Dieselhed

I posted this in the Help section yesterday with little response so I'll try here. It's kind of long winded but gives all of the details.

I've got a Walbro fuel pump with an inline regulator in the return line set at 29 psi. I run a 12 mic strainer between the pump and fuel tank leading to the stock canister with the 5 mic Baldwin then to a 2 mic Cat then to a Floor It Diesel stage 2 CP3. I use Stanadyne PF at every fill up and truck has close to 92,000 on the clock and shows no codes from the symptoms I am about to describe.

A little history over the last 3-4 months. I have a DiPricol mechanical fuel pressure gauge in the cab. About 4 months ago I started the truck to go somewhere and noticed the pressure only topped out at 22 psi. First thought, filters caught something and are plugged. Changed all 3 filters about a week later and on initial start up the gauge returned to 29 psi. Problem solved, so I thought. On second start up pressure reads around 20 psi. Now I'm thinking fuel pump is failing. I drive the truck in this condition seeing different pressures every time I start it ranging from 11-22 psi. I carry a spare Walbro in the truck waiting for it to crap out as these things are pretty easy to change out on the side of the road. Two weeks ago I pulled into work after my 28 mile drive to get there and as I'm letting the egt's cool down the idle starts to stumble like it's running out of fuel. 8 hrs. later drive it home, runs good no problems. Since it's cold outside I decide to go ahead and install the new pump in my warm garage. I did not replace the filters. Start the truck, pressure rises to 29 psi. Once again problem solved, so I thought. Left for work the next morning pressure rises to around 18 psi. Same small stumble at work as I let er cool down. Leave work only getting 11 psi on the gauge. Get home return Smarty to stock. Runs good for 3 days, no stumble or anything. Yesterday on the way to work, leaving a stop light 1/2 block from work I get a little stumble when taking off. Pull into work parking lot truck just dies and lucky me I coast into an open parking spot.

Rail pressure has been reading between 6,500 and 7,000 at start up and anywhere between 5-6,500 right before I shut it down. I have heard it usually drops a hair when it's cold out. My next move when I get the truck towed home tomorrow is to replace all of the filters and the fuel line and fittings. Maybe something is lodged in there? My pressure gauge is attached via steel braided line right before the CP3. Any thoughts would be appreciated.

Now for my question. Could this possibly be from a plugged draw straw? When I ordered the Walbro kit Richard told me the '04.5 had a good pick up tube and there was no need to replace it. I've had this system in place for almost 3 1/2 years with no problems. I am just at a loss as where to start. No codes doesn't help either. I've thought about just buying a whole new Raptor fuel system and lines and fittings but that is probably just a waste of money seeing as I believe the pumps are good. Maybe something is clogging the stock canister? How much fuel pressure does the CP3 need to run?

CamperAndy

Have you verified the return regulator is not sticking?

Dieselhed

I should have the truck home sometime today and this is where I was going to start. I called Richard Martin at Glacier Diesel a couple of weeks ago as this is what I thought was the culprit. He said he's never seen one go bad. When you think about it, would that make the fuel pressure drop so much the truck actually dies? I've heard the cp3 can actually pull fuel from the tank itself. But that is a long way and alot of filters to pull it through. I've got the tuning kit from GDP which is actually just different shims. I'm gonna put the 22 psi shim in and see what happens. If that's not it, I thought about bypassing the stock canister to see what happens.

AH64ID

I would change your filters before you assume anything else. One bad batch of fuel can kill brand new filters.

Once the filters are replaced then start at other things.

29psi does seem a bit high for the stock canister, they are only good to 30 psi, but that would manifest in a leak.. so just throwing that out there as additional information.

Dieselhed

Changed filters as well as the pump. Initial start up after changing both had me back to 29 psi and assuming it was fixed. The next start up it was topping out anywhere from 11-22. I've been reading some older posts and it looks like it may be the regulator in the return line. Someone also stated that they had problems when they switched to the locking fuel cap. I just did that last year. I've still got the original, I'm gonna try that too. Like I said, reaching at straws here.

AlCorr

I'm not sure if this is correct but, I was told pushing more than 25 psi into a cp3 would damage it over time.

Dieselhed

The problems not the CP3. The builder recommended 29 psi to it.

It's not the regulator in the return line either. Changed springs and same thing, around 2-4 psi. Thinking something is in the tank restricting flow. Sludge of some kind perhaps. The truck does have 92,000 miles on it. Sucks to have to drop the tank as it's 3/4 full.

CamperAndy

If it was the pick up tube then it would not change with each start the you describe and it would get much worse when you got hard on the go pedal.

Try back blowing from the pump to the tank on the pick up line to see if that clears the suction strainer if you think that is the issue. That or pull the bed off (easier then dropping a full tank) so you can pull the pick up tube out for an inspection.

BigIron70

If you are using the stock module in tank it has a small screen that always gets plugged up. I change many of these fuel module's and they are always plugged up. Do yourself a favor and drop the tank you will be surprized how much crudd is on that little filter screen. Check the vents on top of the tank also they always get plugged up with dirt. Put a hose on the vents to prevent water from getting into your tank also. Chrysler came out with a recall for that but didn't include every model year even though they have same tank.

Dieselhed

Thanks for the reply's. I think before dropping the tank I'm going to change the filters and undo the line right before the 12 mic strainer and drop the line in a bowl of clean diesel. I'll start the truck and see if the fuel pressure doesn't raise to where it should be. I also think I'm gonna get rid of the isolator on the fuel pressure gauge and run it straight to the cab.

If I do have to drop the tank and it's 3/4 full. What do you guys think about siphoning the fuel out of the filler hole? I've got 5 empty fuel cans from back when I raced dirt bikes I haven't used in years. I would lift the bed but I've got a Leer 100XQ shell on the truck and that thing is several hundred pounds if not more. It's a dually as well. What do ya think? Any tips I should know to dropping the tank a well?

truckbouy2

Try disconnecting the line feeding the fuel cannister, extended it to a bucket, or extend it to the fuel filler, and run that walbro and monitor the flow. Keep running it until you get that pump heated up good and hot and see if the flow changes....
Drive the truck as usual, if or when things begin to shut down, stop, shut the engine down and quickly open the fuel cap and listen for air movement. If venting is not an issue there won't be any pressurization or de-pressurization.