Well the first thing i noticed when i started reading his thread was the fact that the inlet side of his oe pump was full of junk from the tank. Well i decided to clean out my fuel bowl last night and sure enough there was a bunch of sandy rusty looking grit at the bottom of the bowl . i am now 99% sure that my pump inlet has the same junk built up from the last 17 years. There is my fuel pressure problem and probably my horrible fuel mileage ive been trying to figure out for the last 2 years . I am really glad i installed the racor ps 120 now . i had no idea that much junk could get by the in tank filters before i deleted them. just one more reason im glad i did the hutch mod!

 

...with 5 rounds in the cylinders.


jstihl - Yeah... you can never go wrong with the Hutch mod, if done properly.

 

I feel a need to clarify something about fuel supply here, especially with all the junk that can be found in the screen at the inlet of the fuel pump. I use my truck for pulling an RV that weighs 13K.
At the beginning of this adventure, and at all times through it all, the fuel pressure measured at idle was always good, 60 psi. But the problem was as soon as I put a load on the engine, the fuel pressure would drop off pretty quickly to 25 psi or less. I Hutched the tank pickup. No help there. I eliminated all quick connects between the tank and the pump. No help there. At idle, 60 psi, all day long. Normal driving, light cruising on a straight, level roadway, 60 psi. But step on the accelerator, or try and pull a hill, the fuel pressure would dip way down and the truck would loose a bunch of power after about 5 seconds without recovery until I backed out of the throttle and tried again.
The problem was FUEL VOLUME.
That screen inside the inlet of the fuel pump was hopelessly blocked up with debris and the design simply had to be changed. That is the only reason I took the trouble to modify the fuel supply system like I did with the fuel pump immersed in the tank at the end of the fuel tank pickup. It solved all the fuel pressure/supply issues it had. The pulling power on a big hill is fantastic. Total vehicle weight is around 26k when we are loaded for vacation with everyone in the truck. I never have to shift down until about a 4% grade is encountered. Truck just muscles up, pulls the grade without a hint of power loss.
SO DON'T BE FOOLED BY GOOD FUEL PRESSURE AT IDLE.
The important number is what is the fuel pressure at full throttle, on a hill or pulling a heavy trailer.
Fuel VOLUME. Fuel VOLUME. FUEL VOLUME.

 

You moved the fuel pump to inside the tank? Why did you go that route instead of just doing the hutch mod and replacing the pump on the rail? Just curious.

 

It all boiled down to the laws of nature that convinced me to put the pump in the tank. It's way more efficient to push a fluid than to rely on a partial vacuum to deliver it to the inlet of the fuel pump.

 

WOW. Good to hear to hear from you, Dan. (A little OT)

 

kwik, think your idea is genius which I will definitely consider down the road but for right now I would need a quick fix. I have the same fuel pressure problems that you had, idles at 60 PSI but dumps down when you step on it. Being that you have a 550 I'm guessing that you have a metal aft rear axle tank like I have in my 450. I don't think that the thought came up to most people since everyone has plastic tanks, but Little bits of rust particles gets in the fuel and clogs the inlet screen on the pump. I was amazed at how much junk was in my fuel bowl, I'm surprised the pump still even works ! How much was the in tank fuel pump? Where the modifications that you had to do difficult? My only issue with that setup is you would probably need a pretty good filter on the in tank pump and would need to be cleaned every once in awhile which could be a pain compared to the racor and inline pump. Definitely a great idea, wish I had the time and resources to do it

 

Someone else had very similar problems about 6 months ago. After having his truck towed to a shop, a new Bosch fuel pump fixed the problem.

 

Totally makes sense. Thanks for explaining.

 

That is until the pump goes south ,then you are dropping the tank again. I vote for the hutch mod and put a filter just before the pump on the rail like some guys have done. I have done the hutch mod I get 60psi at idle and it only drops a few psi when I push down on the right pedal. my 2 cents.

 

Yes, and I completely agree. I just wondered. I had never heard if someone doing it that way on our trucks.

 

I have mixed thoughts on this one. I see the merits of it and it is not a bad idea. All three of my other vehicles have in tank pumps and I haven't had one of them fail on me yet. I do recall having some issue on my '94 Corolla but it wasn't the pump, it was the tubing on the sending unit. On that Corolla it was accessed under the rear seat, easy peasy. I don't see why they don't provide an access door in the floor of the bed that can be unscrewed so we could get that thing from above.

 

A lot of guys in the Jeeping community just cut a piece out of the rear "bed" to get to the pump. I dropped the tank because its gasoline, then cut a hole in the bed. I drilled 4 holes and welded threaded bungs under the 4 corners of the bed of the Jeep. I can now just bolt a larger plate down to the bed. Easy access down the line and no need to drop tank.

 

sounds like a new mod in the fte community

 

The pump that I ended up using was a Bosch 69430, available for about $120.00-130.00 on Ebay as of this writing. What I like about this particular pump is it lacks that inlet screen. And that is completely not an issue, since I took the pickup screen off of the fuel pickup and attached it to the inlet side of the fuel pump. These pumps use stainless steel rollers as part of the impellor so any sort of debris that might get through the screen will get "processed" by the rollers and sent forward to the fuel filter where it is filtered out. I've run this setup for more than five years now without a single incident save one. The power wire that I ran to the pump wasn't rugged enough and the fuel sloshing fatigued the electrical fitting on the pump to the point where it was cracked. Had to drop the tank and re-do that setup with a more secure, rugged electrical connector.
And dropping the tank on these trucks is a breeze!!
Drive up onto some blocks to raise the rear enough for you to be able to work underneath. Reach over the rear axle, disconnect sender and fuel lines. Disconnect fuel filler hoses. Rubber hose with screw clamps. Put a floor jack under the tank as close to the middle of the tank as possible. Loosen the tank straps and lower away. From there, you don't have to pull the tank out but if there's room go ahead. Tank sender is held down with eight nuts and the whole assembly comes out the top of the tank. Modify from there.....