Losing fuel rail pressure 96 GC 4lt.

[Doctorbob]

Hi guys,
Askng this question here as i cant seaech forum threads for some reason. I am losing pressure in fuel rail and having to turn ignition many many times to start engine. There are no apparent injector leaks when running and no leaks in fuel line. After googling i suspect fuel pump check valve may be faulty and letting fuel in line drain back into tank.
Can i safely trial an inline fuel check valve to see uf it fixes pressure loss or will this be a increased fire risk??.
Thought this would be a good start rather than changing out fuel pump strait up.
Thanks Rob

[Doctorbob]

Come on guys, plenty reading this thread how about your thoughts on this.
Thanks Rob.

[bodgie]

There aren't many 4.0l owners here so this is probably an area where there isn't a lot of experience. I'd be inclined to look at one of the US forums or have a look at YouTube.

Perhaps the TJ wrangler forum may also be a good place to ask the question here.

[FRANKIDOWNUNDER]

Rob, have you put a pressure gauge on the fuel rail? The 96 model has a fitting on the rail itself to connect a gauge to. Normal fuel pressure is 49.2 psi plus or minus 5 psi. With the pump not running and the system pressurised it should hold 30 psi for five minutes. The 96 model has a different pump to 97 and on so be careful if you decide to change the unit. An electrical check of the pump should give an amperage draw of about 2 amps,near enough when pump is running. Can you hear the pump, is it really noisy? Have you tried running a good quality injector cleaner in you fuel tank. Mine was problematical in staring but after using injector cleaner and cleaning out the throttle body and Idle control valve most starting problems disappeared except for an occasional need to take two hits at it.

You sound like you are having similar problems to those I had as a result of the car sitting around for too long and not moving. Mine were compounded by some nut having pressure washed the engine and not run it long enought to dry out the electrics.

See how you go with this anyway. I'll help if I can but I'm not on the forum much now.

Denis.

[Doctorbob]

Thanks Denis,
Has good pressure when keyed on/off multiple times as nd pressure builds to 49ish psi. Drops to zero almost immediately when shut off and no pressure in line at all when it has sat over night. Thinking i might try an inline fuel check valve as a diagnostic tool.
Rob.

[FRANKIDOWNUNDER]

Rob, you can try that, it'll prove where your problem is for sure. Seems like your pump is fine, just the check valve playing up. I have read of others doing that same thing. Mine played up for a bit and then came okay so I've left it alone. Don't fix what ain't broke is my motto.

Denis.

[Doctorbob]

Thanks for your replies, I was a simple job to install inline check valve however did not fix starting issue. Still losing fuel rail pressure quickly after stopping vehicle. I guess next possibility is internal leaking injector/s, but there is no visible fuel leaks in line anywhere.
Thanks Rob