924Board.org

[JoeShmo]

Sorry for posting yet another question about this topic, as a search returns all sorts of fuel pump issues, but I have other questions.

I don't hear the fuel pump kick on untill the engine is actually turning over, and trying to start. When it does start, I think I hear it, and when it stalls I hear it kick off/on and studder for a second.

My question is, is there an easy way to bypass the relay, and just run the pump when ignition is on? If that fixes it, then I'll just order a $40 relay (not to worry, I dont think I'll drive it around with a bypassed relay).

I would try to do the pressure/flow test, but I cant get it to kick on. and there seems to be no electrical connector (air flow sensor?) under the fuel dist.

I posted a video of the problem on YT:
http://www.youtube.com/watch?v=GTZQfSa8NCU

1977 924 N/A M&R (possibly closer to '76 than '77?)

[rkn]

Hi -

The pump is not supposed to run before the starter turns over. It is a safety feature in the high-pressure CIS system.

But to test your pump just remove the pump relay and jumper these pins - the pump will run continuously:


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1980 924NA ROW

[dpw928]

Connecting the 15 and 87 connections will cause the pump to run when the ignition is turned. This works on the 928 but it has a 12 gauge 15 circuit wire supplying the fuel pump relay. The 924 has a much smaller 15 wire which would overheat with the draw of the pump. If you can find an unused 15 connection with a 10 or 12 gauge wire, that could be jumped to the 87 relay connection. Also, this technique would disable the pump auto shut off safety feature.

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

[JoeShmo]

thanks. It was actually the relay to the right of the one rkn indicated. The haynes manual even said which ones to jumper as well.

But, that didnt change anything, still started, ran for about 2 seconds, and stalled. So next, I guess is the fuel pressure/volume test. Then go out and try to find a CIS tester thingy.

[fiat22turbo]

Have you checked your ignition switch?
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[dpw928]

[JoeShmo]

fiat22turbo, already replaced the cracked ignition switch about 5 months ago.
the annoying thing about testing flow is the line from the fuel filter goes into a "Y" thingy, so I'd need to fit that whole Y piece into a super wide mouth jar, because I'm guessing it'll flow out of there pretty fast, and splash all over the place.

[fiat22turbo]

You've checked the plunger on the fuel distributor?

No vacuum leaks?

I think that Y spits the fuel to the cold start and the fuel distributor.

Just taking the line loose from the fuel distributor should be enough with a jumpered relay.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[JoeShmo]

plunger? you mean the thing under the air intake thing? I took that air intake off and cleaned up all the white water/oil grime thats all over it.. pushed the plunger down a little.. it moves.. (shrug).

I started to take the fuel filter off, but upon breaking loose the output side, it started leaking fuel there (this is of course with the car off, fuel relay NOT jumpered, had been sitting about 1/2 hour since I tried starting it last). So this tells me that theres pressure there of some sort. I tightened it back up until I could get the proper rags and pans to catch any leaking fuel.

[JoeShmo]

ok, so if I take out an unjector, and put it in a jar, turn the key on, and lift the plunger thingy, I can hear the fuel pump kick on, but nothing comes out of the injector. (no need to jumper relay i guess)

If I remove the fuel inlet thingy, and put that into a jar, lift the plunger, I get quite alot of fuel being dumped into the jar, but its a bit brown.

So should I see fuel spurting out from the injector, or is there something else that has to happen for that? I'm guessing I'll need to flush the tank and lines or something.. The car has been though around 10 fillups at least, with little problems before. So I'm guessing a big enough chunk came through to block something, or the crud built up to the point where it wont stay running?

Odd thing is that it will immediately start, first try. Last time I drove it (about a month ago?) it seemed fine.

[dpw928]

Brown gas is bad!!! You should get a conical spray at the injectors when you lift the air sensor plate. Try cleaning the injectors and the wire mesh filters (if equipped) on the distributor and WUR inlets with throttlebody cleaner.

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

[JoeShmo]

Is there anything I can use aside from the fuel filter to filter the brown out of the fuel? As its obviously getting past the filter, and the filter is new as of about 4 months ago. Ultimately, would be nice to somehow run a line through a filter, then back to the tank.

Also, is there a guide to taking apart the fuel distribution system, and putting it back together? I thought it was called the WUR, but found out that "WUR" is Warm Up Regulator (wheres that?). So whats the proper name for the fuel dist. so I can look up how to clean it?
I suppose I'll start by taking off the "banjos"(?) on the fuel dist, and looking for/cleaning the mesh filters. I've read up on injector cleaning (they are about a year or so old, so shouldnt have any rust, plus I have the set that they replaced (via previous owner)). I dont have access to a sonic thingy, but do have an air compressor. I wonder if I can buy an el-cheapo airbrush system, and spray 30-60psi air into the injector with some injector cleaner. I saw a suggestion on another post about filling the input of the injector with cleaner, then blowing it through with around 60psi of air. Would be better if there way a way to blow it backwords, so instead of blowing junk THROUGH the injector, blow it back out the bigger end.

Also, from my understanding, the whole fuel system looks amazingly simple. Fuel goes to the dist, then air moves that plunger thingy, which allows some fuel to go to the injectors. No real per-cylinder timing involved. So why bother with 7 lines to the various injectors? Why not a single line going to something everything taps off from? The line from the tank is only so big anyway, so cant really be because of volume...?

[Joes924Racer]

Remove the intank fuel pump and clean the pick - up screen.
The external pump is ok by the sounds of things.
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

[dpw928]

[Joes924Racer]

You really dont want to rip into the fuel dizzy.
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.