Electric fuel pump

Hold on! You need a friend like me to solve all your problems.

The first problem has to do with how much gas you dumped in the tank. If you put in any less than five gallons, stop all your other frustrating steps and do that, then cycle the ignition switch from "off" to "run" at least two times, with a couple-second pause in between, then try to start the engine.

There is every possibility you're creating more what you think are problems by not knowing how these systems work. I just hopped out of my daily driver 20 minutes ago, a 1994 Grand Voyager. My last one was an '88 Grand Caravan, so I know these vehicles well.

Do this first. I'm posting this first part of my reply so it will reach you as soon as possible. I'll be back with part 2 in a few minutes.

You didn't say what problem or symptom led up to the fuel pump diagnosis. Knowing that, I might have saved you having to do that repair.

Starting from the beginning of your post, $800.00 is way too much for this service, but be aware, there's more than one way to approach the solution. For $32.00, you got a pump and motor that had to be transplanted into the fuel pump housing once it was removed from the tank. That's the way I do it on my vehicles, but in a minute I'll mention the strainer on the pick-up tube on the bottom of that housing. With my '88, and with two older cars with carburetors, that strainer can be replaced separately, and it is a common but elusive cause of intermittent stalling. It's common for the pump / motor assembly to come with a new strainer, but the package is going to cost more than $32.00. The clinker is on the '94 model, that strainer can not be purchased or replaced separately. The only way to get it and replace it is to replace the entire housing with the new pump, motor, and strainer already assembled and ready to drop in. Those cost a lot more than just the pump and motor, and you get a new fuel level sending unit with it. That takes care of another common problem, an intermittently-dead fuel gauge on the dash.

The next problem has to do with listening for the hum of the pump. GM fuel pumps, especially for their trucks, are very noisy and easy to hear when standing some distance away. Chrysler fuel pumps have very tight clearances and as a result, are very quiet. With two different designs, they fail in two different ways. GM pumps almost always start up, then they fail when they get warm, letting you sit on the side of the road. They also commonly fail to develop sufficient fuel pressure, and coupled with that, many of their engines will not run when fuel pressure is as little as five pounds too low. Chrysler fuel pumps rarely fail once they've started up. They fail by failing to start running, so they leave you sitting in your driveway or a parking lot. A lot of auto parts store chains buy their Chrysler replacement fuel pumps from the same supplier that built them for Chrysler, so they're just as quiet. Napa is one of those stores, and I'm sure there's others.

You're going to have to listen very closely for the hum of the pump, but then, that is only going to occur for one second when you turn on the ignition switch. If you turn the ignition switch on, then jump out and run down by the tank, expecting to hear the pump, you'll be disappointed and perhaps frustrated. There is no car or light truck model where you'll find the pump running all the time. To do so would present a serious fire hazard. If a fuel line gets ruptured in a crash, and the pump keeps on running, it will dump raw gas on the ground, creating a major fire hazard. Instead, most Engine Computers will run the fuel pump for one second to insure fuel pressure is up for starting. It should hold for weeks or months, but it's not uncommon for it to bleed down over time.

After that initial one-second pulse, the computer turns the automatic shutdown, (ASD) relay on again during engine rotation, (cranking or running). It knows that by the signal pulses it receives from the crankshaft position sensor and the camshaft position sensor. Those sensors are different between the 3.0L and 3.3 / 3.8L engines, but the fuel pump circuit is the same for all the engines.

