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Can a bad fuel pressure regulator cause a whining fuel pump?
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shabutie
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PostPosted: Wed Jan 06, 2021 6:44 pm    Post subject: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

It's simple, a faulty regulator could mean the pump is starving, correct? Am I safe in assuming that?

About 5,000 to 10,000 miles ago, I replaced my fuel pump as well as fuel filter. Because the pump was whining like a bumble bee.

Now, barely 10k miles later, it is whining again. I'm starting to think it is the pressure regulator itself, am I safe to assume that?

And, before anyone tells me to do the pressure test on it, I have no idea how, don't have the parts, and a new regulator is only $100 so I'd rather just replace it on the hunch. (And your guy's affirmation Razz )
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shagginwagon83
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PostPosted: Wed Jan 06, 2021 6:50 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

https://www.harborfreight.com/fuel-injection-pump-tester-62623.html
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PostPosted: Wed Jan 06, 2021 7:02 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

shagginwagon83 wrote:
https://www.harborfreight.com/fuel-injection-pump-tester-62623.html


Hi, I appreciate the help, but I guess I am a bit confused. This is a product for a fuel pump tester? Also, ironically enough, it states: "Fits most systems (except for Bosch."

Also, as I mentioned, I don't see the benefit of purchasing this for $25 some odd dollars, spending the time and money on it; when if the regulator is actually bad, I need to order one asap because the van is my only vehicle.

My question is more of a yes or no one. "Can a bad fuel pressure regulator cause a whining fuel pump?"

I hope none of this comes across as rude at all as that isn't my intention. Hopefully you can still give me advice but about the regulator.
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shagginwagon83
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PostPosted: Wed Jan 06, 2021 7:15 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

No worries. Don't take offense by just dropping links

https://www.gowesty.com/tech-article-details.php?id=115
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shabutie
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PostPosted: Wed Jan 06, 2021 7:41 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

shagginwagon83 wrote:
No worries. Don't take offense by just dropping links

https://www.gowesty.com/tech-article-details.php?id=115


Haha, that didn't answer my question either. I'm just gonna go ahead and buy it. Thanks anyways.
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PostPosted: Wed Jan 06, 2021 7:41 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

That is just a typo error in the HF text.
They should not have put a comma between Bosch and CIS. Bosch made various systems and the tester is fine for most Bosch but not fine for the Bosch CIS system.
There is a special tester for Bosch CIS, which our vans don't use.

Mark


shabutie wrote:
shagginwagon83 wrote:
https://www.harborfreight.com/fuel-injection-pump-tester-62623.html


Hi, I appreciate the help, but I guess I am a bit confused. This is a product for a fuel pump tester? Also, ironically enough, it states: "Fits most systems (except for Bosch.".....
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PostPosted: Wed Jan 06, 2021 7:44 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

The pressure regulator is on the return to the tank. Itís 97% not causing the pump to make noise. Generally itís starvation on the supply side that causes the noise. There is a mesh filter in the tank on the outlet.

Once a pump is making noise, itís likely not to stop.
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PostPosted: Wed Jan 06, 2021 7:44 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

crazyvwvanman wrote:
That is just a typo error in the HF text.
They should not have put a comma between Bosch and CIS. Bosch made various systems and the tester is fine for most Bosch but not fine for the Bosch CIS system.
There is a special tester for Bosch CIS, which our vans don't use.

Mark


shabutie wrote:
shagginwagon83 wrote:
https://www.harborfreight.com/fuel-injection-pump-tester-62623.html


Hi, I appreciate the help, but I guess I am a bit confused. This is a product for a fuel pump tester? Also, ironically enough, it states: "Fits most systems (except for Bosch.".....


Am I wording things incorrectly? Sorry, if so. My question isn't about the fuel pump.

Again, it is about the fuel pressure regulator. I already know my fuel pump is starving, I can literally hear it. I don't think I want to buy gauges and kits to tell me it's low on pressure, I already know it is. Again, because I can hear it.

