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Fuel pump troubles. Car won't keep running on idle.


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#1 StanTheMan

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Posted 06 December 2016 - 03:09 AM

Hey guys,

 

I am trying to fix the crap the previous owner of my car did. He was in the middle of switching from EFI to carbs when I bought the car and I decided to go with EFI. Anyway, I mounted the EFI back, changed the hoses and all as the old ones were cracked and leaked fuel. Car fires up easily, holds 2k RPM for about 3-4 seconds or so and then just dies. If I give it a little throttle it keeps running but if I let it idle even after that, it still dies. My guess is that for some reason there is a cut in fuel supply in the system but I can't figure it out. Anybody got a clue what could be causing that? Thanks in advance gents.



#2 softopz

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Posted 06 December 2016 - 05:40 AM

Would help if you specify motor, car, year efi parts in question. 



#3 NewZed

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Posted 06 December 2016 - 11:28 AM

My guess is that for some reason there is a cut in fuel supply in the system but I can't figure it out. Anybody got a clue what could be causing that? Thanks in advance gents.

 

Not a bad guess.  Here's what they used in 1975-77.  They changed it in 1978.

 

Note that the PCV system pulls air through the crankcase.  So the crankcase needs to be sealed otherwise less air passes through the AFM causing less flap movement.  Emissions chapter.

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#4 ZHoob2004

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Posted 06 December 2016 - 05:48 PM

Make sure the afm is installed and securely connected, and make sure the boot isn't torn. You can test the afm fuel cut by turning the key to on and moving the flap with your hand. The fuel pump will turn on.

I personally had a similar problem with my motor that I found to be the injectors falling to fire after initial startup, causing it to run off the cold start alone, so also make sure your ignition is properly connected to your injection system.

#5 StanTheMan

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Posted 12 December 2016 - 09:05 PM

Soooo after a week of trying to figure what the heck is going on, I found out that I have air leaking around the injectors. I blew smoke into my intake to see where I might have vacuum leaks and the smoke started coming out around the injectors mounting... WHAT THE HELL?!?!?!



#6 NewZed

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Posted 12 December 2016 - 09:24 PM

Can you make a video?  I'd like to see it, I'd laugh I'm sure.  The gaskets are just compressed rubber that eventually hardens up and shrinks, or the previous guy tried to reuse old shrunken gaskets.  Pretty simple repair.  http://www.thezstore...ZS/PROD/11-3402

 

The 3-4 second running then dying is still probably your AFM switch.



#7 StanTheMan

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Posted 12 December 2016 - 11:13 PM

Can you make a video?  I'd like to see it, I'd laugh I'm sure.  The gaskets are just compressed rubber that eventually hardens up and shrinks, or the previous guy tried to reuse old shrunken gaskets.  Pretty simple repair.  http://www.thezstore...ZS/PROD/11-3402

 

The 3-4 second running then dying is still probably your AFM switch.

Well I probably miscalculated. It runs for more than 3 or 4 seconds. Say 10 or so and then it starts to die but if I manually open the AFM flap, it keep running. So my guess is that it sucks in so much air from the injectors that it can barely keep the flap of the AFM open so at one point it just dies. I dunno, just guessing






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