Finally I narrowed all my car troubles down to one thing, the carb. I got a second hand Qjet from a L69 because my carb wouldn't start the engine on cold days (don't know why, but the carb caused a low vacuum and I suspect the TPS being bad, although the ECM didn't have the code for the TPS in memory).
Switched to the new carb and the car started OK but after a few days of driving I noticed the car was using lots and lots of fuel 160 miles on a full tank. While the other carb gave me something like 300. So I went to the garage and measured the CO output on the engine, it was around 10 while the maximum by law on these cars in holland is set to 1.5

Fiddled around with the new carb but nothing seemed to adjust the CO, even unplugging the O2/TPS or M/C solenoid didn't affect it.
SO now I'm back with my old carb and it did run great (probably the new gaskets that fixed the vacuum problem) but now the car isn't starting anymore in cold conditions.
Could it be that my tps is really dead without setting a code??? And on the other carb, could it be that the M/C solenoid is broken/damaged???? Any tips are welcome as I'm going to put the M/C solenoid from my old carb to the L69 one, and see how that works out.....

Marald


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Pontiac Firebird 1985
LG4 Qjet

 

I would suspect the choke thermostat on the original carb for your cold starting problems. Have you verified its function?

Otherwise, you'll have to check each component to determine if it's good. A q-jet book like Haynes should get you started at least. Sounds like at the very least you could make one good carb out of the two.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, WP 305 heads ported & polished, TBD headers & hi-flow cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

Check your TPS by pushing down on its pushrod (which is under the accelerator pump
lever) with a feeler gauge. If the engine
stumbles and runs rough, the TPS is not dead, although an Ohm check should still be
done. The M/C solenoid should be clicking
when the engine is off with the key turned
to ON , as well as when the engine is running. The choke should be closed with a
light resistance to opening with finger
pressure. The choke pull-off should open the
choke 2-3mm upon starting the engine.

 

Today I found out a problem with the first carb. it was the choke pulloff, as stated above (thanx), it wasn't holding vacuum as it should. It did on the other carb so I replaced it from one to the other. Tommorrow I'll try if this was the thing that kept me from cruising. Also found out that the TPS on the 2nd carb had endless resistance (ohm) so that could cause the high CO measurement.

Thanks for the info so far guys, I'll let you know if this worked (or not)

 

Thanks, marald. We appreciate feedback on advice given. In a way, it is like being paid!

 

Hi, here's you pay/my reply. It didn't work... Although the choke-pulloff is probably now in working order, the car still ain't starting so I tried the other carb (the one with the broken TPS and now leaking choke pull off) and it wouldn't start either..So something else must be wrong besides carbs. The TPS can't be it, because it was broken before. The only thing I changed is the CTS (the previous one gave me wrong readings) and I removed the EGR blockoff I made myself and put back the EGR.

Any tips welcome, because I'm getting quite desperate with two carbs & no running engine..


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Pontiac Firebird 1985
LG4 Qjet