# How do I check if fuel pump is bad??? or pump relay



## trademarktm (Jan 15, 2007)

Car wont start, gave me obd scanner coed p0321 (Engine Speed Sensor) and replaced but still nothing. Only way car will start for a second when spraying quick start in throttle body. Im wondering if its the fuel pump relay or pump. 
My questions are?
If I take off the FPR and try to start the car should I see gas moving cause I saw nothing.
I have a check light so can I connect the ground wire and test the pins on the harness that go to the pump. I tried that and the light on the check light didnt come on after I checked all the pins. I did this while trying to start the car.
Could this mean my Pump relay 409 is bad? I check fuses in fues box and all seem to be good. And my battery is good to. Im trying to narrow everthing down before I buy another part. Any Ideas. Thanks
My car is 2004 gli 1.8t AWP 6 spd


_Modified by trademarktm at 10:18 AM 5-31-2008_


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## rracerguy717 (Apr 8, 2003)

*Re: How do I check if fuel pump is bad??? or pump relay (trademarktm)*


_Quote, originally posted by *trademarktm* »_
Could this mean my Pump relay 409 is bad? I check fuses in fues box and all seem to be good. And my battery is good to. Im trying to narrow everthing down before I buy another part. Any Ideas. Thanks
My car is 2004 gli 1.8t AWP 6 spd
 
Did you check all the fuse type links in the small black box mounted under the battery cover?? make sure with a test light that they are good first . 
If so I would go straight to the fuel pump under the back passenger bottom portion of the seat its very easy to remove . Then under there you will see a round cover take the 3 Phillips screw off and you will see the electric connector to 
A) the fuel pump and B) the fuel Gage .
I don't remember the wire colors its been a long time since Ive been in there but look for the thickest wire which should be the fuel pump power and check for power there.
summary to check 1) fuse-able type links under the battery
2) power at the pump
3) drivers door switch which activates the fuel pump 4 The FP relay 
5) wiring somewhere in between 

Hope this helps a bit







Bob.G


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## stevemannn (Apr 17, 2008)

*Re: How do I check if fuel pump is bad??? or pump relay (trademarktm)*

you should hear the pump turn on when you turn the key on.
try getting someone underneath with rubber mallet and have them smack the tank as you try to start it. if it starts for a lil you know its the pump.....
my friend used to hang out the door of his old neon at my old job and have me crank it over so he could limp it into the shop....**** was halarious
give it a try and good luck


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## trademarktm (Jan 15, 2007)

*Re: How do I check if fuel pump is bad??? or pump relay (rracerguy717)*

I will try that, I did check the blue wire that seems to be connected to the 409 under the steering wheel and penitrated the blue wire with the check light and got no light to come on the check light. Dont know if that means anything but ill go check the black fuse box now.


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## trademarktm (Jan 15, 2007)

*Re: How do I check if fuel pump is bad??? or pump relay (stevemannn)*

Pump does not seem to be comming on. I have no back seats and the black cover off and put my ear to the pump and hear nothing. Used check light on the pins and also no voltage.


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## trademarktm (Jan 15, 2007)

Checked the fuses in the black box under battery cover, all were fine. There is a blue wire that seems to go to the 409, should that have power going to that wire. I used a probe light and got no probe light response.


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## stevemannn (Apr 17, 2008)

*Re: How do I check if fuel pump is bad??? or pump relay (trademarktm)*

i would belive its shot if you cant hear it comming on
try swapping the relays real quick and still if nothing.. you know its the pump


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## rracerguy717 (Apr 8, 2003)

*Re: How do I check if fuel pump is bad??? or pump relay (trademarktm)*


_Quote, originally posted by *trademarktm* »_Pump does not seem to be comming on. I have no back seats and the black cover off and put my ear to the pump and hear nothing. Used check light on the pins and also no voltage.
 
Then work your way back when you pull the FP relay check the sockets and see if there power there. 
There is also a FP activation switch when you open the driverside door .







Bob.G
p.s 
Even thou you check those fuseable links under the battery cover and they are good make sure that the wires that attach to both sides are not burnt off corroded bad ,etc and make sure there no bad connections there, grab a hold of them and tug on them and check power at those points , not just checking power at each end of the fuse/ link itself .


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## trademarktm (Jan 15, 2007)

*Re: How do I check if fuel pump is bad??? or pump relay (rracerguy717)*

IF there is no power to the FP relay than what would you think the cause could be? I check that and dont seem to be getting power there.
I will go back over the black box and again check the wires and all.
If all else fails than I will check the door switch if I can find it.


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## sabredylan (Nov 10, 2005)

*Re: (trademarktm)*

The blue wire which comes off relay 409 goes to fuse 28 on the panel at the side of the dash. check to see if its blown


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## trademarktm (Jan 15, 2007)

*Re: (sabredylan)*

Well holy crap buddy your on to something! The fuse was blown, infact, when the car didnt start at work the fuses was the first thing I looked at and saw # 28 blown so put in a new fuse and didnt realize it blew again when I tried to crank the engine. Just put in a new fues and again it blew.
Im guessing I need to follow this fues to see where it leads and what the problem is. Any quick answers whould be helpfull. I guess for now I will do a search. 


