99 Explorer EFI fuel pressure question

[rjrobin2002]

Why are you guys running the external regulator. I went with the stock pump assembly and let it handle the return and regulation. “Returnless” has a damper on the fuel rail not a regulator. Works well and the install is really clean.

Hindsight I would have. I had done several efi conversions with the return style efi with the external pump. So started building it similar.

Then I did this returnless style for the first time without realizing I still needed a return, LOL.

 

[Broncobowsher]

I'm looking at those fuel pressure numbers, and the drop in pressure as fuel use increases. I am seeing that as a fuel pump that can't keep up. Could be filter that has a stuck open bypass, but pinching off the return line will answer that question real fast.

 

[Rox Crusher]

I just installed the Tanks Inc sender in my BC tank and from what I am hearing it's quite accurate for fuel reading. Fingers crossed.
Also just missed out on an SS Kincer fuel tank for a good price. Damn those things are like works of art!

I didn’t know Kincer made a tank. I’ve been eyeballing the one from Duff’s / Lick Creek.

 

[fordguy]

The tanks sender mentioned is sold by length (1 inch increments) and ohms ( stock bronco gauge ohms available).

 

[Rox Crusher]

I'm looking at those fuel pressure numbers, and the drop in pressure as fuel use increases. I am seeing that as a fuel pump that can't keep up. Could be filter that has a stuck open bypass, but pinching off the return line will answer that question real fast.

Most of The times I had the pressure drop low enough to quit running were when it was super hot out (105 - 110F) and I was doing 75 - 80 mph. You could see the pressure drop as you increase throttle. You could also get the fuel pressure to creep back up by staying off the skinny pedal.

So I also thought the pump (I’m using the aeromotive stealth) was bad. Replaced it with a different pump which was annoyingly loud….problem remained. Replaced it with another new aeromotive and problem remains but not quite as bad. My current situation is that it will start and hold anywhere between 59 - 62psi but slowly drop while driving to as low as 50 psi But keeps running without issue.

I’ve even thought about replacing the power supply wire to the pump thinking it needs to be upsized.

 

[rjrobin2002]

I'm looking at those fuel pressure numbers, and the drop in pressure as fuel use increases. I am seeing that as a fuel pump that can't keep up. Could be filter that has a stuck open bypass, but pinching off the return line will answer that question real fast.

Good idea on pinching the return. I'll do that and check back.

 

[rjrobin2002]

Nothing, just building up my karma bank

I'll send you my address.

 

[rjrobin2002]

Most of The times I had the pressure drop low enough to quit running were when it was super hot out (105 - 110F) and I was doing 75 - 80 mph. You could see the pressure drop as you increase throttle. You could also get the fuel pressure to creep back up by staying off the skinny pedal.

So I also thought the pump, I’m using the aeromotive stealth, was bad. Replaced it with a different pump which was annoyingly loud….problem remained. Replaced it with another new aeromotive and problem remains but not quite as bad. My current situation is that it will start and hold anywhere between 59 - 62psi but slowly drop while driving to as low as 50 psi But keeps running without issue.

I’ve even thought about replacing the power supply wire to the pump thinking it needs to be upsized.

I'm running the same e2000 pump externally mounted like I have done on 4 previous efi swaps.

 

[bigmuddy]

The tanks sender mentioned is sold by length (1 inch increments) and ohms ( stock bronco gauge ohms available).

Yes thats correct, so measure the tank and subtract and 1"or 2 and order accordingly. I run an aftermarket gauge but it was ordered with the stock ohm measurment.

 

[rjrobin2002]

I'm looking at those fuel pressure numbers, and the drop in pressure as fuel use increases. I am seeing that as a fuel pump that can't keep up. Could be filter that has a stuck open bypass, but pinching off the return line will answer that question real fast.

So when you read fuel pressure regulator instructions. It says it needs to mount as close as possible to the fuel rail, mines mounted on the frame under the drivers seat.

How does the factory explorers regulator being in the tank 15foot away not cause issues?

 

[rjrobin2002]

Well, I pinched the return and cycled the key on and pressure shot up to 90spi.
i then started it in the shop when I got home and it was idling and revving fine at 50psi. No drops in pressure with rpm.

