Help ! no Idle

[projekti]

I know i asked for this, but iīm a never learning optimist.

I have 1973 1/2 , and I bought an wrecked 1974, with an 3,0 204 HP.
Fixed, a few oil leaks and swapped engine & transmission.
The good news is that the engine does not leak oil and does not smoke, the bad news is that i have had to do some guessing with the electrics but most of all
I canīt make it idle !
It starts fine, on the first click, but after a few seconds the idle starts to drop and if I do not keep the foot on the accelerator the engine dies. Thereīs a lot of back firing also.
So far iīve been tampering on the big idle screw and the throttle linkage,
but nothing helps.
I still have the 1973 1/2 fuel pump in.
Any ideas where to start looking ?

regards

John from sunny Finland

[ossiblue]

Welcome aboard.

Sounds like you have typical lean running issues with a CIS induction. Lots of threads here so using the search function should lead you through to a solution, but here's a start.

The CIS is dependent on fuel pressure and vacuum to perform. If there's failure in either of these areas you will develop running problems. I suggest you begin with a system pressure test--fuel pressure, that is. You will need to measure the system pressure cold and unregulated, cold and regulated (by the Warm Up Regulator), warm and regulated, and the pressure with the system off to see how long the pressure holds. This test should be your first step--to get the fuel system in specs--and from there, if the problem still exists, move on to other area such as vacuum leaks and faulty components.

From what you describe, you have a lean condition which can result from fuel pressure problems, fuel mixture problems, air leaks, or faulty warm up components. Can't tell if the 73.5 fuel pump is adequate for your car given that it is 35 years old and built for a smaller engine. Someone else will verify that, I'm sure. Regardless, begin with a pressure test, do some searching, report your results, and keep asking for help. Your problem doesn't sound major but finding the answer will take some investigation.

[projekti]

Thanks Ossiblue, I do not know what I did but now it seems to work !
I tried first to swap my old fuel pump to the one that came with the wreck,
but I couldīnt make it work, metallic noise, just as if it would be running dry.
And it was for the same period as mine, 73 - 76.
So I put my original pump back, and now I have an idle !
I will take it later for a pressure test, to know that all is ok.
My next task is to try to find out why my tach is not working, probably something to do with the difference between 3 and 6 pin CD box.

Here are a few pics from the wreck, you understand now why i was a bit nervous
if the engine would run at all, good news is that no one was badly hurt, even if the driver & co pilot had to be removed through the roof !

[ossiblue]

Glad to hear you solved your problem--at least for now. The symptoms you describe about the other pump match one with failing bearings so it's probably good that you put the old one back in. Now that the car idles properly and the only change has been a fuel pump switch/switch/switch, quite possibly the original pump is a bit weak and fluctuates in pressure. My advice would be to replace the pump with a new one (several aftermarket models will fit) even if it's not the culprit. The pump is 35 years old and you don't want a failure while you're out on the road.

BTW, glad to see all were well in the wreck.

[T77911S]

how much for the rear PORSCHE reflector?

[projekti]

sorry, it went with the wreck, the guy who bought it said he would actually rebuild it ! He must be a magician.
The pictures are after I had taken of the engine , transmission and a lot of Small
stuf, like a pair of perfect ( well, yellow painted that i had to strip of) S - aluminum front brake calipers, 300km / h ( 300 straight down) speedo, a good pair of Bilstein rear schock absorbers etc.