Fuel pump test - fuel supply line location

[The Grizz]

I wanted to test the fuel pump by pulling a supply line and seeing if there's any pressure on start up.

I was wondering if the top tube on the fuel rail was the supply line.

Thanks.

[veeyarrSUPERsix]

They normally have arrows on them or on the rail...

[The Grizz]

That's what I was looking for but there are no markings on the lines at the rail or on the rail. The lines look like they have been replaced.

[veeyarrSUPERsix]

Sorry. Can't off the top of my head remember top or bottom. I want to say top though. Look at the rail, whichever has the separated hard line coming out of the fuel pressure regulator is the return

[The Grizz]

thank you.

so the FPR regulates after injection?

I'm trying to go through the motions and figure out why this car cranks away but wont turn over.

[dogyouare]

well i think its the top fuel line as well one way to know bump the ign and see where fuel comes out. also the fpr is located on the fuel rail end (tranny side). now did u check to see if it got spark? check for code?

[The Grizz]

well I've ran vag com a couple times and it hasn't found anything

and I haven't checked for spark because...

sometimes the car starts. After a failed attempt to start I will leave the key in ON position, after some time the CEL will light (I can hear the throttle adjusting and I possibly hear the fuel pump prime) and I can crank it and the engine will fire up. When it finally turns over the CEL turns off and the car will sometimes run for 15 seconds and kill itself or it will run perfectly.

coil, plugs and wires have about 7k on em.

I figured to check fuel supply. Is this a bad assumption?

If I pull the supply line from the rail and attempt to start the car I should get a nice stream of fuel shooting out of the line, correct?
If no fuel is present, can I assume the pump is shot?

[dogyouare]

check relay and fuse but after u crank for long time did u smell gas from tail pipe? or even backfire? u might have fuel go in. or pull ur plug and see if it has gas on them

[The Grizz]

Though I haven't table top tested a relay with a 12V supply I can feel it "click" when I turn the key to start.

I don't smell gas at all when cranking away on the engine either.

What is consistent though is

failed attempted start > CEL light > throttle body high pitched tone > successful start

though sometimes throwing the CEL light doesn't happen.....

[veeyarrSUPERsix]

thank you.

so the FPR regulates after injection?

HIgh pressure from the supply is laid out across the while rail and the excess pressure is taken out by the regulator and recycled to the ta nk via the return.

As for your problem, I would start by replacing the ignition switch. Buy it from germanautoparts.com and look in the mk3 faq/diy thread for two ways to do it.

[The Grizz]

well that would be nice considering the replacement price of a switch vs fuel pump.

does a faulty ign switch effect the function of the pump? or something that controls the pump?

[dogyouare]

usually ign switch cause weird problem. common issue is vehicle will have power but no crank issue. but im saying that that might be possible issue as well but... do no fuel comes out on any lines? did u jump the fuel pump or see if u had 12v going to it? it primes when key is on "ON" position for 3 to 5 sec and then while u crank. because of nature of how relay works it might have carbon build up so in sever case and it does happen contacts gets bad internally also pull it out and look at prong to see if you have heat damage on any prong if it does replace it! Dont for get to use VW Bible

[The Grizz]

visually inspected 167 relay in slot 12 - looks good but I understand about carbon buildup

Im going to take a voltmeter to the pump later today.

When should the pump have 12v going to it? does the key need to be in ON or START position?

I've ran across different info on pump priming - I've read it only primes when cranking and I've also read that it primes with key in ON position....

[veeyarrSUPERsix]

On a mk3 the pump should prime when the key is turned to on. Remove the relay and put a jumper wire between the two big pins I believe it's 86 and 87 to get constant power to the pump with the key on. I forget the hot wire color on the pump harness but I know ground is brown and the purple with black stripe is fuel level signal.

For $13 the switch gives you great piece of mind. The last one I did took me less than 25 minutes. I use the method where you remove the whole steering column and that's the 5th one I've done. That thing controls so many things and does very odd things when it starts to go bad...

[The Grizz]

Thanks for your input on this.

I replaced the switch and I'm still getting the same start up difficulty.

I wanted to clarify the relay jump- do I take a small gauge wire and jump from 86 to 87 and turn the key to ON and expect to hear the pump running in the back of the car?

I'm going to post another thread about "no start - CEL - Throttle adjustment noise" to see if someone has run across this before.

Thanks again and any other input would be appreciated

[brian500]

First of all dont do it that way. Top hose is feed. Take it out put it in a bottle crank it check for fuel. To test the pump the easy way is to take a piece of wire stick it in M2 then touch the Y slot for power.

[clvpr2]

I sorta have the same problem turn key no prime from fuel pump hooked battery up to fuel pump started right up. now my fuel pump doesnt work picking up a new one thursday. checked to see if i was getting a signal to pump and its getting signal, steady 10 volts or so when i turn the key. any thoughts? heres a link to my thread

http://forums.vwvortex.com/showthrea...me-help-please

[The Grizz]

Thanks for the direction on this pump test. I'll have to check it out when I get home.

couple quick questions though....

If I pull that top line and send it into a bottle a properly working pump will feed fuel while cranking the car correct?

Also, that colored board you attached (thank you for that) - is that located above the relays?

Thank you

[dogyouare]

this might help

http://www.a2resource.com/electrical/CE2.html

[brian500]

If everything is working properly then yes it will pump fuel into the bottle. The pic that i posted is the back of the fuse box. If you look at each slot it has a letter and inside of the slot have numbers which are for the pins. so you want to put a wire into m2 and use the y slot for you power source.

[The Grizz]

Thanks for all the help.

I've just gotten back in town and want to try this jump but wanted to find out one more bit of info. Sorry for my late response.

Should I perform the M2 to Y jump with the fuel supply line removed from the rail and then attempt to start? I'm assuming yes because of possible flooding potential.

Also, I did remove the top line from the rail and can confirm that while turning the key to START and cranking the engine no fuel is discharging from the line.

I've didn't wait for the ECU light to turn on and then attempt the start with the line off. I do know the car will start when the light does come on though.

Can this be a potential ECU problem? Should something be reset or is there a vag com test I can perform? Again, this seems so odd because once the car fires up it normally runs perfectly and only sometimes will start and run for 15 seconds and suddenly shut down.

Thanks again

[brian500]

Yes for m2 to Y. What is the part number on the ecu?

[The Grizz]

Address 01: Engine Labels: 021-906-259-AES.lbl
Part No: 021 906 259


Is this the part number.

I can remove the rain tray and check if needed.

Thanks

[The Grizz]

It's definitely a delayed priming issue.

The line will supply fuel after some time of having the key in the ON position. Until the CEL lights up there is no priming with the key in ON.


Random note-
Another variable that might have some effect is the extreme heat - it seems that the last couple of days, which have been 20 degrees cooler than the 90+ days we have had for the last month, the time of the CEL illuminating has happened much quicker. During the heat I waited for a minute or two for CEL, whereas the last couple of cooler days the CEL lights up in seconds.

any other ideas?
Appreciate the help.

[brian500]

Yes if you can. But is your car a swap?

[The Grizz]

car is not a swap.

only motor tune is a c2 chip and a high flow air intake.

Another random note-

Whilst accelerating around 80mph last night the car choked up twice in quick succession and each choke lasted a half second. wasn't a good feeling. CEL lit up in synch with the choke.

[brian500]

I wanna say its the chip

[The Grizz]

so you think it may be the chip. not the ecu?

after the choking effect last night I want to dial this problem down.

Thanks for your help.

[brian500]

On the other hand it does sound like a vss cut out were you cruisin or were you reving out. And is it a swapped car?