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914World.com _ 914World Garage _ Porsche 914 1.8L FI flooding

Posted by: Rod911964 Dec 16 2018, 07:10 PM

Greetings and HELP
Purchased a 1974 914, 1.8L FI.
This Porsche has not been started in 24 years.
So I have...
Replace the tank
Replace every fuel line
Replace fuel pump
Rebuilt injectors
New Spark Plugs
Replace all vacuum lines
New Cap & points
New spark plug wires
checked for spark (got it)
Check fuel pump function (OK)
Checked for vacuum leaks (none found)
Checked AFM (made lean, the changed back to orig. setting)

So my problem.
The engine starts for only a moment, say about NMT 10 seconds then dies out.
Upon cranking the starter I am getting a lot of raw gas in the exhaust system, so much its spitting out the pipes. I collect about 3-4 ounces is a catch tray.
Could I have the fuel tank lines reversed?

So what am I doing wrong or what is wrong.

Thanks in advance.

Posted by: Mark Henry Dec 16 2018, 07:57 PM

Flooding? Like you gave it too much gas and you can smell it?
I'd look for a hose leak, regulator leak, maybe injectors leaking?

Head temp sensor?

Posted by: falcor75 Dec 17 2018, 12:10 AM

Stock or aftermarket fuel pump?, what is your fuel pressure set too?

Posted by: Rod911964 Dec 17 2018, 06:49 AM

Aftermarket pump (from Autoatlanata, "sanctioned as correct").
Have not yet installed a pressure gauge. This on the list of things to do.

I have checked the seals to all 4 injectors and appear to be installed and sealing ok.

Nonetheless, something is not correct with fuel delivery. There is so much gas collected in the exhaust system, I know its just a matter of time when it will ignite if not corrected.

How can I confirm I have the fuels lines (output and return) at the tank thru the newly install SS lines in the tunnel correct?

Thanks!
Rob

Posted by: jim_hoyland Dec 17 2018, 07:16 AM

L=Jet ? If my L-Jet AFM is not connected to that 7-pin plug, the engine will run for about 5 seconds and then die too.

I would recommend testing the AFM, either directly, or by exchanging it out; then I would look at the connections at the seal relay.

Lastly, test those smaller vac hoses, I have found they can become brittle and look good, but actually leak. Once a broken T in a hose line created an air leak.

Posted by: jim_hoyland Dec 17 2018, 07:26 AM

Connector numbers on the AFM Plug: 27, 36, 6, 9, 8, 7, and 39

The resistance between the following pairs of AFM connectors:
Between 6 and 9 =200 - 400 ohms
Between 7 - 8 =120 - 200 ohms
Between 6 - 27 =2K ohms at ambiant temp
Between 36 - 39 =Infinate with flap closed; Zero with flap slightly open

These are for a '75 L-Jet with a 7 pin connector; the '74 may be 6 pin

Posted by: ClayPerrine Dec 18 2018, 06:27 AM

Also check the cylinder head temp sensor to insure it is hooked up. If it is disconnected, the engine will think it is -80 degrees and go full rich on the injectors.

BTDT.

Posted by: IronHillRestorations Dec 18 2018, 08:51 AM

I don't know the 1.8 injection system very well, but I wondered if your injectors are gummed up and sticking open.

My own advice is to make a logical checklist and eliminate each possible problem area.

Posted by: Rod911964 Dec 18 2018, 12:35 PM

Thanks all,
So the next on the list is to...
1) 4 baby food jars and check the injector flow rates
2) Check (and replace) Cyl Head Temp Sensor
3) Adjust dwell at Distributor

Report to follow.

Posted by: jim_hoyland Dec 18 2018, 01:15 PM

If your '74 has a dual relay; check all the connections. If there is a base that blocks the view of the connectors, check each for tightness; especially the ones on the right side.

Posted by: Rod911964 Dec 23 2018, 06:08 PM

Update...
This will sound routine, however a good day in the garage with my 914.
Replaced fuel pressure regulator
Did injector flow test (see pic)
Replaced CHT (this was the silver bullet)
Now on to final tuning and putting up.
Then onto the brakes.
Thanks all!

Posted by: Rod911964 Dec 23 2018, 06:58 PM

Pic 1

Attached thumbnail(s)

Posted by: rhodyguy Dec 23 2018, 07:36 PM

The head temp was the culprit?

Posted by: Rod911964 Dec 23 2018, 08:04 PM

Yes, it appears to be the CHT.
I replaced the fuel pressure regulator today also.
Nonetheless, when I started the 914 (after being in hibernation for 25 years) it started right up an settled down. No flooding :)

Posted by: IronHillRestorations Dec 24 2018, 07:22 AM

Huzzah!