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Car Cranks but Doesn't Start


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Greetings guys:

I am having a little trouble with my 2001 996 Turbo. First, let me state a known fact. For some time now, I am having a check engine light that gives the code P-1325 which is associated with the Bank #2 variocam system. Since I am pretty sure it is mechanically related, I have no plans to deal with it right now. Yesterday I used the car without any issues besides my common CEL. Last night as I am usually doing after dirving for I while, I clear up with my OBD2 scanner my CEL and left the car it alone for the day. Today when going to work, I got in the car and it didn't wanted to start. It does crank, but it doesn't start. Is there a possibility that after clearing several CELs without fixing the problem the ECU may enter in a "protection" mode (or something similar) until the fault is corrected? It may sound weird but since I didn't do anything else besides the CEL clearance, I don't know what else to think.

Once I get home from work I will be checking for the basics. Ignition supply and fuel. Plus will connect the durametric to see if there are any codes. Any advice on what to check would be greatly appreciated.

Best regards, Andres

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Good morning Andres. First fuse check: C2 (ignition relay) and especially C4 (fuel pump) also try to found out if the fuel pump is turning... If it is not turning it can be the pump relay located above the fuse panel on relay panel #1. Or fuel pump failed.... Start with that and will see.... The only "protection mode" that I am aware of is the limp mode and it provide the driver with limited performance so the car should start anyway....

Edited by jpflip
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As stated, the "limp mode" is designed to restrict performance, but not shut the system off (prevent starting). As far as what is wrong, I suggest you start by reading the codes again...(what code reader are you using BTW?) If using a durametric, PST2 or PIWIS you get no codes there are a host of things from fuses, to clutch sensor, to alarm module, etc...It is possible the two events are unrelated.

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Hi jpflip:

As always, trying to help up. I really thank you and appreciate it. I will absolutely verify this. As I am at work right now and the problem was this morning, I haven't done no troubleshooting at all. Will post back with the findings.

Best Regards, Andres

Always happy to help Andres + I can end up with problem too and your help will be appreciate.... Keep us inform of your findings...

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Hi WRoss996TT:

I agree with you. Since I still haven't hooked up my scan tool after this issue, the first thing I will do is to check for error codes using my Durametric tool. I have an Actron Scanner which typically I use to clear my infamous P-1325 code since it is more handy than hooking up my laptop to clear it with the Durametric Software. But this is the first time that this happens to me. Is great to know that the "limp" mode will still allow me to startup the car, hence this discards the possibility of some relationship with the CEL clearance. In addition, since the car cranks, I understand that I can discard the clutch switch.

If I recall correctly, I read your topic associated with the hose inside the gas tank that due to deterioration may release the fuel pressure. I will be checking this after the other battery of tests: fuses, relays, etc.. This could be a probable cause of my problem. I will let you know.

Thanks guys!!!

Andres

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Alright guys:

I am happy to tell you that I was able to start it up!!! :) However, I have a problem that needs to be solved. :( Let me provide the details. First off, I connected my Durametric tool to find out that there were no errors with the exception of the alarms attached. So I proceeded to check all the fuses. None was blown. I then started to manipulate the fuel pump relay with the Durametric and to my surprise the system sound like operating but the sound came from the back of the car!!! How come if the pump is in the front!!! Well, the answer to that is that it seems that for some reason when I activate that relay, other artifacts activate like for example the rear fan and the vacuum pump(both of them at low speed). Now, I went to the front of the car and unplug the fuel pump harness. I found curious that the brown cable(ground for pump) was like overheated and the plastic area surrounding its connection pin was melted. Humm!!! It doesn't look good. I attached some pics of what I found. I wiggled everything a little bit. Cranked the engine and.....surprise!!! Car was alive again. However, since I didn't like what I saw I continued monitoring the power leads to the pump(the brown cable and the green with white stripe). I noticed that as the car remained turned on, temperature was increasing to a point that is for concern. So in order to understand if it is a failing fuel pump or relays/fuse/short circuit related, I applied 12V straight to the fuel pump with its harness unplugged. The result was interesting, the cables I used started to increase their temperature which makes me understand that the problem is related to the fuel pump. Now my question is, lets say that for some reason I have a clogged fuel filter, could this increase the pump's work making it overheat hence overheating its power leads? I have always thought that these types of things were supposed to be captured by the fuel pump fuse. Have some of you heard anything related to a similar issue before? I verified that the fuel pump fuse was the correct grade and it is the right one: 30 Amps. At this point I may think on ordering a new fuel pump based on my testing but would like to know your opinion.

Thanks, Andres

post-37848-1235611113_thumb.jpg

post-37848-1235611119_thumb.jpg

post-37848-1235611127_thumb.jpg

Edited by Iceyankee-Tsi
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Strange. Like your saying the fuse should melt before the wire. Wiring diagram show 30 Amp for the fuel pump fuse. I guess now you can reach the primary filter to see if it is clogged and eliminate this possibility. But the heat around the pump area seems to be a faulty pump.... It is only a guess... Good luck with that one Andres. I am convince you will found the problem...

