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cjoenck, I'll be sure to check the plug wires again.
I agree that the temp and O2 sensors shouldn't keep it from running. I've cleared those codes and they haven't resurfaced.
So at the moment, I have no codes in the system.
I don't have the means, yet, to check for fuel pressure. Guarantee I'll install a fuel pressure gauge in the near future!
As for the new parts; I replaced the fuel pump & fuel filter in March. Crank ref sensor done the same day as the pump. The swap to 993 coils were done in April.
I've driven it several hundred miles since then, but I would not put it past it that any one of those new parts went bad again or something came loose. I just have a hard time thinking that's it though.
Doesn't hurt to double check though.
Thanks!
Cars up on my lift now and I'll spend some time this week to get under to inspect the fuel pump and its connections again.
Also will pull a spark plug to see if I have anything there.
So far, I haven't found any cracked or disconnected vacuum hoses.
Bad cylinder head temp sensor and bad oxygen sensors shouldn't prevent ignition. Engine will just run badly.
For the OP, from my own personal experience a bad cylinder head temp sensor caused my engine to stall almost immediately after starting (but it would start to your point). I could feed it gas to keep it running through, it just wouldn't hold an idle.
The car's up on the lift and I jumpered (is that a word?) the DME (pins 3 & 7) to get power to the fuel pump.
Verified with volt meter that I'm getting 12v to the pump. But the thing doesn't sound or feel like it's running. Ugh.
When I can, I'll pull the pump off and bench test it. WTH.
The last time I tangled with the fuel pump, the fuel filter was changed. I had a ton of sediment in that filter. I wonder if I've got a gas tank full of sand.
I had to pull the fuel tank on mine due to 15 year old fuel and found the in-tank filter had holes in it from plastic degradation. Yours might be in a similar condition if the filter has never been replaced.
So if you have sludge, sand or any contaminants in your fuel then it would all be going through the pump. I replaced my pump and installed a new filter and new fuel lines from tank to pump while I was in there.
When I get back under the car, I'll pull the fuel pump again, bench test it to see if it really does run or not.
Then look at the state of my fuel tank. Would suck if it had a bunch of sediment at the bottom that's messing up the works.
When I get back under the car, I'll pull the fuel pump again, bench test it to see if it really does run or not.
Then look at the state of my fuel tank. Would suck if it had a bunch of sediment at the bottom that's messing up the works.
It’s pretty easy to pull the fuel level sensor you can then get a hose right into the bottom of the sump and get most of the fuel out it’s been awhile but I think then you can see the bottom of the tank
It’s pretty easy to pull the fuel level sensor you can then get a hose right into the bottom of the sump and get most of the fuel out it’s been awhile but I think then you can see the bottom of the tank
Yes, that is what I did to empty my tank, but be careful as the rather delicate (due to old age) in-tank filter is right there and can be damaged by the hose. Here is what my filter looked like.
I'll be sure to check that out guys.
As for the fuel pump, I pulled it, put it on the bench and put 12v dc through it. Guess what? It works! I left it in the rubber sleeve and I could still feel it run and hear it hum.
SO...I'm going to go upstream from there again and verify my DMEs are working. I had previously put a volt meter on the terminals at the pump and read 12v there when the key was turned. My assumption there is if I see 12v there, then the DME is good. No?
Earlier, I had done this same test while the pump was in the car, Then I did not feel it run or hear it hum.
Weird. We'll see what happens now.
On a side note, when I pulled the pump, I released the hose clamp crimping the fuel line into the pump. I let fuel dump into a pan I had in order to inspect for sediment or other contaminants. Nothing. Clean fuel.
Fuel Flow test?
shows if blockages downstream ie in tank.
Change fuel filter anyway?
Regulator is cheap..part # pic attached.
fuel pressure test. If original should be replaced for peace of mind as our cars are gettin older.
no fuel leeks on floor right?
back to our regular scheduled program...
on to electrical
Last edited by TJ993; 08-15-2021 at 01:15 PM.
Reason: Fuel P Regulator my 97
That's great news that the fuel drained out was clean. When you bench tested the pump did you check how many amps it was drawing while it was humming?
I didn't think to check how many amps it was drawing. But now that I think this through, would it not pop the fuse if drawing too much? Or is the concern drawing too little?
I suppose a fuel pressure or flow test would be warranted next.
As for the fuel pressure regulator, I've never changed it and I don't see any record that it was done when the engine was rebuilt.
I've read a few posts on how to test it, but don't see an easy way to get to the vacuum line in order to pull it.
Might have to disassemble a bit just to test.
First though, going to pull the fuel tank filter out and the filter in the engine compartment again. Check them.
My failed (seized fuel pump) was drawing 11 amps and therefore did not blow the 15 amp fuse. It did hum however, so a hum is not necessarily indicative of a working pump. I went back through my notes during troubleshooting. For what they are worth, here they are:Brown wire is ground, the other wire (green/black) is power.
Both wires were disconnected prior to voltage and resistance testing.
Applying 12 VDC caused a hum but no fuel appeared in the jug at the disconnected fuel filter.
Pump motor was drawing 11 amps on Fluke ammeter.
Resistance measured between two pump terminals was 20 ohms.
Resistance between brown terminal and ground was infinity.
Resistance between green/black terminal and ground was infinity.
Resistance between brown wire and ground was 3 ohms
Resistance between green/black wire and ground was . I didn't write it down.
Mine ended up being the coil pack and a (possible) faulty ftech9 Pump Prime DME...updated to the 993 coil and went back to the OEM DME and seem to be back in business!
The issue with ftech9 Pump Prime DME--they are sending me a new one...great customer service and quick turnaround. Fuel pump would run and then shut down after 3-5 minutes (according to my mechanic).
Well, it didn't take long to do my test of fuel pressure.
I took the hose off the fuel rail closest to the fuel filter. Setup a small bucket and dropped the hose into it.
Then I cranked the car. Zero, absolutely nothing came out.
Checked the voltage at the pump again and got about 12v. Again, heard the pump hum.
I haven't pulled the pump out again because I'm pretty pissed right now.
Receipt shows this pump was bought 4/12/21
Porsche Fuel Pump - 96462010400 - Bosch 69468
08-10-2021, 03:37 PM
