Chris, you may consider running a 3/8" fuel hose from the tank to your prepump filter and fuel pump. I removed my pusher pump when I changed out all my fuel lines for 3/8" hoses. It seems to feeding my Walbro GSL392 without any problems. The Walbro really sucks! Pun intended. The combination on the pusher pump and Walbro drove my pressure ot over 100 psi, even with a stock FPR and homemade CCK mod.

 

Thanks Roland. I hadn't thought about the possibility of not enough restriction being a problem. I've got a 3/8" line from the tank to my pre-filter and then tie the 3/8 line into the factory hard line to run up toward the fuel pump. Then I use 3/8" line before and after the pump to couple the pump in and get rid of the factory "quick" connects. Barry has the same set up though and he's not having any problems.

 

You coming over today?

 

Chris I don't know if it will help you or not but someone on here came up with the idea to run a direct heavy gauge wire from the battery to the fuel pump though a relay controlled by the fuel pump hot wire. Cookie88 was eating alot of fuel pumps and when he changed the last one he wired in the relay and so far so good . I did the same when I changed mine last year. I believe the thinking behind it is problems caused by varying voltage and amps being hard on the pump.

 

I had a problem back when I had the factory pump, along with the pusher pump, not giving adequate fuel delivery. My fuel pressure drop was ~30 psi at WOT. That's when I switched to the Walbro and still kept the pusher pump, which was wired in with a separate relay with battery feed until I upgraded the lines. Funny thing is that same factory pump, that I removed from my truck, is on Franko72's truck and provides excellent pressures. I guess my truck is just thirsty!

 

Dave,
I know Scott had some problems with fuel pumps dying. I'm still thinking some of this is just a coincidence. The pump that died 6 months ago literally split the housing apart. I don't remember ever hearing of another failure like that. It still pumped fine, but dumped a whole lot of fuel on the ground.

Did Scott ever have an issue with too high of fuel pressure? Since he installed the carter lift pump to help cure his problem, I'm guessing he was more worried about a possible restriction from a pre-filter or starvation for some other reason.

I seem to have 2 issues. High fuel pressure and pumps that stop working. I'm really starting to think the two are related, but want to keep an open mind. After all, 92 psi isn't enough to split a fuel pump housing wide open.

And what is considered a heavy gauge wire? After my walk yesterday, I'm thinking 2/0 welding cable, but that might be a bit overkill.

 

Well here's the update for today. I have my suspicions of what the problem might be, but it's purely a guess and really want to hear input from everyone else. Here's what I did today with the help of Barry.

Drove over to Barry's house this morning since he has a shop with concrete floors and a heater. Fuel pressure settled in at 82 psi on the drive over. Removed FPR spring that was silver (stock) and replaced it with green spring that was about 1/8" longer. Cycled key to fill the bowl and lines and found the fuel pressure with the longer spring was 82 psi.

Thought, OK, I've got a problem with my return line so I pulled the return line off the FRX and stuck a hose on it so all the fuel coming out of the bowl now went through a short hose into a can instead of back into the tank. Cycled the key a few times and the fuel pressure read 82 psi.

Put the return line back together and pulled the supply line off the back of the fuel pump. Ran a short hose off the back of the fuel pump and stuck it in a can of diesel fuel so I was no longer pulling fuel from the tank. Cycled the key and found 82 psi. Starting to see a pattern here.

So put the fuel line back on the pump, removed the longer spring and cut it down about 1/8" or so shorter than the stock spring. Stuck it back in, cycled the key a few times and got 82 psi.

Took the stupid spring out of the FPR and put it back together just to see what kind of pressure I would have with NO spring and it started out at 55 psi and slowly worked it's way down to 46 psi as the gauge grew so dim I could no longer read the numbers. Looked at the volt meter and I was at 7.something volts because I never disconnected the glow plugs for all that key cycling. Anyway, it turns out I apparently would have enough fuel pressure to run the truck with no spring at all, and that the scanguage becomes worthless below 8 volts (get's dim below 9.something)

So it seems I've ruled out most things one at a time and it looks like I've gotten a bad FRX from Clay and it's causing all my problems. So I remove the FRX and stick on a brand new FPR stock housing that Barry had and my fuel pressure is...........82 psi.

So we pull the fuel bowl just because. Look everything over and clean everything up the best we can. Put the FRX back on so it can at least bleed the air from the fuel rails. Take apart the FPR rebuild kit parts to inspect the pieces and o-rings. Put it all back together, and now I have 85 psi.