The ASD relay sends current to the ignition coil, (coil pack in your case), injectors, alternator field, oxygen sensor heaters, and fuel pump or to a separate fuel pump relay. This means when you have a crank / no-start condition, 95 percent of the time you'll have a loss of spark, injector pulses, and fuel pump, but too many people get hung up on the first thing they find missing, and for some reason that is the fuel pump, and they neglect to look for any other things that are missing. This can be misleading too because fuel pressure will appear to be normal, thanks to that one-second pulse of the fuel pump. Some people find the missing spark, then tear that system apart, again, failing to notice there are other things that are missing. When you run into this problem of a crank / no-start condition, a quick test is to use a test light to back-probe through the dark green / orange wire at any injector, or at the coil pack, or either smaller terminal on the back of the alternator, and watch if it lights up for that one second when you turn on the ignition switch. If it does, it proves that part of the system is working. Next, it must turn on again during cranking. 95 percent of the time it will not. That indicates a problem with one of the two sensors I listed. If the light does turn on steady during cranking, the two sensors are working, and that is when you have a problem with one of the individual circuits for the fuel pump, (roughly 3 percent of the time), or the ignition system, (perhaps 2 percent of the time). The biggest initial clue here is if you can hear the fuel pump run for one second. If you do, forget looking at the fuel supply system.

Your comment about the clogged fuel filter caught my attention next. Except for diesel engines, you will never solve a running problem on a Chrysler product by replacing the fuel filter. They last the life of the vehicle unless they rust out and start leaking. That happened once on my '88, but you're more likely to run into a dry-rotted and leaking hose attached to the filter. New filters come with two new pieces of hose, and new, special fuel injection hose clamps. Don't try to use older-style hose. That's meant for cars with carburetors. Fuel pressure rarely goes higher than 5 psi. You must use fuel injection hose. It costs about $4.00 per foot at the auto parts stores, and will withstand the much higher pressures. All four of my Caravans / Voyagers run over 50 psi at times. The special hose clamps are bands tightened with a bolt and nut. The more-common aircraft style with a worm gear screw will cut into the hose and lead to a leak. This story doesn't pertain to other vehicles, GMs in particular. Those still require periodic replacement of the fuel filter.

Don't overlook the possibility you have the two hoses switched at the gas tank. I had to replace the strainer in my '88 two times, and both times I accidentally switched the hoses even though they're different sizes, ... And I'm supposed to be the expert.

Don't waste your time and money with Haynes or Chilton service manuals. They cover the common stuff, but never much related to electrical, and they never include wiring diagrams. Nothing beats a paper copy of the manufacturer's service manual. You can find them all over on eBay. I bought a lot of them from "LorieandJeff" from Tennessee some years ago for my classroom. Today they go by "Blackhatauctions". There's many others out there too. '94 service manuals have a sea green cover.

Chrysler wiring diagrams appear very confusing at first, but I can help with reading them. Only Ford's are better where they put an entire circuit on one or two pages. Chrysler puts fairly little on each page, so they have you bouncing around between multiple pages. That becomes extremely frustrating when trying to find anything on a DVD.

Getting back to dumping the gas into the tank, if you look inside, you'll see there is a metal bowl in there that the pump housing and strainer sit in. That is to prevent gas from running away from the pick-up when you go around a corner with just a few gallons in the tank. That was never a problem with carburetors because there was enough gas in the float bowl to keep the engine running for a couple of minutes. There is no such storage in the fuel supply system with fuel-injected engines. If the strainer sucks up air for just a fraction of a second, the engine would stall or at least sputter and stumble. The gas in that bowl will keep the engine running for quite a while. Once the engine is running, a really high volume of gas is being pumped, but just a tiny fraction of that is tapped off to go through the injectors into the engine. Well over 99.9 percent of that gas goes through the pressure regulator, then back into the tank. It's that gas that flows out of a tube and up a ramp, around and into the bowl. That gas flow creates a venturi effect that drags more gas along with it to keep the bowl full.

The problem is when the tank is empty, or you run out of gas, that bowl is empty, so no gas gets pumped to the engine, and no gas comes back in the return line. This is where I suspect all of your frustration started. On my '88, when I pour just a little gas in the tank, it drops from the filler tube right into that bowl. A pint of gas will get the engine started. On my '94, the filler tube misses that bowl. The gas just goes into the rest of the tank, then, it takes about five gallons before the level gets high enough for it to spill over and fill the bowl. That's when the engine will start, and from then on, the returning gas will keep that bowl full even when you're down to your last few spoonfuls of gas.