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Doesn't Murphy's law state that a $300 fuel pump will always blow to protect at $0.20 fuse?

If you can unplug the connectors and measure the current draw, it may be high enough to cause it to get hot but not high enough to blow the fuse. If the current draw is normal, you can try to clean the connectors or tighten the pins up a bit to reduce the local resistance and see if the temp drops before replacing the pump.

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  • Moderators

Turbo fuel pumps takes more Amps. on full boost than on idle or partial load, the problem becomes worse with the age. We have got problems with a brand of satellite track system which use the pump currant as fuel cut in case of theft, the sat. track control box connector was melted every time the car(s) was on the race track under approx. continuous full boost, never under normal driving conditions. A pump replacement was the solution, the line between the fuse/wiring/pump under full load looks very thin. Hope it's helps.

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Well,

At this point I think I have found a good way to sort this out. I will connect to the car's fuel pump harness a spare Walbro 255 ltr/hr fuel pump that I have from my 1991 Eagle Talon TSi just to see if the wiring overheats the same with this pump. If it does, I will know that I have to search for a short circuit,bad grounding, etc in the car. In the other hand, I will connect again the car's original fuel pump to a spare 12 volt source to see if the wiring overheats as previously happened. I guess that would be the final check that will prove a defective fuel pump. I will let you know my findings. Thanks for all your comments. Its great to have available all this wisdom and technical knowledge that you guys provide.

Best regards, Andres

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Well guys:

No luck at this point. Tested the car with my Walbro 255 ltr/hr fuel pump installed in place of the OEM one and the brown ground cable overheated. I verified continuity against ground in the green/white cable which is the 12V power source to the pump and it measured 6.5 ohms!!! Isn't supposed to be zero? can somebody unplug their fuel pump/fuel sender electrical connector and check this reading for me please? At this point I think I may have a short somewhere but I removed the fuel pump fuse and the pump's relay and I still have 6.5 ohms in my fuel pump power cable. Is there a specific wiring diagram that may show me where do these two cables (the brown ground cable and the green with white stripe power wire) go from the fuel pump plug? I have tried to find it without luck. Thanks.

Andres

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Are you measuring DC 6.5 ohms through the power connector to gnd of the fuel pump? I don't know what the value should be but it should not be zero else the pump is shorted out and will draw lots of current (I=V/R so with V=12V, R=0 is bad). You can disconnect the hot wire from the fuel pump and measure the resistance to ground at the fuse block. The resistance should be quite high unless there is something else either connected to the wire or a short to ground. Likewise, you can measure the resistance from the ground wire of the pump (disconnected) to a solid gnd point in on the chassis and the resistance should be close to zero. Is the entire brown wire (gnd) hot or just at or near the connector - the wire is a good heatsink so if the connector is hot, the wire by the connect will be hot? Depending on the maximum current rating of your meter, you could also remove the fuse and measure the current drawn by the pump. If they all seems reasonable and the connector is getting hot, it may be that the connector is not grabbing the terminal tightly and causing a high resistance point that will get hot. If you can get your probe on the gnd terminal of the fuel pump with the gnd wire attached, you can measure the voltage between the pump gnd terminal to chassis gnd to see if there is any excessive voltage drop (which would suggest a bad connection or gnd point along the wire).

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Okay guys:

Let me tell you what I have found. First off, let me explain in better detail what I previously said. As all of us can see, there are two cables that connect to the fuel level sender that go to the fuel pump. These are the green cable with the white stripe(which is the pump's 12 volt source) and the brown cable(which is the pump's ground). What I did was to measure the resistance of the green cable. The lecture was of 6.5 amps. After posting this message I went disconnecting fuse by fuse until I found the fuse that was creating that resistance in my green fuel pump power cable. I found out that there was a 5 Amp fuse connected in row C5 that was creating this "mini short". When looking at the fuse diagram in the manual, I noted that this fuse slot was meant to be empty by the manufacturer. The only extra thing I see in the car besides the OEM stuff was a Passport SRX radar(which doesn't work).

I may think that the previous owner used this fuse slot to power his radar. I left out the fuse and now with power off and green cable unplugged, I have zero resistance as it is meant to be. However, this may have been part of the problem but it didn't fixed it. The brown ground cable kept overheating. I went on and removed the brown cable lead from the fuel pump/fuel level sender connector. The contact area with the fuel level sender lead was pretty much fried. So using the same connector, I cut and removed the remains of the fried brown cable and soldered a new piece of wire with the same specs as the old fried brown cable to the connector. I then solder the other end of the new cable to the section of brown cable that went to the car(see picture and sorry for the quality).

Left the car running for 1/2 an hour and the condition seems like it has improved(the brown cable goes a little bit warm but it doesn't get as hot as before). Can anybody confirm me is a 0.30 Amps current is reasonable for the pump operating in idle? This was the measurement I took from the brown cable with the car on. After all, I think I may need a new plug. Thanks.