This is the second fuel pump in 6 months.

So, again, I'm asking if the issue could lie in the regulator itself. Not, the fuel pump.
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shabutie
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PostPosted: Wed Jan 06, 2021 7:47 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

MarkWard wrote:
The pressure regulator is on the return to the tank. Itís 97% not causing the pump to make noise. Generally itís starvation on the supply side that causes the noise. There is a mesh filter in the tank on the outlet.

Once a pump is making noise, itís likely not to stop.


This was actually very helpful and I appreciate it. So, instead of a pressure regulator I'll suppose I'll just buy another pump and filter, although I can't seem to figure out why my van is eating them up.

Unless I just happen to get a bunk one, which totally might be the case.
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PostPosted: Wed Jan 06, 2021 7:49 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

You don't really know the pressure is low unless you measure it.

One of the ways the regulator can fail makes the pressure too high and that would make the pump strain harder to push fuel against the higher back pressure.

Mark
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PostPosted: Wed Jan 06, 2021 8:06 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

There were some production changes to the fuel system. What year van? Also what is the tank outlet size and is the fuel filter in front or after the pump. What is the age of the tank?
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PostPosted: Wed Jan 06, 2021 9:15 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

the FPR is like a "dam" in the fuel system. at idle with the vacuum line connected you should have 30 psi. disconnected it should jump to 35-40

(i don't know the spec's off the top of my head, so take the #'s for illustrative purposes only)

so at idle the "dam" should be open and it's returning the unused fuel to the tank. when you put the coals to it (hit the gas) the vacuum drops and the "dam" closes keeping more fuel on the supply side, feeding the engine.

if the pump is whining it could be fuel starvation (most likely the issue) or it could be that the FPR failed and the pump "dead headed" and can't push excess fuel back to the tank. this could also be caused by a restriction on the return line

think of it this way, cavitation is when you drink your milkshake to the bottom and start sucking air. dead heading is when you try to blow into that fresh milkshake and your cheeks puff up like a squirrel and you go cross eyed

either way, a fuel pressure test is in order before you go loading the parts cannon and shooting parts into something not knowing what your starting point is.

a bouncy needle indicates a weak pump/cavitation
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PostPosted: Wed Jan 06, 2021 9:19 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

Gowesty's article, mentioned above, states in the last paragraph "Also, if there is not enough back-pressure, that could cause it to make noise, too. The back pressure in the fuel supply system is controlled by the fuel pressure regulator"
So, yes, it could technically cause it. Like others have mentioned, it is quite unlikely. More likely is an intake problem. On my fuel pump (OE Bosch as far as I know), there was a bunch of crud in the intake side. I sprayed carb cleaner in there, blew some air, then ran the pump in reverse (with some fuel in a container - do not run your pump withour giving it fuel, it will seize and fail) to get the crud out. I was amazed by the amount.
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PostPosted: Thu Jan 07, 2021 11:58 am    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

MarkWard wrote:
There were some production changes to the fuel system. What year van? Also what is the tank outlet size and is the fuel filter in front or after the pump. What is the age of the tank?


Thank you for your help! The van is a 1985 1.9 waterboxer.
I do not know the outlet sizes and have no way to measure right now. However, the filter and pump are both bosch, purchased from Bus Depot, nothing fancy or aftermarket.

The filter is before the pump itself, meaning directly from the tank comes the filter, then directly after the filter comes the pump, then into the rails etc.

The age of the tank is that it is the original tank haha.

A bit of information, though. I just went out removed the hose from the filter 'in,' and then blew back into the tank itself with my mouth. I detected a lot of resistance. (I've done this before so kind of know the level of resistance.)

There was a lot of crud in the line somewhere which I blew back into the tank, only buying myself more time before it builds back up, and I get another mouth full of tasty gasoline, yumm!!

