77 280z. Apologies for the crusty picture. Is the circled object at the top of the screen a damper or a regulator? And if its a damper, is it adjustable? 

Struggling with fuel pressure. I have an in-line gauge installed after the fuel filter. When the car is running, fuel is only at ~25PSI (compared to 34-36PSI expected). I took apart this whole section to remove some of the rust and replace the hoses, but I can't remember if I messed with the bolt on the top of the damper (and if it matters).  

Edited October 29, 20213 yr by Muzez
fixed photo

you should read the FSM fuel section. It explains how the entire fuel injection system works, including the fuel pressure. You should get a vacuum gage to confirm the fuel pressure reading with the engine running. most see about 29-30 psi at idle, you may have more vacuum than typical (16-20 inHg), or you may have a fuel delivery problem 36-38 is more normal engine off pump on.

 

Edited October 29, 20213 yr by Dave WM

Did you recently replace the factory pump with the aftermarket model. Controversial subject I know.

I removed my dampener all together I know that’s even more controversial 

1 hour ago, Dave WM said:

you should read the FSM fuel section. It explains how the entire fuel injection system works, including the fuel pressure. You should get a vacuum gage to confirm the fuel pressure reading with the engine running. most see about 29-30 psi at idle, you may have more vacuum than typical (16-20 inHg), or you may have a fuel delivery problem 36-38 is more normal engine off pump on.

 

Thanks Dave! Good to know this is closer to expected pressure. And apologies for the laziness in not reviewing my copy of the FSM. In Chicago, antique license plates only allow you to drive through 10/31 so I was outsourcing the research to you guys to maximize my remaining days of drive time when I am out of work today 😛 

1 hour ago, Yarb said:

Did you recently replace the factory pump with the aftermarket model. Controversial subject I know.

Not sure if it has the OEM fuel pump, this is the one that came with the car when I bought it. My assumption is that it is not factory though given that this was one of the truly shiny things on the car when I bought it. 😛 

27 minutes ago, AZDatsun said:

I removed my dampener all together I know that’s even more controversial 

Chaos reins lol. Does it run well without it? I wouldn’t mind cleaning up the shitty plumbing from the PO if possible.

Edited October 29, 20213 yr by Muzez

That’s an aftermarket pump. Way less expensive but….again controversial.

16 minutes ago, Yarb said:

That’s an aftermarket pump. Way less expensive but….again controversial.

Without inflaming the internet in anger and despair, is there a substantial benefit to the OE fuel pump that is worth dumping this one to go back to stock?

I have not seen any controversy over aftermarket pumps on an EFI car, except for people who use a very high volume pump like the Walbro 255.  It's noisy because it's way too much fuel for the system.   Otherwise, they are common, there are many good brands.  The factory pumps are super expensive if a person can even find one.  Not sure how controversy got involved here.  

The simple test for the pump is to remove the small wire from the starter solenoid and turn the key to Start.  The pump will run, but the engine won't turn so you'll see the base no-vacuum pressure.  As Dave WM said - it should be around 36.3 psi.  (The FSM says 36.3 psi, which is 2.5 bar).

a lot of running issues can be traced back to fuel issues (including running out of gas like I did before getting the gauge calibrated).

things to be aware of re fuel:

gas gauge accurate (don't run out of gass).

tank rust can be a big problem

Hard line rust again can be a big problem.

Turning left when low on gas (for me anyway) will slosh the gas away from the non existent pickup sock (removed when tank was renewed) causing fuel starvation and misfires

heat induced hard restarts (hot weather esp). if this happens floor the throttle while cranking (see the owners manual).

regarding the pump, I like OE stuff  just cause i trust it. You can get OE pumps for about 250-300$ vs 75ish for cheap pumps. Its up to you if you think the price diff is too much, but I just like the fitment and the built in regulation. Thing about pump is if it fails you are dead in the water. I take a LOT of long trips so I opted for the OE thinking why not, AND i carry a spare (the aftermarket that was on it). IIRC the stock pump keeps the fuel pressure at no more than 60psi, so my thinking is if there is a regulation issue there will be less of a possible over pressure as after markets can go a lot higher (at least that is what the specs say).

You may want to install a pre filter (a filter in front of the pump). If you go this route you should look for a filter that is so designed, most filters are for after the pump. You really want a very low restriction filter that will not make the pump work too hard. I had a restrictive filter installed and the pump made a lot of noise. I went to a large, low restriction filter designed for this purpose and the noise went away.

