1G No power after 3,000 rpm

[krayola]

I have a suspicion it's my fuel pump but before I order another new pump I thought I'd ask.

93 TSI stock 6 bolt with a big 16G. Stock 450 injectors, walbro 255 pump. No tune.

I'll be driving like we do and it will Intermittently not let me go past like 3,000rpm. It acts like the fuel is being cut. If I push in the clutch it will let me go to red line. If I shut it off and start it again, it will let me go to red line again.

My pump is only a year old but it is most likely a knockoff. It's very loud. Not like a humming that I can hear if I listen. It's obnoxious. It starts off not so bad and gains volume till its almost ear piercing.

It's gotta be the pump, right?

 

[pauleyman]

You are wild ass guessing. No it does not have to be the pump. What have you diagnosed? Measured? Visually inspected? Jiggled? Codes? Tell us what you've done so far.

Also please fill out a profile. We know nothing about the car without that.

 

[4G63510]

I once forgot to hook up my TPS sensor and it wouldn't rev past 2500rpm I think. Wires get old and brittle over time, so I would look at wiring first. It could also be a MAF issue. My guess either way is wiring. Do what @pauleyman suggested and jiggle some wires.

 

[krayola]

Thanks for the direction. I had a couple set backs I had to fix before I went on to try and resolve my issue.
My pump is overbearingly loud. If it's not my pump than the issue can wait till I resolve the noise issue.
I was back there tonight. I put my meter on the hot wire to my pump. 13V. The pump goes through a relay. As I moved wires, the pump changed sound.

 

[krayola]

Oh no.
While I was typing that, I realized I don't have a fuel return line.
That's my issue, isn't it?

 

[pauleyman]

Why wouldn't you have a fuel return?

 

[krayola]

Why wouldn't you have a fuel return?

Cause I'm an idiot.
My sending unit was in bad shape. I had to fix it and I ended up modifying it a lot. I don't recall eliminating the return line under the hood but I must have because I don't have one on the sending unit anymore.
Just went out for this picture. What's the line on the right? I can't remember and it's too late to dig into tonight.

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[We're on Boost]

Just went out for this picture. What's the line on the right? I can't remember and it's too late to dig into tonight.

That line on the right with the blue thing in it is a vapor hose, not the return line. The blue thing is called the Overfill Limiter. It's a 2-way valve. The way I understand that is it is normally closed but a small amount of pressure in either direction will open it to flow air, vapor, or whatever.
The vapor hose is #5 in this diagram and the blue overfill limiter is #15.

The Return Line is shown here as #4. You can see it goes into the tank way forward of the fuel pump sending unit. I don't think you can see it looking like the view of your picture. Anyway it has nothing to do with the sending unit.

I'd be pretty surprised if you somehow accidentally removed the return line. You would have had to plug it somehow, or there would be fuel pouring out somewhere.

Actually it looks like you did some nice work on the sending unit. The hose 90 degree elbow fitting, and the electrical. Looks pretty neat.

Pump sound changing when you move the wires around is a little weird.

Take a look at the sock that's on the pump inlet before you order a new pump. The sock might just be clogged up real bad.

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[krayola]

Thank you. I did buy a new pump but I am hoping to not have to put it in. It just came yesterday. The wiring just after the sending unit goes to a relay. That has been messed with. And I spliced into it to hook up my pump. Orange connector is me. My wire is pretty thin. Could that have anything to do with it?

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[pauleyman]

Let's start with what maintenance have you done? If car sat that long have you addressed the basics? Emptied gas tabk? Fuel filter? New plugs or you just know they're ngk?
You should protect those wires from the cam gears.
I agree with other boost leak test also. If it drives well at part throttle past 3k that's a definite possibility of leaks.

 

[krayola]

The car runs and drives good most of the time. I can start it right now and rip all the way through all the gears. It sometimes will act up where it won't accelerate for shit over 3,000.

Maintenance is good but ok, let's do it.
This is everything I can remember.
I bought the 6 bolt to replace the wrecked 7 bolt. Head rebuilt by a buddy. I assembled the engine. Ported intake manifold if i remember correctly correctly. New clutch. Good used 16g. Spark plugs and wires, Engine transition gear oil, radiator flush, oil filter, air filter, fuel filter, walbro 255 fuel pump, pump stock, checked Injectors, cleaned the tank very well, new gas lines from the pump to the filter, vacuum lines, belts, grenade tensioner. Sent the non eprom ecu in to repair and prep for link. New alternator, battery, windshield washer tank and pump, 300gt brakes, CV axles, bypassed hazard switch, fuel gauge from a spare cluster, left tail light assembly, and a handful of bulbs and fuses.

