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I agree with your logic, Pete. That would explain the unusually high pressures in the system and yet, running lean as well. I hope none of the little pieces of rubber are lodged in your injectors. Mechanical injectors cannot be back-flushed, just in case you are thinking about that. If memory serves, I think there is a micro-screen at the top of the injector to catch debris before it enters the barrel, That may save the day here.
I agree with your logic, Pete. That would explain the unusually high pressures in the system and yet, running lean as well. I hope none of the little pieces of rubber are lodged in your injectors. Mechanical injectors cannot be back-flushed, just in case you are thinking about that. If memory serves, I think there is a micro-screen at the top of the injector to catch debris before it enters the barrel, That may save the day here.
Someone said acetone may dissolve the rubber bits. The little filter screens are in the outlets of the FD, not the inlets of the injectors. I'm going to take them to a diesel performance shop and see what they say.
I think there may also be inlet screens down inside the injector. Not sure if acetone would dissolve that material, but no harm in trying. Looks like you have plenty of little chunks of it to try it on in a jar.
I think there may also be inlet screens down inside the injector. Not sure if acetone would dissolve that material, but no harm in trying. Looks like you have plenty of little chunks of it to try it on in a jar.
Yes, yes I do. I'll do some experimenting with stuff in the chemicals cabinet
For the time being, I've reset the mixture screw baseline from Jim Doerr's advice - jumpering the fuel pump, enriching the mixture until it squeaks and then backing it off again until the squeaking stops. Hoping that gets me close enough to run and I'll adjust from there.
My idle screw is probably out of whack now too. Is there a baseline setting or trick for that one as well?
Lightly turn the idle speed screw in till it just closes. Then back it out 2 full turns. That should provide too high of an idle speed, but it will allow you to get it going at least. Then you will adjust from there.
Lightly turn the idle speed screw in till it just closes. Then back it out 2 full turns. That should provide too high of an idle speed, but it will allow you to get it going at least. Then you will adjust from there.
Had what I think may be a Eureka discovery this evening.
Earlier today I was reading some CIS information that had been shared with me by Ron Borras and one of the articles was "Playing with your K-Jetronic Warm Up Regulator, or WUR". In this article, the author (who isn't listed) states that "if your control pressure is high, you need to find out if if is due to incorrect calibration of the regulator, or a blockage in the system somewhere".
Well, based on the manual, my control pressure was way high - 145 psi vs the around 90 it should be at the top of the range, so it got me thinking about blockages in the fueling system. Though I had installed a couple of Greg Brown's fuel lines, I actually don't think I was able to install the right lines in the right places and a couple of those lines had little adapters with small holes in them, and though I'm sure they were fine (since all of Greg's stuff if first rate), I decided it was time to start eliminating variables, compared to how the car used to run. Before the engine swap, it would start immediately and run perfectly with a rock solid idle, great responsiveness, good AFR numbers, etc. The fuel distributor and/or the WUR don't just go bad when being removed from one motor and installed on another, so I decided to go back to the original hard fuel lines. I was initially just going to run the 2 from the Fuel Distributor to the WUR, but decided that still leaves too many variables, so bit the bullet and started taking stuff apart again, including removal of all the fuel lines.
The stainless injector lines I had installed had different end connectors for the injector side than the OEM hard lines, and I figured because of that, is why each one had a small o-ring inside. Here's a picture of the #4 line I didn't use in its original form because it sticks up off the injector and interferes with the heat exchanger for the supercharger, so for #4 I had reused my OEM hard line. (Note: Greg's version of these stainless lines have 90 degree ends, probably have the stainless sections coatedlike his others to not abrade themselves or other things they contact, and I would guess the ends can be tightened independently of the line rotating also like his others, all of which would make his much nicer than these).
Well I took the first couple lines off the injectors and saw this squiggly black stuff drop down onto my pristine cam towers, so the next few I was more careful about as I took them apart...
Here's the Eureka moment
I don't know what those o-rings were made of, but they certainly weren't fuel resistant, and essentially disintegrated and exploded in the injector inlet. In fact looking at the taper inside the fuel hose, and how that would mate with the injector, they probably didn't need to be in there at all, but each line had one.