_Modified by trademarktm at 9:02 PM 5-31-2008_


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## trademarktm (Jan 15, 2007)

Ok, I tried to put in another fuse but this time I disconected the fuel pump harness from the fuel pump and tried to start the car and the fuse didnt blow.
When I reconected the harness to the fuel pump and tried to start the car the fuse blew.
any idea what this means???? This has to be the answer to the problem. Can anyone help a brother out. Thanks


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## stevemannn (Apr 17, 2008)

*Re: (trademarktm)*

hmmm...wires might be frayes going to it.. or its shorting somewhere....tracing electrical is a bitch... good luck


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## sabredylan (Nov 10, 2005)

*Re: (trademarktm)*

Have a look at the engine speed sensor on the gearbox. This sensor is linked to the fuel system sensors. Unless you have done any other electical work recenty, this could well be your problem. Hope this helps.


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## rracerguy717 (Apr 8, 2003)

*Re: (trademarktm)*


_Quote, originally posted by *trademarktm* »_Ok, I tried to put in another fuse but this time I disconected the fuel pump harness from the fuel pump and tried to start the car and the fuse didnt blow.
When I reconected the harness to the fuel pump and tried to start the car the fuse blew.
any idea what this means???? This has to be the answer to the problem. Can anyone help a brother out. Thanks
 
Sounds like a bad fuel pump to me . 
Take the fuel pump assembly out of the tank. You could then bench test it with 12V battery source be gently/ careful when removing this assembly from the tank so you don't bend and damage the gas gage float . 
I would bet with having a dead short which blows your fuse you will see signs of burning on the exterior of the fuel pump somewhere because it has to be drawing alot of amps to do this.Good luck







Bob.G


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## trademarktm (Jan 15, 2007)

*Re: (rracerguy717)*


_Quote, originally posted by *rracerguy717* »_ 
Sounds like a bad fuel pump to me . 
Take the fuel pump assembly out of the tank. You could then bench test it with 12V battery source be gently/ careful when removing this assembly from the tank so you don't bend and damage the gas gage float . 
I would bet with having a dead short which blows your fuse you will see signs of burning on the exterior of the fuel pump somewhere because it has to be drawing alot of amps to do this.Good luck







Bob.G


I have the fuel pump assembly out of the tank but if I bench test it should I first take the pump out of the assembly or can I bench test it when its still in the assembly.
One other thing, I have a APR stage III +. If the pump was bad do I need to still go with the apr intank pump or can I just use a walbro? There is a price difference if Im not mistaken and I am on a budget.


_Modified by trademarktm at 11:56 AM 6-1-2008_


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## trademarktm (Jan 15, 2007)

Ok, so I guess this is the million dollar question.... I took the fuel pump out of the assembly, on the bottom of the fuel pump (looking down into the bottom of the pump) there are what looks like alot of very small fins. I used a 12v source and conected straight to the pump + and -. The pump shuterd and the fins wouldnt move. I disconected and repeted several times. I could get the fins to move by reconecting but the fins would only move for about 1/4 inch before they stoped moving again.
Now I am not a fuel pump pro here but should these fins always be moving once you apply current to it. Thanks for all the help.
Oh, one other thing. I used a car battery for the current, was this ok? I say this because while applying current for more than 10 seconds I saw a little bit of smoke comming from inside the pump. I am guessing this was because the motor is stuck?????
_Modified by trademarktm at 12:55 PM 6-1-2008_


_Modified by trademarktm at 1:04 PM 6-1-2008_


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## Old Dude GTI (Dec 25, 2007)

Sounds like it's seized to me. Do you have 12V at the connector you pulled off of the pump? Then you know the pump is bad.


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## rracerguy717 (Apr 8, 2003)

*Re: (trademarktm)*


_Quote, originally posted by *trademarktm* »_
Now I am not a fuel pump pro here but should these fins always be moving once you apply current to it. Thanks for all the help.
Oh, one other thing. I used a car battery for the current, was this ok? I say this because while applying current for more than 10 seconds I saw a little bit of smoke comming from inside the pump. I am guessing this was because the motor is stuck?????
_Modified by trademarktm at 12:55 PM 6-1-2008_ 

_Modified by trademarktm at 1:04 PM 6-1-2008_


The pump is dead LOL









_Quote, originally posted by *trademarktm* »_
One other thing, I have a APR stage III +. If the pump was bad do I need to still go with the APR in-tank pump or can I just use a walbro? There is a price difference if Im not mistaken and I am on a budget.

_Modified by trademarktm at 11:56 AM 6-1-2008_

The APR Pump is just a factory Audi TT 225 in-tank pump modified . APR just plug off one of the pump fuel supply holes that needed for the split/ dual gas tank used in the Audi 225 TT. 
IMO try and find the part # and just order one from a vendor here , FYI APR will charge you $ 209. if you buy it from them .







Bob.G


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## trademarktm (Jan 15, 2007)

*Re: (rracerguy717)*

Wow, your the best. I just looked at my fuel pump and it did have one of the holes blocked off.
Maybe now I can fix this and start my vacation. Thank you!


