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914World.com _ 914World Garage _ AAR year result on 1.7 FI | cold start suction means OK?

Posted by: Tdskip Jan 11 2019, 01:25 PM

First of all thank you for all your help and patience as I work through these issues on the ‘73 1.7 FI car.

I’m having idle and loss of power issues that I’m trying to get sorted out.

Brand new MPS from Jeff
40 PSI fuel pressure at the pump outlet

Just did a cold start test on the AAR by immediately pulling the hose that goes to the rubber install and I had suction there. That suggests that my AAR is OK and I should keep moving on to other components, correct?

Posted by: BillC Jan 11 2019, 02:14 PM

I think your fuel pressure is too high. Have you checked the fuel pressure at the rail? The fuel rail should be about 28 psi.

And, yes, you should have suction at the inlet to the AAR at startup. The suction should diminish over time as the AAR closes. If the AAR doesn't close, you'll have a very high idle once the engine warms up.

Posted by: Tdskip Jan 11 2019, 02:16 PM

Hi there, and happy Friday to you.

I have not checked it at the rail - oops

Posted by: BeatNavy Jan 11 2019, 02:23 PM

Bill's right - ~28/29 psi +/- at the rail. On the 1/2 side fuel rail there should be a stub. Either it's blocked off with a very small bolt or it has a fuel line routing over to the cold start valve. That's a good place to attach a fuel pressure gauge -- just disconnect the CSV as needed.

AAR should slowly close off in a few minutes, assuming the heating element is working. I think I timed mine at 7 or 8 minutes once, just because I wanted to know.

Posted by: Tdskip Jan 11 2019, 03:15 PM

May be tomorrow before I can get my hands back on that but will test at the rail and report back.

Maybe I goofed on the pump number and installed a higher pressure one than I was supposed to....this one came with the car.

Posted by: 914_teener Jan 11 2019, 03:42 PM

Tom,

You can remove the AAR and bench test it by looking at it visually.

12v and just ground to the body of the AAR and the valve should slowly close.

Easy peasy.

Posted by: JawjaPorsche Jan 11 2019, 03:51 PM

Idle issues usually is a vacuum leak somewhere.

I had a hard time sorting mine out. I noticed your hoses look new so we can cancel that off the list.

Things to replace:
Manifold gaskets.
Injector seals
Air intake gasket
Oil fill gasket

Good luck!