Electrical Fuel Pump Pressure Problems

[Dave WM]

here I go in to detail about testing voltages

 

[Yellow78]

 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 October 29, 2018 by Yellow78

[Dave WM]

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.

[Yellow78]

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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[Zed Head]

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

[Yellow78]

That’s the one I got on there now they had only pump up to 26 PSI. Maybe I just got a bad one.


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[Zed Head]

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.

[Dave WM]

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 October 30, 2018 by Dave WM

[Dave WM]

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 October 30, 2018 by Dave WM

[Yellow78]

Yes  it is new . I holds pressure fine at 26PSI  To make sure I was doing the check correctly I watched this video.

 

 

[Dave WM]

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?

[Yellow78]

Yes yes just like the video.