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## trademarktm (Jan 15, 2007)

*Can I use a MK4 jetta fuel pump assembly on a MK4 GLI 1.8t*

Well my fuel pump died and replaced it and started right up. Then realized I cracked the nipple on the top of the fuel pump assembly and its leaking gas. I dont feel good about using opxy. I was thinking of just going to the junk yard to find a new one. So my question is. 
Are all fuel pump assemblys the same on the jetta MK4 as the MK4 2004 GLI? Are there differences between the automatic, 5spds, non turbo or turbo models that might make the assembly different? Thanks. My car is a 2004 Gli 1.8t awp if that helps.


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## bongoRA3 (Oct 8, 2003)

*Re: Can I use a MK4 jetta fuel pump assembly on a MK4 GLI 1.8t (trademarktm)*

all the same http://****************.com/smile/emthup.gif


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## trademarktm (Jan 15, 2007)

*Intank fuel pump!!! I need serious help pleaseeeeeeeeee*

Ok, So i changed the fuel pump because it froze up on me and blew #28 fues (fuel pump). I took fuel pump out and benched tested it with a car battery. The little fins on the bottom would not spin (not even sure it they are supposed to). So I buy a new audi tt 225 drop it in and engine starts right up. I can now see that I am getting fuel pressure. However, I crack the nipple on top of assembly so I take it back out to fix, drop it back in and blow another fuse. car will carnk but not turn over. WTF is going on. I take the new pump out and bench test this and it its doing the same thing. Is there something I am missing here.
Now I have a complete fuel pump assembly sitting around with a fuel pump from a 2002 jetta 1.8t. Lets say I drop this whole assembly in my stage 3+ can I just get an inline fuel pump and drive it soft for a week or so till I buy the inline pump?

My car is a 2004 gli 1.8t awp




_Modified by trademarktm at 8:17 PM 6-4-2008_


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## trademarktm (Jan 15, 2007)

bump for help


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## mirror (Dec 18, 2006)

*Re: (trademarktm)*

yes you can. 
check your connector at the pump. something is grounding out.


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## enginerd (Dec 15, 2001)

*Re: (mirror)*

If you are siezing pumps I bet you have some nasty water in your fuel.


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## trademarktm (Jan 15, 2007)

*Re: (enginerd)*

Ive re checked the conections over and over. Im starting to think it is contamination of some kind. There was one thing I did different when all this started. I always keep the gas at 1/4 tank and less. Ive been doing this for a year. Then I was going to take a drive to the west coast of Floirda so I filled the tank all the way up. Hours later is when all this started to happen.


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## ruetzal (Dec 17, 2007)

*Re: (trademarktm)*

actually keeping your gas tank filled up cools the fuel pump when it gets low that doesn't cool the fuel pump and your most likely to blow the fuel pump out.


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## trademarktm (Jan 15, 2007)

*3 fuel pumps failed on me on 3days..... Whats wrong???*

At this point I know I need to take to the dealer to have checked out. Im done with car. The problem is, the car is modded. Will they even work on it??? 
Was going to leave work and car wouldnt start #28 fuse blown (fuel pump fuse). Took the pump out and bench tested it and it was frozen, it would click but no run. 
So put a new one it and started right up. I let it idle and turned it off. Next day I go to start up and fuse is blown again, replace the fuse and same thing fuse blows and car wont start. 
Took it out and benched tested it and its frozen. So I go buy a used assembly from buggydoctor.com and we bench test it there and its working fine. 
Drop it in the tank and frozen again. I dont think it even started pumping fuel out before it froze. Took it out and benched tested it, same thing as all the rest.
I cleaned the tank to make sure there are no particals on bottom of tank that could cause it to freeze. 
I can get a new pump and assembly for 45 dollars that works and put it in but this is likely going to happen again. What other things should I have checked. Pump relay is fine, I had an extra to test it. I am getting power to the assembly, I checked that. 
THe car is a 1.8 gli 2004. Any ideas because I have about 2 weeks before I can even afford to have someone look at it.


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## dirty2003 (Feb 4, 2008)

*Re: 3 fuel pumps failed on me on 3days..... Whats wrong??? (trademarktm)*

i would check all your wiring... you might have something that is causing the pump to fry its self which in turn also blows the fuse... i had a problem kinda like that and it was from my exhaust frying wires and causing fuses to blow...


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## Old Dude GTI (Dec 25, 2007)

But that wouldn't fry the pump since a short would not fry the pump. And isn't there a screen on the pump to keep out debris?


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## trademarktm (Jan 15, 2007)

*Re: (Old Dude GTI)*

If anyone wants to add any input to what I should inspect than feel free


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## enginerd (Dec 15, 2001)

*Re: (trademarktm)*

Drain the monkey piss fuel out - use it for your lawnmower. siphon it out 
Replace the fuel filter in case it's clogged. 
Try again with a new batch of fuel. It could be water contamination, not just debris contamination that can kill a fuel pump. 
I have a spare in tank pump ill sell you for 50$. But I can't ship till monday.


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