So the blockages they surely caused is why I think whenever I'd try to give the motor some fuel, the AFR gauge would go super lean and why when using the mixture screw to try and enrich it would be able to do that at idle when the demand for fuel volume was very low, but not under any load since I'm sure I had a very compromised flow through the injectors. The sad part is that these were brand new injectors and the way the o-rings disintegrated into tiny pieces, I'm sure they are now completely full of rubber debris and ruined so I'm going to have to throw them out.
Tonight I moved the new tension rings and sealing washers from the new injectors over to the old injectors that I had removed when the 4.5L was running perfectly, and have now reinstalled them. I was going to reinstall the hard fuel lines, but they look crappy compared to the rest of the engine, so I decided to mask off the ends and use some high temp engine paint to freshen up the outside of them.
I'll reinstall them on Wednesday when I return from a business trip and see where things stand.
My theory is the super high fuel pressure was being caused by the fuel distributor not being able to push any fuel through the injectors which then backed up through the WUR outlet line and effected the WUR inlet line pressure as well. The surging witnessed in the video was because once the pressure built up high enough, it was able to push some fuel through the clogged injectors, but once the pressure subsided a bit, the car got no fuel and wanted to die, but just before it would, the pressure got high enough again to force more fuel in.
When I tried to drive it around the neighborhood yesterday, any time I would give it any gas it would go full lean - of course it would without any fuel getting through the injectors...
I'm glad I didn't make a bunch of changes to the fuel distributor or the WUR as my gut feeling is that this was the primary running issue and once the correct fuel lines are reinstalled, it will just be a matter of tuning with the mixture screw, idle screw, and timing and then I'll be back in business.
Fingers crossed....
Just to be clear....none of my injector, fuel distributor, or cold start lines have any rubber inside.
Where did those lines with the rubber inside come from?
Someone said acetone may dissolve the rubber bits. The little filter screens are in the outlets of the FD, not the inlets of the injectors. I'm going to take them to a diesel performance shop and see what they say.
Just to be clear....none of my injector, fuel distributor, or cold start lines have any rubber inside.
Where did those lines with the rubber inside come from?
Correct, I thought I was clear in saying the "non Greg Brown" lines. I have 3 of your lines and installed 2 of them - the ones from the WUR to the Fuel Distributor, but couldn't maje the 3rd line work, which I think was for the cold start valve - I think you were going to email me some directions (petza914@gmail.com).
The lines that run from the fuel distributor to the individual injectors that had the rubber o-rings that disintegrated were NOT your lines and were sourced from another member who was going to use them with a new fuel rail setup on an L-Jet car, but we thought they'd work for my K-Jet setup too. He had never installed them.
Your injector lines are much better for at least 3 reasons:
Your braided stainless is costed so the lines don't abrade or get abraded.
Your injector ends have 90 degree turns on them so they are lower profile and don't stick up like these straight versions I had installed
The injector ends turn independently of the line so the banjo fitting at the fuel distributor can sit perfectly flat and the hoses can run next to each other like the factory hardlines do, and the hoses aren't under any twist load when attached at both ends.
Roger is checking current pricing for me on the set he has on-hand in case I decide to reconnect the 2 WUR to FD LINES, figure out how to install the 3rd line, and add the injector lines, but for right now I'm going to run the car with the old injectors that came out and the OEM hard lines to get it tuned and running like it was before without additional variables.
I'm going to see if someone can clean the injectors of the rubber that's in them by dissolving it by passing a chemical through it. If not, I'll just use my old injectors or purchase another set if necessary.
Correct, I thought I was clear in saying the "non Greg Brown" lines. I have 3 of your lines and installed 2 of them - the ones from the WUR to the Fuel Distributor, but couldn't maje the 3rd line work, which I think was for the cold start valve - I think you were going to email me some directions (petza914@gmail.com).
The lines that run from the fuel distributor to the individual injectors that had the rubber o-rings that disintegrated were NOT your lines and were sourced from another member who was going to use them with a new fuel rail setup on an L-Jet car, but we thought they'd work for my K-Jet setup too. He had never installed them.
Your injector lines are much better for at least 3 reasons:
Your braided stainless is costed so the lines don't abrade or get abraded.
