The Diesel Stop banner

1 - 20 of 69 Posts

·
Registered
Joined
·
371 Posts
Discussion Starter #1
Short story::read:

2 weeks ago my issues started when post filter fuel pressure would drop to 0 under moderate acceleration.

I replaced the fuel filter on the roadside, with no improvement. Replaced the pump a couple days later.

Problem fixed for a few days and then gradually came back. Monday I dropped the tank and cleaned the pickup and in tank lines. A significant amount of algae-like debris were found on the pickup screen and in the in tank lines. Re-installed tank. But only minor improvement.

Tuesday morning dumped 3 bottles of CRC Bio-Con in tank.

Drove truck Wednesday, but could not maintain highway speeds without experiencing extreme pressure drops.

Today: Blew out all supply and return fuel lines between tank and bowl, not finding any significant debris. Changed filter again. Re checked Gauge wiring, cleaned fuel bowl. No improvement. in fact the situation is worse.
Now the pressure will not get any higher than 20 psi at idle.

Any Ideas? Please Help. I really need my truck back on the road, but dont want to throw any more money at it blindly.
 

·
Registered
Joined
·
371 Posts
Discussion Starter #2
Could it be the filter check valve? I can remove the internals of this without any problems right?

Maybe the FPR?
Bad replacement fuel pump?
 

·
Registered
Joined
·
946 Posts
Have you pulled and cleaned the little screens that are on the fuel-lines to head entry valves? Some people refer to them as check valves. They're on each head where the fuel lines connect from the factory motor mounted fuel filter.
 

·
Registered
Joined
·
946 Posts
Could it be the filter check valve? I can remove the internals of this without any problems right?
Yep, many people just gut them out....just don't ever forget to install a fuel filter in the fuel bowl.
 

·
Registered
Joined
·
371 Posts
Discussion Starter #5
Have you pulled and cleaned the little screens that are on the fuel-lines to head entry valves? Some people refer to them as check valves. They're on each head where the fuel lines connect from the factory motor mounted fuel filter.
No, but my pressure sender is on the bowl. Wouldn't that isolate the problem to pre-bowl fuel system?

I will check these out though.
 

·
Registered
Joined
·
371 Posts
Discussion Starter #6
didnt know there were more screens inside the mixer. Just found that out.
I guess Ill be dropping the tank again to clean these.
 

·
Registered
Joined
·
371 Posts

·
Registered
Joined
·
38 Posts
Did you check the FPR. If the spring is weak or the poppet seal is broken it will not allow pressure to build.
 

·
Registered
Joined
·
370 Posts
Yea I got the same prepump kit setting in my workshop to put on my truck , was going to install today, but it was raining all day. I'm lucky I can use my son in law's lift and transmission jack at his auto repair shop.
 

·
Registered
Joined
·
371 Posts
Discussion Starter #11
I got the screens out of the in tank mixing chamber. I will post some pics later. They were plugged up solid. I stuck the hose from my parts washer into the open end of one of them, hoping to flush them out, but nothing would go thru them. I used a 1/2" round brush to clean them out, and got them spotless.
Put it all back together except for the skid plate ( I'm leaving that off until this is fixed for good) I can drive the truck now, but still get pressure drops down to 40 psi during moderate acceleration. Once I reach highway speeds, the pressure quickly climbs to 70 and I can cruise with no problems, but I cannot hold the throttle at 80% for more than a couple seconds without loosing all fuel pressure.

What else could it be? Did I cook the new pump over the 1 week period I drove it with a clogged in-tank filter? Is it possible I am sucking that much air into the system due to the factory setup? I will order the "hutch mod", but I am not convinced it will fix the problem. I cant think of anything else that would be causing a restriction. I have examined the FPR, and everything seems ok with it, but maybe a rebuild is in order.
 

·
Registered
Joined
·
371 Posts
Discussion Starter #12
Any thoughts?
 

·
Premium Member
Joined
·
14,748 Posts
There is a small screen in the inlet of the fuel pump. You think enough junk got past the screens to plug that?


Sent from AutoGuide.com App
 

·
Registered
Joined
·
371 Posts
Discussion Starter #14 (Edited)




Here are the pics of my basket filters from inside the mixing chamber.

I did not know about the screen inside the pump, but I guess its possible some of this stuff got to it. Is it serviceable?

