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FiTech Frustration! Fuel pressure takes a dive once hot

MultiBeast

Jr. Member
Joined
Sep 19, 2018
Messages
103
Loc.
NC
So that’s just it. I’m still getting this thing dialed in. Have yet to do any real driving with it, just cruising around my neighborhood. Everything has been running great since I figured out a noise issue coming from my Msd a couple weeks ago. I’ve been tying up loose ends, flushed radiator/heater, fixing door latches, etc. I had it idling in my driveway on Friday at operating temp and all of a sudden it almost died, like it was running out of gas. Then it came back for a minute and did it again. I pulled it out and could cruise with it just above idle, but it would fall on its face with the slightest pressure on the pedal. I parked it and came back to it the next day. Fired up and ran completely fine until it got up to ~200 degrees and the same thing happened. Isles fine but fuel pressure plummets as you hit throttle. So pissed as I thought I about had this thing sealed up. I have found this:
https://www.fitechefituning.com/fitech-efi-tuning-forum-2/topic/no-fuel-pressure-when-engine-hot/

Which says to check filters. I’ll do that tomorrow, but this thing has only had about 15 gallons through it.

I’m not pulling my hair out yet...
 

1sicbronconut

Contributor
Bronco Guru
Joined
Dec 26, 2006
Messages
2,420
Are you using the command center? I've heard bad things about the early versions of those.
 

75Bronc

Sr. Member
Joined
Feb 5, 2008
Messages
425
Do you know what your pressure is at the throttle body? I put an inline gauge right there. Any issue you are having the techs will question fuel pressure. Best to have a gauge there to keep them from telling you that is your issue if it might not be.

I had a similar problem, turned out I didn’t have a full 12v to my coil with the engine running.
 
OP
OP
M

MultiBeast

Jr. Member
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Sep 19, 2018
Messages
103
Loc.
NC
No command center. Using fitech pump. I will check coil voltage this afternoon but battery voltage stays at 13.8-14.
 

surfer-b

Contributor
Bronco Guru
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Sep 7, 2006
Messages
2,971
If the pressure is dropping when you hit the throttle, and you know the pump is good, I would look at the fuel pressure regulator
 
OP
OP
M

MultiBeast

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Joined
Sep 19, 2018
Messages
103
Loc.
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And I put an in line pressure gauge just before fitech and pressure drops down to 15-20psi after it heats up and when you hit throttle.
 

surfer-b

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IT is either the pressure regulator or the pump, is the pump you have a frame mount or in-tank
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,821
Have a return line off the throttle body? If so get it to the problem state, rev it up until the pressure drops, needle nose vice grips on the return line. Pressure stays low, supply issue. Pressure spikes, regulator issue.

What condition is the fuel tank in? Do you have the stock filter sock on the in tank pickup?
What is your complete fuel supply system made of?
 

surfer-b

Contributor
Bronco Guru
Joined
Sep 7, 2006
Messages
2,971
Have a return line off the throttle body? If so get it to the problem state, rev it up until the pressure drops, needle nose vice grips on the return line. Pressure stays low, supply issue. Pressure spikes, regulator issue.

yes, exactly, I should have mentioned this but didn't think about it, good call
 

Mikesimp70

Full Member
Joined
Jun 20, 2017
Messages
341
IT is either the pressure regulator or the pump, is the pump you have a frame mount or in-tank


Pressure regulator is built into Fitech. Should have full vacuum hooked to it on the passenger side of the TB. Needs >58psi from the pump. What is the PSI at idle before giving it gas?
 

surfer-b

Contributor
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Sep 7, 2006
Messages
2,971
Pressure regulator is built into Fitech. Should have full vacuum hooked to it on the passenger side of the TB. Needs >58psi from the pump. What is the PSI at idle before giving it gas?

yeah I had one go bad on me, FITech sent me a new one
 

75Bronc

Sr. Member
Joined
Feb 5, 2008
Messages
425
I think Fuel Pressure is regulated at 43.5 psi with FiTech. Just FYI.
 

markw

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Sep 10, 2009
Messages
2,047
AARG! This seems to be a recurring theme. we're fighting the same issues. Following.....
 
OP
OP
M

MultiBeast

Jr. Member
Joined
Sep 19, 2018
Messages
103
Loc.
NC
So I am using a stock tank. Clean tank. I have a stock sending unit in there with no pickup, use it just for fuel gauge. Modified tank with an fittings and made pickup out of larger tubing. IMG_20180814_125010030.jpg
I have the fitech pump on frame rail. I will check pressures after work today. Keep in mind it has run fine for two weeks, hot/cold whatever. This just randomly started.

Not sure how to post images. Need to read up on that

Oh no markw, what’s yours doing exactly?
 
OP
OP
M

MultiBeast

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Joined
Sep 19, 2018
Messages
103
Loc.
NC
Complete fuel system is 5/8” tubing bent in same shape as stock pickup welded to an 8an fitting coming out of bottom of front of tank, under stock assembly. 8an line to filter, filter directly into fitech pump on rail, then 6an braided up to smaller filter, then 6an to throttle body. Then 6an on return all the way back to 6an fitting welded on front part of tank
 

markw

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Sep 10, 2009
Messages
2,047
We had problems holding fuel pressure. Replaced the in tank with a Fitech pump and put in a fuel pressure gauge near the throttle body. Still having a lot of problems running lean and backfiring when RPMs get over 3000. Then the handheld seemed to fail. We have a loaner but that's where we stand today. Still and frustrated. I wish there was an authorized rep we could take the thing to and just let them fix it. At this point $ is less concern than time.
 
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OP
M

MultiBeast

Jr. Member
Joined
Sep 19, 2018
Messages
103
Loc.
NC
So I just talked to fitech. He says that their pump cannot suck up even the slightest of an incline. Of course being frame mounted it’s about 5” above pickup. He says that pump cavitated and damaged... user error right, ;)
Like I said in the OP, it runs like a champ until it gets hot, but the fuel pump is regular temperature (can hold hand on it no problem). Fuel pressure is right at 60 then drops to 0-10 when you give it throttle.
So I’m hoping that’s all it is. But I need a new pump to even test it.
Questions:
- what in-line pumps are you guys using?
- how are you mounting them?
- are they sucking “uphill” at all?
Thanks fellas!
 
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