new fuel pump still won't start

[Gary944T]

Well I keep replacing parts and still the car won't start. Yesterday I replaced the fuel pump, FPR, and fixed the vacuum hose from FPR to intake manifold.

I read some old threads and found 911tracker85 had same problem. He finally had success replacing the temperature sensor. It seems that this car has several temperature sensors. Please can someone tell me which temperature sensor would be involved in cold start?

[soxnail]

That would be the NTC water temp sensor. Car will start without the sensor but will run lean if it is shorted, and rich if it is open.
Sox

[soxnail]

I would recommend dropping the shot gun approach and follow a structured trouble shooting process.
1 Ignition.
Check for spark, if yes then move on to step 2.
If no then look for tach bounce at crank. It should be very visible.
If not look for the speed and reference sensor out put.
If present check for drive to the ignition coil.
If yes then look for the connections in the distributor.
If no then we will need to look at the DME connections or DME itself.

2 are you getting fuel:
check for fuel pressure on the fuel rail.
If no then does the fuel pump run with the DME relay jumped.
If you have pressure then are the injectors firing.

Start with the above, if you need further info on any of the above steps, post and I will try to walk you through them.
Sox
Ps your tool box will need patience and cuss words

[Gary944T]

Thanks. I don't see the NTC temp sensor for sale here.

Is this it?
https://www.pelicanparts.com/More_Info/94460612500.htm?pn=944-606-125-00-M14&bc=c&SVSVSI=0756

I finally had some success today! The car started with the key and ran until I shut it down for a gas smell. It turned out that fuse #34 labeled fuel pump sender was blown and I checked it last week. It was difficult to get in and out so I put some dielectric grease in the socket.

Last night I replaced the fuel pump and with no pressure the banjo fitting was leaking. I took it apart and put some teflon tape on the threads for the 19mm top cap nut, also tightened the 17mm crush washer which was installed on the check valve at the factory. This appeared to fix the leak.

Well no, today the car started and I went around to the back where I saw gas pouring out. By the time I shut off the car, I had at least a gallon of gas all over my garage.

Any ideas why this banjo fitting is leaking?

[soxnail]

944 606 125 00 is the engine temp sensor used by the DME to trim fuel for cold and hot engine conditions.
The fuel pump has a check valve on it ( 944 608 952 01) it is 31 in the drawing, followed by a crush washer (N 013 812 2) it is 19 in the drawing, then the banjo bolt, followed by another crush washer same part #.
If the washers are deformed, under or over torqued they will leak.
Sox

[Gary944T]

Thanks to all. My new Rennline fuel pump came with 30 and 31 preinstalled. But no 19s so I bet that is the problem. I researched crush washers and mechanics that work on tractors prefer steel washers with inner o-rings so I ordered them and I'm hoping this nightmare will finally be over tomorrow !!

BTW, my Rennline fuel pump did not come with 29. At first I thought maybe the new fuel pumps don't need it but at the last minute I decided to cut the old one off and glue it on the new one.

[soxnail]

Glad it worked out, I did the same with my new pump (the cover). Download a PET for your car so you can have part and drawings for it.
Sox

[Gary944T]

Thanks. Where do I get this PET?

It runs fine at idle but at 3000 rpm it runs really well for a few minutes and then it starts choking and I can't keep it running. Have to restart.

I ordered a new CTS but it doesn't come until Friday...bummer.

[soxnail]

Look in the sticky on top of the forum...
Is the car under load at 3k or you just revving the engine in neutral ?
Ps. word of caution on the steel washers, their crush torque may be a lot higher then the fasteners on the pump can handle.
Sox

[Gary944T]

Just revving the engine in neutral.

[Gary944T]

Originally Posted by soxnail

944 606 125 00 is the engine temp sensor used by the DME to trim fuel for cold and hot engine conditions.
The fuel pump has a check valve on it ( 944 608 952 01) it is 31 in the drawing, followed by a crush washer (N 013 812 2) it is 19 in the drawing, then the banjo bolt, followed by another crush washer same part #.
If the washers are deformed, under or over torqued they will leak.
Sox

I just found out the hard way that 944 606 125 00 is not the coolant temperature sensor for a 1986 944 turbo (my car). I bought the URO equivalent locally and it has a 2 prong electrical connection. The CTS I just pulled out of my car is 1 prong. I should pull parts before ordering or buying new ones I guess.

[soxnail]

So it gets to 3k and you are holding the gas peddle steady to hold 3k and it dies after a few moments, or you are trying to rev it up higher and then it dies ?
Sox

[soxnail]

I believe that you have the old style temperature sensor there. the new one has 2 wire connectors.
As far as I know from looking at my car and DME schematics:
944 606 125 00 is the dme temp sensor.
928 606 201 01 is the water temp and idiot light sender.
Sox