stalling / loss of power

by Dinomyte Sat Jun 29, 2019 7:16 am

I got the car out last weekend and went for a drive just around the city, not hing too exciting and had the following experience.

Made a very hard stop as somebody ahead of me was stopping before I realized it, I stopped fine but engine actually stalled and stopped. Started just fine and on we went.

Later same drive I put my foot into it going up a hill, again in the city so not that steep, and downshifted fine, accelerated fine, then seemed to loose power, like transmission just wasn't engaged, didn't rev high, just no power it seemed like. Let off the gas for a second or so, and then back on gentler, and was fine to carry on.

Any ideas would be greatly appreciated.

by Joe73 Sat Jun 29, 2019 8:59 am

Did you put fuel stabilizer in the fuel over the winter? I'd lean towards a fuel issue in the carb.

by clanceman427 Sat Jun 29, 2019 9:11 am

What type of carb? Sounds like the float needs to be adjusted up perhaps based on the panic stop stalling issue

by Dinomyte Sun Jun 30, 2019 11:37 am

Yes to stabilizer, every year, haven't burned through the tank from the end of last season yet (the one with stabilizer in it )

The carb is a Q-jet, can't remember all it's details but has electric choke, mechanical secondaries (95% sure) was rebuilt by me about 4 or 5 years ago (I must be getting old, it was rebuilt in 2011 or 2012) but no issues till now. I have to say though, lots of hard full throttle starts, but no emergency stops till last weekend.

Thanks for the thoughts, I'll see what I find out if I get a chance to look at it in the next couple of days.

by ant7377 Mon Jul 01, 2019 8:51 am

Maybe fuel filter clogged. Check rubber hoses too. The one in back by gas tank as well. Could be kinked or cracked.

by bracketchev1221 Tue Jul 02, 2019 9:41 am

My first thought I sent separating ethanol gas. After you’ve run out all of it refill it and see if it gets better before going crazy.

by Joe73 Tue Jul 02, 2019 4:39 pm

bracketchev1221 wrote:My first thought I sent separating ethanol gas. After you’ve run out all of it refill it and see if it gets better before going crazy.

Thats exactly my thought in my first post. I know ethanol fuel starts having Phase Separation (ethanol separates from the gas) after about 14 days of sitting. And thats not to take in account of how long the gas has been in the tank at the gas station.

And the ethanol is heavier than gas, so it sits on the bottom. Then if your tank it not at max full, normal temp change during the day (especially night to morning) causes condensation on the inside of the tank where there is air. Move the tank, condensation rolls down the side and the ethanol grabs it.

Especially a problem for gas cans and anything with a fuel tank that has its fuel line connected to the bottom. Ethanol is the first out of the tank and into the engine. Hence no start, or bad running.

by Dinomyte Tue Jul 02, 2019 8:31 pm

Joe73 wrote:
bracketchev1221 wrote:My first thought I sent separating ethanol gas. After you’ve run out all of it refill it and see if it gets better before going crazy.

Thats exactly my thought in my first post. I know ethanol fuel starts having Phase Separation (ethanol separates from the gas) after about 14 days of sitting. And thats not to take in account of how long the gas has been in the tank at the gas station.

And the ethanol is heavier than gas, so it sits on the bottom. Then if your tank it not at max full, normal temp change during the day (especially night to morning) causes condensation on the inside of the tank where there is air. Move the tank, condensation rolls down the side and the ethanol grabs it.

Especially a problem for gas cans and anything with a fuel tank that has its fuel line connected to the bottom. Ethanol is the first out of the tank and into the engine. Hence no start, or bad running.

This is all good information, BUT, the gas in the car is 94 octain 0% ethanol, at best there may be some traces of ethanol as the pumps here are like everywhere else, one hose for 3 different grades of gas, and the lowest grade contains ethanol (up to 10% I believe), the middle grade is a mix of the high and low grade, and as mentioned the high grade has 0% ethanol.

Planning to drive some and see if maybe it is a fuel issues as opposed to fuel delivery issue, but I think a carb tear down is in my future. I think I have a second QJet in the loft, going to find it and see if things are better with it . . .

by bigredlaguna Thu Jul 04, 2019 12:33 am

The problems you describe were under different circumstances and each may have a separate cause.

The stalling on hard stop could be a fuel or flooding issue, or it could be due to an influx of air from the brake booster causing a lean condition. Maybe check the check valve?

The loss of power on WOT going uphill is entirely different and I agree with checking basic things like the fuel filter. I just wonder if you may have had a bit of vapor lock? Were the conditions right for it? Warm day, hot car/engine and just endured some idle time? If your fuel pump is a 2 port, this could happen. Maybe switch to a 3 port pump or fab up a regulator with a return line to keep the fuel flowing. This might help with possible fuel settling issues others have mentioned.

by Dinomyte Fri Jul 12, 2019 9:15 pm

So I finally got some time out in the garage, and pulled the fuel filter and this is what I found

doesn't look quite right to me, the one in the bag is a new one. Not sure how in the world that happens but a dollar and a half later, we might just have a solution.

by Joe73 Sat Jul 13, 2019 8:14 am

Hmmm. Unless that old filter is heavily clogged, I doubt it is your problem. And with the crushing making it actually shorter in length, fuel would bypass the filter easily, hence less restriction. I hope it is your problem since its an easy, cheap fix.

by Dinomyte Sat Jul 13, 2019 12:11 pm

The filter was at the front of the cavity when I looked, not rolling around from what I could tell. My thought was that it wouldn't flow like it should squished like it was (more than in the picture) But I defer to those that know better. I'll take her for a drive this weekend and keep everyone posted. . .

by bigredlaguna Sat Jul 13, 2019 5:59 pm

That is strange. There were different types of filters available for the Q-jet back in the day. Maybe you have the spring for a short filter or a sintered bronze filter. That might be why the long filter is getting crushed like that.