I did not do anything with the fuel pressure regulator. Still have stock 450cc Injectors, stock inner cooler.

The car will run and drive great while the pump is screaming like in the video I posted. The pump sounds like that all the time. That is why I think it's a bad pump My friend ordered it for me and I don't know if he ordered it from a credible site. It may be a cheap knockoff. I also now believe it may have something to do with wiring.

 

[Jk's97DSM]

I’d put a new Walbro in it and fix/change that wiring. The whine is generally a sign but then again if voltages go crazy I’ve seen the same.

 

[We're on Boost]

The car will run and drive great while the pump is screaming like in the video I posted. The pump sounds like that all the time. That is why I think it's a bad pump My friend ordered it for me and I don't know if he ordered it from a credible site. It may be a cheap knockoff. I also now believe it may have something to do with wiring.

We didn't see this line (green arrows) in your first picture, but it's in the video.
Where your fuel line comes out of the 90 degree elbow, does it loop around to the right and come back behind and then go forward again into the remains of the original 1993 fuel line where the green arrows are?
If that's what it's doing, it might be getting kinked or pinched somewhere in that loop under the floor of the trunk where we can't see it.

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[krayola]

I’d put a new Walbro in it and fix/change that wiring. The whine is generally a sign but then again if voltages go crazy I’ve seen the same.

I bought a summit racing pump I was going to try if all else fails.
Why does everyone use walbro?

We didn't see this line (green arrows) in your first picture, but it's in the video.
Where your fuel line comes out of the 90 degree elbow, does it loop around to the right and come back behind and then go forward again into the remains of the original 1993 fuel line where the green arrows are?
If that's what it's doing, it might be getting kinked or pinched somewhere in that loop under the floor of the trunk where we can't see it.

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I hid that line cause it has been eliminated. I just haven't pulled it yet. Fuel line is all new from the pump to the filter.

I’d put a new Walbro in it and fix/change that wiring. The whine is generally a sign but then again if voltages go crazy I’ve seen the same.

Could you get me a photo of your wiring? I got no clue what it suppose to look like. I'd like to eliminate that relay and put in heavier wire to the pump.

 

[We're on Boost]

I hid that line cause it has been eliminated. I just haven't pulled it yet. Fuel line is all new from the pump to the filter.

Good.

I'd like to eliminate that relay and put in heavier wire to the pump.

Actually the relay is how you get heavier wire to the pump.

The relay has a switch and an electro-magnet. The electro-magnet is what pulls the switch to on or lets it go to off.

The switch has 2 terminals that are numbered #30 and #87.
Your #30 has the big fat red wire to it which should be coming straight from the battery (with a fuse inline). That looks correct as you have it, except of course the pics don't show it all the way to the battery so we don't see that. It looks like a 10 gauge wire and that would be good, that's what most of us use for the "rewire wire".
Your #87 has the black and white wire to it which should take power to the fuel pump when the switch is on. That looks correct as you have it, except I can't really see it all the way to the pump terminals that are under the lid of the sending unit. That's where it should go. But can't see it all the way so maybe there is a problem there somewhere.

The electro-magnet has 2 terminals that are numbered #85 and #86.
Your #86 has a wire to it which you have labeled "wire into loom". This wire into the loom should be the wire that originally went all the way to the fuel pump in the OE system. Now what it does is it powers the electro-magnet in the relay and that's all it does. Shouldn't go to the fuel pump anymore.
Your #85 has a wire to it that goes over to the body sheet metal where it's attached with a screw - so that's the ground for the electro-magnet, and that is correct.

You mention somewhere "I spliced into it to hook up my pump. orange connector is me".
I don't see an orange connector. Don't see where you spliced into it.

Obviously the pump is getting power because it runs. The relay seems basically wired correct so I don't know why or what you spliced into it to hook up the pump.

