Engine flooding

[bluemm]

I have a 1975 914 with the 1.8 engine. The engine starts and then floods with gas within seconds. It still has the fuel injection and I would like to keep it that way if possible. Should I replace the mass airflow sensor, the head temp sensor or something else? I'm getting so much gas that it is flooding into the oil sump.

Any help would be greatly appreciated.

[ptravnic]

Check your fuel pressure. It should be around 29 or 30 psi (refer to Haynes manual for exact).

-pt

[jurhip]

After about 6 months of sitting (no Stabil) my car was hard to start and is running rough. I thought I may have had a flooding issue, turns out no, but here's what I would check

fuel pressure regulator - check this and the pressure before and after. I am not sure what the fail mode of these is, but if it closed up, it could increase injector pressures as it is downstream of these. Normally, excess fuel would be routed back to the tank.

I would think the mass air flow sensor either works or doesn't as it is mechanical. However, their is always the possiblity that the air flapper (flow sensor) is gunked up and stuck in a high load position. However, your car would probably not want to idle at the prescribed rpm You can see it if you remove the top of the air box and look down into the intake.

Wouldn't hurt to check all your vacuum hoses while your in there.

[Dave at Pelican Parts]

Are there any hoses or wires that are unplugged? Or brittle and/or cracking? How about ones (particularly the wire to the Head Temp Sensor) that aren't making a solid connection?

How's the ignition system?

What's your fuel pressure when the pump is on and the engine is not running?

--DD

[bluemm]

I have found a hose that appears to be unplugged though I don't know where from. It is a yellowish plastic hose and it goes from the engine compartment down through the floor under the battery. It has a cloth rubber connector on the end. I cannot check for vacuum leaks as the car only runs for seconds before loading the plugs with gas.
I did check the head temp sensor and it is plugged in solid but I don't know if it works. I will check my fuel pressure next as it seems this could be the only way I could raise the oil level on my dipstick 1-1/2 inches in a half hour. This is an insane amount of gas being sent to the engine!!

I did find evidence of a small fire at the entrance to the throttle body. I at first thought it backfired and took out the mass airflow sensor. But again, would I get this much gas?


Thanks for the help. If anyone has any further advice please let me know.

[Dave at Pelican Parts]

Uh, that hose sounds like one of the fuel hoses. If it's the return hose, and someone has plugged up the fuel return to the tank, that would create exceedingly high fuel pressures. Which would make for an insanely-rich mixture, with tons of fuel getting dumped into the combustion chamber.

Take a look at where the fuel hoses go to and go from. Also the vacuum hoses. If your 1.8 is a 75, compare with the diagram elsewhere on this site. If your 1.8 is a 74, well.... The fuel line setup will be similar but not identical to the 74 2.0 one, and the vacuum hose layout will be similar to but not identical to the 75 1.8 one (minus the EGR and such).

Check for hose connections that don't make sense.

You can also pull the filter out of the air cleaner and open up the flap in the air flow meter with your finger or a screwdriver (or a chopstick! Sorry, inside joke.). Make sure it opens and closes smoothly. If it does, it is probably OK unless someone has been messing with it (e.g., the cover over the electrical bit is loose or obviously re-glued).

Eventually, you might want to check the part numbers of the important bits (e.g., air flow meter) to see if they're not from some other car.

--DD

[bluemm]

I have found many vacuum hose problems ( one was made from garden hose, and the charcoal canister was in the rear trunk but still connected) and my airflow sensor has had the electrical cover removed and taped back on. It only sticks if I open it more than 3/4 open. Is this normal? Someone told me that I could tighten the spring to correct this as long as it moves smoothly. I also found a pair of small pliers in the throttle body. They where being used to keep the butterfly open. What kind of spring should be connected to the linkage on the throttle body? Mine appears to be a stretched out screen door spring.

This car was an Ebay special, but it will run again!!

[Dave at Pelican Parts]

Yikes! Sounds like yours is a real basket case!!

The flap in the air flow meter should not stick at all. Period. If it does, then the flap has probably warped, and it's time to get a new meter. It sounds like someone has already been trying to "fix" it (the cover was off) and likely screwed things up even more that way.

The return spring on the throttle body is, as I recall, a long-ish coil spring that hookd to some nearby engine tin.

--DD

[bluemm]

What is the best way to test the cold start valve?

[Dave at Pelican Parts]

Pull it out and stick it in a jar. Run the fuel pump (jumper the relay or turn the key on and push open the flap in the air flow meter). If any fuel comes out, the valve is bad.

The CSV on its own probably will not dump enough fuel in to flood the motor, though.

--DD

[bluemm]

Can the mass airflow meter send enough fuel to flood the engine if it is bad?