mjr45

Fastwoman, I don't know how I managed to jack my own thread but I've calibrated my AFM, all new vacuum lines, fuel lines, my vacuum reads 14"(which everybody is going to say is way to low, but at 9000' its OK) I've adjusted my TPS per FSM, new CSV and AAR(which still doesn't work right), timing has been an issue its at 0° now and stumbles above 4000RPM and at 10° stumbled at 2800-3200RPM which lead me to doing an R&R on the fuel pump thinking it might be a fuel related problem, I'm still waiting on some parts for the fuel pump. My plugs are covered with black fluffy soot as is the tail pipe. What I said in post#17 was prior to pulling the fuel pump. So when the pump is back in and the fuel is flowing if I still have issues I'll look at doing the potentiometer and also look at timing again. Site, I'll probably just put a 10K pot up in the engine bay, I can't get nearly as sophisticated as Fastwoman, I'm just a mountain redneck at heart.

Zed yes I've checked the CTS per FSM and the EFI Bible and is all good, I've also checked the thermotine switch and the AFM electrical with the AFM resistance being off about 12% from normal values. It was my understanding that fingering the AFM vane would tell if the engine wanted a leaner or richer A/F at idle, which should if I understand correctly be the same thru out the RPM as long as the ECU is operating correctly to enrich the mix at higher RPM, or am I totally wrong on all of this? Mike

When I finger the AFM vane counter weight CCW the RPM goes up, by going CW it drops a little. If I'm understanding you correctly its running to lean? If that's the case, I should probably go the potentiometer route rather than adjusting the AFM clock spring. Mike

The 73 would be my first choice, if its all original with no mods. I paid $2500 for my 75 3 years ago and it was running and not in a truly bad state of repair. Off er what you think its worth and the worse that can happen is he says no. Some pics would help.

Sarah, you crack me up . I've tired fingering the AFM and it seems to like a much leaner mix, at one point prior to calibrating the AFM I had turned the "black" wheel 10 teeth clockwise which should have really leaned it out, but didn't or at least very little, maybe I'll try to enrich the mix and see what happens. Cap'n, I may try to fill the pump thru the intake hole prior yo attaching the intake line or maybe just use your approach which would probably be safer than dumping gas all over the place. I'm going to use your the 539 check valve(your idea) with an Audi fuel line after I put new O rings in the pump. Mike

Sarah, I calibrated my AFM per Atlantic Z, new temp sensor which checks out fine and still have lots of fluffy carbon on the plugs, lots of black carbon on the tailpipe. Wouldn't the carbon fouling from extremely lean condition be somewhat harder? Don't know, just getting info to store in my head. One of the issues I have to deal with, not necessarily related to the thread ? is my altitude of 9000' which I understand affects both vacuum and compression, but shouldn't affect the air/fuel ratio, is that correct? Mike

Site, I've got a new temp sensor and this thing has been running way rich from day one. I believe the potentiometer would only make it richer. I don't believe its running super lean, with all the soft carbon on the plugs.

Leonard, that really sucks, sorry for your loss.

Zed, I took the pump off to change the check valve, O rings and replace some old(read original) fuel lines, so the pump is empty. I'm also blowing out the hard lines up to the bay, all in an attempt to get the air/fuel ratio right and to see if this will correct the stumbling and bucking at RPM under load, I'm also changing all the fuel line clamps on the injectors since I believe there are some small leaks. In a past thread, I thought it was ignition related, but want to make sure all is right with fuel delivery before heading back to ignition. Fuel pressure was good @ idle, not so much under load, don't remember the exact number. Mike

Yes, I hadn't thought of that, thanks. Mike

Thanks. I had thought of wedging the AFM flap open, then connecting a fuel line to the pump outlet and cranking the motor, but that seems like a PIA to do it that way. Mike

Anybody got a "best" method for priming an EFI fuel pump besides filling up the tank and cranking the motor?

rossiz, just a quick question. Just where did you file down the lip to get the retainer out? On mine the lip looks rolled over on the whole circumference. Mike

rossiz, nice work, I'm going to try your treatment with mine later today. I've also ordered the 539 valve just in case.