Something you should do is look at the routing of the big fat red wire through the engine bay. It should not be laying across the steering column where the insulation will get worn through causing a short. Seems like a dumb thing to say, but it happens. Follow that wire all the way to the battery and find the inline fuse holder which should be very near the battery. Open the cap on the fuse holder and look at the fuse to see that it is not blown. Now you know where the fuse is for your fuel pump. For a Walbro 255 that should be a 25 or 30 amp fuse. Walbro would say a 25 probably but I think most of us are using a 30.

Why does everyone use walbro?

People use Walbros because they are really reliable, and they fit pretty well in our DSM applications. The install kits they come with are about right. They publish charts that show flowrate vs pressure, and current draw vs pressure. So when you have a Walbro you know what you have. It's not a big mystery.
I don't even know what a Summit pump would be. Summit is not a fuel pump manufacturer. They would be buying pumps that are made by "somebody". I think Summit is a good company so the pumps they sell with their name might be just fine, hard to say!

 

[dwb]

I didn't see any mention of an aftermarket fuel pressure regulator. So if you have a walbro255 but a stock FPR, you may have ruptured the diaphragm inside the regulator. Take the vacuum line off and see if it is wet or smells like fuel.

Man, that pump sure does scream. From the video it sounds much louder than my brand new 255. Maybe because the cover is off...idk

 

[pauleyman]

Could you get me a photo of your wiring? I got no clue what it suppose to look like. I'd like to eliminate that relay and put in heavier wire to the pump.

You need the relay. How else would you turn the pump on and off?

 

[1990TSIAWDTALON]

T I Industries 525 pump, rewire kit, AFPR and proper plumbing and the fuel system is good for plenty of HP and fuel delivery.

 

[Jk's97DSM]

I didn't see any mention of an aftermarket fuel pressure regulator. So if you have a walbro255 but a stock FPR, you may have ruptured the diaphragm inside the regulator. Take the vacuum line off and see if it is wet or smells like fuel.

Man, that pump sure does scream. From the video it sounds much louder than my brand new 255. Maybe because the cover is off...idk

I typed it then backed off because I think the main issue is the pump just from the noise.

 

[krayola]

You need the relay. How else would you turn the pump on and off?

I guess I assumed the pump was always on while the car was running. My wiring looks like someone hacked away at it at one point so I would like to see what stock looks like, or modified with no issues.

 

[TuskeeTuner]

It's good that the pump actually operates without burning your car to the ground. The area in the back could use a vacuum and some cable management. Somebody mentioned they saw no mention of an FPR in your setup. If you're running a Walbro 255, you need an adjustable FRP or the car will run like shit/too rich, your spark plugs will foul up, and you'll dilute your oil. Get a good, stable, predictable platform before adding another big fuel pump.

The Black/white stripe wire goes all the way up to the MPI relay next to the radio and the ECU. The black wire (purple arrow pointing to 'wire into loom') that disappears into the wire loom is the factory ground for the fuel pump. I think you should just build a new ground wire with 10 gauge wire, a 4-6 mm terminal lug for the sender, and ground the other end to either the parcel anchoring point or the child restraint bolt using new stainless steel hardware.


"I guess I assumed the pump was always on while the car was running. My wiring looks like someone hacked away at it at one point so I would like to see what stock looks like, or modified with no issues."
Do you need a photo illustration of how the wiring looks or just a wiring diagram manual?

FSM wiring diagrams 1990-1991
FSM wiring diagrams 1992-1994
FSM wiring diagrams. I know they're long at 1200 pages, but it will make you look like a genius to people who can't figure out wiring. I've got pages printed, 3-hole punched in a binder for when I work on my ride.

I'm still un-hacking a bunch of wiring on my car; and just so happens that I'm working on fuel pump wiring - it's fresh on my mind.

Why is there so much 'dirt' in the back of the car? Was it flooded out??

 

[pauleyman]

I guess I assumed the pump was always on while the car was running. My wiring looks like someone hacked away at it at one point so I would like to see what stock looks like, or modified with no issues.

It does but the purpose of the relay is also to shut it off when the car isn't running. You trigger the relay with the stock small wiring but the relay allows you to control larger gauge wire direct from the battery.

 

[krayola]

Why is there so much 'dirt' in the back of the car? Was it flooded out??

It spent a 3rd of its life sitting around waiting to be saved. Some in a back yard, some in a excavator lot, some in a big shop with a dirt floor.
I don't think it's been flooded.

It does but the purpose of the relay is also to shut it off when the car isn't running. You trigger the relay with the stock small wiring but the relay allows you to control larger gauge wire direct from the battery.