Finding a good tank is hard as most have rust and will often have pin hole leaks after "cleaning" (acid). I paid to have mine cut open and sealed after sand blasting. seems ok so far, but I would prefer a new tank, which IIRC are being made in the UK of all S30 styles.

 

 

 

 

 

 

 

 

 

 

 

2 minutes ago, Zed Head said:

I have not seen any controversy over aftermarket pumps on an EFI car, except for people who use a very high volume pump like the Walbro 255.  It's noisy because it's way too much fuel for the system.   Otherwise, they are common, there are many good brands.  The factory pumps are super expensive if a person can even find one.  Not sure how controversy got involved here.  

The simple test for the pump is to remove the small wire from the starter solenoid and turn the key to Start.  The pump will run, but the engine won't turn so you'll see the base no-vacuum pressure.  As Dave WM said - it should be around 36.3 psi.  (The FSM says 36.3 psi, which is 2.5 bar).

Thanks Zed. I will give than I try tonight. I am expecting there is a confluence of factors at play here since I think there is also a slow leak somewhere in the system. I did a compression test last night. At the start of the test after sitting idle for about a week or two, the inline gauge was reading at 10PSI but jumped back up to ~35PSI at the conclusion of the test. Just checked in a few minutes ago and its back down to 25psi again. 

5 minutes ago, Dave WM said:

a lot of running issues can be traced back to fuel issues (including running out of gas like I did before getting the gauge calibrated).

things to be aware of re fuel:

gas gauge accurate (don't run out of gass).

tank rust can be a big problem

Hard line rust again can be a big problem.

Turning left when low on gas (for me anyway) will slosh the gas away from the non existent pickup sock (removed when tank was renewed) causing fuel starvation and misfires

heat induced hard restarts (hot weather esp). if this happens floor the throttle while cranking (see the owners manual).

regarding the pump, I like OE stuff  just cause i trust it. You can get OE pumps for about 250-300$ vs 75ish for cheap pumps. Its up to you if you think the price diff is too much, but I just like the fitment and the built in regulation. Thing about pump is if it fails you are dead in the water. I take a LOT of long trips so I opted for the OE thinking why not, AND i carry a spare (the aftermarket that was on it). IIRC the stock pump keeps the fuel pressure at no more than 60psi, so my thinking is if there is a regulation issue there will be less of a possible over pressure as after markets can go a lot higher (at least that is what the specs say).

You may want to install a pre filter (a filter in front of the pump). If you go this route you should look for a filter that is so designed, most filters are for after the pump. You really want a very low restriction filter that will not make the pump work too hard. I had a restrictive filter installed and the pump made a lot of noise. I went to a large, low restriction filter designed for this purpose and the noise went away.

Finding a good tank is hard as most have rust and will often have pin hole leaks after "cleaning" (acid). I paid to have mine cut open and sealed after sand blasting. seems ok so far, but I would prefer a new tank, which IIRC are being made in the UK of all S30 styles.

The turning left thing is a real deal haha. Had that experience recently turning on an decline. Love the redundancy of carrying multiple pumps; its clear this is not your first rodeo on a long distance road trip disaster. 

I can check out the tank this winter when I drop the tank to remove the bumpers but I can see on the drain that someone already re-sealed it once with that red stuff. 

Do you have a recommendation for the pre-filter? and do you still have the OE mounting? Or did you opt for the revised version that I see on some of the builds (not sure who makes it or if it is custom)?

How do you check if there is rust in the hard lines? 

In regards to the dampener I haven’t had any issues when I removed it and been driving for about 2 years but I also don’t have oem fuel rail or FPR.  I am assuming it’s probably better to keep it but I didn’t know how to test if it even worked or not, it’s on my shelf if I ever want it again I would just plumb it back in.

4 hours ago, Muzez said:

When the car is running, fuel is only at ~25PSI

 

50 minutes ago, Muzez said:

I did a compression test last night. At the start of the test after sitting idle for about a week or two, the inline gauge was reading at 10PSI but jumped back up to ~35PSI at the conclusion of the test. Just checked in a few minutes ago and its back down to 25psi again. 

The fact that it hit 35 shows that the FPR is working.  It blocks fuel flow until the design pressure is reached.  The leak down to 25 isn't too bad, the systems always lose some pressure when the pump is not running. 

The 25 psi when the engine running is too low.  When you try the pump check test make note of how fast the pressure rises.  You might have just a weak pump or maybe a clogged filter.  Pressure should rise to 36.3 within just a few seconds.