 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / Porsche / Porsche Cars / June 2005Runs great, THEN...
I have a 71 911 T... It runs great for about 20-30 minutes, then the tach jumps around sporadically and it pops and is undrivable. I replace the plugs, wires, points, coil.... It's like a relay or something fails after the engine heats up... Any ideas? This must have happened to someone else at some point. Please help... Thanks. > I have a 71 911 T... It runs great for about 20-30 minutes, then the tach > jumps around sporadically and it pops and is undrivable. I replace the > plugs, wires, points, coil.... It's like a relay or something fails after > the engine heats up... Any ideas? This must have happened to someone else > at some point. Please help... Thanks. I know it's hard to believe, esp since you just replaced them, but your problem still sounds like bad points. The spring may be weak and/or the points may be burned or improperly gapped. File them down (emery board for fingernails), and gap them if you want - or better yet, replace them one more time (with a quality new set and gap them correctly). My 72 911T and 76 911S has the same issue at one point or another (no pun intended) W Thanks for the reply... Here is more information, do you still think it is my points... The last time, I drove the car it left me sit away from home... Consistently after 20-30 minutes of great running, the car goes crazy... This time, I left it running while I was washing it... It idles great for about 25 minutes, then it starting idling really rough, so I got in it and get on the gas, the tack jumps around like crazy then stays around 0, and it would pop.... Usually, if I let the car cool down, it will start without any issue... What would make the points fail, but then work again? Thanks for the help... >> I have a 71 911 T... It runs great for about 20-30 minutes, then the >> tach [quoted text clipped - 20 lines] > > W does this car have a resistor in series with the coil? if yes, check it or replace it > Thanks for the reply... Here is more information, do you still think it > is my points... [quoted text clipped - 34 lines] >> >> W What stood out was the jumpy tachometer you mentioned. I'm not sure a HT (high tension) short due to wet ignition wires or moisture in the cap would cause the tach problem. IIRC, a longtime Porsche mechanic whose shop I worked in during summers said it's usually a symptom of a weak spring mechanism on the points, or burned points. The weak pring causes the points to "float" on the distributor cam rather than make solid electrical contact each time. Same outcome if they're burned. That is why replacing them and the condenser (<$20, yourself) is better than filing "old" ones down. Of course, I could be (and often am) wrong - it was many years ago for me, but it is a twenty dollar gamble. Good luck. Post back if you try this and it works. W > Thanks for the reply... Here is more information, do you still think it is > my points... [quoted text clipped - 34 lines] > > > > W > Thanks for the reply... Here is more information, do you still think it is > my points... [quoted text clipped - 9 lines] > What would make the points fail, but then work again? Thanks for the > help... Ah, there's a device in there that's designed to do just that -- the vacuum advance. If the vacuum hoses that lead to the distributor are cracked and leaking, you'll get all kinds of backfiring and rough running, including stalling. Check the hoses -- it's a cheap fix. Does your '71 have a Marelli distributor or the later Bosch type? If it's a Marelli, I seem to recall that there were particular problems with it, but I can't remember what -- maybe just replacement parts availability. Ed Don't know if this one has been sitting very long...but my '71 sat for about 8 months with just the occasional start etc. Then when I was able to drive it again full time, I experienced the same situation you're talking about. Driving down the road, coff, coff spit...dead. Let it set for a few minutes and zoom...we were off again for 20 minutes or so. Mine turned out to me rust in the fuel tank.....removed it and let an aviation outfit clean and coat the tank, while I replaced all the filters and rebuilt the Webbers...TADA...ran like a champ afterwards. Hope this helps. Gary >I have a 71 911 T... It runs great for about 20-30 minutes, then the tach >jumps around sporadically and it pops and is undrivable. I replace the >plugs, wires, points, coil.... It's like a relay or something fails after >the engine heats up... Any ideas? This must have happened to someone >else at some point. Please help... Thanks. I put in another set of points... Started fine, drove it down road and in about 5 minutes, pop bang boom dead! I engine stalled. I left the key turned to the one position and popped the hood. I noticed something interesting. The wine from the fuel pump (sounded like it was coming from the back side bottom of the engine, near the transmission) was inconsistent. It would change from high to low... I looked at the fuel filter and noticed very little fuel in it and it looked like air would push by it as the wine changed from high to low. Not sure if the fuel pump is strong when started then dies after a bit of driving... Or maybe I do have a clog that happens after gas starts sloshing around... Any ideas or things I can test? > Don't know if this one has been sitting very long...but my '71 sat for > about 8 months with just the [quoted text clipped - 15 lines] >>after the engine heats up... Any ideas? This must have happened to >>someone else at some point. Please help... Thanks. You'll hate this....hook up a 5 gal gas can and run it to the fuel pump...in essence bypass the fuel tank. If you try to drive....I did it in a parking lot. If that works and it gets past the magic time frame...it is the tank. Check with your local aviation shops about cleaning it and coating it. Best of luck, Gary >I put in another set of points... Started fine, drove it down road and in >about 5 minutes, pop bang boom dead! I engine stalled. I left the key [quoted text clipped - 28 lines] >>>after the engine heats up... Any ideas? This must have happened to >>>someone else at some point. Please help... Thanks. is there alot of rust/debry in the fule filter now? try blowing out the fuel line with compressed air (before the pump towards the tank) then drain the tank if lots of rust comes out then you may want to get it recoated and or check the fuel lines for rust or kinks if it looks resonalble run car then blow out the line and drain the tank untill it looks clean again in addition i think your model has brass screen inside the tank as well? > You'll hate this....hook up a 5 gal gas can and run it to the fuel > pump...in essence bypass the fuel tank. [quoted text clipped - 36 lines] >>>>fails after the engine heats up... Any ideas? This must have happened >>>>to someone else at some point. Please help... Thanks. I broke down and took the car to my local Porsche guru... They looked at it and came to the conclusion that the problem was in the tach circuit... When the car was acting up, they disconnected the tach an it runs fine... They were going to do more testing to see if they hook up a different tach if the problem is still gone as they were not sure if the issues was with the tach or a connection or relay somewhere... Any additional help here would be appreciated. > is there alot of rust/debry in the fule filter now? > [quoted text clipped - 48 lines] >>>>>something fails after the engine heats up... Any ideas? This must >>>>>have happened to someone else at some point. Please help... Thanks. |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.