Fuel Pressure Regulator Problems?

[camREEtrDEE]

Hello all! So I have a 1993 Ford Explorer XLT, and I just replaced the fuel injectors. They were all gummed up and some of the nozzles were cracked. After getting them to line up (which was a pain) and seat into the manifold, I replaced the fuel plenum gasket, and upper intake manifold gasket, and I put everything back together. After triple checking the vacuum lines and torque on the manifold bolts, I fired her up. Much to my dismay it runs even WORSE than before. E.I it barely runs. It will smoothen out for about 30 seconds then go back to almost dying, and cycle back and forth. Giving it a small rev helps for a bit. Now I know the injectors are plugged in correctly, and they are all brand new injectors from RockAuto that have been tested thoroughly.

However when I was replacing the injectors, I took the vacuum line off the FPR, I noticed fuel leaking from it, as well as the fitting on the regulator being wet with fuel. From what I understand, this drains back into the engine to be burnt, at the cost of running rich.

TLDR; Would replacing the fuel injectors make an already failing FPR worse? Maybe due to increased demand?

 

[Turdle]

A fuel pressure gauge will tell for sure..

Cheap air gauge will get ya there, engine running .


First though. Fix the common mistake we all make when working on the sweet ol v6

Double check, then, triple check the firing order on the driver side of engine. I bet you have 2 spark plug wires cross connected

 

[camREEtrDEE]

A fuel pressure gauge will tell for sure..

Cheap air gauge will get ya there, engine running .


First though. Fix the common mistake we all make when working on the sweet ol v6

Double check, then, triple check the firing order on the driver side of engine. I bet you have 2 spark plug wires cross connected

I didn’t remove anything with the ignition system though. Maybe that was my mistake and it caused me to unknowingly pull on a plug wire too hard. In any case, the regulator diaphragm is leaking so it needs to be replaced anyways. I was just scratching my head as to why replacing the injectors seemed to aggravate the issue. It was drivable before. Now it’s definitely not. I had the fuel filter show up today since I planned on replacing it too.

 

[wollimann]

the regulator diaphragm is leaking so it needs to be replaced anyways.

If the FPR looks like this, i would change it.

 

[camREEtrDEE]

If the FPR looks like this, i would change it.
View attachment 466495

It is actually all dirty, and most likely the original. It only has 83k miles on it, but from what I understand there aren’t many of these first gen’s on the road with original regulators, reguardless of mileage. I’ll get a picture up soon. Just gotta wait till that next paycheck hits to replace it lol.

P.S. Those zip ties are holding the vacuum line on the FPR. It’s so slippery with fuel it wont stay on.

 

[410Fortune]

Any fuel on the vacuum side of the regulator means the vacuum regulator is bad

There should never be fuel in the vacuum line

You need to test fuel pressure if it acts up after replacing the fuel pressure regulator

The only way fuel gets to the vacuum side is if the diaphragm rips

 

[camREEtrDEE]

Any fuel on the vacuum side of the regulator means the vacuum regulator is bad

There should never be fuel in the vacuum line

You need to test fuel pressure if it acts up after replacing the fuel pressure regulator

The only way fuel gets to the vacuum side is if the diaphragm rips

On the list. lol. I have the lower manifold off right now since I have a coolant leak at the front drivers side, leaking down the block over the fitting for the oil pressure sensor and onto the ground. I could not for the life of me figure out where it was coming from. Sure enough, I take the lower manifold off and gasket around the front drivers side water jacket is split/cracked. I’m hoping thats the problem and not a head gasket lol.

 

[410Fortune]

Lower intake gaskets are known for this
Have a good look at your freeze plugs too they can leak water in that location

Sound Like you found it! I say it all the time, there is not a out 4.0
Put there that does not need intake gaskets they simply do not last 25+ years, especially not with ethenol fuel

 

[camREEtrDEE]

Well. After replacing the lower manifold gasket, and fuel pressure regulator and getting everything back together, it runs just as poorly as before. My coolant leak has also migrated from the front of the engine to the back so I may have to re-torque or do a better job of applying sealant around the rear water jackets. I’m short so it’s hard to reach lol.

So I think I’m going to pull the new injectors out and put the old ones back in. It was running much better before the new injectors were installed so I’m curious if I just bought bad injectors. It’s about the only thing left to do. So far so have:

Made sure all injectors are seated properly upper and lower.
Triple-checked all vacuum lines are connected.
Triple-checked the order of the spark plug wires.
Took the new ignition coil off and put the old one back on
Ensured the injectors are plugged in properly
Found and replaced the old leaking fuel pressure regulator.
Replaced the thermostat while I had the lower manifold off anyways.

