I KNOW WHY THE 931 WON'T RUN

by "K-Roll-PorscheTamer" (k-roll390)
Published 05/24/2017 at 20:28

Tags: 931Lyfe ; 931
STARS: 5

WHOEVER MESSED WITH THE FUEL SYSTEM LAST WAS STUPID.

After determining the fuel pump and relay were both gone(dead), I ordered and replaced them. But when I went to crank the car, instead of fuel reaching the cylinders, it sprayed out and made a mess under the car.

It too some sleuthing and help from the nicest 924 Carrera GT/931 owner I could’ve ever asked to talk to over the phone, but we figured out that the car wasn’t getting fuel at all and why.

Remember this picture of the old pump I showed off last week? That rubber line isn’t supposed to be there. Guess what’s under it: A BANJO BOLT

So not only did the previous pump not have the pressure to make that line burst like the new one does, it wasn’t even installed correctly!! -_-

What the pump needs is one of these adapter fittings and and a cap to keep the fuel pressurized and flowing properly.

Then I need to figure out how to connect all that to this main line here. Probably a hose adapter and clamps.After that, there shouldn’t be any reason as to why it won’t start/run.

Replies (22)

"jkm7680" (jkm7680)
05/24/2017 at 20:33, STARS: 2

that was me, i poured fancy ketchup in there and shook it up a little bit.

"K-Roll-PorscheTamer" (k-roll390)
05/24/2017 at 20:39, STARS: 0

What is this fancy ketchup you speak of? You probably used Heinz you cheapo.

"jkm7680" (jkm7680)
05/24/2017 at 20:42, STARS: 0

It was the shitty brand they give out at third tier burger joints.

"jkm7680" (jkm7680)
05/24/2017 at 20:42, STARS: 0

It was the shitty brand they give out at third tier burger joints.

"Urambo Tauro" (urambotauro)
05/24/2017 at 20:45, STARS: 0

Wow. And that hose clamp was positioned directly over those holes, wasn’t it?

"sony1492" (sony1492)
05/24/2017 at 20:45, STARS: 0

That’s impressive

"RamblinRover Luxury-Yacht" (ramblininexile)
05/24/2017 at 20:52, STARS: 0

I wonder if there’s a single piece that will work, like this?

Of course I don’t think this one fits your model (this fits S from ‘86-’88 and 944), but it’s probably similar. Of course the site I see it on lists it for 90 british pounds, which, ouch.

“94435604112" is the number they have it under.

"RallyWrench" (rndlitebmw)
05/24/2017 at 21:00, STARS: 2

Nice find! Sorry to see such hackery wasting your time. So it’s missing all the right fittings and lines off the pump? Is the stock fuel filter in place in any of this? That main line’s fitting looks like the kind to attach to the outlet of the filter? Is the accumulator still there? Should be right off the pump, it keeps pressure in the system when shut off.

Fuel filter should look close to this, see the fittings:

Accumulator, should be right off the pump if the picture in the manual I’m looking at is right:

Also, YOU KNOW A 924 CGT OWNER?!!? *dies

"RallyWrench" (rndlitebmw)
05/24/2017 at 21:03, STARS: 0

Sounds like a whole bunch of Really Important Shit is missing. There should be an accumulator and the filter near the pump too, the filter is what that main line should attach to.

"K-Roll-PorscheTamer" (k-roll390)
05/24/2017 at 21:21, STARS: 0

Cheap bastard.....I THOUGHT I KNEW YOU

"K-Roll-PorscheTamer" (k-roll390)
05/24/2017 at 21:24, STARS: 0

Something like that would work. Or even this, if I can find it.

The thing on the left. Whatever it’s called would be even simpler and better.

"K-Roll-PorscheTamer" (k-roll390)
05/24/2017 at 21:24, STARS: 0

Correct

"K-Roll-PorscheTamer" (k-roll390)
05/24/2017 at 21:30, STARS: 1

That seems to be all it’s missing just to get fuel to the cylinders at minimum. I know there’s a filter in the engine bay, driver’s side. I don’t think there’s a second one? I’ll have to look more and see. It could be a missing link if there’s a second one.

