96 VW Golf 2L Symptom of a failing fuel pump RELAY

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5,133
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chicago, Illinois
Just noticed recently that upon acceleration engine seems to die out OCCASIONALLY not all the time. Then when you let it come back to lower rpms it will function normally. Not a misfire from what I can tell, it just seems like the engine loses all power. I noticed also it will idle just fine so say you are accelerating and than let off the rpms will come back to idle but if you try and accelerate with the clutch pushed IN the car will die out. What is odd is that it is intermittent.. Today I just noticed that when I turn the key to accessories I can barely hear the fuel pump relay priming the pump (the buzzing sound) normally on this car the noise from the relay is quite noticeable. It DOES seem to be working but the sound is very faint and weak. I did pull the codes from the ECU and the only one that came back was P0327 knock sensor voltage low. I disconnected the sensor and noticed that it did not affect the problem at all so maybe it is just a symptom of the engine losing power from another reason. I wonder what the symptoms of a failing (but not totally failed fuel pump relay would be, are my symptoms in line with that possibility? Thanks.
 

Astro14

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Are you certain it's the relay failing and not the pump? Usually relays just quit...changes in noise, and inability to deliver fuel under high demand points to the pump failing...
 
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Florida
I find that if the fuel pump has stopped, or gotten close to that stage, you can bang on the gas tank. If you get the pump to run better, that means the bearings in the pump failed, and the pump needs replacement. One way to detect inconsistent fuel pressure is to connect a fuel pressure gauge to the rail, and if the hose is long enough, place the gauge where it is visible during driving the car. Major changes mean a fuel system problem. Sometimes the car only needs an inline fuel filter. The debris will settle outside the filter media and let gasoline through. After a certain amount of driving, the debris will clog the filter and make the engine run poorly, or not at all.
 

antiqueshell

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chicago, Illinois
Thanks for the quick response guys... I'm not sure I am right here, I always believed that the buzzing noise just after you turned the key to acc in the car was actually the relay buzzing and not the pump motor itself? But in my case the humming noise (or whine, buzzing) used to be extremely loud (which I believe is typical for this model at least in my case it has been I have owned this car for 18 years now. LOL! Please clarify what I am hearing to be either the relay itself of the pump motor noise? I should know this but not sure about it now. I'm pretty sure that the pump assy is underneath an access cover that is underneath the rear seat, so should I remove that access cover and gently tap with a rubber mallet on the metal surrounding the fuel pump assy?
 
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antiqueshell

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Originally Posted By: crazyoildude
pop a new one in and see..
LOL....well I could do that you can choose from an aftermarket for about 100$ or the OEM for almost 450$. It is easy to access the pump because it sits under the access cover under the rear seat. It is basically remove the old one disconnect the power connectors and reconnect the power to the new unit and drop it back in and screw the big plastic ring nut back on. @crazy, you run a shop, so you have experience...have you ever worked on the 1993-1999 VW Jetta or Golf? I believe the 1986-1992 are very similar in design too.
 
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VA
The hum you used to hear is the fuel pump itself, not the relay. And if you have an access panel you are SO lucky.
 
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antiqueshell

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chicago, Illinois
Originally Posted By: bvance554
The hum you used to hear is the fuel pump itself, not the relay. And if you have an access panel you are SO lucky.
Thanks bvance! Yes right underneath the rear seat there is a hatch and what looks like a huge plastic screw on ring that is twisted to remove and then the pump assembly lifts up out of the tank itself. It is a combo fuel pump and gauge sender assy. Thanks for the tip. I am definitely going towards the pump motor failing because the buzzing noise which used to sound quite loud and notable is now soft sounding and muted, I can barely hear it if I listen while before I didn't have to stain at all to hear it prime. Too much of a coincidence if you ask me. Points towards the pump failing.
 
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MIchigan
Did you check Amazon? The last pump I bought saved me well over $150 versus the auto parts stores prices. It was a Bosch...BTW
 
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Iowa
Agree that the most likely culprit is the pump. From what location is the sound coming? Rear is pump and front is typically the relay. A relay will only make a single "click" when it's powered on, unless it's control voltage is flaky. Then it may chatter- a series of clicks in rapid succession. Naturally you'd want to check it out to be sure, but like I said the pump seems likely. As for which to use- I don't know what your intentions are with the car (keep it until it's fully driven into the ground, or unload it at the first chance), but I highly recommend an OE pump, replacing the fuel filter and even the relay too. The contacts of the relay can build resistance over time from the many switching cycles (tiny amounts of arcing each time you turn a load on). The only aftermarket pump that I would use or recommend would be a Delphi.
 

antiqueshell

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chicago, Illinois
@The_Eric: I believe that the buzzing sound IS coming from the rear seat area, which is where the pump is located. I am going to keep this car, I have NO issues with this car until now and it is nearly 19 years old now, it isn't driven more than 2500 mi a year so it is a safe bet to keep it until it falls completely apart. I'm probably going to go OE if possible which is VDO Siemens.
 
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Kansas City
If you have a hatch for access to the pump w/o dropping the tank, you might consider pulling the pump assy out and looking closely at the sock filter on the pickup end of the pump. I've replaced pumps before that really only required a new sock bc the old one had become occluded. But...I'd have a spare pump hanging around just in case. The idea of an access hatch to get at fuel pumps is one that seems so make so much sense, yet so few manufacturers build them in. Dropping a tank to replace a pump, especially on older rustymobiles is near the top of my hateful tasks list.
 

antiqueshell

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chicago, Illinois
@chestand: I thought about that issue, the sock filter being failed or clogged, but it wouldn't explain when the pump motor sounds so faint and weak. But I will look at it anyhow. VW gets an undeserved reputation for being problematic and difficult to service. My Golf is far easier to work on then my Honda both mid 90s vintage models. Oh, and the VW is cheaper when it comes to OEM brand name replacement parts as well.
 
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