1999 Dodge Ram V8 Two Wheel Drive Automatic 141000 miles .

Originally my fuel pump died. Normally i would hear the fuel pump kick in for its intial 2 second primer, but over the last couple of weeks I had noticed that if i left it idling it would start to die. Then, it just quit starting.

Anyway, so I replaced the fuel pump (not the whole module, just the pump itself) with an OEM replacement.
Got the tank back up, primed the fuel line and got the truck running. But, where as before I could not get the truck to start at all, then it took a couple of turn overs and it would eventually start (although while driving it seemed very sluggish, especially from a stop). That led me to believe that I should have changed the filter/regulator aswell.

I found the shrader valve on the fuel rail and pressed it in, no pressure when off, little pressure from intial 2 seconds, and fuel flow when engine idling.

So, I dropped the tank again and replaced the filter/regulator. Although I noticed two things. 1) there was a slight kink in the plastic fuel line before it hit the metal line to the engine. 2) I aslo noticed two heavy kinks in what i think is the EVAP line, it runs to a canister on the other side of the truck.

I tried to straighten the lines best I could.
Now it runs better, but still not right. It didnt take as much to start it, and seems to be running smoother, but it appears to still be loosing pressure.

Could the EVAP line be causing this? What else should I be looking for?

Thanks For anyones help.

Scott.

 

Welcome to DF.

Let me move this over to 2nd gen to get you some help.

 

Scott,

Whenever changing a pump out, it's best to change everything out including, the regulator. The regulator is the heart of the fuel delivery system as it controls the output.

I noted that you stated: Is it losing pressure or, there is low pressure from the start?

How do you know it's losing pressure? Did you measure this? No disrespect, just as an engineer here, just getting the facts.

<IF> it is indeed losing pressure, that could be the following failure modes:

- leak
- low voltage condition (FUEL PUMP SUPPLY)
- FUEL PUMP RELAY (FAULT / HI resistance / weak coil)
- Low voltage condition supply TO the FUEL PUMP RELAY
- Clog / restriction at the filter level NOTE: if you didn't change the filter, this could be your root cause for failure.

There's a few more but, those are the basics.

IN lieu of this question: The answer is NO. That line as well as the entire emissions / gas recovery system could be totally removed from CKT and, it would not affect fuel pressure. It would however, (if removed) trip a FAULT code and, the MIL lamp would illuminate.

Moving on.

Seems to be a lot of fuel related incidents as of late. This is the second one I'm working on. This system is very simple so, let me draw out a flow diagram so you can see how it works.

The FUEL PUMP regulator output is connected to a flex line with a molded quick connect fitting. (even a slight kink is not going to hold back 50psi in that small diameter so, you should still witness full pressure at the rails WHEN OFF.

However, it will affect flow rate if it is IMPEDING flow. You'd hear this just like a garden hose- it would make an audible sound that is exactly the same as a garden hose that has a kink in it BUT, that would have to be a good one at ~ 90º kink to impede the flow to the point of dropping psi at the other side.

This flex line runs down the side of the fuel tank and is compression and heat molded to a steel line.

This steel line runs along the underside of the truck attached to the side of the frame under the driver side.

It then terminates to another male / female quick connect fitting under the firewall area.

From there, a flex line feeds the engine bay.

The flex line attaches / mates with various styles of quick connects coupled with a failsafe (safety) mechanism to the FUEL RAIL inlet.

That's the flow diagram at the hardware level.

FUNCTION FLOW DIAGRAM.

At time of KEY <ON>, the PCM initiates power by means of engaging the ASD relay. This relay provides the means to switch power <ON>, to the entire EFI system as well as shut it down in case of FAULT.

ASD relay provides power TO the FUEL PUMP CKT which includes: FUEL PUMP FUSE and FUEL PUMP RELAY

Power flows through the FUEL PUMP RELAY into a WIRING HARNESS and down the side of the body to supply power to the pump.

NOTE: Check the harnesses and, verify voltage at the pump input. Not just with a test light. The test light is NOT going to tell you WHAT the voltage is and, that's crucial for, if it's dropping x - volts across the harness, the pump will not operate to full capacity.

This is a quick overview of the fuel delivery system excluding the PCM programming level function.

Now, in order to trouble shoot this problem, we need to know:

- what is the fuel pressure at the fuel rails. HOW TO TEST: get a fuel pressure gauge and attach it to the Schrader valve. KEY <ON> and KEY <OFF> Key off disables all power- safety. For your year, the OEM spec states: you should see ~50 psi. For more accuracy, perform this test with engine up to normal operating temperature. But, to just assess what is going on, cold will do.

- at time when KEY <OFF> is initiated. Pressure is NOT applied thus, the lines bleed off pressure by means of a pressure relief valve (depending on the conditions of the environment) Also, due to ambient temperature and cooling, it will drop to zero after a period of time and conversely, when it warms up again during the day the lines are cold, and as the fuel expands, it now reaches normal psi rating.

So, depending at which time of the day you measure it when <OFF> you may or may not witness fuel pressure. I would not use that method to verify pressure.

I use the KEY <ON> as well as fully operational mode. Run the truck and measure the ouput. These are the best methods to determine fuel pressure. The KEY <ON> is especially helpful for vehicles that do not START / RUN.

CM

 

Hi cmckenna,
Grate information about fuel pump.
Can you tell me name of some good quality of fuel pump.

 

Carter pumps and, OEM are both reliable. I prefer the Carter fitration method vs. OEM. Carter uses a filter that's reminiscent of an air filter, it being round and mounting flush to the bottom of the tank.

Someone on this forum had found a NEW OEM pump on eBay for a really good price. I do not remember WHO made the pump.

It may have been AC Delco or Delphi- I can't recall. I've gone through two pumps and, am on my third now. I'm running Carter at current.

Prior pumps that failed: OEM and Autozone supplied part. OEM lasted YEARS and, AZ Lasted one year before going out. Who made it, if it was REMAN, I don't know.

CM

 

http://www.rockauto.com/catalog/x,ca...,parttype,6256

 

Way cool. It has them all listed. Good show.

CM

 

there prices aint that bad either

 

Hello cmckenna,

Thank you so much for reply my question.

 

Your welcome.

Sincerely,

CM