911 3.2 Won' Start Without Pedal Down

[grb008]

In order to start my 3.2 all of a sudden I need to hold the accelerator pedal down. It will then start, of course billow out smoke/burnt excess fuel and then hunts on the rpms.

I took it out for a drive and it ran smooth. When I returned to the garage I shut the car off. It did start up but not well, hunted a little up and down, I gave her gas to raise rpm, and then it settled in and was ok.

At first I thought it was a spark type issue as it would just crank and nothing which could mean sensors. I tested both sensors, CHT, accel switch, and all looks good. It just seems to be dumping lots of fuel I guess and wont start from being waaaay too rich. When i let her sit and tried to start it was the same thing, only start with pedal to the floor. Then you can take off and everything is good driving.


Only things that changed since it was perfect a week or so ago:

• Repaired Cruise Control module (unplugged it but same start condition, btw it works now after 20 years so I'm ruling that out as i unplugged it)
• Replaced stereo with existing wires which was plug and play, im doubting that
• AND! noticed the vacuum line on the damper was off so connected it.

I'm thinking its definitely fuel related and am leaning toward just replacing the regulator and damper. Should i test the pressure at the rail, other option is someone cranks the car with the hose off the damper and see if its dumping fuel out the vacuum area.

Thoughts?

[FA-18C]

grb -

Been through some of this. Sounds like maybe your fuel pump check valve has crapped out and allowing fuel to drain from your fuel rails. I'd start with checking your fuel pressure and residual pressure after 20 minutes. Also check for vacuum leaks - when idling, take your oil cap off and see if you get a change in idle, that will at least give you an idea if you have leaks - they can be a pain to ID. Make sure all of your vacuum lines are connected, and the elbows are not shot. Stupid cheap to repair.

Others may disagree, but I found the greatest impact to solving some of the problems you described with my car was replacing the FPR and Dampers. Both were leaking fuel into the intakes and creating an overly rich start sequence, and hunting idle. Also, pull your idle control valve and clean the heck out of that. Lastly, I would check your plugs. If you have been running rich, they will caked with carbon.

There is an aftermarket FPR that works great for less than $200 (American something...), and there is a 928 parts guy in Germany that sells the damper for about the same on Ebay. It is IDENTICAL to the Bosch, without the name on it.

I know others smarter on this than me will chime in...good luck.

[grb008]

Thanks, ICV is working, cleaned tested on the bench.

I had a plug or 2 out 2-3 weeks ago and they looked good. Have a stuck plug so letting the Porsche shop handle that one.

Im looking for a damper that isn't $700. If someone can point me to those awesome.

Is the check valve on the pump? i.e. I have to replace the fuel pump? Thank you

[FA-18C]

check valve is on the pump. Mine was old and tired, the ball bearing had a ridge and it would get stuck. Not hard, but not a fun job. You will want to get the fuel out of the tank on that one.

I installed the Standard Motor Products version for ~$125 bucks. Works perfect.

got the damper from a german based 928 parts place via Ebay. Tip was from another member here:
https://www.ebay.com/itm/364049050165

[grb008]

Thanks. I have a full tank. But before I dump all this money could it be just the dampers and regulator. Or is this a sign of the pump is shot. The fuel pump is a light blue so not sure if it’s original. It is 20 years old though as that’s how long I had the car. I think I’ll have to test the pressure.

[FA-18C]

Yep test the pressure first. My FPR and Damper sat for 13 years, and were leaking into the vacuum lines, so it was clear they were shot. I also installed a F9 DME that primes the fuel rail for 3-5 seconds before start. They are pretty fail free, and I keep an OEM german relay in the glove box with a wrench - just in case.

[Cherry Bomb]

I recently had identical starting issue. I replaced everything on this car during a 6yr full preservation, including new damper & FPR from ADAPT MOTORSPORT. Both were around $360-400 shipped from Aus.

I installed the F9 DME also, best feeling to date.

Engine is a total refresh from crank to heads.

All rubber on engine is new Porsche. All fuel lines from tank to fuel rails too. I quadruple checked everything, weekly inspections since I run it as intended.

My fix so far, popped the Distributor cap, cleaned a bit of carbon tracking off all contacts including rotor.

It runs better than last season and it runs very crisp. Wheels spin a lot more and it even sounds happier.

Has been starting perfect ever since!

That's my story and I'm sticking to it!!

[grb008]

I found tons of items removing everything.

- The fuel damper was leaking out of the vacuum line right into the throttle body
- Regulator also had a drop from the vacuum line and wasn't working as well as it should
- that metal pipe with rubber on end vacuum hose is cracked - shade tree fix time
- Injector baskets full of 40 years of crud
- Fuel lines are from 87 so replacing with Paul Mason lines (always interesting when your car is an 84 and has an 87 engine in it from a cabrio when its a targa)
- New CHT going in as its 1 wire and slightly out of spec
- Vacuum Rubber connectors for damper and FPR not really tight on the throttle vacuum line to the T

So everything is getting a good look over now and I am also pulling the intakes to replace all the gaskets and risers, clean fuel injectors and put in new baskets and o rings, new spark plugs, damper, lines, FPR, CHT, steve wong chip to replace the old autothority i found in the DME.

[FA-18C]

Started from one domino tipping over...I started with fuel lines, so rails were out, may as well refurb injectors, plug wires, cap and rotor, then found FPR leaking, then damper. Read about AFM, so reset the arm for a clear path, alternator, cleaned up fan and housing, heat bypass.

Scheduled clutch install in two weeks, will do the triangle of death, engine insulation pad, oil breather hose, and valve adjustment. Then finally install premuffler and AEM WBO2 and Wong chip.

I have a good 4-5 months of projects in the boxes in the garage...

[grb008]

Sounds like me. At least i think all the dominos fell now. I have all the parts so removing intake this weekend, hopefully gaskets clean off ok the block and reassemble

[FA-18C]

There is an end in site! My car starts on first turn of key, normal solid warmup cycle and drops and rock steady at set idle, never misses a beat from there on out. I believe that the greatest difference for my car was the FPR and Damper. They had the largest and immediate impact.