Then went for a drive and it started cutting out at cruising speed and with acceleration.

Drove home and put my guage on it and it read 50psi at idle, but when I revved it up after the drive the pressure would drop as low as 15psi and it would start to die.

I'm putting a new fuel pump on as plan A.

 

[bigmuddy]

I didn’t know Kincer made a tank. I’ve been eyeballing the one from Duff’s / Lick Creek.

304 stainless ISSpro sending unit with skid plate. around $1600. I believe Tanks Inc makes the ISSpro sending units, or I have that backwards?
https://krawlersedge.com/stainless-steel-23-gal-early-bronco-fuel-tank/

 

[Oldtimer]

Could debris in tank be blocking pickup screen at higher glow rates?

 

[rjrobin2002]

Could debris in tank be blocking pickup screen at higher glow rates?

Its all new.

 

[Broncobowsher]

Well, I pinched the return and cycled the key on and pressure shot up to 90spi.
i then started it in the shop when I got home and it was idling and revving fine at 50psi. No drops in pressure with rpm.

Then went for a drive and it started cutting out at cruising speed and with acceleration.

Drove home and put my guage on it and it read 50psi at idle, but when I revved it up after the drive the pressure would drop as low as 15psi and it would start to die.

I'm putting a new fuel pump on as plan A.

When you get tot he point where you are loosing fuel pressure, especially that 15PSI episode. That is when you pinch off the return line.
If you can't build pressure with a pinched return, I'm looking at supply side.
If it suddenly jumps to 90, the regulator is just dumping fuel for some odd reason.

So far I have not seen enough diagnosis to throw parts at this.

If it is supply side, sounds like external high pressure pump, how is the heat? Any chance you are vapor locking the pump? Usually they will change pitch when they are not pumping liquid.

 

[rjrobin2002]

When you get tot he point where you are loosing fuel pressure, especially that 15PSI episode. That is when you pinch off the return line.
If you can't build pressure with a pinched return, I'm looking at supply side.
If it suddenly jumps to 90, the regulator is just dumping fuel for some odd reason.

So far I have not seen enough diagnosis to throw parts at this.

If it is supply side, sounds like external high pressure pump, how is the heat? Any chance you are vapor locking the pump? Usually they will change pitch when they are not pumping liquid.

The pump is not as quiet as it once was and I heard it make some wierd noise a few times when I switched the key to on and it does the 1 second prime.
Non of the fuel line is close to any exhaust.
Fuel pressure seems to go to shit with a 5 minute drive, making me think the pump is getting weaker once warmed up.

I may of damaged it when I plumbed the system wrong originally and didn't have a return after the pump when I first tried to run it. No telling what pressure it was creating with no return.

 

[Rox Crusher]

So when you read fuel pressure regulator instructions. It says it needs to mount as close as possible to the fuel rail, mines mounted on the frame under the drivers seat.

How does the factory explorers regulator being in the tank 15foot away not cause issues?

I'm curious about this as well.

Also, I've never fully understood what the dampner on the "returnless" rail does. If the Explorer's OEM configuration has the regulator and bypass function in the tank, and providing a constant fuel pressure to the rail, what is the dampner for? Maybe it somehow compensates for variations with the injectors. Just spit ballin'.

 

[Rox Crusher]

If it suddenly jumps to 90, the regulator is just dumping fuel for some odd reason.

I keep thinking this is my issue. The FPR is somehow returning more fuel than it should. Also, in my circumstances, it isn't holding pressure at all when turned off.

 

[Broncobowsher]

that's why to pinch the return when it is acting up

 

[toddz69]

I didn’t know Kincer made a tank. I’ve been eyeballing the one from Duff’s / Lick Creek.

The Kincer tank is a beautiful piece but hangs down too far imo. The bottom is 10" below the bottom of the frame rail per email convos with them a few years ago. That's 4" lower than my WH tank (and prob the Duff/LC tank). Not a problem if you're just street cruising but for a guy like me that 'wheels and doesn't have a lot of lift, I'd be hitting it on a lot of rocks, etc.

Todd Z.