94 Dodge Ram 318 Fuel Injection Questions

Hi,
I am working on an intermittant problem on my 94 Dodge Ram. It has the 318 motor. It will intermittantly stop running like it is starved for fuel. This is preceeded by a couple of minutes of barely running while
not under load, (spitting and sputtering through the throttle body). The problem most ofter happens following a normal drive of 15-45 minutes.
I did some of the easy stuff first and replaced the rotor, dist. cap,, coil, and plug wires.
It sounds like it is starved for fuel or that the computer has gone south and messed up the fuel injection or ingition. But am thinking fuel at this point. Does anyone know which relay, location, turns on and off the fuel pump? Does anyone know if there is a fuel sensor in the fuel line, and if there is where it is? Does anyone know if the computer is involved with turning the pump on and off?
Any ideas before I start looking at fuel pump/filter, (expensive for this model and difficult to replace)?
thanks,
Mark
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This sounds more like a possible computer problem.

What about the plugs? Did you pull and inspect them as well? IF you have a timing light, I would check the timing at idle when the engine is running normally and then bring it with you the next time you go out. When the engine acts up again, reconnect it and see what it is doing. If it is still normal, the problem is fuel related (still could be the computer) and if not, this will give you an indication if the problem is ignition related (sensor or still the computer).

I don't remember which relay, there is no fuel sensor in the line, and yes, the computer controls the pump. If it were a fuel starvation problem, the problem should be fairly consistent and not take 40 to 45 minutes to occur and then go away again in a few minutes. The computer OTOH, could have a heat related problem that takes time to build up. Are you getting a check engine light? You might want to have the computer checked for potential codes as these indicate potential and initial problems that have not yet lit the check engine light.

You can use the timing light test to see if your ignition is acting up. As for the pump, it is in the tank and the filter and regulator are part of it. The price is between $150 and $450 depending on who makes it and where you get it and if it is still the origional pump, it is getting up there in age but then again, my Nissan is 17 years old and still has its origional pump. I would find somebody with a fuel pressure guage and both pressure and flow test the pump before swapping it out and do it with a fairly low tank of fuel to rule out cracks in the intake tube sucking air, which could be another cause of your problems (as remote as that may be).
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TBone,
OK, several good suggestions. I do have a timing light and that would certainly tell me if the ignition timing is going south. Yes, I price a NAPA pump filter assy and it was 200. I also had another suggestion earlier on this board about how to replace it which sounds better than dropping the tank. I was told to raise the bed and I could get at the pump/filter assy. I did not know there was a regulater in the pkg also.
The computer controls the pump and there is no pressure switch?? How does the computer control the pump? Or, does it just have the pump on all the time and the regulator provides the right amount of gas? If this is the case I could disconnet the fuel line at the rail, turn the key on, and I should have gas, right?
Will the computer save error codes? I had it at a shop following the second failure, after replacing the failed parts. They said there were no error codes. (They actually put a 100 miles on the truck without it failing, so they were not able to see the failure. (The truck had died on the side of the road and I had them tow it in.) Anyway, could the computer have zered the error codes, if any, when things started working again?
thanks,
Mark
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You can raise the bed but I really don't know which is more difficult. If the tank were near empty, I would think that dropping the tank would be easier and far less dangerous as the bed is always heavy. The fuel system in your truck only has one line and no return path so it has a regulator and it is in the tank with the pump and filter.

The pump uses it's regulator to control and maintain pressure. The computer turns the pump on when the ignition is switched on for a few seconds to build up pressure and turns it back on full time when it senses the engine is running. I would suspect it is done this way to prevent the pump from killing the battery when the ignition is left on and the engine is not running as some do to listen to the radio or run things that do not work in accessory mode.

I don't think so. It can turn off the check engine light after a while but I think that it still retains the codes, at least for a while. If the battery were to be disconnected, they would be cleared. Either way, unless the battery were to be disconnected or they were reset with a code reader, they should still be there for a while if they existed at all.

