weird stalling problem

[ggenovez]

Hi all,

I have a weird problem. Car runs fine in the city and as long as the engine is cold, but after it warms up (oil pressure below max on guage at idle in gear) if I go on the highway, the first full stop withing 1/4 mile it will stall.

If I roll by at 2 MPH, the alternator light might come on but I can continue. If I drive for ~.5 miles I'm ok.

When it does stall, it will fire back up but the RPM's will come down until it stalls again, even in P. I have to start her in N, keep my foot on the gas and pop it in D. I know not very good but when you're in traffic ...

I thought it might be low RPM's (500 RPM in gear) but that wasn't it, then I thought it might be the filter so I changed it last night, but the problem persists.

I'll be testing the pump soon (need to find the manual) but in the mean time any other ideas?

[ggenovez]

Hi all,

Ok I disconnected the fuel line and it was under pressure. bleh! next time keep mouth closed

ok, I hooked up a pressure guage and disconnected the lead from the coil. I had to run it a few times because it was not keeping any pressure. Normal?

Anyways I angled it to I can see it from the drivers seat and it was pulsing between 1 & 2 PSI. Is the pulsing normal? is it supposed to stay pressurized after I stop cranking?

This sounds low but I can't find my manual right now.

[Scutch]

I just put a pressure regulator on today. I read on this board that it should be set to 2.5psi, but when I set it to that my car would not keep running.

It seemed happy at 4 psi. 5lbs psi seems to cause ticks in my idling.

I have tested it a couple times over the last couple days. The pressure does not pulse at all. It is completely solid. But my tester does not allow flow through. The fuel dead ends at the gauge.

This is on a 35/40 Zeniths on a 68 230s Automatic.

Eddie

[ggenovez]

Yeah,

Mine dead ends as well. Did your keep the pressure? or did it slowly decrease? or quickly?

[Scutch]

It kept the pressure until I pulled off the hose.

[MunichTaxi]

As an engine warms up it demands a leaner mixture.
Are the choke flaps fully open when warm?
Are the spark plugs black from an overly rich mixture?

[ggenovez]

Hey Munich,

No, choke is working fine. Also I beleive if it was the choke, then it would constantly happen after the first stall. This is get off the highway, stall, drive 1/4 of a mile, never happens again unless I get on the freeway again.

Seeing that the pressure is not steady from the pump, I think the check valve is sticky.

I've noticed that it tends to happen as soon as I start to drop from highway speeds. I can put it in neutral, as soon as I lay off the gas on the freeway and she'll still stall. Usualy if I restart while rolling on the highway, she'll stay running. Don't ask me why. The really odd thing is you can see the fuel pressure be between 15-30 and all of a sudden it jumps up to max while doing this. From a full stop, she'll run rough until I get her moving again. then she's good.

Also sometimes after I get off the freeway, and she stalls at the stop light, and while waiting for it to change, the engine feels like it's shaking. The type of shake you get when you're trying to adjust the idle fuel mixture and you go too lean or rich.

[nhdoc]

Perhaps the choke is opening too early? I've had this same problem due to the choke adjustment being too lean. The choke opens before the engine has fully warmed up and it stalls. It needs to be choked for a few minutes...sometimes up to 10 if it is cold. You might just try increasing the choke adjustment a little and see if that changes it.

[ggenovez]

thx nhdoc,

But I'm in texas, and I am usualy on the freeway at least 10 minutes doing 70+. Engine is at normal op temp, and it still happens.

I could also see the oil pressure drop to about 10 in the summer (90'), with the engine warmed up. It would usualy not stall though.

[ggenovez]

Munich, Nh,

Just wanted to make sure you did see my post below about hooking up a pressure gauge to the fuel line and at crank the needle was shaking between 1 & 2, and when I stopped cranking the pressure would fall immidiately to 0.

That's why I think it's an intermitent problem with the pumps check valves.

[MunichTaxi]

about the the falied fuel pump. W116 M110 owners w/ 4bbl carb, Beware

[ggenovez]

Originally Posted by MunichTaxi

about the the falied fuel pump. W116 M110 owners w/ 4bbl carb, Beware

Thanks munich,

Just a couple of questions. did you check the fuel pressure on your pump? I'm wondering if the symptoms would be the same as mine.

You mentioned that you took apart your pump. is yours the lever type or the push type? Mine looks like a sealed unit (push)

Is the pump above the oil level? just wondering if I should drain the oil, or at least put a pan under...

[Blue 72 250]

it is above the oil level. You should be fine. Your pump is not serviceable.

[MunichTaxi]

with a Dremel cutter . It is a push pump and I was just curious about the diaphragm.
A gas/oil mixture was 'weeping' out the weep hole; the crankcase oil was getting behind the diaphragm. It is not designed to allow this.

[ggenovez]

New pump. same problem.

Ok, installed teh new pump yesterday and tested it, PSI got to 4 and stayed pressurized. WOOHOO!

Unfortunately she died again after getting off the highway. Chokes work.

I'm wondering if that little flap in the air filter housing that connects to the exhaust manifold to bring in warm air is not opening enough.

Could that be the culprit?