

Leaking pressurised fuel and high temp underbonnet/undercar ignition sources are not to be taken lightly.

Edited 02/11/10 09:19 AM by Smoke them tyres

[Ralph Wiggum]

Most decent Hyd suppliers (pirtek etc) can supply Parker JIC/AN flare washers for fittings with damaged seal faces. They work very well on JIC/AN that just wont seal.

Anthony,

When was the last time your car got a new fuel filter?