If there isn’t one in-line with the pump, I can use this adapter/fitting on the left that looks to be the match for the pump. I just need to know what it’s called and where I can find one.

Also, the car has two pumps (in tank and exterior [the one I’m dealing with]), so which pump is the accumulator related to?

And yes, at least over the phone and on WhatsApp. He’s a cool guy. Unfortunately with him being in Europe, time zones aren’t friendly for working on the car.

"Tekamul" (tekamulburner)
05/24/2017 at 21:32, STARS: 1

That’s so wrong, I’m not sure how it worked before. This has to be an accumulation of mistakes, not a fuck up in just one go, right?

"jkm7680" (jkm7680)
05/24/2017 at 21:37, STARS: 0

But you don’t even know what I put in your engine yet!?

"RamblinRover Luxury-Yacht" (ramblininexile)
05/24/2017 at 21:48, STARS: 0

If the banjo bolt adapter will screw out of the top of the pump, you might be able to get a washer-seal hose or fitting to screw in. If you can ID the thread, O’Reilly might even have a suitable hose in their system - they have a good system for parts sorting by ends/fitting types, but the guy behind the counter has to know what he’s doing. Alternately just find all the right brass, with the aid of a part like this:

http://www.oreillyauto.com/site/c/detail/MTM0/55141/N1166.oap

And maybe something like this

http://www.oreillyauto.com/site/c/detail/DORN/072980BP/N1166.oap

and one of these

http://www.oreillyauto.com/site/c/detail/DORN/072960BP/N1166.oap

I don’t know. If you can just ID the correct size for what’s in the top, say, by measuring and getting a bolt to double-check, all the rest shouldn’t be too hard. That hose end should be a standard hose sizing.

"K-Roll-PorscheTamer" (k-roll390)
05/24/2017 at 21:56, STARS: 0

It does and I have bought those tonight as a last resort. I’m just concerned as to if there’ll be any problems replacing the banjo bolt with a regular fitting. Will it affect the fuel pressure any? If not, I’m doing this the easy way like you described.

"Urambo Tauro" (urambotauro)
05/24/2017 at 22:00, STARS: 0

*shakes head* Geez, how did it ever run like that? The old pump looks weathered, as if somebody actually managed to drive it like this for a while. That’s so weird.

"K-Roll-PorscheTamer" (k-roll390)
05/24/2017 at 22:07, STARS: 1

My friend got it to run once. ONCE. we’re not sure how, knowing how messed up the thing was now.

"RamblinRover Luxury-Yacht" (ramblininexile)
05/24/2017 at 22:29, STARS: 1

If you think about the banjo bolt, it’s really secure, sure, but in terms of the amount of fuel it can pass, its max area is the area of those two holes, which is *way* less than the cross section of the fitting. So, moving to something that’s not a banjo is freeing you up a good bit. Probably half the pressure drop through the fitting.

"RallyWrench" (rndlitebmw)
05/24/2017 at 22:59, STARS: 1

The accumulator should be next to the main (external) pump. The in-tank pump is just a lift pump to feed the main, but the main can generate enough suction to render it unnecessary most of the time.

That fitting is just a union, nothing too special, I have a box of miscellaneous CIS fittings at work I can look through.

I forgot the filter is underhood, that’s the only one. That means the main line you show should probably be leaving the accumulator.

I’ll email you my number so you can text or Whatsapp, probably easier than email for me for the time being, I haven’t been able to keep up with everything lately.

"BiTurbo228 - Dr Frankenstein of Spitfires" (biturbo228)
05/25/2017 at 06:08, STARS: 0

Wahey! It does feel excellent to finally find the one thing that’s stopping a car starting :)

If you haven’t done it before, it’s definitely something to tick off the automotive bucket list. Looking forward to seeing it up and running :)