05 Baja Turbo Overfueling - Looking for Fuel Pump?

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nmibaja
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05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by nmibaja »

Hi everyone. It is a year later, and my Baja has acted up again. This time with an overfueling issue. We're talking fuel out the tailpipe, liquid locks, all that.

I sent it away to a Subaru specialist shop across the state, and it has been there over a month now. (Busy shop, not enough mechanics)

They've been troubleshooting it, and so far we put OE injectors into it, as I had some cheep ones from before. And they say it seems better, but is still overfueling (fuel out the tailpipe, etc).

They've looked at my one year old fuel pump, and told me that it is the wrong one. There is a Subaru number on it: 42021AE06B. But apparently, my car is supposed to have a 42021AE08B in it. That frustrates me on a couple levels, as I looked hard to get the right one last time, and ended up on a new Bosch unit that was supposedly for my 05 Turbo. That 06B number codes to only NA Bajas.

And, I drove it over 15K miles over the past 12 months, without a single problem. Then this.

I have a few questions for everyone:

1. Where can I get the proper fuel pump? Subaru discontinued them.
2. What the heck could the difference be between the NA and the Turbo pump anyways? (that would allow it to run fine for a year, then suddenly start overfueling?)
3. Point of debate between myself and the mechanic; is the 05 Baja Turbo fuel pressure regulator a return to tank system? I thought that was how the FPR worked; by bypassing a certain amount of fuel back to the tank to regulate the pressure. The mechanic said it wasn't a return to tank system. I'm just curious now.

I'm just super frustrated at this point. I sent it away to be fixed, because I didn't want to just throw parts at it, and it seems that might end up being the solution....and I'm in the hole $1500 so far with all the troubleshooting they've done.
Last edited by nmibaja on Wed Aug 11, 2021 7:09 am, edited 1 time in total.
Reddog
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump

Post by Reddog »

Try :
https://www.subarupartsdeal.com

Put your VIN in and search for Fuel Pump

This is what it shows for 05 Turbo but i selected Auto. Could vary.

2005-2006 Subaru Baja 42022AE01B
mike-tracy
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump

Post by mike-tracy »

I have an 01-04 H6 Outback fuel pump in mine, it was a bolt in. I'd imagine since that engine and yours is rated roughly same power, it would be plenty of fuel for yours. It is different from a 4-cyl non-turbo pump.

I've swapped an 05ish STI fuel pump into my old Legacy turbo, that too was a direct fit (talking about just the pump, not the plastics and etc). That one would definately have enough flow for a stock turbo baja
1992 Legacy SS, 5mt and heavily modified
2000 Impreza RSTi Coupe
2003 Baja, H6 and Dual Range 5mt swap
nmibaja
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump

Post by nmibaja »

Thank you for the link to that Subaru parts site Reddog , that p/n you mentioned is in fact the pump that goes into the proper assembly. :)

I will go that way, if needed.

An important thing that I am asking myself right now, is "Can the fuel pump even be the problem here?"

This is a one year old Bosch pump assembly, that had the car running perfectly for a year (16,000 miles); with decent mpg as well (23mpg consistently).

Could this pump suddenly be overpressuring the system all on it's own? That's the part of the repair shop's conclusion that I'm not buying into.

In talking to them, it seems like the main reason they want to replace the pump, is that it isn't the proper Subaru unit p/n.

They have NOT performed a fuel pressure check, even though I have asked them to several times.
20Baja06
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump

Post by 20Baja06 »

I can only think of a couple things that would allow for over fueling that badly, neither of which is the fuel pump:

1) Stuck open injectors
2) No spark, allowing injected fuel to pass through the cylinder and exit out the exhaust.

Fuel can only make it to the exhaust / tail pipe through the combustion chamber. There is no other path for it. In any case, I would at least suggest an oil change as well as that much fuel would almost certainly make its way past the rings and into the oil pan.

I would imagine the only difference in the fuel pumps is flow rate, since non-turbo engines generally need less fuel supplied than turbo engines. I don't have access to my service manuals to double-check that is a fact, but I've seen that as the common trend in other makes and models with N/A and turbo versions. Using the non-turbo fuel pump may not have as much of an effect on the daily commuter as it might someone who is always pedal to the floor. Depends on how you drive the car.
-Brian
nmibaja
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by nmibaja »

Agreed on both points, 20Baja06

We mostly ruled out the injectors, by replacing all four of them. We had to go with used ones, but they were tested on the bench before being installed.

They checked the spark on all cylinders as part of the tests; and did actually sort of get it running after swapping the injectors, so maybe it helped (?) a little.

Oil was changed once, when the injectors got swapped. And it does need it again, before any idling/running takes place.

I contacted them today, and have requested that they do the fuel pressure test, please. That way we can get some direction on this problem.

If the pressure is actually too high, then we can go down that merry road of looking at return lines, regulators, and maybe even pumps.

If the pressure is normal, and it is still overfueling, then that would indicate more of an ECM problem. To me anyways.

I've heard that those can go bad sometimes, and screw with your fuel delivery, via how long/how much it lets the injectors pulse.
mike-tracy
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by mike-tracy »

It sounds too simple, but is the vacuum line on the fuel pressure regulator in good shape and connected properly?
1992 Legacy SS, 5mt and heavily modified
2000 Impreza RSTi Coupe
2003 Baja, H6 and Dual Range 5mt swap
20Baja06
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by 20Baja06 »

nmibaja wrote: Wed Aug 11, 2021 12:58 pm Agreed on both points, 20Baja06

We mostly ruled out the injectors, by replacing all four of them. We had to go with used ones, but they were tested on the bench before being installed.