I found an old post on this forum where someone recommended placing a steel ball behind the fpr spring to put more pressure on the poppet seal. I will try this tomorrow to see if the frp is the problem. I did notice when I removed the return line from the fpr, there was a small amount of leak-by, but I thought this was coming form the small hole in the center of the poppet.
 

·
Super Moderator
Joined
·
25,495 Posts
Man, those are some slimey filters. You probably should add some biocide to your tank. Bugs growing in the fuel can do that.

The "bb" mod has been used, but it'll usually run your fuel pressure up high enough to shorten the life of the fuel pump. When I had a stock pressure regulator, I found that a 4-40 cheese head screw with a head that measured 0.060 inch thickness gave me 65 psi. The shank of the screw fit into the spring perfectly.

There's a brass plunger with an o-ring type seat on it, and if the seat is damaged, it won't operate correctly. The plunger also has a tiny bleed-down hole in it as well. Ford sells an FPR repair kit.

There's a check valve inside the fuel pump, so you can't backflush it. There is a coarse screen inside the pump like RT said and it may be slimed also. Running biocide thru it may help clean it out.
 

·
Registered
Joined
·
3,500 Posts
You may need to do this a few times if you rule system is tht bad.

Get some:
90119 FPPF 90119 KILLEM BIOCIDE 16 OZ. BOTTLE, TREATS 1920 GALLONS OF DIESEL FUEL PER BOTTLE - Fuel Additive Online

And also get the prepump kit so you can stop dropping your tank. The next time you drop it, clean it as well as you can.

Keep an eye on the pump inlet screen - it is pretty course, but that slime builds up..

Also, I would replace the FPR internals as the plunger can wear -goto diesel orings - $60 kit.

You have good pressure, but it is just when you start to draw more fuel, the excess is still bleeding by the FPR it sounds like. New spring and plunger may help here.

How nasty was the fuel bowl?

Curious, what is your gauge set up - electronic?
 

·
Registered
Joined
·
371 Posts
Discussion Starter #17
Thanks, I ordered some Power Services Bio Kleen a week ago. It should be here today. I didnt think this stuff could grow in wmo, but Maybe it was around before I started running wmo. I will not use the bb fix for more than a diagnostic. I just dont want to order the fpr rebuild if I dont need it.
 

·
Registered
Joined
·
371 Posts
Discussion Starter #18 (Edited)
I found a machine screw that fit inside the fpr spring, and tried the "BB" trick. It was effective in that it increased my pressure to 85-90 psi, but I still get drops down to 20 psi or lower when accelerating to highway speeds.

I have ordered another pump ($40) and I'm sending this Bosch one back if that fixes the problem.

My fuel Bowl had some very minor sediment in the bottom of it, but its clean now. I also cleaned the tank the first time I dropped it. I will use the BIO KLEEN as soon as I get it, but there seems to be a mix-up with the shipping. My tracking number says it was delivered to another state 3 months before I ordered it.:lol:

Thanks for all the help, and I will keep posting the progress until I get this fixed.
I'm curious though, Do most guys still run stock pumps with stage ones and tunes? Should I be considering a high performance pump setup? I don't ever plan on going to bigger injectors, but I was just wondering if my setup needs more fuel that the stock setup is capable of.
PS: the gauge is electronic, but the pressure readings coincide with the sound of the pump, performance of the truck, and I have triple checked all the wiring. I trust the gauge.
 

·
Registered
Joined
·
3,500 Posts
The stock pump should be ok - sounds like you have another issue still going on - get your idle pressure back to 65-70psi and see how the new pump does now that the lines are cleared.
 

·
Registered
Joined
·
371 Posts
Discussion Starter #20
Got the BIO KLEEN last night. Did the shock treatment, and installed the second sender for my fuel pressure gauge. Now I can read pre and post filter pressures by flipping a switch. I also removed the screw to put the fpr back to normal. Everything is still the same. Fuel pressure is still pretty inconsistent at idle, and I can still hit 0 PSI when I get on it.

The difference between the pre and post filter sender is 10-14 PSI. seems normal I guess. Ive got a new pump on the way and Im going to go ahaed and order the FPR rebuild. I will probably order the crossover kit at the same time.
 
1 - 20 of 69 Posts
Top