1979 928 Has No Power Above 3000 rpm
#16
pitman,
Warm control was tested with engine cold and electrical element fully warmed. Specs in the WSM indicate that warm control should be 3.4 to 3.8 bar. So to that end, the warm control is in spec. Also, the shark will have these symptoms engine warm or cold. By the way, I can go faster than 20mph, in fact she will do at least 50 mph, I just have to take my time getting there. Easy on the throttle.
Randy,
I'll try the additive, but not optimistically. The shark ran fine on this very tank of gas several weeks ago.
Dennis,
I have not checked the push valve assembly at the back of the distributor. I had assumed that this was ok since my system pressure was within spec and my fuel pressure leak-down time was within spec as well.
All,
One thing that puzzles me is the 450L difference in fuel volume between the dist. inlet and tank return lines. Is due to "normal" pressure drops in the distributer or is this excessive? I should also mention that when swapping the WUR inlet adapter from my old to new WUR, I found a metallic shaving in the screen - looked like brass. Upon discovery, I removed fuel lines to and from WUR and cleaned, no other debris was found. Don't really know where this came from, I suspect it may have been in my test gauges ar came from the distributer. Nevertheless the shark did not run any better after finding and cleaning.
Warm control was tested with engine cold and electrical element fully warmed. Specs in the WSM indicate that warm control should be 3.4 to 3.8 bar. So to that end, the warm control is in spec. Also, the shark will have these symptoms engine warm or cold. By the way, I can go faster than 20mph, in fact she will do at least 50 mph, I just have to take my time getting there. Easy on the throttle.
Randy,
I'll try the additive, but not optimistically. The shark ran fine on this very tank of gas several weeks ago.
Dennis,
I have not checked the push valve assembly at the back of the distributor. I had assumed that this was ok since my system pressure was within spec and my fuel pressure leak-down time was within spec as well.
All,
One thing that puzzles me is the 450L difference in fuel volume between the dist. inlet and tank return lines. Is due to "normal" pressure drops in the distributer or is this excessive? I should also mention that when swapping the WUR inlet adapter from my old to new WUR, I found a metallic shaving in the screen - looked like brass. Upon discovery, I removed fuel lines to and from WUR and cleaned, no other debris was found. Don't really know where this came from, I suspect it may have been in my test gauges ar came from the distributer. Nevertheless the shark did not run any better after finding and cleaning.
#18
I think the different delivery rate just reflects the distributor pressure regulator holding back fuel to produce the required system pressure...but I may be wrong - only a rebuilt distributor will tell, unless somebody else had measured flow here?
I had a similar no power, gentle acceleration only once in a Mini - found in the end that the mechanical advance in ignition distributor was frozen solid. Once that was fixed, it was fine again. Check that rotor can be turned easily and springs back, and that sucking on the vacuum advance/retard lines moves base plate, and hold vacuum.
jp 83 Euro S AT 49k
I had a similar no power, gentle acceleration only once in a Mini - found in the end that the mechanical advance in ignition distributor was frozen solid. Once that was fixed, it was fine again. Check that rotor can be turned easily and springs back, and that sucking on the vacuum advance/retard lines moves base plate, and hold vacuum.
jp 83 Euro S AT 49k
#19
Pitman,
I'll take a look at the ignition rotor tonight. Your system pressure theory makes sense. By the way, my system pressure is within spec.
jyoon,
The plug wires, rotor, cap and green wire are all new.
I'll take a look at the ignition rotor tonight. Your system pressure theory makes sense. By the way, my system pressure is within spec.
jyoon,
The plug wires, rotor, cap and green wire are all new.
#20
Mine had a similar problem, and it ended up being the fuel distributor.
And yes, it's expensive.
So the best advice is to borrow one from someone, swap it out,
and see if it fixes the problem...
And yes, it's expensive.
So the best advice is to borrow one from someone, swap it out,
and see if it fixes the problem...
#21
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From: St Augustine, FL
My euro, when I used to press down the pedal quickly, stumble horrible around 3k rpms, then back fire violently and BWWAAAAAAAAH! it would act normal. Then it would continue to act normal until i shut'er down and start up later, when it would do the same thing over again. I hope my distributor isn't going bad. I have asked around the chicago area shops and none rebuild k-jet distributors. Does anyone know of someone that will? and how much???
#22
It's not cheap.
I think it's like $2000 for a new one, and $1500 for a rebuilt one.
