steel-and-fire

This just started happening as soon as I had an exhaust flange fixed and alternator changed; about two weeks ago. Never happened prior.

If I go wide open throttle, 1st is fine, 2nd is fine, 3rd it immediately bogs. No idea what it is. It is like the lockup is engaging too early, but then feels like it is getting starved for fuel or going in and out of limp mode.

If I just do 1/8 to 1/4 throttle and gradually accelerate it'll go up no problem, but if I stay at 60 - 65 or try to go faster is sounds like an intermittent sputter that gradually gets worse and worse until I'm really decelerating.

Sometimes letting completely off the throttle and going back on it lightly gets it going again, but this can be a huge highway hazard.

Trying to determine the problem. Included a video. I'm pedal down the entire time.
Specs: 307 Olds stock, CCC, 3.42 with TracRite Helical Gear 30 Spline, CK Performance 2004r, Dual exhaust with Flowmaster 50.

Sugar Bear

Sounds like running out of fuel as in a clogged fuel filter, fuel pump going bad, rubber fuel hose cracked sucking air, or a clogged sock in the fuel tank.

Good luck!!!

shiftbyear

Inspect the areas where the work was done with mirror and flashlight. Something may have been disconnected or melted. Good luck

steel-and-fire

I caved and took it to my mechanic. Turns out the heat riser flange valve wasn't opening and caused no vacuum for the secondaries to open under WOT. It must have gotten stuck when the exhaust flange was repaired.

joe_padavano

If you are talking about the heat riser valve in the exhaust manifold outlet port, there is no connection between it and the secondaries on the carb. Qjet secondaries are not vacuum operated in any case. Ask your mechanic again.

dragline

Is the car performing correctly now? I can see a stuck heat riser acting a clogged exhaust and not allowing the engine to rev under load.

steel-and-fire

Yes. Just did a 4 hour drive to then from Virginia. No shortage of power (even for the 307) and didn't miss a beat.

69HO43

Let me see if I can translate. May not be correct in what happened, but I bet I'm close:

During reinstallation, the EFE valve somehow got placed in the closed position and got stuck there. Should fail open, but in this case, whoever installed the exhaust never bothered to look/check. This means it would be acting like the EFE temp control valve would when it was applying vacuum to hold it closed when "cold". In this case though, it was closed even when warm. But regardless, it somehow got stuck closed.

When trying to open the secondaries after the heat up, the throttle blades opened (normally would be locked out during cold engine conditions), but there wasn't enough vacuum generated by the engine to tip in the air flaps on top and rev any higher. It's just as dragline stated. And the reason behind the secondary lockout.

Getting the EFE valve unstuck solved the issues. Luckily it looks like is was a very simple fix. If I were going to do the complete exhaust, I'd put a new EFE valve on it too while I was in there, but that's just me.

Always check those EFE valves, kids!

deltsanddueces

I know this thread is kinda old but the same thing is happening to my 98 regency. I changed the fuel pump and fuel filter and it’s still starved for fuel. Should I look into the heat riser too? or is it more likely and issue with the carb?

Sugar Bear

Consider starting a thread about your car. Include the year so we can determine if it has Computer Command Control(CCC).

Did this start on its own or after other work was done? Did it occur suddenly or gradually? How many miles? What engine? Carb original?

deltsanddueces

it does have a ccc
I bought it in Green Bay Wisconsin and drove it nearly 4 hours back to gary indiana and on the last leg of the trip it started bogging, i replaced the fuel filter and it ran a little better but then fuel pump quit working ab a week after I brought it home and I replaced it but it still running like it’s not getting fuel

Sugar Bear

If it is starving for fuel it could be a pin hole in a rubber hose allowing air inside or a clogged strainer in the tank.

olds 307 and 403

Test the output of the fuel pump. Years ago, I got one bad Carter fuel pump that just didn't put on the fuel volume it should have. I thought it might be because my car was a 2 line and it was a 3 line pump. I tried capping the 3rd line, starved for fuel. I even uncapped the return line on the frame, ran a hose to make it a 3 line, a Canadian emissions 307 powered 81 Delta 88, all sort of weird things like that including factory plugs in the heads for air lines on our cars up here including no CCC, except a few till 86. I kept it on shelf, tried it again on another 3 line car, same thing, threw it out. You could try some of the super concentrated fuel cleaner in the tank. It could also be a vacuum leak, is it starting and idling normally?

deltsanddueces

should I just like let the fuel collect in a jar as I crank it over to test the pump?

it starts and idles fine it’s when it hits ab 40 mph or goin up a hill it gets sluggish

olds 307 and 403

Yes, crank it into a gas can. Does it still have the original catalytic converter? They plug overtime, maybe it came apart and plugged inside. Another thing to check is timing, maybe somehow the distributor moved.

Sugar Bear

X2 on catalytic converter becoming plugged. A sign of this was the air filter getting extra black exhaust soot clogging it.

deltsanddueces

It does have the OG cat, I don’t need emissions to pass emissions so maybe I’ll just hack it off there