rafikdous Posted 9January, 2015 Report Share Posted 9January, 2015 Ok I need help here because I am getting really cheesed off My '79 SC has been difficult to start for a while, cold and much worse when warm/hot I have replaced the pump which made things worse so went back to the original that came with the car I also replaced the fuel accumulator. Now the car starts first click in the morning but drive it for a short while then try to start it again and it won't. It tries to fire up but it won't. I leave it for an hour then things are good again Reading the Pelican and Rennlist forums, it could be the pump check valve. It's a royal pain in the a#%€ to replace it at home with no access to a hoist so I want make sure I don't waste more time and money for nothing Is there anyway to test a check valve before fitting it? Any other tests I can run to confirm its a check value problem? Thanks Rafik Link to comment Share on other sites More sharing options...
Russ Posted 9January, 2015 Report Share Posted 9January, 2015 Do you know for sure its fuel related and not the CDI/any other part of the ignition system? a failing CDI makes starting hard/impossible when warm too (and will come good when cooled off) Link to comment Share on other sites More sharing options...
tazzieman Posted 9January, 2015 Report Share Posted 9January, 2015 Cold start and warm start problems are different. The car should fire almost immediately when cold providing the ignition is strong and the timing set to spec. What else have you checked/replaced/fiddled with ? WUR , CSV , FD pressure valve etc etc Do you have access to a set of gauges? Link to comment Share on other sites More sharing options...
Harvs11 Posted 10January, 2015 Report Share Posted 10January, 2015 Capable/knowledgable mechanics on CIS are rare. I had dramas with mine stalling and being difficult to start, erratic idle, poor acceleration etc. I took it Louie at Motion Automotive in Sth Melb. who handed it over to a fuel inj. specialist in North Melbourne. I don't know the name so perhaps speak with Louie. It was a problem with the fuel frequency valve/O2 sensor/computer and a few things being out of spec. thanks to successive efforts to tune the problems out. It runs very well now. If you are not sure, it's best not to fiddle with CIS as it's a black art getting it all in sync. Link to comment Share on other sites More sharing options...
tazzieman Posted 10January, 2015 Report Share Posted 10January, 2015 It was a problem with the fuel frequency valve/O2 sensor/computer I think the '79 if stock is devoid of those bits! Which narrows it down quite a bit. The black art is much less of a mystery when you hold the wizard's magic book - fuel pressure gauge set for a start... http://www.jimsbasementworkshop.com/CIS/ Link to comment Share on other sites More sharing options...
Stew F Posted 10January, 2015 Report Share Posted 10January, 2015 Hey, just remember that K-Jetronic isn't something that's unique to our Porsches. It was also used on Audi, BMW, Benz and Volvo to name a few. There is a lot of troubleshooting info on the web. There is a good TS guide called the K JET DEBUGGING GUIDE. It's from a Volvo site if I remember correctly. Like they say, unlike the later bosch efi system, kjet has only two types, NA and Turbo. Link to comment Share on other sites More sharing options...
Stew F Posted 10January, 2015 Report Share Posted 10January, 2015 I just had a read of it. It could be one of the following; cold start injector, thermal time switch, or low rest pressure. Or something else. Good luck. Link to comment Share on other sites More sharing options...
rafikdous Posted 10January, 2015 Author Report Share Posted 10January, 2015 Tazzieman, I haven't fiddled with anything else apart from replacing the pump and accumulator I am a 356/912 person so all this 911 complicated stuff is new to me I thought it could be something fairly simple to repair. It sound like I might have to take it to someone By the way, cold start is no issue now, it starts on first click after the pump was replaced Is it worth replacing the check valve? Link to comment Share on other sites More sharing options...
Nick_911 Posted 10January, 2015 Report Share Posted 10January, 2015 Usually fuel accumulator is the culprit for warm start issues like that but could also be the check valve. Another test is when it's hot and won't start , with ignition on lift the sensor plate for a second or so to prime the system then try kick it over. Cheers Nick. Link to comment Share on other sites More sharing options...
Stew F Posted 10January, 2015 Report Share Posted 10January, 2015 Also, check the electrical connection on the warm up regulator. I was going to say check it's fuse as well, but on your year the WUR runs off the fuel pump relay according to the workshop manual. Previously, this fuse was on the rear fuse panel, in the engine compartment. I have a Bosch K-Jetronic manual which is pretty good in explaining the system in simple terms. You can get it off the web for free. Link to comment Share on other sites More sharing options...
jnr356 Posted 11January, 2015 Report Share Posted 11January, 2015 think i have replaced only a handful of accumulators in 30 years you need a fuel pressure gauge and see what the warm up reg is doing,can be adjusted,if that fails it will need to be reco'ed you need to know what you are doing also has the mixture been set with a co2 meter? Link to comment Share on other sites More sharing options...
rafikdous Posted 11January, 2015 Author Report Share Posted 11January, 2015 Thanks all Mark, simple, I don't know what I am doing so struggling If you have time to check it out, let me know, I can drop it off anytime you are available Link to comment Share on other sites More sharing options...
rafikdous Posted 11January, 2015 Author Report Share Posted 11January, 2015 And by the way, it is running rich so most likely the mixture needs to be set too Link to comment Share on other sites More sharing options...
