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bnoon · Posted: Fri Jul 30, 2010 11:07 am Post subject: Fuel pressure issues AGAIN!!!

WTF?!?!? I replaced the pressure pump with a brand new one and it ran great on the way to work (about 5 miles). After work, barely started, and I sputtered around the parking lot a little bit and didn't want to chance it. I got a ride home and came back with some tools and my fuel pressure tester and I've only got about 40-50 psi pressure. HELP!!!

Dizzy is currently shimmed to where just last week it held 100 psi. If I un-shim it, it drops to 30-40 psi. Something ain't right.
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Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

Just a few shots in the dark. Fuel filter been changed and is it facing the correct direction? What pump did you end up buying?
Shawn
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1980 931
That's thirty minutes away. I'll be there in ten.

bnoon · Posted: Fri Jul 30, 2010 10:56 pm Post subject:

Pierburg # 98154 is what I got for the pressure pump. Main filter is new and has MAYBE 200 miles on it.

What I'm questioning now is more previous owner repairs, such as the in tank pump. Possibly the fuel dizzy again, but I'm confident that I've got that right.
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'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
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Smoothie · Posted: Sat Jul 31, 2010 1:31 am Post subject:

You have to consider possible junk in the tank, clogged and/or nonfunctional/non-powered in-tank pump, and if junk in the tank, then possible junk in the new pumps' inlet.
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"..it's made in Germany. You know the Germans always make good stuff."

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Zeek · Joined: 09 Jul 2010 Posts: 107 Location: Shady Side, MD

bnoon · Posted: Sat Jul 31, 2010 3:05 am Post subject:

Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

On a related topic, did we ever determine if the Pieburg has a built in check valve? If the 1980 pump was original , it had an internal check valve.
The filter flow is pointing towards the driver? Also easy to put in backwards on the 80 model.
Shawn
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1980 931
That's thirty minutes away. I'll be there in ten.

bnoon · Posted: Sun Aug 01, 2010 2:12 am Post subject:

Filter is the correct direction (flow arrow poining toward windshield) and worked fine at the end of last year and beginning of this year with no pressure issues.

I have not heard of a check valve. Someone with the Pierburg # 98154 care to chime in? Needed, no needed?
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'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
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dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

My Pierberg (6.5 bar version) came with an external check valve and about 6 other fittings to adapt to a variety of application.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

Smoothie · Posted: Sun Aug 01, 2010 4:09 am Post subject:

That's similar to what was packed with my first Pierburg*, except the piece that looks like a check valve is actually only a banjo adapter - there's no spring and ball (actual check valve) built into it. I reused the external check valve from the old fried Bosch pump.. Built in to the Pierburg as far as I could tell is only an overpressure relief valve at the inlet end which limits its' output to about 100psi.

If you're replacing an early Bosch that had the long neck and built-in check valve, pretty sure you'll need to obtain an external check valve for use with the Pierburg.
Not sure, but you -might- also need a different pump-to-accumulator fuel line (if the earlier long-neck pump setup did not use a banjo style fitting).

*- (still in use in the car)
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

You can get a check valve to replace the straight thru adapter at AutohausAZ.
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1980 931
That's thirty minutes away. I'll be there in ten.

bnoon · Posted: Sun Aug 01, 2010 5:19 am Post subject:

OK, I didn't install a check valve and I am replacing an original style pump with the long hex on the top of the pump. I just used the adapter that came with the new pump and didn't know there was supposed to be a check valve in there. I ordered a check valve from AutohausAZ, thanks for the tip.
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'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
Porscheless

bnoon · Posted: Sun Aug 08, 2010 5:42 am Post subject:

Check valve installed this morning. Running better, well enough to get it home anyway (it sat in my work parking lot for the last week and a half). Haven't checked pressures yet, but I know it's lean when warm so yet again with the WUR removal/adjustments. I think I'm going to come up with a remote mount WUR kit so that people can make their own manually adjustable WURs on tufahs and not be such a pain to adjust.

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'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
Porscheless

bnoon · Posted: Sun Sep 19, 2010 3:31 am Post subject:

Pierburg 98154 part number is incorrect!!! Tops out at 65 or so psi no matter how many shims you use in the dizzy. Correct part number is Pierburg 7.21659.70.0 for CIS cars.

EDIT: 98154 IS CORRECT for US cars from http://www.alleuro.com/miscparts.php
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'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
Porscheless

KDJones2000 · Joined: 14 Sep 2010 Posts: 322 Location: Phoenix, AZ

I have a question related to this check valve thing.

We just replaced the OEM pump in our race car with some Chinese pump from our FLAPS. The new pump came with an external check valve that will screw into the female threads on the outlet side of the pump. However, there is currently no way to interface the outlet side of the external check valve to the fuel system (A banjo bolt is what the OEM uses).

I can blow into the new pump from the inlet side and pass air through it, but there seems to be some internal valve blocking flow from the outlet side backwards. I thought that this must be a check valve, but now I am questioning that conclusion.

At this time we have the new pump hooked up like the OEM (No external check valve), and the car has started and run for us. We are just sorting the CIS and engine out now. When I spoke with the person at the autoparts store they mentioned that the new pump came with the "Check valve" while the OEM/Bosch pump did not, and that you had to order it separately.

My question is: Should we be using this external check valve somewhere else in the fuel system? It looks like we could put it in just after the fuel filter, based upon what's there. Is there supposed to be one there? We would like to try and keep the fuel pressure up as much as possible so that we don't have any problems startig the car up after refueling at the track.

Thanks for any help, Keith
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1987 924S SPEC car
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1988 944 Turbo S