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Yellow78

Electrical Fuel Pump Pressure Problems

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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.

image.png

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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.  

 

 

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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.

IMG_0322.JPGIMG_0323.JPG


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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.

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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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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.

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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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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.

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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.

image.png

 

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 So the Bosch fuel pump, I spoke of is the Bosch 0580254044 fuel pump,  i’ve read they had a lot of the Z guys use this pump.

I’ll check the resistance on the pump tomorrow. Thanks for all your help any other suggestions always welcome.

Edited by Yellow78

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Checking the resistance of the pump is not what I am talking about, its the resistance in all the wiring including the relay that supplies the pump with current. You need to check the voltage at the pump terminals while its running. Just make sure it does not drop too much (it will drop some compared to when the pump is disconnected, you just don't what a LARGE drop in voltage.

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So it is definitely the pump is not pumping up to adequate pressure. I’ve done electrical test with a pump under load and I get less than
.02 voltage drop on the positive side and .005 on the negative side.

So I’m thinking that BOSCH 69136 would be adequate pump for my 280.

Has anyone used the BOSCH 69136. On Amazon for $74

Any feedback would be appreciated.


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Seems much more than adequate.  I don't know why they don't just put the specs out there somewhere.  That pump is a replacement for Ford F350's with 445 CI diesel engines.  Which means high volume of a more viscous fuel.

The general spec for a stock L6 is about 30 gph at 36 psi.  Higher volume means bigger draw on the electrical system.  You don't want that on these cars, the electrical is on the weak side already. 

The Airtex E8312 is a common replacement.  I have one, it's worked great for years and many miles.

https://www.amazon.com/Airtex-E8312-Electric-Fuel-Pump/dp/B000DT7Y7K/ref=sr_1_1?ie=UTF8&qid=1540865716&sr=8-1&keywords=airtex+e8312

 

Here's the data for the 69136 - 

https://www.summitracing.com/parts/bch-69136/applications

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Is it new?  Pumps do go bad if they get crud in them, or rust up.   I had a wrecking yard pump that seemed fine in the first few minutes but would slowly lose power and pressure as it ran.  Even with the fuel cooling it the motor got hot and crapped out.

It's still unclear how, exactly, you're testing the pump.  Would love to see just a pump, some hose, an FPR, and a pair of pliers for pinching the return line.  With a gauge reading of course.

You're probably going to find that it was something simple once it's done.  Carry on.

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11 hours ago, Yellow78 said:

So it is definitely the pump is not pumping up to adequate pressure. I’ve done electrical test with a pump under load and I get less than
.02 voltage drop on the positive side.

 

that seems odd, I would have expected more of a drop than that. That pump has to pull a few amps easy, with all the wiring and relay I would expect a bit more. Not a lot but more than .02v. Are you sure you are getting a good fuel supply to the pump? . I am going to take a reading later today on my setup and see what I get.

Maybe a current draw test would be a better idea. could do right at the battery. Pull the start solenoid, disable the cold start, ign to on, get a current reading, then to start get another reading. I will try that as well, give you something to compare to. Or I will just get a current reading right at the pump, that is better, but means having to disconnect one of the pump leads.

You could always just buy the OE pump they are out there, expensive but that should eliminate the issue. think it you shop around you can get them for around 200$ I replaced my working setup just to take advantage of the built in pressure relief the OE pump has. But still the after market pumps should work. I too had one of those airtex and it worked fine.

 

Edited by Dave WM

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ok reading the amperage at the battery (start solenoid off, cold start injector unplugged) when switched to "start" to energize the pump was a fail, over 10 amps meter would not read, so no idea of what it should be. But if you want you can duplicate and at least confirm you are over 10 amps. Will try for a voltage drop at the pump later with my helper around.

Edited by Dave WM

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So just to be sure, you ran a wire all the way back to the pump and connected from the pump terminals and then compared to the battery post?

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I get a 2.0v drop video to follow.

I also checked by leaving the setup but rather than look for  drop (pump + term compared to Batt + term) I connected from Pump + to chassis ground. got about 10v suppled to the pump. This is with the engine not running. Typical battery voltage with the alternator working would be close to 14v so a 2v drop would supply the pump with approx. 12v.

 

Edited by Dave WM

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