I'm sure Jim or Marc will chime in with some prices.
Used is also an option... But why spend $500 or $800 for a used one, if you can get a rebuilt one for a little more.
But yes, it's not cheap at all.
I think it's like $2000 for a new one, and $1500 for a rebuilt one.
I'm sure Jim or Marc will chime in with some prices.
Used is also an option... But why spend $500 or $800 for a used one, if you can get a rebuilt one for a little more.
But yes, it's not cheap at all.
#26
http://cgi.ebay.com/ebaymotors/ws/eB...sPageName=WDVW
CIS fuel distributor on ebay, 12 hours, now at $99.00. I'll pm you.
CIS fuel distributor on ebay, 12 hours, now at $99.00. I'll pm you.
#27
Originally Posted by SteveG
http://cgi.ebay.com/ebaymotors/ws/eB...sPageName=WDVW
CIS fuel distributor on ebay, 12 hours, now at $99.00. I'll pm you.
CIS fuel distributor on ebay, 12 hours, now at $99.00. I'll pm you.
As I posted earlier, I had similar problems with my '79 Euro and tested all the spark and fuel elements. If someone wishes to attempt a rebuild on their own I prepared an extensive white paper that oulines the steps, send a PM if you want an e-copy. However, a back yard rebuild misses the most important issue, confirmation of flow. If you have the time, you could create your own flow-test rig. You just need to fab your own lines (the metal Porsche 928 fuel lines would have to be bent and likely would be destroyed) and a calibrated jar. You would have to experiment to determine what the proper flow rate is, I don't know that. If you don't flow check, you drive the car and feel if it is running OK.
I PM'd Scott with the name of a reputable CIS rebuilder (he asked that I do not post his name, he doesn't normally do retail work). He has a test rig that is used to validate that the rebuild worked and the fuel flow is proper in total and for each cylinder.
#29
Made some progress this evening - here is the low-down:
I went after the ignition system since the fuel system seems to be within spec. I removed the ignition distributer cap and checked the meckanical advance and the vacuum advance. The rotor moved freely and sprung back and when pulling vacuum the oppropriate movement in dist. was noticed. Here is what was not so normal:
For info - cap, plug wires and rotor are new. When I removed the cap I noticed some very small scratches on the tip (metal tab) of the rotor. I also noticed some charred spots on the plug wire conductors in the cap. Conductors for cylinders 3,7 and 2 were charred on the upper portion of the conductor and other conducters were charred on the lower part. As if the rotor was not completel pressed when last installed and was cocked a bit. I cleaned everythig up and reasembled - now to check the timing.
Connected strobe and started car. When I pulled the vacuum line the idle increased about 200-300 rpm. (Is this right?) Plugged line and checked timing - was slightly off. After doing all this she ran much better, no more drastic sputtering at higher rpm's but still a lack in power and a slight miss.
Brought her back home and looked around some more - found the coil wire about halfway off the coil terminal. I had to press it back down. Haven't ran the shark after this and will get to it tomorrow. Hopefully my issues will continue to improve.
I inspected the the coil and the coil wire required re-seating - it was about halfway off the post and had to be pressed back down.
I went after the ignition system since the fuel system seems to be within spec. I removed the ignition distributer cap and checked the meckanical advance and the vacuum advance. The rotor moved freely and sprung back and when pulling vacuum the oppropriate movement in dist. was noticed. Here is what was not so normal:
For info - cap, plug wires and rotor are new. When I removed the cap I noticed some very small scratches on the tip (metal tab) of the rotor. I also noticed some charred spots on the plug wire conductors in the cap. Conductors for cylinders 3,7 and 2 were charred on the upper portion of the conductor and other conducters were charred on the lower part. As if the rotor was not completel pressed when last installed and was cocked a bit. I cleaned everythig up and reasembled - now to check the timing.
Connected strobe and started car. When I pulled the vacuum line the idle increased about 200-300 rpm. (Is this right?) Plugged line and checked timing - was slightly off. After doing all this she ran much better, no more drastic sputtering at higher rpm's but still a lack in power and a slight miss.
Brought her back home and looked around some more - found the coil wire about halfway off the coil terminal. I had to press it back down. Haven't ran the shark after this and will get to it tomorrow. Hopefully my issues will continue to improve.
I inspected the the coil and the coil wire required re-seating - it was about halfway off the post and had to be pressed back down.