Sorry for the delay. I'm known for typing long replies, but then I typically proof-read them twice. To speed things along for you, I didn't proof-read that until after I posted it, so now let me add some details.

First, if you disconnected the battery at any time, there's two things to be aware of. The first is if there were any diagnostic fault codes in the Engine Computer, they were erased, so that valuable information was lost. Related to that, when you have the crank / no-start I mentioned, most often it is caused by the crankshaft position sensor or the camshaft position sensor, and while there are diagnostic fault codes that can be set related to them, they commonly do not get detected just from cranking the engine. They need more time to be detected, as in when a stalled engine is coasting to a stop. Even when you do get any fault code, always remember they never ever tell you to replace a part or that one is bad. When a sensor or other part is referenced in a fault code, it is the cause of that code only about half of the time. First we have to rule out wiring and connector terminal problems, and mechanical problems associated with that part. Fault codes only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition.

If you don't know how to do this already, Chrysler made reading the fault codes yourself much easier than any other manufacturer. Cycle the ignition switch from "off" to "run" three times within five seconds, without cranking the engine, leave it in "run", then count the flashes of the Check Engine light. You'll get flashes for the first digit, a slight pause, then more flashes for the second digit. After a much longer pause, the next code will flash the same way, if there is one. Ignore code 12 if you get it. That just means the battery was disconnected on some models, and others it means the ignition switch was turned off. Also ignore code 55. That just means it's done reading out the codes. If you think you may have miscounted, turn the ignition switch off, then back to "run" one time and do the count over. You can go here to see the codes for '95 and older Chrysler products:

https://www.2carpros.com/articles/retrieve-trouble-codes-for-chrysler-dodge-plymouth-odb1-1995-and-earlier-car-mini-van-and-light-trucks

I can interpret them for you if necessary. Also be aware only fault codes related to things that could adversely affect emissions are the codes that turn on the Check Engine light. About half of the codes do not turn that light on. "Running cold too long" is a perfect example. Just about every Chrysler product will have that code in winter if you're in a northern state. It sets when the engine doesn't reach a specific temerature within six minutes of starting. If you let the engine warm up before driving, it will set that code, but you'll never know it unless you read them. When you have an intermittent problem and it stops acting up, the code it sets will self-erase after 50 ignition starts, which for most people is about one or two weeks.

The second thing to be aware of after disconnecting the battery is every Chrysler product will have idle speed that's too low. The engine may not start unless you hold the accelerator pedal down 1/4". You won't get the nice "idle flare-up" to 1500 rpm at start-up, and it will tend to stall at stop signs. All other sensor personalities, fuel trim data, and other learned data will be relearned as soon as you start the engine, except for "minimum throttle". The computer needs to see a very specific set of conditions to initiate that relearn. Until then, it won't know when it must be in control of idle speed. To meet the conditions for that relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.

There had better be a bowl in the tank or you would definitely not "run it to fumes". By the time you reached the last two to three gallons, the gas would be spread out over the entire bottom of the tank and it wouldn't be high enough to be picked up by the strainer.

I suspect you missed an important part of my description. That five gallons is only needed to get the fuel level high enough to spill over into the bowl and fill it. That is only necessary after running the tank empty or after draining it to replace the pump. Once you have the engine running, you can definitely run it down to almost empty. The engine doesn't stall when you get below five gallons. Once the engine is running, that bowl will stay filled as long as there's any gas in the tank. The only way this can work with no bowl is if there is a low spot in the tank where the strainer sits, then all the last few drops of gas will run there to keep the strainer submerged so it won't suck up air.

As I mentioned, my daily driver is a '94 Grand Voyager, which is identical to your Caravan. I purposely ran it out of gas twice to learn how far I could go once the "Low Fuel" light turned on. Believe me, no amount of crying, standing on my head, or shaking the van got it started until I put the entire five gallons in that I had in the can. If you insist on looking somewhere else for the cause of the no-fuel, you'll be in for a lot of wasted time, and frustration.