So, do you think the tank has too much crap in it? Should I replace the tank? That could be what is clogging my fuel system over and over?

EDIT! Also, probably the most important thing I left out, is that after I blew the crud back into the tank, the pump is back to it's normal hiss now. Not quite like a bumble bee, more like a calm (but still pretty noisy) hiss.
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PostPosted: Thu Jan 07, 2021 12:21 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

You can purchase a tank with a larger 12mm outlet. Later vans did away with the filter in front of the pump and added a larger filter after the pump. This should solve the crud problem and get you better fuel volume to the pump. You need to pay attention to the filler neck diameter when buying a replacement tank.

Edit: Here's the interior of a stock tank. Not my picture.
Image may have been reduced in size. Click image to view fullscreen.

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PostPosted: Thu Jan 07, 2021 12:48 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

MarkWard wrote:
You can purchase a tank with a larger。。。


I really appreciate you taking the time to help me out with this.

So, if I purchased a tank with a larger diameter outlet, how would I connect it to the 'in' on the pump then? (Assuming I also moved the filter after the pump too)

And then that also raises the question, if I switched the pump and filter position, how would I then connect the pump out, to the filter in?

I'm assuming just a bunch of metal step downs/step ups?

One more question, if I switched the pump/filter position, you said it would get rid of the crud problem, but wouldn't the crud then be going directly to the pump instead of directly into the filter? Wouldn't that make it worse?
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PostPosted: Thu Jan 07, 2021 12:53 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

MarkWard wrote:

Once a pump is making noise, itís likely not to stop.


is the noise a signal of impending failure or does it just make noise?
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PostPosted: Thu Jan 07, 2021 1:06 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

dabaron wrote:
MarkWard wrote:

Once a pump is making noise, itís likely not to stop.


is the noise a signal of impending failure or does it just make noise?


I think what he was meaning is that a pump that makes a crazy noise because the pump has been suffocated and is likely near almost failure. And even if you fixed every issue in the fuel line perfectly, the pump has still been suffocated for too long that the pump will still be a failure even if the outstanding issues have been fixed.

I would likely agree with him, although a pump that makes noise only for a day or so, not driven on for too many miles, can still be silenced if you hurry up and fix the outlying issue.

But generally he's probably right, a starved pump won't be fixed unless you catch it just in the nick of time. (Which luckily for me, I have, as I listen to the sounds from my van extremely closely and jump on issues once I hear or feel the slightest issue.)
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PostPosted: Thu Jan 07, 2021 1:18 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

The factory pump inlet is actually also 12 mm. The cube filter acts like an adapter from 8mm to 12mm. You really need to pay attention to the filler neck and I recall there are an early and late fuel sender. The wire connector fits either, but I think how it attaches is different.

Don't take my word for any of this though. Wink

edit: Noisy pumps can run the engine for quite a while. Usually, the symptom is short trips the pump is fine. Full day highway driving the pump gets hot and looses pressure. The pump is way over kill for the actual fuel requirement to run down the highway.
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PostPosted: Thu Jan 07, 2021 1:22 pm    Post subject: Re: Can a bad fuel pressure regulator cause a whining fuel pump? Reply with quote

MarkWard wrote:
The factory pump inlet is actually also 12 mm. The cube filter acts like an adapter from 8mm to 12mm. You really need to pay attention to the filler neck and I recall there are an early and late fuel sender. The wire connector fits either, but I think how it attaches is different.

Don't take my word for any of this though. Wink

edit: Noisy pumps can run the engine for quite a while. Usually, the symptom is short trips the pump is fine. Full day highway driving the pump gets hot and looses pressure. The pump is way over kill for the actual fuel requirement to run down the highway.


Okay, but ignoring the outlet/inlet sizes and talking back on the crud in the tank. Won't it be bad if the pump comes directly after the tank? Doesn't the filter need to be there first to actually catch the crud?
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