Your injector ends have 90 degree turns on them so they are lower profile and don't stick up like these straight versions I had installed
The injector ends turn independently of the line so the banjo fitting at the fuel distributor can sit perfectly flat and the hoses can run next to each other like the factory hardlines do, and the hoses aren't under any twist load when attached at both ends.
Roger is checking current pricing for me on the set he has on-hand in case I decide to reconnect the 2 WUR to FD LINES, figure out how to install the 3rd line, and add the injector lines, but for right now I'm going to run the car with the old injectors that came out and the OEM hard lines to get it tuned and running like it was before without additional variables.
I'm going to see if someone can clean the injectors of the rubber that's in them by dissolving it by passing a chemical through it. If not, I'll just use my old injectors or purchase another set if necessary.
That's a boatload of rubber...seems like way more than what would come from an O-ring.
You suppose that rubber was plugs that were there to keep the lines clean?
That's a boatload of rubber...seems like way more than what would come from an O-ring.
You suppose that rubber was plugs that were there to keep the lines clean?
Greg, I don't think so. I think the o-rings just swelled up and then shredded under the pressure and clogged everything up. If you look at the photo of the scraps on the pan, they have a curve to them, like they were circular at one point. There weren't any plugs in the end as all the lines looked like that one photo of the 1 line I didn't use - just the metal tapered end with the o-ring up against the flat cap portion outside the taper. With the end of the line being tapered and the connection at the injector having the reverse cone shape, I'm not sure why a sealing ring of any kind was in those lines. Seems like they would have sealed up fine without them just like the factory lines did/do.
At this point, those lines aren't going back on. I'll either run a set of your SS lines with the correct 90 degree ends and fittings or the OEM hard lines. I'm going to get the car running with the OEM lines first.
Reinstalled all the (freshly painted) OEM fuel lines this evening, but it was too late to start the car to see if that was the issue. Maybe tomorrow, but have a bunch of people coming to stay for the weekend starting in the morning so might not get to run it and start tuning until Sunday afternoon.
They actually make the engine bay look neater and work better with the intercooler (currently not installed but the fluid hoses are coupled so as not to make a mess) as they're lower and flatter where the intercooler sits in the back on the passenger side. May just stick with them although I left the 2 GB lines from the WUR to the FD installed as routed, just disconnected the ends, in case I want to go back to those 2.
I jimpered the fuel pump and ran it for about 1 minute to check for leaks at the injectors, FD, and WUR. Didn't see any but will check again when it's running.
Started the car today with the original injectors and OEM fuel lines installed, expecting to be able to fine tune mixture, timing, idle etc and no luck. Runs exactly like it did with the clogged up fuel line ends and injectors. I can get it to idle reasonably stable, but as soon as I give it any gas (even without any load on the motor) it goes full lean to an 18 AFR and won't rev past 2,000 rpm. If I make the mixture screw way rich to where I can keep the AFR at 13 or below at 3000 rpm, the AFR at idle is like a 10 or richer and I can see the richness coming out the exhaust.
What's weird is disconnecting any of the electrical plugs (WUR, cold start injector, air control valve) seems to have no effect on the way the engine is running so I thought maybe I had an electrical issue. I cleaned the contacts and pins in the 14 pin connector and no difference. I jumpered the fuel pump and no difference.
Tried spraying some ether around everything looking for an increase in RPMs from a vacuum leak, but didn't detect any. Replaced my braided stainless vacuum lines with tighter fitting silicone ones and no difference there either.
Getting pretty frustrated with it and about ready to cancel my Rendezvous reservations, put it up on the lift in storage for the next few months to enjoy the rest of my summer while the kids are off from school, unless someone has some additional ideas on what to try.
So sorry to hear this Pete. We spent TOO much time today trying to get the 1990 928 running so we could bring two to Rendezvous. I'd honestly suggest you trailer the car and get the experts on hand to at least help with diagnosing it. If it doesn't improve, you'll have feedback and can tackle it in the Fall.
I did a top-end refresh on my 1990 and now I have half the cylinders getting spark, etc..., etc... It is maddening but you've got a pretty unique opportunity to get several qualified eyes on your car. Just food for thought!
06-11-2019, 10:54 AM