One more thing to consider, you may want to remove the check valve in the new filter if it has one. I had a weird situation a short while ago where the valve got pulled out the end of the filter and completely stopped fuel flow.

by Dinomyte Sat Jul 13, 2019 7:42 pm

bigredlaguna wrote:That is strange. There were different types of filters available for the Q-jet back in the day. Maybe you have the spring for a short filter or a sintered bronze filter. That might be why the long filter is getting crushed like that.

One more thing to consider, you may want to remove the check valve in the new filter if it has one. I had a weird situation a short while ago where the valve got pulled out the end of the filter and completely stopped fuel flow.

Thanks for that, I checked and the long filter is the one, the short one way too short, and the crushing has to have happened when it was installed as the new one fits in the right amount with the spring, and no crushing, checked these things before putting it all together. . . clearly I made a mistake with I rebuilt the thing. Embarassed

No check valve in the filter.

We are having lots of rain / thunderstorms right now, expecting 1/2" of rain by nightfall, going to get out tomorrow.

by clanceman427 Sat Jul 13, 2019 7:54 pm

Pretty sure you have the wrong filter. A Quadrajet gets the little stubby filter and spring. I think the long skinny filter may seem to be correct without a spring but I think you’ll know if you install your new skinny filter and then disassemble it and check it. Here’s a photo of my quadrajet setup for 1973

by bigredlaguna Sat Jul 13, 2019 10:09 pm

Looks like the older Q-jets got the shorter filters. My 1976 Q-jet has the extra casting that was put in place before the electronic feedback system was available. Rochester just added length to the filter housing at the same time.

by clanceman427 Sat Jul 13, 2019 10:49 pm

ok cool. If I were you I would still install your new filter, then take it apart and make sure the new one didn't get crushed like the last one did, just to be sure.

by clanceman427 Sat Jul 13, 2019 10:56 pm

just one other thought on this: I noticed on my fuel filter, that the fuel actually enters the center of the fuel filter and the fuel pushes thru the pleating to the outside of the filter, to then enter the fuel bowl. So there is an end with a hole in the filter, and a blocked-off end. If the fuel flows the same way on yours, is it possible that someone might have installed the filter backwards, and the fuel was dead-heading against the (closed) end and then eventually crushed it enough to allow some fuel to get around it?

by Joe73 Sun Jul 14, 2019 6:41 am

Kevin, going from memory here, but when I would change the filter on my stock Qjet back in the 80s, both ends of the filter had a metal cap. But one cap had tiny like bends in it. Kind of like tiny needle nose pliers grabbed the edge and bent it out just a pinch all the way around. The filter would not fit in backwards because of this. The the inlet end had a rubber gasket with a tiny spring (check valve I believe) on it that sat inside the filter. The head mechanic at my buddies shop always threw that rubber check valve thing away.

I remember those tiny bends on the metal end caps on the filter and that it wouldnt go in backwards.

by clanceman427 Sun Jul 14, 2019 10:14 am

Do you think his filters resemble what you remember?

by 73ss Sun Jul 14, 2019 10:48 am

OK, Heres the deal. Carb model numbers starting with 704, use the short filter. Model numbers starting with 1705/1708 use the long filter. Usually, but not always, divorced choke models use the short filter. Electric and hot air choke models use the long one.

The check valve was used to prevent drainback. It's not a good idea to remove the check valve because you also remove the gasket and the filter will no longer seal and no longer filter.

Duralast # FF1104DL or Fram CG12 are the correct long filters without the check valve.
Don't be tempted to cut up the factory lines and add a external filter, this will cause vapor lock and it's a fire waiting to happen. The check valve free filter will easily support 500 HP.

by clanceman427 Sun Jul 14, 2019 11:25 am

Thanks very good information 73SS!

by bigredlaguna Sun Jul 14, 2019 1:47 pm

I put the gasket back on after removing the valve. It's easy to see what you need to do remove the valve and retain the gasket if you happen to have a filter that has the check valve.

by Dinomyte Sun Jul 14, 2019 8:40 pm

Got the filter out after having gotten everything together and leaks stopped, and it's still full size, no squishing. My carb starts with a 170, so clearly the one I took out was put in incorrectly. Checked all the lines, both new and old, from front to back that could be seen / felt.

Next went for a drive, and even after idling for a while and lots of full throttle starts, and hills, no issues with loss of power. I also tried a couple of really hard stops in a parking lot, and tho I didn't actually stall, I got really close, I'm sure none of my attempts to stop hard were like the one a couple of weeks ago where I got caught off guard.

That's the new filter after being installed and then removed to check that it wasn't crushed.

Just for reference that's the carb.

I'm beginning to thinking that filter might not have been an issue, I thought crushed like that it might have let less gas flow. I guess I'll need to find the tool to measure the height of the float without opening the carb.

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