They checked the spark on all cylinders as part of the tests; and did actually sort of get it running after swapping the injectors, so maybe it helped (?) a little.

Oil was changed once, when the injectors got swapped. And it does need it again, before any idling/running takes place.

I contacted them today, and have requested that they do the fuel pressure test, please. That way we can get some direction on this problem.

If the pressure is actually too high, then we can go down that merry road of looking at return lines, regulators, and maybe even pumps.

If the pressure is normal, and it is still overfueling, then that would indicate more of an ECM problem. To me anyways.

I've heard that those can go bad sometimes, and screw with your fuel delivery, via how long/how much it lets the injectors pulse.
I'm not sold that it's actually a high pressure situation as they think it is, either, so I definitely agree with your train of thought.

Keeping in mind that pressure is resistance to flow, I'm not seeing how the pump is "creating" an over-pressure situation, especially in an idle scenario. Something after the pump has to be restricting flow to cause high pressure. And if something is restricting flow causing high pressure, then the injectors certainly aren't stuck open.

Curious to see what the results are, and although I'm still learning these trucks / engines, my mind also went to the ECM in that changing injectors didn't affect anything. Keep us posted!
mike-tracy wrote: Wed Aug 11, 2021 1:06 pm It sounds too simple, but is the vacuum line on the fuel pressure regulator in good shape and connected properly?
If the vacuum line is not connected or cracked / broken, would the fuel pressure ever rise above the regulator's spring pressure?
-Brian
ZUBAJA
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by ZUBAJA »

Vacuum applied to the fuel pressure regulator REDUCES pressure by opening the return line (idle = high vacuum, less fuel). A LEAKING diaphragm in the FPR could cause fuel to be sucked straight into the intake, but any half good mechanic should go for this instantly. Dennis
nmibaja
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by nmibaja »

I checked the vacuum line to the regulator before I sent it off to the shop, and it wasn't pushing fuel through it at that time. As to whether it could be leaking? I didn't check for that.

I would hope it isn't a hole in the FPR diaphragm, as I installed a brand new, Subaru FPR, last summer.

There is a possible smoking gun, in the form of the fuel line going to the FPR. It is looking not so good to me (possibly partially kinked?). And I asked the shop to look at it especially. Something that they did not do. Even when they took off the intake manifold, which would have been the golden time to access that short length of hose.
20Baja06
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by 20Baja06 »

@nmibaja

Any updates to this issue? I'm curious what the diagnosis is!
-Brian
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by nmibaja »

I'm arranging to pay the troubleshooting bill today, and get it shipped back to me. I will be able to do some work with it this weekend probably.

The shop still insists it is the fuel pump; I still insist we should probably try a fuel pressure check first. And that's the basic disagreement, and why I'm taking it back still not working.

I plan on buying a fuel pressure test kit from NAPA or something, and seeing what I can see with that.

Also: I ordered a new fuel pressure "IN" hose that goes into the FPR; as the one that is on there is a straight one, that is bent for the application, and is partially kinked, and could very well be the problem all by itself. That should be here this week as well. But I'm going to do the pressure test first, just to see.

Does anyone happen to have a pressure chart that might show what fuel pressure should be at a given manifold pressure? I have one of those hand pump vacuum/pressure testers, so I think I can apply either a set vacuum or pressure to the fuel pressure regulator sense line; which should allow me to vary the fuel pressure for the testing?

Or maybe does anyone know what a Baja turbo should be producing for vacuum/pressure in the manifold at a normal idle?

Since the car isn't running, I wanted to fake it to get some "idle" numbers....

If I pull the plugs, so I don't get any fuel sitting in the cylinders, I should be able to crank it and get some useful readings from the fuel pressure test gauge anyways, I think.

I will post anything I find.
nmibaja
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by nmibaja »

I got the car flat-bedded back to me on Thursday. I couldn't resist, and tried starting it.

It fired right up, and idles for a hot second or two, then drowned and died.

I didn't get a chance to work on it this past weekend, I got roped into rebuilding an old utility trailer to help the in-laws move.

I got my small length of pre-bent hose going to the FPR from Subaru, so that's ready to go in, probably before I do the pressure check. Might as well replace what I can physically see is not good, right? Not fun to reach, not looking forward to it.

Soon.
nmibaja
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by nmibaja »

PROBLEM FIXED!

I finally found half a day to work on it, over the holiday weekend.

I believe the fuel overpressure was caused by that short, 45 degree bent, fuel hose that goes into the Fuel Pressure Regulator. I can't confirm if it was 100% blocked by the kink in the straight hose I had on there; but it was definitely restricted.

Part number for the hose is 807707111 on the Subaru parts pages; and it's about $4.00 USD.

For the curious, this is what I removed and reinstalled to access it:

- Top Mount Intercooler and Y pipe
- Short "S" tube from bleed valve to turbo intake
- The turbo intake assy (and all the associated little tubes/fittings)
- Vapor canister purge solenoid (and that little rats nest of vacuum tubes in front of it)

Doing all that, got me pretty clear access to get the old crappy straight hose off; and the new 45 degree pre-bent hose back on, with new fuel line clamps as well.

Leak checked, then reassembled everything; and it started up on the first crank. Purred like a kitten.

An oil change, and I was off for a Sunday drive.
InkedFPR Parts Diagram 2005 Subaru Baja Turbo_LI.jpg
InkedFPR Parts Diagram 2005 Subaru Baja Turbo_LI.jpg (692.84 KiB) Viewed 3041 times
20Baja06
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Re: 05 Baja Turbo Overfueling - Looking for Fuel Pump?

Post by 20Baja06 »

Great news! Glad it wasn't too difficult of a fix.

Thank you for following up!
-Brian
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