Ok. That's what I was thinking, the little wire going to the loom is the control wire. I looked up a thread on wiring and a guy has an image of my relay and wiring but the 12v and the pump wire are switched on his compared to mine. How would I know if I do t have them backwards? I'd imagine it wouldn't matter but I'm not a relay expert.

 

[We're on Boost]

I looked up a thread on wiring and a guy has an image of my relay and wiring but the 12v and the pump wire are switched on his compared to mine. How would I know if I do t have them backwards? I'd imagine it wouldn't matter but I'm not a relay expert.

The relay we are talking about is a standard Bosch type relay which has standard numbering on the 4 or 5 pins. Yours is a standard 4 pin. The numbering and how each pin is used is exactly how I wrote it in post #15.
If you have a diagram from someplace for how to do this rewire, the diagram will probably show the pin numbers, and they will be the same as I wrote in post #15.
The numbers are generally molded right into the plastic body of the relay. I can even see one of them in one of your pictures. The number I can see is 87.
The wires to pins 85 and 86 can be either like you have them, or reversed. Either way, doesn't matter.
Some relays even have a nice little map (schematic) of what's inside the relay and what each pin does, and the current ratings. Like this one does. I'm sure your relay is just like this except yours doesn't have 87a which is good, 87a you don't even want really. You just want 87:

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[krayola]

Good.


Actually the relay is how you get heavier wire to the pump.

The relay has a switch and an electro-magnet. The electro-magnet is what pulls the switch to on or lets it go to off.

The switch has 2 terminals that are numbered #30 and #87.
Your #30 has the big fat red wire to it which should be coming straight from the battery (with a fuse inline). That looks correct as you have it, except of course the pics don't show it all the way to the battery so we don't see that. It looks like a 10 gauge wire and that would be good, that's what most of us use for the "rewire wire".
Your #87 has the black and white wire to it which should take power to the fuel pump when the switch is on. That looks correct as you have it, except I can't really see it all the way to the pump terminals that are under the lid of the sending unit. That's where it should go. But can't see it all the way so maybe there is a problem there somewhere.

The electro-magnet has 2 terminals that are numbered #85 and #86.
Your #86 has a wire to it which you have labeled "wire into loom". This wire into the loom should be the wire that originally went all the way to the fuel pump in the OE system. Now what it does is it powers the electro-magnet in the relay and that's all it does. Shouldn't go to the fuel pump anymore.
Your #85 has a wire to it that goes over to the body sheet metal where it's attached with a screw - so that's the ground for the electro-magnet, and that is correct.

You mention somewhere "I spliced into it to hook up my pump. orange connector is me".
I don't see an orange connector. Don't see where you spliced into it.

Obviously the pump is getting power because it runs. The relay seems basically wired correct so I don't know why or what you spliced into it to hook up the pump.

Something you should do is look at the routing of the big fat red wire through the engine bay. It should not be laying across the steering column where the insulation will get worn through causing a short. Seems like a dumb thing to say, but it happens. Follow that wire all the way to the battery and find the inline fuse holder which should be very near the battery. Open the cap on the fuse holder and look at the fuse to see that it is not blown. Now you know where the fuse is for your fuel pump. For a Walbro 255 that should be a 25 or 30 amp fuse. Walbro would say a 25 probably but I think most of us are using a 30.


People use Walbros because they are really reliable, and they fit pretty well in our DSM applications. The install kits they come with are about right. They publish charts that show flowrate vs pressure, and current draw vs pressure. So when you have a Walbro you know what you have. It's not a big mystery.
I don't even know what a Summit pump would be. Summit is not a fuel pump manufacturer. They would be buying pumps that are made by "somebody". I think Summit is a good company so the pumps they sell with their name might be just fine, hard to say!

Thank you for all that info. I finally for an hour to swap the Summit/AEM pump in. The stock was a little dirty to my surprise. I did clean it very well twice and put that pump in last year. The wires I used are very small. Like, 12g or probably 14g. I'll rewire that later. The splice is just the 2 wire connector I used. I can plug and unplug the sending unit in with it. Gas level and fuel positive.
I took the car for a drive after doing the swap. I got on it pretty good too. Nice and quiet the whole time. No cutting out. I went only about 6 miles round trip though. Well see how it does one the next few days. If I don't get any cutting out after a week of driving it I'll put up a resolved post.