Andres

post-37848-1235835746_thumb.jpg

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You are wright the slot C5 should be empty and slut C4 should have the fuse for the fuel pump 30 amp. IMHO I think you got your problem which was a defective connector. But your first problem was the car didn't start... Seems to be good now ???... Sorry about the resistance I cannot answer that one... Just to give you a small example: I had to install "daytime running light" on my car due to Canadian regulation. There is a way to do it on the internet without having to change the relay which is really expensive... You have to jump the fuse for the light with the fuse for the seat heater. You have to used 18 gauge wire. I did not have any so I used 20. You should see how hot the wire became... So in your case if there was a couple of broken strand it will increase resistance and heat up.... But of course I think you now that... By the way Andres the picture is really bad a little bit overexposed ;-)

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ja ja ja. Thanks for that JP :D :

Well, to start off my car did'nt want to start. The answer to this one is that probably due to overheating of the fuel pump ground cable, its contact to the car's ground was lost. Hence, not allowing the engine to start due to lack of fuel. After I wiggled the brown cable a little bit, the car started. Since this was the only thing I did prior to the engine starting and since after it has started every time, I understand that was the problem.

That brought me to find out the problem regarding the overheating ground cable. It seems that the cable mod I made worked pretty well since even though the cable is not completely cold, it gets warm to and acceptable level. What I mean with that is that I know it is not capable of melting nothing. However, do any of you know if this fuel pump/level sender plug is sold separately that I could purchase and reconnect the wires the right way? It is not that I like to have a car like this looking like a project car. :)

Thanks,

Andres

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Andres in the wiring diagram Sheet 25 "Plug". They show you all the different plugs and the part #996...... over each one. Do you see yours ???? I tried a couple of numbers in PET and they work...

Just for your info there is a test for the fuel pump that can be done. One main fuel line disconnected and into a bucket, you switch on the ignition and within 30 seconds you should get 1.25 liters... Info only ...

Edited by jpflip
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I verified the diagram and the plug is not there. It seems that some VW/Audi supplied parts are not included in the manual. The part number for this plug is 357 906 231 and has the VW/Audi symbol stamped in the side. I looked at Rector Motors web page and it has a list price of $6.20 which is reasonable. However, I wonder if it includes the pins where the cables are crimped to or if I have to purchase them separately? I guess I would need to call to find out that one.

Regarding the fuel pump test, thanks I read that info while looking across the manual for the fuel pump. That would be the appropriate way to test fuel flow. Since I am using at this time a Walbro 255 ltr/hr high pressure fuel pump, I understand everything is running as it should. For some reason, i don't think that the stock fuel pump can flow more than this. However, this is just speculation since the stock pump I have doesn't have any part number or inscription(other than the VDO letters) that I could use to identify its operation characteristics. That would be a great piece of info if somebody has it. :thankyou:

Andres

Edited by Iceyankee-Tsi
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  • 4 years later...

I verified the diagram and the plug is not there. It seems that some VW/Audi supplied parts are not included in the manual. The part number for this plug is 357 906 231 and has the VW/Audi symbol stamped in the side. I looked at Rector Motors web page and it has a list price of $6.20 which is reasonable. However, I wonder if it includes the pins where the cables are crimped to or if I have to purchase them separately? I guess I would need to call to find out that one.

Regarding the fuel pump test, thanks I read that info while looking across the manual for the fuel pump. That would be the appropriate way to test fuel flow. Since I am using at this time a Walbro 255 ltr/hr high pressure fuel pump, I understand everything is running as it should. For some reason, i don't think that the stock fuel pump can flow more than this. However, this is just speculation since the stock pump I have doesn't have any part number or inscription(other than the VDO letters) that I could use to identify its operation characteristics. That would be a great piece of info if somebody has it. :thankyou:

Andres

Hi mate, sorry for pushing a very old post, I am currently having the exactly same suitation and symptom, I have the fuel sender replaced due to melted a hole there, and car can be started, but I cannot figure out how and why it did melt. My car still stuck in workshop as the plug is getting hot in few minutes, appreciate if you can advise what did you found and fix. Thanks

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Hi Superboyg:

Sorry to hear this is happening to you. I can tell you that after replacing the plug and insuring all the wires were properly connected to the fuel sender plug, evertything worked fine. My assumptions are the following in my old case: A poor connection between the fuel level sender and the plug in addition to the high Amp draw of the old fuel pump(maybe due to a deffective pump) created an overheating condition in that area that made the wire start to melt. Like I mentioned in the previous posts, when I replaced the pump with a walbro unit, the change in wire temperature was considerably noticeable. Hence, I would suggest to change the plug, insure proper connection between the fuel sending unit and the plug. If this doesn't work, replace the pump. That would be the path I would follow. I no longer have my 996 Turbo, yet after this was done I've never had to mess with it again. If I can be of any additional help, please feel free to let me know.

Good luck sir!

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