FortuneAuto Posted 13January, 2015 Report Share Posted 13January, 2015 Easiest way to diagnose the fuel system is by hooking up a fuel pressure gauge to check the fuel pressure going into the warm up regulator and the pressure bypassing it too. Both pressures have to be within specification. Having a gas analyzer will be good too to monitor your fuel mixtures between cold and hot operations. You do not want to set the fuel mixture until you are 100% sure the entire fuel system is good. Link to comment Share on other sites More sharing options...
rafikdous Posted 16January, 2015 Author Report Share Posted 16January, 2015 I think I found what could be the problem (one of them anyway), one of the pins on the WUR has snapped off. See below pointed to by the yellow arrow. I assume my first step is to get this fixed first http://i21.photobucket.com/albums/b277/karmann_ghia60/2015-01-16171738_zpsc189bfce.jpg Link to comment Share on other sites More sharing options...
Coastr Posted 16January, 2015 Report Share Posted 16January, 2015 ^ Picture for you Link to comment Share on other sites More sharing options...
Shady Speedway Posted 17January, 2015 Report Share Posted 17January, 2015 That snapped pin won't help. The WUR is quite easy to pull apart. The plug that is damaged is for the heater coil around a bimetalic strip. Once the WUR has been opened up you can see how the clip holds it in place. Very easy to replace. You won't need to replace the entire WUR. In saying that you will need to identify what heater coil you have, they are rated by resistance it has the numbers printed on it. They changed depending on where Porsche sent the car... warm or cold climate. It basically dictates the warm up fuel pressure. Kind of like how long the choke stays on for. Here in Adelaide we have a wrecking yard called "U pull it" you go in there, unbolt what you want and pay for it on the way out. I bought 3 WUR's for $10. They are on old Mercs and Volvos so don't let anybody multiply the cost by the Porsche factor. If you can identify your heater coil and it is close to one I have here, you can have it. I'll pop it in the post. Once that is sorted, if your problem persists you will need to get your hands on a fuel pressure gauge set. I made mine from hoses I took from a Merc at "U pull it" a bicycle pump pressure gauge and a tap from and old air compressor. It does not have to be super accurate. What you are looking for is residual line pressure once the engine has stopped. With the gauge attached you can see if your check valve is working (new check valve is about $30). Another check for residual pressure is at the injectors. If the pressure drops straight off after the engine stops it could also be the injectors leaking, They should hold back around 50PSI of fuel pressure. If they are old and dirty, they will dribble the pressure that the accumulator creates into the inlet manifold, effectively flooding the engine creating a hard start. Once the engine has stopped, the check valve should stop pressure bleeding back to the tank. And the injectors should seal up creating a pressure in the system that resists vapor lock. This pressure is applied to the system by the spring in the accumulator. If your pressure is dropping off, then it can take some cranking to get the system pressure back up to the point where your engine will fire. The gauge set is quite cheap, there are plenty of CIS videos on youtube showing how to use them and what to look for. Good luck. Pic is of the WUR heater coil removed from housing. Link to comment Share on other sites More sharing options...
Stew F Posted 17January, 2015 Report Share Posted 17January, 2015 I'd say that broken connector is the root of the problem. Nice bit of info Shady. I didn't think of Upullit. I might head down and grab some K-Jet gear and pop them in the shed for a rainy day. Lots of Euro cars had it. It's is as common as stomberg carbies. Upullit is pretty good. I rebuilt the front of my son's BMW E30 from upullit parts. All up I spent about $200 on bonnet, guard, bumper, radiator, and a heap of small parts. And they were an exact colour match for his car. How's my luck.. Link to comment Share on other sites More sharing options...
Caledonian Posted 17January, 2015 Report Share Posted 17January, 2015 That snapped pin won't help. The WUR is quite easy to pull apart. The plug that is damaged is for the heater coil around a bimetalic strip. Once the WUR has been opened up you can see how the clip holds it in place. Very easy to replace. You won't need to replace the entire WUR. In saying that you will need to identify what heater coil you have, they are rated by resistance it has the numbers printed on it. They changed depending on where Porsche sent the car... warm or cold climate. It basically dictates the warm up fuel pressure. Kind of like how long the choke stays on for. Here in Adelaide we have a wrecking yard called "U pull it" you go in there, unbolt what you want and pay for it on the way out. I bought 3 WUR's for $10. They are on old Mercs and Volvos so don't let anybody multiply the cost by the Porsche factor. If you can identify your heater coil and it is close to one I have here, you can have it. I'll pop it in the post. Once that is sorted, if your problem persists you will need to get your hands on a fuel pressure gauge set. I made mine from hoses I took from a Merc at "U pull it" a bicycle pump pressure gauge and a tap from and old air compressor. It does not have to be super accurate. What you are looking for is residual line pressure once the engine has stopped. With the gauge attached you can see if your check valve is working (new check valve is about $30). Another check for residual pressure is at the injectors. If the pressure drops straight off after the engine stops it could also be the injectors leaking, They should hold back around 50PSI of fuel pressure. If they are old and dirty, they will dribble the pressure that the accumulator creates into the inlet manifold, effectively flooding the engine creating a hard start. Once the engine has stopped, the check valve should stop pressure bleeding back to the tank. And the injectors should seal up creating a pressure in the system that resists vapor lock. This pressure is applied to the system by the spring in the accumulator. If your pressure is dropping off, then it can take some cranking to get the system pressure back up to the point where your engine will fire. The gauge set is quite cheap, there are plenty of CIS videos on youtube showing how to use them and what to look for. Good luck. Pic is of the WUR heater coil removed from housing. Technical information that is easy to follow and to understand, well done and well written. Link to comment Share on other sites More sharing options...
rafikdous Posted 17January, 2015 Author Report Share Posted 17January, 2015 Thanks gents, great help I will pull the WUR apart, get it sorted then move on to the next step is the problem still there Link to comment Share on other sites More sharing options...
Stew F Posted 1February, 2015 Report Share Posted 1February, 2015 How did you get on? Problem solved yet? Link to comment Share on other sites More sharing options...
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