I know our 93's have the return style fuel system, and from what I remember we have a specific pcm module for that, as the 94-up didn't have the return line. Were our dakotas the only trucks to have the return system? Seeing as the 3500 Ram 5.9 is a 93' and has a returnless style fuel rail, what should I look for as far as a pcm goes? Or can I just get any pcm for a 5.9 and disconnect my return line to the fuel pump?

 

I'd play it safe and stick to a PCM on the "approved list". 'What's that?' you say. Most parts houses on-line ask for your vehicle particulars so they can filter parts searches. Additionally, many furnish the OEM part number. Do that on a few sites so equipped and you have a shopping list of OEM part numbers specific to your application to guide you on your quest.

 

And thats what I have heard at every parts retailer known to man by the uneducated honda driving moron 15 year old kid. No offense man but thats about as helpful as removing scratches from a window by throwing a brick at them.

...maybe I'm not asking the right question here.

I need to know if there is a difference in the pcm to adjust fuel rates etc between return and non-return style systems.
I am avoiding a mopar performance pcm as it will not allow me to tow with my truck, or so I have been told.
I have a return style V8 rail, but its bent up to where I'm not sure it can be un-bent without damage. That being said, the motor I already have is year matching, but has a non-return fuel rail already attached and in perfect shape, so what all would need to be done to change from a return system to a non-return system? Do I need a diffenrent fuel pump? Is it as simple as just un-hooking the return line and capping it on the pump? What options do I have to work with here.

 

Folks in Tennesee sure know a thing or two about tact. Yessiree...

Lets take a look at the fuel system on a '93 Dakota. The pump pushes fuel to the regulator mounted on the fuel rail @ 40 psi. The regulator uses engine vacuum to limit that to 31-32 psi @the fuel rail and returns the excess fuel via the return line. No PCM paticipation, so far.
The PCM runs the engine according to values loaded into ROM based on the expected fuel pressure until the engine warms up (Open Loop), then switches to Closed Loop. In Closed Loop, the PCM monitors feedback from various sensors and varies pulse width to the injectors to keep sensor readings within programmed limits. It seems safe to say the limits are established for the given fuel inlet pressure and expected engine characteristics. In the case of a '93 Dakota, those options are 2.5, 3.9 and 5.2 litre engines.
Logic would lead me to believe a 5.9 litre engine from a full size truck would require migration of the corresponding fuel pump, PCM and maybe the fuel tank to accomodate the pump, unless the pump will drop into a Dakota tank.
I am sorry my uneducated honda driving 15 year old mentality is not versed in the details of a 3500 Ram fuel system and PCM, this is the best I can offer. Good luck with your project, Veteran.

 

Ok that tells me any pcm will work, thank you for that clear answer.

Fuel pumps for the 3.9-5.2 are the same part number, and since i have replaced mine, it runs more pressure. The Airtex I installed is rated for 70-80 psi. A 5.9 requires 60, so my pump will work fine. My concern is do I need to change anything with the fuel lines to switch to a returnless system? I'm aware the pressure regulator is on the fuel rail on 92-93. And I know the trick to using a 2.2 Intrepid regulator to get the 60psi from the pump.
So if I were to change that, what all would I need? New fuel line from a 94-up? new pump hookup for said line? This is the only thing I have yet to get any clear answers on for my build, and seeing as it's a major one its not something I can skip.

 

So your dropping in a 5.9 in place for your 5.2? You will be fine with your stock return fuel system with any 5.2 or 5.9 pcm. The Mopar Performance PCM will be your best bet, it is fine for towing, trust me I tow all the time. The 94-95 Mopar HP PCM will be fine on your fuel system with just the upgrade on the fuel regulator.

 

I don't have a 5.2 I have the 3.9! lol I have a 5.2 rail but the fuel lines on it are bent up under it and I don't have the first idea on how to un-bend them without kinking them. Hence my asking about changing the system to non-return since the local pull yard has never had any dakota with a V8 sit for more than an hour before having the motor pulled.

Ok thats good to know the mopar pcm actually does work for towing, since all I've been hearing about it says its not good at all for towing...guess every forum tells you something different.

 

So you have a 3.9? Are you considering putting in a V8? I confused because you're talking about a bent 5.2 fuel rail, a 5.9 computer, and a 3.9 engine. I installed a 5.9 in place of a 5.2 in my '94 and converted my returnless system to a return. I've messed with different computers and fuel pressures with both types of systems. I probably have the answer you're looking for but I need to know what you are trying to do first.

 

^ Perfect.
I currently have the 3.9, and I am getting ready to swap in a 5.9. The 5.9 I have is a 93 from a ram, and I know what all I need to swap it in as far as oil pan, sensors, extra wires etc etc thanks to your write-up actually lol.

Fuel rail - I managed to procure a return style 5.2 rail from a member of another forum, but the fuel inlets are pretty badly bent, and I'm not sure if I can un-bend them without kinking them to the point of being un-usable.

The returnless rail that is on the motor I have is perfect and doesnt have a scratch on it, hence my asking about switching to returnless since that may be much easier than trying to find another return rail thats not damaged.

 

Okay, that makes more sense.

If you want to convert to returnless, you'll need a new fuel pump module which should just drop in your tank. The regulator is built in the fuel pump module. You might have to fabricate the connection to the fuel rail. I don't recall what the returnless fuel rail connection looks like. If you go returnless you are going to have to use a '93-'95 5.9 PCM.

If it was me I would keep it a return system because it gives you more options. You could post a pick of the fuel rail so we could see how badly it's bent. If you stay return you can use 5.2 or 5.9 computers '92-'95. I'm currently running a '94 5.2 computer with a '98 5.9 engine with higher fuel pressure because I like the performance of the 5.2 PCM over the 5.9 PCM. I did back to back 1/4 mile runs with a '94 5.2 and a '94 5.9 computer. This explains what I did for my fuel pressure problem: https://dodgeforum.com/forum/1st-gen...-360-swap.html. If you choose a returnless computer just leave the vacuum line off of the fuel pressure regulator (5.9 PCM) or use the Intrepid 3.3 regulator to up the fuel pressure or build an adjustable like I did (5.2 PCM). If you run a return with a 5.9 PCM use the stock fuel pressure regulator. If you use the 5.2 PCM use the Intrepid 3.3 fuel pressure regulator with the vacuum line attached.