Recently had an attack of serious flooding on my Qjet. It was dumping fuel out of the discharge clusters at idle, so I pulled the top and figured it was a defective needle and seat. Just happened to have a new one and installed it. It worked great for a day. Back to the flooding again. Checked fuel pressure,but my gage goes only to 7 psi and the specs go to 8 psi. Of course the gage topped out. since the float floats nicely and I have a new inlet needle and seat, I am wondering if pump pressure can somehow go up out of spec without warning. Any ideas?

You COULD always weigh your float, but I would just throw a new one in there. If that didn't fix it, I'd be measuring the fuel pump pressure with a guage that went up to 19 psi or so.

You didn't mention whether or not the fuel pump was changed recently.

Mike

Uncle: I changed the float a year or so ago, so I decided to look elsewhere, especially since the problem seems to be on-and-off in nature. Today I put a Tee in the fuel line and checked pressure; it is bouncing badly between 9 and 22 psi.When shut off it is holding an indicated 10 psi, so I think the carb is ok. New fuel pump tomorrow, I guess. My suspicion is that the drive spring in the pump is broken and is now working at a shorter length, but a highr rate. You are right to suspect that the pump is old; it has been on the car for the 5 years of my ownership and who knows how long before that. Thanks for the suggestions.

Let me know what happens when you change that pump.

Mike

The record for me is 21 psi from a stock mechanical pump. Needless to say, something inside of it got stuck! You're right on track. A new fuel pump should fix you up.

Got the new pump in place and it makes a steady 10 psi, so that is an improvement. However, I still got the flooding. Tomorrow will be a carb kit and a new (again) float. A check in Doug Roe's book on Rochester carbs says that any thing over 8 psi is asking for trouble. I certainly do not look forward to putting on a pressure regulator to make a stock pump work with a stock carb. But,,, I do have a pressure regulator left over from another project, but I would rather just do it without all the high tech stuff. The saga continues.

JW I would go with Unclepennybags advice and try a float before I did anything else. There is little margin for float sink before you start having flooding problems. And what you describe is a classic float sink symptom. JMHO

After checking the float out, you might want to make sure that you have the right year fuel pump. I heard from a good source that the later 70's fuel pumps ran a little more pressure than those from the 60's to overcome the check valve in the fuel filter.

Did you get a generic replacement pump, or did you get the correct GM "AC" unit?

Probably isn't it, but thought I'd mention it.

And here's a good method I've used over the years to check for a saturated float.
After removing the float, I set it on the floor of my garage and stomp it real hard with the heel of my boot. If fuel splatters out, it was saturated. If not, floats are cheap. http://www.chevelles.com/forum/smile.gif
The point is, when you rebuild a carb or if you even suspect float problems, go ahead and replace it.

Too much work Randy. A simple flick of your bic will tell you instantly if the float is saturated.

Ok, here is the Saturday follow up. I got a new pump at Checker (master brand pn 409870 and put it on and got 12 psi of fuel pressure. I checked the float valve holding pressure at 10 psi, so that seemed good.Took it back and got another one.Same story. Got a Borg Warner pump at Pep Boys (pn 40987, dang!)and it makes 7 psi. Just for fun, I put in a carb kit and new float. Whoopee. Don't ask about the shop rag that got sucked into the intake manifold when I was checking fuel pressure.

We all love happy endings!! http://www.chevelles.com/forum/smile.gif

Thanks for the follow thru, glad you got it fixed.
http://www.chevelles.com/forum/biggrin.gif
Mike