[elefantrider]

What is the proper pump shot starting procedure for a stock '69 428 with a quadrajet?

Here's my problem:
Cold start is fine with one short pump (half to 3/4 pedal push).
Hot start less than 5 min after shutting off: starts fine on the key, no or little pump.

Hot start 5-30 min after shutting off: will not start unless I hold the pedal halfway or fully open and keep cranking, 5 seconds. I have tried all sorts of pump shots, is hit or miss.

What is wrong?

[70pontiaction]

It's bubbling all the fuel out of the carb and into the intake manifold.
The crap gas we get now boils at a MUCH lower temp than it used to.

There are two possible reasons why it has to crank longer:

1 - It's flooded and you have to clear the intake.
2 - The fuel bowl is empty and you have to refill it.

You could try the heat shield between the carb and the intake.
They've worked well for me in the past.

Questions:

Do you already have an electric fuel pump?

When it finally does start do you get an excessive fuel
smell, sputtering and then clearing with black smoke
or does it just start up?

[elefantrider]

Sounds like it is number 1.
Can't be number 2 because it starts fine cold.

I don't have an electric pump.
It feels like there is not enough spark to ignite a slightly rich mixture.

[70pontiaction]

If your coil is still mounted on the intake the engine heat
might be soaking into it and causing the weak spark (?).

Possibly check the spark from the coil wire to ground cold
versus hot and see if there is a huge difference?

I had a 64 GTO with tripower that I thought was starving
for fuel periodically - ran great below 3k but SOMETIMES
would sputter and cough above that. Other times it was
fine to 5200 - no rhyme or reason.

New fuel pump, rebuilt carbs, new filter and replaced all
the rubber hoses and it did the SAME thing. Crap!!!

I had already changed points, plugs, cap, rotor, wires.
Coil looked good until I took it off the engine. There was
an almost invisible crack around the bottom and ALL the
cooling oil was GONE. I'm surprised it still sparked at all.

[dmac]

That's not unusual for those who grew up before fuel injection. My guess is that the problem is NOT fuel evaporation from the carb. If it was, then you would have problems when cold too. If the gas was evaporating or dripping into the manifold when hot, everytime you started it when cold, you would have a drained carb, and it would not start as easily as it does now when cold.
Just about every carbureted vehicle I ever owned had it's own routine as to how it would start. Most involved first turning the engine over a couple times before ever touching the gas pedal when hot. Then 1-3 pumps, and start with the foot partially on the gas.

Your situation may be curable somehow, but sounds completely normal. You might get some improvement by doing as suggested- turn over a couple times before giving ANY gas when hot. I had vehicles that needed my foot fully on the gas, others just a little. Turning over before adding any more gas gives cooler air into motor, and if you did have any flooding, will clear that. The reason I don't think it is flooding in the usual sense of wet plugs, is because the engine will be so hot that any dripping fuel will likely just evaporate when it drips into the HOT HOT HOT intake manifold.

When you shut off the motor, at first the engine temp will be about the same as while running which is why it will restart quickly for a couple minutes after shutting down.. After a few minutes, your temp gauge will show a huge rise as all the hot metal heats up the now non-circulating coolant. If you have an electric water pump, and fans that keep running after you shut down the motor, I would bet that your problem disappears. Maybe just the fans alone would help, but I don't think so.

[elefantrider]

I will check the parts for defects but I think dmac nailed it.

It does seem to start better hot when turning it over a few turns before touching the gas a little. Need to be careful not to give it too much. Will experiment more tomorrow and report back.

Takes a special technique for a tired motor i guess. Never had any problems with my hotter spark, higher compression motors, gapped at .045-.050.

[elefantrider]

I had what sounded like a rod knock or a dead cylinder.

It turns out I got 2 fouled spark plugs which isn't helping the starting situation. The strange thing is the idle seems ok, but when I start pulling wires off the distributor cap, there are two cyl that do not affect the idle when disconnected. The wire sparks at the cap but the plug is wet. I haven't pulled the other plug yet.

[elefantrider]

Now I'm thinking there is too little compression in those 2 cyl..... There is some blowby and a little intermittent white smoke out the left and right pipes on idle, even amount on both sides.

[dmac]

Fuel fouled or oil fouled? Wires in correct order? Good time to do a compression check to find out just how tired that motor really is. Good luck. This is how a rebuild project can start from what seems like a nuisance problem. Hopefully that isn't your result. Those old pontiacs used to run until they were down to running on just a couple of cylinders.

[elefantrider]

The fouled plug i took out looked oil-fouled to me. Wires look new so that is a good idea to check the order. I just put in a half quart of Lucus oil supplement. Will do a compression check this week. It really is amazing how good she moves on 6 cylinders! Will get two more r45s plugs and see what that does.

[dmac]

I would guess that those plugs are firing when under speed at full compression without any lifter bleed down. If it is oil, not fuel, could be a lot of things-rings, valves, guides, etc. If it is fuel,crossed wires could be a possibility. Crossed wires wouldn't cause oil fouling, and probably not even gas fouling, without other symptoms. Even if compression is low in a couple cylinders, if it runs good other than the start problem, I would drive it as is, find another block, and take your time building your 'dream' motor until your current motor dies.

