Electrical Fuel Pump Pressure Problems

[Zed Head]

Any chance you could take a picture of your fuel system and post it?  The top of the engine.

Still not getting a full picture of when things happened and which of the things you did were to fix a problem or just coincidental.  It sounds like your FPR might be be dead but a plumbing error is possible also.

[Zed Head]

On 10/26/2018 at 3:08 PM, Yellow78 said:

10. Blown compressed air into return line until fuel comes out of filter before fuel rail. (Clear)

Just looking back here...this should have required very high pressure to do because in reverse the FPR has a very very small area to press on to get the valve to open.  You might have actually blown a hole in the diaphragm, or maybe even expanded the FPR body.  In normal flow direction the fuel has all of the diaphragm to press on to get the valve off of its seat.

If you blew a hole inthe diaphragm you'll be pumping gasoline through the vacuum hose to the intake manifold.

Imagine the fuel flow in reverse in the image.  That's what would happen if you used compressed air from the return line at the tank.

[Yellow78]

Here two photos of the engine bay.
One from each side of the engine bay. The fuel regulators is on the firewall buy the battery. I plumbed it back just in a different location as it was before.




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[Yellow78]

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[Zed Head]

I see two gauges.  Do they both read the same?  There are a lot of questionable quality gauges out there.

You've done so much work there that just pulling the pump and regulator and setting up a loop in to a gas can might be the simplest way to test the two main components.  Avoid sparks, be aware of wind direction, have an extinguisher handy, etc.  I put a filter in-line also to protect the parts when i do that kind of test.  

 

 

[siteunseen]

18 hours ago, Yellow78 said:

Here two photos of the engine bay.
One from each side of the engine bay. The fuel regulators is on the firewall buy the battery. I plumbed it back just in a different location as it was before.




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That's exactly how I have my FPR.  One day I'll Dremel that extra mounting ear off and try and make it look a little better.

Did you run a hose to the cold start vale?  I ran a T off the rear, one side to the FPR the other to the CSV.

[Yellow78]

I get virtually the same reading from both gauges. Currently I only have the gauge above the filter hooked up it only get 26 PSI. I’m going to buy a new Bosch 044 pump. And then I will start the process over again.
1. Check to make sure fuel tank line is clear to pump.
2. New Bosch 044 pump. (no damper)
3. All new rubber fuel lines from tank to pump and from pump to hard line.
4. New rubber fuel line from hard line to new fuel filter.
5. From new fuel filter to pressure gauge oil filled with the T with one of T’s plug for now.
6. If I get 40 PSI then I’ll unplug the T and hook it into the rail.
7. I will plug off or pinch off outflow side of the rail.
8. If I’m getting 40 PSI then unplug the outflow side of the rail.
9. New fuel line from rail to FPR and to hard line.
10. New vacuum line from intake manifold.

As a do each step I should me able to find the problem.

If you have any other suggestions on steps I should take please let me know. I appreciate all the help.

We got to keep the Z’s on the road so young people don’t even know what type of car they are.



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[Dave WM]

check the voltage at the pump under load. IIRC you have tried two pumps both give you the same result. I suspect the pump is not the issue, but do as you plan, if a 3rd pump give you the same results I would suggest re reading my prior post about eliminating variables.

[siteunseen]

As said above, I believe I'd try a smaller fuel tank feeding the pump first off.  You'll be eliminating most of your list.

Edited October 28, 2018 by siteunseen

[Yellow78]

I understand checking the pump under load but what will that tell me?
I have checked the wiring with it not connected to anything and I’m getting 12V


I like the idea of using a smaller fuel tank to eliminate that is not any fuel tank problem.


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[Dave WM]

it will tell you if there is a high resistance in the pump electrical supply. I don't know how you took the 12v reading. If you did that with the pump disconnected, you gained little knowledge about the power supply viability.  A high resistance in the circuit would still read 12v, put a pump load on it and it could drop a lot.

[Zed Head]

2 hours ago, Yellow78 said:

2. New Bosch 044 pump. (no damper)
3. All new rubber fuel lines from tank to pump and from pump to hard line.
4. New rubber fuel line from hard line to new fuel filter.
5. From new fuel filter to pressure gauge oil filled with the T with one of T’s plug for now.
6. If I get 40 PSI then I’ll unplug the T and hook it into the rail.

That Bosch pump should get you about 120 psi.  I don't think that they have a pressure relief inside.  They just keep cranking until flow stops.  Be careful you could easily pop a hose, or balloon your filter.  The Bosch 044 is way over-spec. for what your engine needs.  You might reconsider.

https://www.highflowfuel.com/i-13775895-genuine-bosch-044-320lph-inline-fuel-pump-includes-an-fittings-of-choice-0580254044.html

Did you say if you've checked the vacuum hose to the FPR for fuel?  Your FPR really should be causing pressure to increase.