Cap'n I appreciate the offer on the O rings, I ordered the new ones about an hour before you posted the offer, my impatience sometimes gets the best of me. I just might take you up on cutting the check valve down, since I had planned on doing it with a Dremel, which would work, just not as smooth and probably not anywhere near as straight on top of which my Z will be down for at least another couple of weeks, to damn cold and snowy still up here in the thin air.:tapemouth Send me your address by PM, thanks. Mike

Cap'n. I ordered the Viton O rings from a place called the O Ring Store or Connection, I looked at McMaster and didn't feel like I needed 50 of them which was the minimum order, in hindsight it would probably have been cheaper to get the bag of 50. I'll go and get the Audi line sometime next week after I get the check valve and put it back together and see what happens, I'll let you know. Mike

Chas, you're right I ordered 2 new Viton O rings today in 2mmX33.5mm. From what I read(I think is was a reply of yours in the O ring thread) that is the correct size. I actually did get that ring to go back in, but that only after leaving it out overnite in the garage at 20°. Thanks. Mike

Cap'n, I opted for the check valve with the Audi fuel line, just because it's easier to find the Audi fuel line. I took off my pump yesterday and the stock check valve sorta works, just real sticky so I'll change it out and keep the old valve. When I took off my pump head, the second O ring was so distorted it won't fit back in, its stretched about 1/4" larger than the groove in the pump, and while I didn't have any fuel leaks and it made good pressure I'm sure it wasn't helping. Have to order those O rings today, I read the thread on sizing so its all good. Thanks for your info, it really helps make things easier. Mike

Cap'n, just as an FYI that Bosch sealing cap for a banjo style line is NLA, so it'd have to be obtained from a bone yard.

Euro, I just read the thread on the check valve and will definitely be doing that, my intake is the open type. I'll also be changing the fuel rail to a single aluminum rail as I believe there is a very tiny almost microscopic leak right at where my #1 line comes off, I always find some burnt brown looking crud on the heat shield after running, but never see any fuel leaking. Oh well, another mystery for me to follow.

My 75 had the problem last summer time(when it was running right) it has a 79 block with a N42 head, new injectors, 79 fuel rail, new FPR, stock 75 exhaust manifold and heat shields. Did not have it this winter before I started having some issues with timing and fuel. My check valve is toast, holds pressure for maybe a minute. Don't know if this adds to the discussion, but there it is, I am convinced it only occurs with higher atmospheric temps, at least at it seems that way up here in the thin air.

I used a bronze bushing which I cut to size and used on the drivers door, worked great with no click for about 3 months and now the click is back. I think my hinge part with the detents is toast.

Zed, I have a fuel pressure gauge up in the engine bay, so I'll get some more fuel line tomorrow and run it up to the wipers and see what is happening as I drive, good idea from you since I'm beginning to suspect something in A/F ratio. The AFM was calibrated per the Atlantic Z site. Yesterday when I had the timing set at 0° I got 13" and at 10° 14" of vacuum which is OK for 9000' (at least as far as I know) and the needle was steady, so that leads me to suspect that at 10° and lots of stumbling @ 3500 RPM and the tach bouncing all over the place that the mixture is rich and the fuel pump is not able to keep up, @ 0 ° it does it at 4-4500 RPM, so maybe the mixture is leaner at that setting allowing the pump to keep up at higher RPM, maybe, I don't know, I'm confused at this point. I will try your work on the dizzy vacuum advance first, just to see and then hook up the fuel pressure gauge after I know all is right with the dizzy. Just as an FYI, the pump end of fuel delivery hasn't been touched, I know I should have done this in the "refresh" but somehow didn't. Thanks for the help. Mike

Walter, the dizzy is a 79 it appears to be in fairly good shape and it does have the vacuum advance which I disconnected to check timing, it "appears" to work in that with some suction the breaker plate will move.

I had one other thought(these are few far between) that maybe the issue is with fuel and not spark. I've not done the fuel pump lines from the tank to pump and pump to fuel line and maybe they are clogging up or collapsing under load?