The possible 'rod knock' mens that you don't want to press it too hard or go too far from home. Even with a rod knock, you might get another 20,000 miles(or maybe just 20)

If it is an original 428, it may be suffering from the low octane gas. The compression test will help with that as well if you don't know the cr.

[elefantrider]

That sounds like an accurate diagnosis, I will do a comp check today. It is an original small valve '69 428 in my multipurpose wagon. I might rebuild it or build a 455 short block. The small valve heads are suppose to provide better torque which is why the factory used them, I believe?

It sounds more like a dead cylinder than rod knock, but the sound does come and go, so not sure what it is. Oil press is 20 at idle and 35-40 at cruise.

[elefantrider]

Compression check is ok, but spark is weak. Will replace the coil.

On another topic, can I use a stock 69 428 q-jet on a 468 motor with no changes? Or would it be better to find a 455 q-jet?

[arcitech]

Originally Posted by elefantrider

What is the proper pump shot starting procedure for a stock '69 428 with a quadrajet?

Here's my problem:
Cold start is fine with one short pump (half to 3/4 pedal push).
Hot start less than 5 min after shutting off: starts fine on the key, no or little pump.

Hot start 5-30 min after shutting off: will not start unless I hold the pedal halfway or fully open and keep cranking, 5 seconds. I have tried all sorts of pump shots, is hit or miss.

What is wrong?

I had the same hot/warm start problem with my 455 in a 66 Tempest. The problem is heat soak of the fuel lines running along the frame next to the exhaust manifold. the fuel basically is boiling out of the carb bowl and the fuel lines (thanks ethanol) and there isn't any fuel available to start the car, or in my case, there was just enough in the carb to start, then it would stumble and die. Check your fuel line routing and insulate as necessary, then get an electric booster pump to feed the mechanical on startup.

With today's gas, this problem is going to haunt many of us old timers using carburated engines with factory mechanical style fuel pumps. The cure is a full electric pump setup with a return line and regulator, or just get used to cranking for 5-30 seconds (foot on or off the gas wont' matter if it is a dry line)

[elefantrider]

Thanks, I guess that is the case. I was thinking weak spark but heat soak sounds more correct. The carb line is pretty close to the motor. Maybe there is a big aluminum plate type insulator that I can put under the q-jet?

[arcitech]

Originally Posted by elefantrider

Thanks, I guess that is the case. I was thinking weak spark but heat soak sounds more correct. The carb line is pretty close to the motor. Maybe there is a big aluminum plate type insulator that I can put under the q-jet?

There are resin style spacers that may help, aluminum will transfer heat just as bad as the current mounting does. Re-routing the line away from the engine and exhaust will help too, but if you are trying to keep a stock looking restoration, then I would look at removeable type of heat shield and some wrap that you can put around the line.

I'm going with a 7 psi inline fuel pump and a regulator with a return line back to the tank. Pump will be on all the time since I'm not using the mechanical pump.

[Greg Reid]

Originally Posted by elefantrider

Compression check is ok, but spark is weak. Will replace the coil.

On another topic, can I use a stock 69 428 q-jet on a 468 motor with no changes? Or would it be better to find a 455 q-jet?

Any Q-Jet you decide to use will work better if it's tailored to the engine. Grab Cliff's book and read it while you work the engine. The slightly later carbs, mid to late '70s for instance, are generally considered a better starting point but you could use the '69 carb.

[elefantrider]

I will pick up the book. Does the book or the specialists recommend any insulator/spacer in particular?

The car does start fine when cold so not sure it could be 100% due to heat soak.

How do you know if it is time for a rebuild kit? Carb doesn't leak and is original to the motor and car - although has probably had a rebuild before.

[elefantrider]

I just started the car after 2 months of sitting. Two pumps and it started right up. No starter fluid needed. So I know the carb is holding fuel. I don't think it is heat soak either because their would be no more fuel in the carb from when I last parked it. So that leads me to believe it could be the coil... When too hot I think it is giving a weak spark. Agree/disagree?

[dmac]

You could try replacing the coil. A stock, cheap coil would be a test. But if it runs okay when hot, I would think the coil is okay. Have you tried a higher octane?

The fact that you have had a couple fouled plugs can't be helping. Could have been the plugs.

I think I mentioned that I had the same problem but with a Holley. It fired up with about a 1/4 pump when cold, but when hot I needed to crank it a couple of revolutions, pump it twice, then on the third pump, hold the pedal down all the way, then it would fir up instantly but be prepared to let off the gas as soon as it fired.

Think about it, when hot, if you pump the gas, it will turn to vapor almost instantly when it hits the hot intake manifold.At low RPMs as when starting, the engine isn't pulling as much air, and with the choke open, maybe it takes more fuel going into the manifold to end up getting into the cylinder.

I learned to live with my situation. Your case maybe similar, or could be something entirely different, like a coil issue. Have you removed the cap and checked the condition of the cap, and rotor, and verified that the distributor isn't worn? Two adjacent wires in the cap not firing seems like it means something. I once bought an old Pontiac Grand Safari wagon that the owner had given up on. The distributor shaft wobbled so bad that it would were out rotors and caps in just a few hours of running. A new distributor and it ran great. I wish I still had that wagon.