I'm working on fixing up my neighbors 1975 914 that she has had in her garage for 20 years. Car starts and idles fine, however when I open up the throttle, the car will accelerate for maybe 3 or 4 seconds then lose power and fall into a very clunky idle, almost stalling. Fuel injection systems are new to me and I'm just trying to find ways to troubleshoot this problem. I have replaced all the vacuum hosed and fuel injectors. I found diagrams online to ensure the hoses are connected in the right spots and nothing is missing. I have also re-timed the engine. I'm thinking maybe its a fuel pressure issue, which I have not checked yet, but its the only thing I can think to try. I'm used to working on pre-60's carbureted engines so this is a learning experience for me. Any input would be appreciated.

That sounds like a likely fuel issue to me.

I'd start by replacing the fuel filter, as it should probably be done just as a normal maintenance item.

After that, you can look at the in-tank fuel strainer (requires removing the tank) and/or fuel pump.

For troubleshooting, you can splice in a fuel pressure gauge and watch the needle. If you need to watch it while driving, you can mount a cellphone in the engine compartment and capture a video of the gauge to look at later.

Good luck.

For a car that's been sitting you need to troubleshoot / repair / service the entire fuel delivery system. I'd recommend as a minimum changing the fuel filter and sending the injectors out for servicing and testing. It's a very cost effective service. Here's one option: Mr. Injector. But I would also recommend pulling the tank, changing the sock, and changing the fuel lines.

And yes, check the fuel pressure.

EDIT: Sorry, I missed the part about you changing injectors.

Yes, like Not A Six my bet is on fuel starvation, and I would go for a new filter first.
But since you already replaced hoses and injectors, I bet this might be something you already did ?

I guess I forgot to mention that I pulled the fuel tank out, refinished the inside, (the old gas had turned into a foul smelling sludge), replaced the filter, replaced all the old fuel lines in the front and engine bay ( I haven't touched the lines that run down the center of the car), made sure the fuel pump worked, flushed the fuel pump with clean gas and made sure there were no leaks anywhere before I even started the car. I am going to get a fuel pressure gauge tomorrow and check the pressure.

I guess I get intimidated by all the sensors and wires that when the engine's not working right, its hard to know where to look.

Oh, I also replaced all the plugs and points, new distributor cap and rotor and new plug cables.

Also, I haven't road tested it, as the wheels are off while I also service the brakes.

since you took the tank out....and replaced fuellines....it could be that you have a kinked fuelline under the tank. Worth a check !

under tank hoses should be the length they need to be,coiling up under the tank is not good,in the end the hose will kink,seen it SO many times.
Sorry to say but sounds like a nearly dead pump,most likely not making full running pressure,plenty of wiser folks on here to help you on here,just my 2cents worth, good luck.

yep, have done this myself before as well, could be pump too, so put a gauge in line so you can see that pressure is maintaining a 28-30psi.

good luck!

I tested the fuel pressure and it was 28-30. I did notice that sometimes the fuel pump decides to randomly stop working or hardly working at all, so I ordered a new one, still waiting for it to come. I hope it fixes things because Im running out of ideas on what to check.