Relay Testing and Fuel pump help

[Zed Head]

20 minutes ago, nefiwashere said:

I did test by removing the fuel return in the engine compartment gas does come out fine. Fuel pressure was at 40psi and voltage on fuel pump was at 11.4

Reconnected everything and letting car run. Fuel pressure was at 50psi. After a letting run it seem to settle around 45. Rev the engine and it bounces up to 50.
Voltage at pump is at 13.6

Need to take her out for a drive and see how she does.
1978 280Z
EL Paso TX

Good luck.  You're way off spec.

[nefiwashere]

Good luck.  You're way off spec.

Could it have anything to do with not having the fuel damper bypass?
Any way to bring it down if it continues to stay high?


1978 280Z
EL Paso TX

[Zed Head]

The damper should be on the inlet side so would not cause higher pressure.  Maybe somebody plumbed it in to the return line?

It looks like you have a restriction in the lines somewhere after the gauge.  Try moving the gauge to the return line, in the engine bay.  If the pressure stays high that means the restriction is between the engine bay and the tank.  If the pressure drops that means the restriction is between where you had the gauge before and where it is in the second location.

You need to find the restriction to get the pressure corrected.

Pump > damper > filter.

[Zed Head]

Also, is there any chance that your gauge is causing a restriction?  Where is located?  If the adapter "T" is small diameter is might cause a problem.

 

[nefiwashere]

Have the fuel pressure gauge after fuel filter.
If I move it to the return right below I should still get fuel pressure? Not sure of the size of the T thing in fuel pressure tester. It’s the OEM brand set from Autozone.



1978 280Z
EL Paso TX

[Zed Head]

18 minutes ago, nefiwashere said:

Have the fuel pressure gauge after fuel filter.
If I move it to the return right below I should still get fuel pressure? Not sure of the size of the T thing in fuel pressure tester. It’s the OEM brand set from Autozone.

Yes, move it down to the return line.  You should not get much pressure at all after the FPR but if you do that means you have a restriction back toward the tank on the return line.

When you have it off just eyeball the size of the hole in the T.  If it's comparable to the hose it's not going to be the problem.  You should be able to see right through the T fitting.

Edited March 2, 2019 by Zed Head

[nefiwashere]

Ok I’ll move it to the return line. If there is hardly any pressure on the return. There would restriction somewhere on the fuel rail correct? Clogged injectors?


1978 280Z
EL Paso TX

[Zed Head]

Not injectors.  They are not in the fuel path, they are on separate branches.  The fuel passes by them.  It would have to be in the FPR or one of the hoses in the fuel path.

[nefiwashere]

Not injectors.  They are not in the fuel path, they are on separate branches.  The fuel passes by them.  It would have to be in the FPR or one of the hoses in the fuel path.

Would it be good time to get a fuel rail from zcardepot? Or Just replace the FPR if it is bad

What i noticed while driving is lack of acceleration power. In neutral car would seemed to rev up fine. When driving I would pretty much floor it and it would gradually accelerate. After a few minutes car then started to accelerate normal. Would that being something with the AFM? Or also clogged in the fuel line?


1978 280Z
EL Paso TX

[Zed Head]

You have to isolate the problem first I think.  Can't say what you need.

With the 280Z EFI cars everything needs to be right.  Fuel pressure is one of the most important things to have correct with EFI.

Edited March 3, 2019 by Zed Head

[nefiwashere]

Hooked up the fuel pressure gauge to the return line in the engine compartment, I get no pressure on the gauge. Also the “T” conector is a good size and should not be an issue.

 

 

I did also change the rubber hoses on the fuel line when I moved the pressure gauge. I could not tell if they were EFI rated but they did feel soft in comparison to the new EFI rubber hoses. They could have been regular fuel line hoses.

 

 

1978 280Z

EL Paso TX

 

[Zed Head]

5 hours ago, nefiwashere said:

Hooked up the fuel pressure gauge to the return line in the engine compartment, I get no pressure on the gauge. Also the “T” conector is a good size and should not be an issue.

I did also change the rubber hoses on the fuel line when I moved the pressure gauge. I could not tell if they were EFI rated but they did feel soft in comparison to the new EFI rubber hoses. They could have been regular fuel line hoses.

Since you replaced some hoses you should move the gauge back to right in front of the rail and measure there.  You're narrowing things down.  Zero pressure on the return line might be good.  seems like you would have seen a pound or two.  If you still get high pressure from right in front of the rail, then the blockage is in the rail, or the FPR, or the line to the FPR, or the return line between the FPR and where you have the gauge now.