Boogieman28

So I’ve got a 1979 Porsche 924 2.0 base model nothing fancy. The car was my dads been sitting since 2000 (2 years before I was born). Mechanically I know a lot about cars more of a domestic car guy myself but I took on this project. Now down the special stuff I got the car roughly 2 weeks ago first day I did the basic get a battery change the oil and check for spark. All 4 wires and plugs were giving spark so I screwed them in. I sprayed some starter fluid inside the throttle body and it ran it ran rough and it didn’t run on it’s own. My father told me it needed a fuel pump so I took them both out and they both were bad. This system had the dual fuel pumps so I’ve read on other forums people bypass the pre pump or the i tank pump so I did the same. The pumps does it’s jobs and pumps a good amount of fuel to the filter which was leaking at the fitting which I replaced. I would fire it up every so often and let it run of the gas I sprayed in the throttle body. When I got everything hooked up after the pump I tried to start it by itself. Would fire but would bog down right away and wouldn’t really “catch”. So I started by undoing the injectors and busting my knuckles and laid them in a cup of carb cleaner to get all the dirt and grime off them. 2 were very good while the other 2 were ok. I ordered injector o rings and in the meantime I replaced all the small vacuum lines with new hoses. All the hoses were put in the standard way they were when running. After a couple days of sitting I tried the injectors and they all sprayed at the same rate and sprayed relatively clean fuel that I put in the tank signifying that when he parked it he drained the tank like he said. So when I was bench testing the o rings the motor would fire off the wd40 I sprayed on the injectors to loosen the seals. After the new o rings I put in the I figured it would atleast sputter a little but nothing I sprayed starter fluid and nothing the fuel pump is pumping I have no fuel leak and I hear the injectors whining and I hear the fuel after I try and crank it. So as of right now I’m stuck I know the pump is working I know fuel is getting past the fuel distributor evenly as I saw it I don’t think the order of the fuel injectors matter so that couldn’t be an issue. Any ideas on what this problem it could be. It ran off wd40 for a couple seconds but won’t even sputter off the injectors. I figured it had to be something with the vacuum lines so I tried to move the diaphragm on the fuel distributed by hand and nothing changed at all. If anyone knows anything about these reply here of just text me at8038041005 I really appreciate it.

PF

Have you checked that you still have spark?

Boogieman28

Yes I’m still getting spark I have not messed with any timing since it first started and since it last ran 20 years ago

PF

Ok so if you are 100% that fuel gets past the injectors and you see that you have spark at the plug you should atleast get some indication that it wants to start like coughing from the engine. If no sign of it wanting to start I still wonder if you really have both. Double check.

Boogieman28

i let the car sit for 2 days to handle other things and I thought maybe it was flooded. So am I did was pop the hood put the battery terminals on and turned the key and it started without much cranking and I ran it for a couple of minutes and it would idle itself for a couple seconds before dying. This whole time I had the air tube disconnected from the throttle body. I noticed that it wanted to start smoking from under the manifold heat shield what could cause this or is it just from sitting up. So after I ran it without the throttle body I put it on and made sure all the vacuum connections were correct and it wouldn’t start cough or anything. It smelled horribly of gas so I thought it may have been flooded again. I let it sit over night and this morning I went out there to start it it took a little while or cranking and then it cranked no starter fluid of gas tapping it started. This is whole the throttle body is off. I ran it for probably 10 minutes. It ran but I had to keep giving it gas. As soon as I turned it off I tried to start it and nothing at all. Any ideas I thought maybe the metering plate on the fuel distributed wasn’t allowing enough air and it kept flooding itself out. But when I looked the bowl was shiny and the plate moved up freely with little effort. As all I know the vacuum lines are all right and no leaks I’ve replaced the small hoses with new rubber. So we are getting spark and fuel and it does run off the gas from the tank which is good I just have to figure out why it doesn’t want to start with the air cleaner and why it doesn’t want to start when it’s hot any ideas?

PF

Hot start issues with the 924 is very common. Porsche made several technical bulletins about it. I am not familiar with the system but a search will tell you several areas that can be faulty.
Also it would be good to have your fuel metering head serviced by someone who knows these systems. Few really do nowdays.
Sorry I cant be of more help.

Boogieman28

Just a follow up I put all the intake stuff and vacuum things back and it idled and ran like it should. I ran it for probably 30 minutes and revved it s bit to clean out the engine not much smoke which is good the car doesn’t want to rev down fast and it stutters when you rev it could this be a cause of sitting and I just need to run it more or another problem. And after I ran it I started it up and it ran fine . So I let it sit for probably 10 minutes and came back and it wouldn’t crank or cough I know you said you couldn’t help me but does this sound like the issue everyone else has or do you think I just need to run it more and it might clear up and when it doesn’t crank it stinks of gas

PF

Yes it sounds like the hot start issue. Do a search on it and you will see.
Issue is that after shut down the fuel system looses its built up pressure somewhere between the fuel pump to the fuel regulator in the fuel distributor. If pressure is lost, engine heat will cause a vapor lock which in turn hinders fueldelivery.
I know there is a quickfix with a switch for the issue that over comes it in a cheap nonfactory manner but I have no experience on it.

As said search 924 hot start problem and you will learn