1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Car running good, then bad...

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Old 12-14-07 | 01:29 PM
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Flight Doc89's Avatar
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From: Tuscaloosa, AL
Car running good, then bad...

stock 12a, rats nest and emissions removed (ACV blocked off, the works). Got some junkyard carb floats, and after tweaking i have the fuel levels pretty close in the sight glasses (both a little high, but close; wierd thing is they keep moving around, but maybe my imagination?). Car will run if i stay on the gas, but won't idle. when i first started it up the first few times, smoked like crazy (oil smoke), but once it was warm eventually tapered off and stopped smoking. Car WILL drive, but runs good for 30-45 seconds, then starts bogging like its not getting fuel, and it just goes back and forth from running great and bogging out. The harder i push it, the more it bogs out. eventually it will die (like 5 min of driving), and i stomp the gas ~10 times to get the accel. pump to dump in some gas, then hold WOT to start it back up, and it usually starts fine and runs for a few more minutes.
Fresh self-rebuilt carb (i probably screwed something up, but not sure what). Had to get floats from a junkyard carb, but new needle valves and ****, new accel pump diaphragm. I removed stuff and blocked off according to the rats nest manual on mazspeed.com.

a side note question: on the primary throttle rod, theres a linkage coming off the front side of carb to the block. whats that for?
Old 12-15-07 | 01:35 AM
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From: Lenexa, KS
my 85 is doing the same thing, local mechanic and i discovered the needle and seat were leaking... but for me at least it means i got my dcoe early
Old 12-15-07 | 02:45 AM
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have you inspected your fuel filter?
Old 12-18-07 | 11:03 AM
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From: Tuscaloosa, AL
Originally Posted by boyee
have you inspected your fuel filter?
replaced it, no change.
Old 12-18-07 | 11:24 AM
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From: St Joe MO
Sounds like fuel supply problems. Trouble shoot in this order, fuel filter, filter screens under carb banjo bolts, filter screens under needles/seats, fuel pump, drain/flush fuel tank.

The linkage on the front of the carb is for the TPS.
Old 12-18-07 | 05:14 PM
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From: kalamazoo, mi
has it driven okay since you removed the rats nest?
Old 12-18-07 | 10:15 PM
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From: Tuscaloosa, AL
Originally Posted by mikewoodkozar
has it driven okay since you removed the rats nest?
runs better than it did before; didn't run for **** before i pulled carb and remooved emissions, now it does this.

I think i found the problem (found A problem at least). Fuel pump not flowing enough, so i got a new one from Oreilly's.

new problem: the new pump works fine when testing it (ran some hoses to buckets of fuel, and clipped it to the battery. pumped like a champ), however, it won't run when wired to the stock pump's wiring. I had to leave town oday before i had time to troubleshoot, and don't have much time tomarrow. short of tracing/rerunning the wiring from the pump, what are some obvious spots to check?
NOTE: the stock pump DOES pump when reconnected to the factory wiring, just not the new pump :shrug: there IS juice, just not enough?

When i rebuilt carb, i removed the screens from the banjo bolts because they were rusted and ripped/collapsed. the screens atop the needle valve seats (whatever they are called, the whole brass assembly) were intact, so i sprayed them out with carb cleaner and reinstalled them with the new hardware.

Thanks for the help guys!
Old 12-18-07 | 10:17 PM
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AAB valve?
Old 12-18-07 | 10:36 PM
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From: Tuscaloosa, AL
Originally Posted by Vashner
AAB valve?
removed
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