Relay Testing and Fuel pump help

[nefiwashere]

9 minutes ago, Patcon said:

What year car? It's not in your signature line...

i have a 1978

[Patcon]

I am unfamiliar with the 78 tank. On the 76 tank the lines come in near the center of the tank and go into a central area that is baffled to prevent fuel sloshing. I would expect the dent in your tank is not the issue

[Zed Head]

On 2/19/2019 at 2:55 PM, nefiwashere said:

So letting the car sit for about 10 minutes, fuel pressure still at 20psi. I started it up and fuel pressure at 48 psi and fuel filter is filling up with gas.
 

 

On 2/19/2019 at 2:49 PM, nefiwashere said:

it started struggling. when i pulled up to my house i checked the fuel pressure and it was at 20psi and clear fuel filter by the pump was 3/4 empty.   Yes there is gas.   same thing that happen before but i thought i had ran out of gas.      Gas Gauge is Semi faulty so i just added another 5 gallons of gas the first time it happen.

20 hours ago, nefiwashere said:

I did as you suggested and turning they key to the on position the fuel pump is working but it looks like its not getting gas.   I have a clear fuel filter on the outlet of the pump and its barley pushing any gas into it.  it get some pulses of gas but its not very much and sometimes it goes a good while with no gas pulsing in. is that normal or should there be a constant flow of gas ?   i have put at least 10gal of gas so i know there is gas in the tank.  sometimes during when it does pull gas from the tank i here some burping in the tank.   when i turn the car off i also here some burping. 

Meter stayed around 11.45 volts

You should get a constant flow.  Pretty strong too.  If you want to be sure, remove the return hose and put it in a container, then run the pump again.  

You have odd things happening with your fuel supply.  Maybe your fuel pressure regulator (FPR) has foreign material in it.  Your pressure fluctuates from too high to too low.  You might have crud in it blocking the outlet, raising pressure, then holding it open lowering pressure.  Who knows.

Let the pump run like you just did and report the fuel pressure.

 

Sorry for the weird quotes.  Turns out you can only "multi-quote" from one page at a time.  Not the whole thread.

 

[nefiwashere]

 

You should get a constant flow.  Pretty strong too.  If you want to be sure, remove the return hose and put it in a container, then run the pump again.  

You have odd things happening with your fuel supply.  Maybe your fuel pressure regulator (FPR) has foreign material in it.  Your pressure fluctuates from too high to too low.  You might have crud in it blocking the outlet, raising pressure, then holding it open lowering pressure.  Who knows.

Let the pump run like you just did and report the fuel pressure.

 

Sorry for the weird quotes.  Turns out you can only "multi-quote" from one page at a time.  Not the whole thread.

 

disconnect the return at the tank?       also just to clarify  the return is the bottom hose on the tank?   thats the way it is connected now,

[Zed Head]

I would disconnect it in the engine bay by the filter.  It's easier to access and get a container in there.  A clear two liter bottle would work well.  Plus you can watch the gauge.  You'll have flow and pressure right in front of you.

Are those hoses high pressure EFI rated?  You should check.  They might be splitting internally.  Even the return line could be failing.

You can still run the pump and report pressure before you do anything.  Ideally you get all of your measurements at the same point in time.  You have your pump voltage and weird fuel flow above, but no pressure readings.

 

 

[Zed Head]

SAEJ1532 is transmission fluid hose.  I would do that flow test in the engine bay, get your numbers written down so you can study them, then maybe tear your system down and get the right hoses on it.  

https://www.sae.org/standards/content/j1532_200503/

[nefiwashere]

Should those 2 hoses be getting pressure at the tank? ill change them out to proper ones either way.
In the engine compartment it still has old hoses, not original ones but there not the same as above

As far as fuel pressure it has been recently at 40psi when I been doing the current test with the weird flow.

Before it did seem that fuel pump was shutting off cause fuel pressure would drop and filter would be empty. So maybe the oil sensor is bad as well. But will address that later once I can get to the bottom of the fuel issue.


1978 280Z
EL Paso TX

Edited February 28, 2019 by nefiwashere

[Zed Head]

My mistake, they don't need to be high pressure.  They should be fuel rated though.  I don't know if automatic transmission fluid hose will swell in the presence of gasoline.

The one on the other side of the fuel pump needs to be high pressure EFI hose though.  I've found that when people start using the wrong hose in one place they tend to do it in many places.

 

Edited February 28, 2019 by Zed Head

[nefiwashere]

2 minutes ago, Zed Head said:

My mistake, they don't need to be high pressure.  They should be fuel rated though.  I don't know if automatic transmission fluid hose will swell in the presence of gasoline.

The one on the other side of the fuel pump needs to be high pressure EFI hose though.  I've found that when people start using the wrong hose in one place they tend to do it in many places.

 

ill get them changed out,   Going to be lowering the tank this weekend to look inside and make sure there is nothing getting stuck or if there is some holes in the pickup line.  Never had this issue before with the tank but just want to look.  also i want to remove the bumper shocks either way. ?

 

Will it cause any issue if i use an air compressor to blow air into the Flow out and return line on the outside of the tank?   want to see if there is something stuck in there.   according to mechanic that cleaned out the tank said there should not be ?? 

 

[Zed Head]

A little compressed air shouldn't hurt anything.  You can probably knock some of that dent out with a broomstick too.

I would do as much testing as possible before dropping the tank.  You don't know what the root cause is.  You could put it all back together and be in the same spot.

[nefiwashere]

 

Need some clarification on which is the fuel out and fuel return.

 

The pics I find it’s very hard to tell what hose is what. Also my hose location is on the passenger side other pics show it in the middle.

 

Found a decent pic. So top is the fuel out by the look of it.

 

 

 

[nefiwashere]

Progress update

I did drop the tank. Nothing much to tell on that. Did dump some black stuff out with last remain gas.

Replaced hoses with fuel ones from the tank to pump and return.
blew air in fuel return from engine compartment with hose disconnected at tank. Air passes through with no issues.


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