Your welcome.
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Oh, and this might be a bad idea to try this as you are dealing with a high pressure pump and it could make a real mess that could be a real fire hazard. The pump will also only run for a few seconds without the engine running. You should use the proper tools here.
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Actually, its a bad idea because most fuel rails have a test port, no need to disconnect anything. And yes, a proper guage would be best, but simply tapping the pin in the valve should allow fuel to spurt out. Cover the valve with a rag, and take appropriate precautions.
As to the filter and regulator, by 2000, the pair with in a seperate housing on top of the pump. Both are removable as a unit and can be done without pulling the pump out of the tank. Not sure how far back this goes, but OP should check to be sure, as it might cut cost and time for repairs. I would also check to be sure any pump OP gets has this unit, as $200 almost sounds too low to be a full assembly.
Last, buy the Factory Service Manual, its irreplaceable for good info.
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engine
valve
Most is not all and if you damage the test port taping a pin in it, then you really are SOL and you will still have fuel spraying at high pressure into the engine compartment, not a good idea. My 97 manual say's that SOME of the fuel rails have a test port, not all of them. The appropriate precautions are to use the correct tools and use them correctly.

housing
I don't think so. How would you disconnect it from the fuel pump. Come to think of it, how exactly would the fuel pump be mounted if not to the upper flange. Again, in 97 they started doing this as the manual also says SOME OF THEM have a removable fuel filter / regulator assembly but you still had to remove the entire assemply from the tank to get to it.

On a 94, it would increase time as the pump still has to be removed and now disassembled. With a pump that old and the amount and difficulty of work involved, if he is going to remove it he should just replace the entire assembly anyway.

sounds
I don't think that the pump for the 94 comes any other way although it might be comming without the fuel guage sensor. Mine was complete and for less than that but I know somebody who works at a major parts distributor and gets a significant discount.

Good advice here but Dodge is not known for keeping manuals for a vehicle this old.
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True, but I'd bet on a Dodge, there is one.

If you do it while the engine is running, yes. If you take "proper precautions", such as not doing it when the manifolds might be hot, the engine won't be running, and it will be a minimal amount of fuel.

Yup, a small flat blade screwdriver and a bit of finesse, and you won't hurt the valve.
If you are going to advise a person on how to fix something themselves, the first rule is to tell them how.

Well, my FSM has instructions and several pictures showing EXACTLY how its done. Now, if the same design was in use as early as 94, I don't know, and I wrote as much.

As I said, I wasn't sure when they started using it, nor am I sure if any were retrofitted.

If he has the assembly I mentioned, he would only need to remove the filter/regualtor. Otherwise, I wouldn't have mentioned it as being easier.

There are several sources on the net where an FSM for this truck can be purchased. Limiting a search to the dealer network would be foolish.
Are you always trying to be difficult and contradictory? Oh wait, you are Tbone, of COURSE you are always that way..
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into
What purpose would doing this really serve? While the spray may indicate pressure, it will give you no value of how much pressure (especially spraying into and under a rag) or valid flow amount this way and you still risk damaging the port.

hurt
And you can guarantee this??? Will you offer to pay for a new fuel rail if he damages it with your method or a new vehicle if he catches it on fire?

the
No, the first rule is to do no harm. Giving him bad advice on how to test for pressure could get him hurt, damage the rail, or at worst, get him killed and or destroy the vehicle. The manual has specific warning about doing crap like this and I think that they know just a little bit more about it than you. Playing games like this requires experience and I don't know if the OP has it, do you?

without
I
Well I do and it wasn't. I also both own the FSM for a 97 (same basic series as his) and replaced the pump in mine and if it was possible and easier to just replace the filter and regulator I would have suggested it in my list of things to do but until he sees the actual pressure and flow amount, replacing it is just blindly throwing money at the problem.

SOME
97 had both replacable and not and I'm not sure if it goes back further but even the ones that do have replacable filters require removal of the entire assembly to get to the filter / regulator. It may be different in 2000+ but not the 94.

work
Well, since I own a 97, it is far more likely that it uses a pump similar to mine than your year and in reality, how much easier is it? You still have to either raise the bed or drop the tank to get to it and still have to remove the fuel lines so unless something is very different with the 2000 and up, there is not much more to removing the pump after that point besides removing the locknut and an electrical connection and lifting it out.

less
vehicle
I never said anything different but Dodge will be of no help here.

LOL, what a case of PKB here Maxi. You have offered nothing of and added value here, only to try and contradict what I have said.
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LOL, this is fairly minor compared to the crap that usually starts between us. It's too bad that it has to start when I am trying to help someone but I expect nothing less form some in here.
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Mark
There is a pickup coil in the distributor. Disconnect it close to the distributor and put a meter or something for continuity on it. Then wiggle the wire to see if it develops an open or any change. Replace the coil iof any doubt.. Bob AZ
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I'm having the same problem with my 94 Dakota. I've replaced the relay to the fuel pump and the problem is still happening. Voltage also is fluctuating greatly. Do you know where I could get a new/refurb computer at a decent price?
MarkInNC wrote:

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