car stalls randomly

[monzacoupe]

All suggestions welcomed!!! Here's the problem now, my car is stalling at random times. I went for the first drive of the year last week, just around the block, no problem. Took it to work Friday and Saturday, 10 miles one way, no problem. Sunday morning while driving to work, my car stalled while driving up a gentle hill doing 70km/hr. This was the issue last year before I moved the fuel pump to a different location.
The carb has been rebuilt recently. The in-line fuel pump was mounted onto the firewall, now relocated to the fuel tank area. Carb had a bunch of emmission control pipes attached to it but all are now sealed off.
Anyone else with a similar problem? Any suggestions about what I can do to fix this prior to me going to a mechanic?

Rick

[marco_1978_spyder]

Hmm... here's my armchair mechanic offering..

I had some idea's until I read.."Carb had a bunch of emmission control pipes attached to it but all are now sealed off."

I remember doing this in my early cars, and having the similar mystery issues.. With the random things simply unhooked and sealed off, who knows what lean condition / overly rich condition, or whats plugging up or fouling out with too much carbon buildup.

It can be hard keeping all that stock plumbing and doo dad's up to snuff. Even getting it all connected correctly can be a challenge without a factory service manual. But it's the best way to enjoy a stock ride.. they will be reliable.

Did the car fire back up? Thats the next thing I'd like to know.. It would be helpful to know it it flooded, or starved fuel, or if fuel seemed fine and possibly it was an ignition issue. Is this a V6, getting the low oil pressure syndrom? Since the fuel pump has been in question recently I'd suspect fuel starvation.

The first thing I do in just such a stalling situation is remove the air cleaner and check for visible fuel to squirt upon moving the butterfly, and go from there..

Hope this helps

[monzacoupe]

The mechanic who rebuilt the carb checked the fuel flow when it stalled after the rebuild and fuel-flow was not happening, he suggested moving the fuel pump so it would push the gas to the carb rather than sucking it from the tank for the length of the car. Does this make sense? the fuel pump now draws gas from about 2 feet away from the tank. Had the car towed home, will try to start it up tonight.

Rick

[marco_1978_spyder]

Yes that makes sense.. if the pump is still struggling, you may need to drop the tank and see if the old dead pump is now restricting fuel flow.. at that point just replace the old assembly..

[cjbiagi]

Electric pumps are designed to push fuel, not suck it. That is why they are mounted in the tank. Where do you have the pump picking up fuel from the tank? Is it connected to the stock pickup tubes? If so, it could still be starving for gas especially when going up a hill. Go back to basics and put the pump in the tank where it belongs. If the pump is mounted higher than the fuel pickup point that could be a source of the problem.

[monzacoupe]

The fuel pump is new, mounted just above the tank, drawing fuel from the original pickup tubes. My fuel pump is an in line one, maybe about 2" in diameter, does anyone have a diagram/picture of what it should look like in it's original form? Is it supposed to be attached to the pick-up assembly tubes?

[cjbiagi]

Yeah, having it mounted up high outside the tank could be the problem. It has to suck the the gas up from the tank. Here's a pic of a similar stock type pump that mounts in the tank on the float assembly. Caution, this may not be the correct pump for a Monza, it is just for reference.
http://www.ebay.com/itm/BOSCH-69552-Fue ... es&vxp=mtr

[hammerdown7]

I may be way off here but here's my thought. By the way my fuel pump has been under my hood for four years without a problem. You plugged many hoses and fittings, possibly one might be a return line to the gas tank. You may be seeing a vacuum forming in the tank. I don't know if the stock gas cap allows air to pass. If it stalls again, loosen the cap and see what happens.

Dick

[cjbiagi]

Good point Dick, it's hard to evaluate every different problem without seeing what's going on. The stock cap is a vacuum/pressure cap. It is designed to vent or "open" at a predetermined vacuum or pressure but it may not be enough to prevent a problem in a non stock application. There are always exceptions to the rule as far as your pump setup goes. As long as it works that's the main thing. I ran my car for about 25 years with the stock gas cap while I utilized the vapor line (vent) as a fuel return line. Never had a problem with it, I did however eventually devise a small vent to relief any possible vacuum or pressure in the tank.

[monzacoupe]

The return line that runs from the charcoal cannister has been removed and that tube is now open to the air(I will be putting a filter of some kind on it) so I don't think it"s that. Apart from the pump not working right, I'm not sure what to do. I can get an in tank fuel pump from Carter for about $95, but I want to exhaust all possibilities prior to spending the money.

Rick

[marco_1978_spyder]

Ok...

Turn the key to run, and listen for the noise of the pump ...do you see gas squirt into the venturies when you crack the butterfly open? this should be your next step..

[monzacoupe]

Ok car is squirting gas when I open the throttle but still stalls. The fuel pump is making alot of noise when the power is on but the car is not running. Just tried to start it but battery is too low, but I smell alot of gas, so it seems like it's flooded. Here are some pictures of what I'm dealing with and what I've done. The fuel pump is mounted onto the bvody of the car, below the trunk, front edge of the tank, passenger side.

[marco_1978_spyder]

Ok ....The car is getting gas so you can focus away from the fuel pump for now it's doing the basic job.

It indeed sounds as is it's flooding out... how long does it stay running when you do get it to start...does it idle for a while? is there any sign of black smoke from the tailpipe when it stall's out? some simple tinkering you can do... pop the distributor cap, (mark your wires first) and see if the rotor is still twisting freely and springs back nicely. Check for any bad Vac lines and make sure the vac. advance and egr are hooked up and functioning correctly.

That carb is a Dual Jet.. It's literally, the front 2bbls of a Quadrajet.

Here's a crazy possibility... Your fuel pump is actually working to good, or some dirt or debris has lodged into the needle seat assembly creating a flooding condition.. Do you know what the fuel pressure is? too much might reak havok... if gas pours out the vent and onto the engine as you drive...well you could have an engine fire or worse... Maybe the monza stalling on the road is it's way of preventing catastrophy?? Sounds crazy, but after having 20 of them, I've confirmed that they all have there own personality.

If the needle/seat is jammed ie; float stuck open it will idle for a while maybe even run at speed but will load up with fuel and stall with the throttle closed.

[monzajer]

Ok ....The car is getting gas so you can focus away from the fuel pump for now it's doing the basic job.

It indeed sounds as is it's flooding out...

That carb is a Dual Jet.. It's literally, the front 2bbls of a Quadrajet.

Here's a crazy possibility... Your fuel pump is actually working to good, or some dirt or debris has lodged into the needle seat assembly creating a flooding condition.. Do you know what the fuel pressure is? too much might reak havok...

If the needle/seat is jammed ie; float stuck open it will idle for a while maybe even run at speed but will load up with fuel and stall with the throttle closed.

Yes, this is a possibility. 9PSI is MAX for these carbs. If you find this is the problem, do yourself a favor and purchase a GOOD fuel pressure regulator. There are some cheap ones out there and they don't work for squat. It is GAS so don't be frugal here!!!

Let us know what you find.

Good luck.

cheers, jer

[heinz057]

the large vacuum plug on front of the carb needs to come off ,that is a vent . it should go to the charcoal canister