1999 Dodge Caravan Stalling - Fuel System
Question: My 1999 Grand Caravan, 72, 000 miles will all of a sudden start to deaccelerate giving the indication that the vehicle is out of gas, even though there's still gas in the tank. This has happened with many different amounts of gas, with 3/4, 2/3, 1/2, and 1/4 of a tank. Once this has happened, you can usually wait approximately 10 minutes, and then it will restart. Once it has restart it will only drive about 4 miles and then it will stop again. Even when there's at least 3/4's of a tank, by filling the tank up all the way, then it will restart and then it's anyone's guess how far you can drive it before it stops again. Last year I had the fuel pump/pressure regulator unit replaced, it seemed initially that it had taken care of the problem, but it was only a matter of time and it started stalling again. The last time it happened, the Engine service light came on. I've taken the vehicle to the Dodge Dealer and they went through everything and found that the o2 sensor was shorted out, they checked the fuel pressure, cleaned the ejectors, and the vehicle stalled again just the other day. It only had a 1/4 tank of gas, and once it restart, drove to a gas station and filled it up. It's only a matter of time, and it undoubtely will stall out again, just went; no one seems to know or can figure out what the problem is. Any thoughts on this problem, thanks.
Technican: I think of several things that can cause these kind of problems.
Does it start without adding any gas? If not, we will focus on the fuel delivery. Check the gas cap. If it not allowing any air to enter the tank, it could allow the vehicle to start again by simply opening the cap. Do you get a big vacuum sound when you open the cap? If so, change the cap.
If the cap is OK, I would consider the fuel pump. We see repeat failures at times. Check for dirt/water in the tank, check for restricted fuel filter. These can cause premature fuel pump failure.
If you do not find a problem in these areas, you will need it looked at WHEN the PROBLEM is OCCURRING. Then fuel pressure can be measured, and other "live" readings can be taken....check for spark, check crank sensor, etc.
I've re-opened this question at the customer's request.
Owner: Q. Will vehicle start without adding fuel?
A. Yes, but only after letting it sit for at least 10 minutes, but will only run for a short time before stalling again. Once I refill with gas, then it's anyone's guess how far it will run before stalling again.
Q. When removing gas cap, is their a suction sound?
A. Don't remember, but will check it out the next time I used the Caravan.
My additional question. Is the gas cap the only way that pressure can escape the gas tank. In other words, if the gas cap is faulty and won't allow pressure to vent, could this cause the problem of stalling?
Technican: There is the canister system which is supposed to vent any excess pressure and permit fresh air to enter the tank. I am supposing the tank may be building a vacuum which makes it hard for the pump to suck the air. The next time the van stalls, try opening the cap and see if it will start and run again.
The fuel cap is supposed to release pressure or vacuum over a certain point. The canister is to do the same. If you have a multiple failure, it could create a vacuum in the tank in such a way that the van would stall.
What you said, makes sense and I'll try it the next time the problem appears again. I'm amazed that the Dodge Service Center couldn't come up with this same possible solution that you came up with. Thanks again.
Well, it happened today to my daughter and I told her to open the gas cap and listen for any hissing of air flow. She said that she didn't heard anything and then try to start the vehicle with no luck. She waited awhile and it restarted and she drove to a gas station to wait for me. I told her not to fill it up yet. Also, the engine service light came on. I swap vehicles with her and started to drive the van, and it immediately started to slow down and wouldn't accelerate at all. I was able to get to another gas station and filled it up. It took approx. 10 gallons and when I started it up, it ran fine with no apparent problems, except the engine service light was still lit. If the vent system and the gas cap both are faultly, how many gallons would normally be used up before a vacuum lock would be create it. What I'm thinking is now I have a possibly of two problems, the original one with the venting not functioning properly and now causing the failure of the gas pump. Anyway, any thoughts. Also, I'll probably call the Dodge service shop and tell them I still have a problem.
Not having the vehicle in my shop, I cannot test exactly what is going on. I suspect a faulty fuel pump, or dirt in the tank that gets sloshed around when filling. Generally, the current generation of electric fuel pumps are strong enough to overcome any potential vacuum lock.
Hope this helps,
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