I wanted to add two more comments of value that pertain to our vans. The first is there are two common problems with Chrysler fuel pumps. The first is one common failure, especially at the mileage you listed, is worn brushes in the pump's motor. The symptom is always a dead pump when you try to start the engine. It never stops running after it has started up and you're driving. You can often get them started by banging on the bottom of the gas tank. You can try that yourself, but sometimes that jarring only works when voltage is applied to the motor, which means you have to be banging when a helper turns the ignition switch on, or while they're cranking the engine. Remember, you only get 12 volts to the pump for one second after turning on the ignition switch, then again during cranking. This problem gets progressively worse over the next few months. It may fail to start up again the next time you try to start the engine, or it may not act up again for months. Don't try to rely on banging on the tank, but if you're out in the wilderness with no help in sight, that just might get you going again so you don't have to walk home.

The second type of pump failure is related to that strainer becoming plugged. The strainer almost always causes the engine to gradually lose power after driving about 15 miles or more, and then the stalling occurs when the highest volume of gas is being pumped, which is during coasting down from highway speed. The engine runs fine at higher speeds. The first time this happened to me with my '88, I drove over 200 miles just fine, then the engine sputtered when taking off from a stop light. Thirty miles later, it stalled when I slowed down for my turn-off. I was able to nurse it along, then eventually it took me over four hours to get through Minneapolis with their road construction on all three interstate bypasses. Once back on the highway, it ran fine for three hours at highway speed until I turned off onto local roads at home.

In my case that was the first of two strainers it needed in 420,000 miles, but a related problem has to do with people who replace a dead pump with an aftermarket model, and it fails within a few weeks. They get it replaced under warranty, then that one fails. After the fourth or fifth replacement, they get frustrated and buy a pump from the dealer, then they don't have any more problems. Logic would dictate the aftermarket pumps are inferior, but that is not the case. In fact, a lot of the aftermarket pumps come from the same manufacturer that made them for Chrysler, then they just slap their own brand name on them.

I don't know this for a fact, but I have a strong suspicion this is caused by the mold that feeds on the ethonal in today's gas. A friend who runs a small engine shop has a jar with that gas in the window, and you can see the mold growing over time. What is happening with those repeat failures, is since Chrysler's pumps are built to very tight clearances to make them quiet, the impellers become plugged with "microscopic debris", as explained by one of our Chrysler instructors. That crap is still in the tank when you put the new pump in. That one also collects some of that debris, and it locks up, just like the first one did. By the time you go through three to six pumps, they've collected all that debris, then the next one doesn't fail. It is just coincidence that last pump that doesn't fail is the one that came from the dealer. The proper repair for this is to take the tank to a radiator specialty shop and have them steam-clean it, then put the new pump in. No one has a repeat failure when they do that, but you have to know to do that.

The last thing I forgot to mention has to do with the fuel level sending unit on the side of the housing. A common problem is the gauge on the dash reads correctly when the level is between empty and 1/4, and it reads correctly when the level is between 1/2 and full. When the level is between 1/4 and 1/2, the gauge drops to below empty, and it may occassionally jump up to where it should be. Most mechanics will replace the sending unit, which is available separately, and while that will solve the problem for a little while, it's the same part built the same way by the same supplier, so you can expect to have the same failure in the future. Instead, any time we had the pump pulled out of the tank, solving or preventing that problem takes the better part of 20 seconds.

The float arm pivots on a pin, and is held from sliding off by a little plastic finger with a hook on the end. All you have to do is pull that finger up a little to allow the arm to be slid off. On the back side are two tabs with contacts on them, one for the gauge and one for the "Low Fuel" light. Bend those tabs out as little as 1/16", then snap the arm back in place. That extra tension keeps the contacts touching the resistor assembly. That simple repair is much more effective than snapping on a new sending unit, and you don't have to buy any parts.

That housing is not the bowl I was referring to, but it could be performing the same function. Anyways, I only know three things, and one of them is my van won't start until I dump five gallons of gas in the tank. That is not true for my '88 Grand Caravan, and I haven't experimented yet with my other vehicles. Happy to hear you're on the road again. Please come back to see us again.