Came home and can add the following comments. Fuel pressure now seems to bounce up and down more than it used to. Seems to hold in the 85 - 86 range, but will bounce up to 93 and down to 82 fairly often. Sometimes as high as 95.something and as low as 80. I inspected the old pieces from my FPR before the rebuild and the o-ring that holds the piece I referenced earlier in place is crushed flat (which is why it probably fell out). The new replacement did stop the original problem with the pump cycling on and off. I also noticed the old poppet seat washer is crushed flat while the current one has a tapered look to it like the one in Bob's picture. If you rotate that piece around, the tapered poppet seat isn't symmetrical. Parts of it are crushed a little, but not much and you really have to be looking to see it.

So that's where I'm at now. Thoughts?

 

Chris sorry you are having problems. Might want to call Bob or Clay. My thought was one of the check valves at the head may have a problem. What was your theory?

 

Chris,

trying to find the link, but I know I saw someone having high pressure issues when the center post in the fuel bowl was sticking.

I installed a fuel pressure gauge last summer, what i found interesting is that if I keep DK or other lubricant in the fuel, my pressure stays 61 - 63, if I skip a dosing on an empty tank, mine will bounce from 54 - 75, something is definitely sticking due to lack of lubricity.

A little rusty on my skills, work has been all consuming the last 5 or 6 months, but I am hoping that is about to change. Good luck, will be following this one.

 

Chris,
Your fuel pump must be putting out pressure/volume exceptionally well. That's sort of the problem I had with the Walbro. I removed the billet DI FPR housing from my fuel bowl, drilled and tapped the FPR housing to 1/4'' NPT, and plumbed in an adjustable FPR between the bowl and return line, then adjusted it to 62 psi. Problem solved. Ran it like that until I changed out all supply lines & fittings and still running the same 62 psi.

 

Something to do with my rebuild FPR. I'm going to find the pieces from the old one, clean them up and see if I can narrow this down any. I've done my best to only try one thing at a time so far. I'm running out of parts to eliminate.

Interesting. I would have thought if the center post had an issue, it would cause low pressure to the injectors, but the pressure in the fuel bowl would remain the same since that is supposed to be controlled by the FPR. Did he experience low pressure post filter and high pressure pre-filter? If you find the link I'd love to read it.

I did notice that my spring under the center post is slightly deformed, but as I said, I didn't think that could cause high pressure in the fuel bowl since excess fuel should still return to the tank.

The difference is the walbro is supposed to be an upgraded pump. These have been carter and airtex stock replacements.


Did you consider trying to cut down the spring to reach a lower pressure? I was surprised to see how little travel there is by the plunger for fuel to flow around. If I end up having to go through the trouble of an adjustable FPR, I'd probably just upgrade to a full regulated return kit that came with one.

 

Just take the complete fuel bowl out of your wives pink panther when she is not looking.

 

I have done abunch of searches, but I cant find it. I thought I book marked it on my old PC, will have to dig it out of the bone pile tomorrow.

The theory on it was that it was wide open and flowing more fuel than the return could handle, or stuck shut, forcing too much back, at least that is my vague rememberence of the post. Was one of the oddball posts I always try to save, 99.9% of what happens to our trucks, someone here has done ten times, this was one of those off the wall ones.

 

Chris, i feel ur pain, bro. I too, rock'n the first gen, and experienced the same thing, but not that high of a reading, but well into the 80's. I to, took apart the FRx / FPR, and wet-sanded the plunger..etc, re-installed everything, and bam, still sit'n at the 80-ish psi. So i removed everything, again, but this time, cut a coil off the original stock spring, installed everything back together, and WHAM, rock'n 65psi, all day long, 62-63psi, when get'n on it...

 

The problem is I'm running a 2nd gen now, and when I removed it and went back to a stock FPR it didn't change anything. I also cut down a spring and installed a longer one with no change.

I did find my old plunger from the original FPR and polished it up since it had a flatter o-ring and mic'd out just a hair smaller than the new plunger from the rebuild kit. If anything, that bumped the pressure up a couple of more pounds. Next time I get a chance I'll swap out the piece the plunger slides into. I just need to swap out the o-ring from that piece to the new one since the old one was so warn it would fall out of the bowl.

I know a place I can get a used fuel bowl for $50. Is that a good price? I think I've isolated each piece one by one and am down to the piece the plunger fits into and the stand pipe in the fuel bowl. What else am I missing?