wrd1972

iTrader: (12)

Engine was running like crap so I naturally blamed the opti. Hey that worked nearly every time in the past.

But it appears that the fuel delivery may be bad. So I need to know the proper way to troubleshoot the fuel system so I can ensure I get the faulty component this time.

When I turn the key. I think I am hearing something from the back of the car but I cant tell if its a "normal" sound. Also if I hook a fuel pressure gauge to the fuel rail and turn the key, the gauge is not showing pressure. If I remove the gauge and manually press the schrader valve, I get a small spritz of fuel but nothing to speak of.

Does this sound like a fuel pump? Could it be anything else in the fuel system? I dont want to go after the pump if there is anything else it could possibly be.

Thanks.

BALLSS

if the FP gauge shows no PSI...pump is bad

just a few PSI is enough for gas to come out the schrader valve...but no where near enough to start it

get a BFH and wack the bottom of fuel tank where pump is. This "sometimes" wakes it up. Not always but if it did it would be another sign the pump is...intermittent at best

still if FP gauge shows zero...that is enough to show pump is not working itself or the wiring to it has been compromised

wrd1972

iTrader: (12)

Got it.
So I will be dropping the tank to do even though its more PITA. I just cant bring myself to do the access panel above the tank.

That said, can the rear end just be lowered to the floor or does it need to be completely removed from under the car?

Fast350Z

iTrader: (2)

Since you have a convertible it makes sense to drop the tank to replace the fuel pump since you don't have quite the space to cut an access panel. I think you have to remove the rear end to get the tank out.

Gangly

You dont have to remove the rear end to get the tank out. Disconnect the LCA's, the panhard rod, and slowly lift the rear body of the car. Keep the rear end connected to the driveshaft and just lift the car. That will give you enough room to get the tank out.

Words of caution, be careful of the brake lines being stretched. If I remember correctly, there is an attachment point on the body in the rear axle cavity where you can disconnect the lines from the body and get the extra length needed.

BALLSS

OP

while a tank drop and pump replacement is likely......you could swap the fuel filter first to see if that resolves your problem. You mention you hear the FP prime and if it is FP that needs replacing, you should do a new fuel filter anyway.

Best case you are back on the road for a few $ and WAY easier than dropping tank but if not you should replace fuel filter anyway

You will have to disconnect fuel lines and EVAP lines from tank before you slide it out

Spartan7

iTrader: (7)

Agreed with most of that. I've dropped the tank a couple times, but it's been a while so I might be forgetting something. Get the *** end of the car up high, take off the rear wheels, and drop the rear end to the ground.

The LCA's and torque arm (stock one anyway) do not have to come off. The panhard rod and brace come out, shocks unbolted and springs removed, as well as unbolting the sway bar end links. The brake line bracket attached to the body comes loose from the frame rail, so you do not have to break the rear brake lines. The exhaust has to drop and preferably come out, which should be possible with the rear end so low. It's still a PITA, and is made more difficult with any amount of fuel in there.

Make darn sure it's the pump, because it's going to take you at least a day to do it yourself. Check your PCM BATT fuse, as that powers the fuel pump.

wrd1972

iTrader: (12)

Thanks for the replies guys. Yes I do need to just replace the filter to rule that out. And check the power delivery to the tank area. Will do this first.

Gangly

Within the wiring harness on the passenger side of the engine compartment is the fuel pump prime connector. With the engine off, hook up a 12v supply to it and the pump will power up. It's a good way to listen to the pump while the engine is off to mmake sure it's actually working. Check the fuel pressure while the pump is on.

smitty2919

I agree, change fuel filter and test for pump priming. Putting pressure gauge on fuel rail will be real obvious to tell.

wrd1972

iTrader: (12)

Gangly,
Always wondered what that wire was for.

A million thanks.

ACE1252

A little gotcha to watch out for....

My fuel gauge is from autozone and it can be put on the fuel rail schrader valve and not read a thing. The center pin of that gauge doesn't stay centered and will slip to the side and not press in the scharader valve pin.

I'm not saying that is happening, but it's made me go wtf more than once.

SS RRR

iTrader: (2)

Mine does the same thing. Sometimes have to loosen/tighten a few times before any pressure is read.

wrd1972

iTrader: (12)

Turned out the fuel pump was good after all. I think I ran into a similar issue with the gauge not attaching properly and therefore giving a false reading.

Wohoo....but the car still aint running. It has a new opti so I wanna rule that out. All thats really left is plug wires, plugs, coil and ICM.

KW Baraka

iTrader: (7)

1. How new is the opti?

2. What brand is the opti?

I ask because it's not completely unheard of that aftermarket/rebuilt optis come dead on arrival.

The best-bet replacement is a new AC-DELCO opti.

KW