replaced fuel pump on SC, won't run

[Flagstaff_911SC]

I just replaced my fuel pump with a new one (pierburg) on my '83 911sc, but I can't get it to run. It will start for a split second and then die. I am getting a gas smell around the engine after I try to start it. Do I have to do any special procedures after replacing a fuel pump. Any ideas or suggestions would be greatly appreciated?

Thanks.

[Jim Sims]

Did you purge the air out of the fuel injection system by turning the ignition key on and then lifting the air metering plate under the air filter so the pump runs until the system is filled? Only takes a few seconds; one can hear the sound change and the meter plate "stiffen" as the system fills and purges the air. Only do this for a few seconds: 5 or less. Jim

[Flagstaff_911SC]

Jim,
I lifted the air metering plate for just a few seconds and heard the sound change (like a squealing sound), but when I try to start it, it will still run for just a second or so and then die. Any ideas what to check?

Thanks

[Jim Sims]

Then it sounds like an air leak (vacuum leak); was anything done to the engine? Did you experience a bad backfire without a pop-off valve? Look for something disconnected on the CIS system. Jim

[Flagstaff_911SC]

Jim,
Nothing was done with the engine, no backfire (I do have a pop-off valve). I will have to check around and see if something is disconnected. I did replace the fuel filter (before replacing the fuel pump) when my car woudln't start, thinking it may be clogged. I loosened the outlet line to see if fuel is coming out and I did get it. I'll have to look around for something disconnected.

Thanks

[fintstone]

If you smell fuell at the engine; sounds to me like you have an ignition problem and not a fuel problem. Did you check for spark at your plugs?

[Flagstaff_911SC]

fintstone,

I checked, and I am getting a good spark. It almost seems like I may be getting to much fuel possibly (a lot of fuel smell around the engine). It will start and run for a second or two (like it is loaded up) and then die. Any suggestions?

thanks.

[Paulporsche]

Make sure all electrical connections are tight. A poster had similar symptoms yesterday and his connection to the CD was loose. Check the blue and green connections behind the air flow sensor housing. Check the big rubber boot above is tightly in place. Check the DME and relay, distributor cap and rotor, etc etc etc

[hkspwrsche]

silly question but, You didnt say.. was it running before you replaced the pump? what was the reason you replaced it?

Harold

[Flagstaff_911SC]

Harold,
it just wouldn't start one day, just spin over. Started checking everything out, spark, fuel etc. and found out I wasn't getting fuel. I could use some starter fluid and get it to start so I started going through the steps and came to the conclusion the pump wasn't working. But before the problem occured, to answer your question- it ran fine.

[ruf-porsche]

Sound as though the engine is flooded if you can smell the fuel. Take out the plugs and dry them off with a clean rag or if you have a compressor, you can use the air to dry them off. Or you can replace the plugs with new plugs.

Did you hook up the fuel pump correctly? There is a positive and negative terminal for the pump.

[rcwaldo]

Originally posted by Flagstaff_911SC
I could use some starter fluid and get it to start so I started going through the steps and came to the conclusion the pump wasn't working.

Be careful in using that starting fluid (Either)sp?. Been known to cause damage if too much is used..

Chris

[Flagstaff_911SC]

ruf-porsche,
sounds like a good idea, I think I will pull the plugs and take a look at them and more than likely just replace them.

I hooked up the pos. and neg. terminals correctly. I marked them so I wouldn't make a mistake

Just seems funny that I would have this problem with just replacing the fuel pump and now getting this excessive gas smell, and acting like it is flooded.

thanks for the help

[David]

You need to make sure you're getting enough fuel by measuring the fuel flow at the engine. Disconnect the fuel line at the accumulator and run it into a container.

If fuel flow is good, then measure fuel pressure. You have CIS gauges don't you?

You can also pull out individual injectors and check the flow pattern.

Then it's on to ignition.

All of this is in the Bentley manual.

[fintstone]

Too much fuel? Cold start injector might be stuck open.