 

[Nicky Chrisman]

Hello all! So I have a 1993 Ford Explorer XLT, and I just replaced the fuel injectors. They were all gummed up and some of the nozzles were cracked. After getting them to line up (which was a pain) and seat into the manifold, I replaced the fuel plenum gasket, and upper intake manifold gasket, and I put everything back together. After triple checking the vacuum lines and torque on the manifold bolts, I fired her up. Much to my dismay it runs even WORSE than before. E.I it barely runs. It will smoothen out for about 30 seconds then go back to almost dying, and cycle back and forth. Giving it a small rev helps for a bit. Now I know the injectors are plugged in correctly, and they are all brand new injectors from RockAuto that have been tested thoroughly.

However when I was replacing the injectors, I took the vacuum line off the FPR, I noticed fuel leaking from it, as well as the fitting on the regulator being wet with fuel. From what I understand, this drains back into the engine to be burnt, at the cost of running rich.

TLDR; Would replacing the fuel injectors make an already failing FPR worse? Maybe due to increased demand?

Well. After replacing the lower manifold gasket, and fuel pressure regulator and getting everything back together, it runs just as poorly as before. My coolant leak has also migrated from the front of the engine to the back so I may have to re-torque or do a better job of applying sealant around the rear water jackets. I’m short so it’s hard to reach lol.

So I think I’m going to pull the new injectors out and put the old ones back in. It was running much better before the new injectors were installed so I’m curious if I just bought bad injectors. It’s about the only thing left to do. So far so have:

Made sure all injectors are seated properly upper and lower.
Triple-checked all vacuum lines are connected.
Triple-checked the order of the spark plug wires.
Took the new ignition coil off and put the old one back on
Ensured the injectors are plugged in properly
Found and replaced the old leaking fuel pressure regulator.
Replaced the thermostat while I had the lower manifold off anyways.

Did you check or replace the fuel pressure regulator and possibly the fuel pump?

 

[410Fortune]

He changed the fuel pressure regulator

You should check your fuel pressure

You can also bench test / clean each injector before installation,
No need to buy new ones if yours are still testing good

I am also short (5’-10), so I have a topside creeper in my shop it allows me to work on the back of engines even on lifted diesel trucks.. $200 Amazon

You really need to: check your fuel pressure
Make sure the lower intake it torqued properly and in proper sequence, you must have clean surfaces for gaskets and use rtv in proper locations and proper amounts

I would suggest you stop buying new parts until you know that the issue is. To do this we have to rule things out
Fuel psi can be tested
Fuel injectors can be bench tested
Spark can be tested

 

[camREEtrDEE]

Did you check or replace the fuel pressure regulator and possibly the fuel pump?

I replaced the fuel pressure regulator yes. And the fuel filter with a Motorcraft one. I haven’t replaced the fuel pump, but I will add that the truck was running mostly fine before I replaced the injectors. I replaced them because I was having the issue of rough start and idle after warm starts. I replaced the injectors cause I thought that was the issue, but I found out after disassembly this was caused by the leaking FPR. After shutting the truck off, the remaining fuel pressure in the system would slowly leak out the vacuum line into the manifold and drip down into the cylinders. All the fuel in the rail would leak out in about three hours and there would be no pressure held in the system. I still have the old injectors and they work fine so my after-work project is to put them back in.

 

[camREEtrDEE]

I replaced the fuel pressure regulator yes. And the fuel filter with a Motorcraft one. I haven’t replaced the fuel pump, but I will add that the truck was running mostly fine before I replaced the injectors. I replaced them because I was having the issue of rough start and idle after warm starts. I replaced the injectors cause I thought that was the issue, but I found out after disassembly this was caused by the leaking FPR. After shutting the truck off, the remaining fuel pressure in the system would slowly leak out the vacuum line into the manifold and drip down into the cylinders. I still have the old injectors and they work fine so my after-work project is to put them back in.

He changed the fuel pressure regulator

You should check your fuel pressure

You can also bench test / clean each injector before installation,
No need to buy new ones if yours are still testing good

I am also short (5’-10), so I have a topside creeper in my shop it allows me to work on the back of engines even on lifted diesel trucks.. $200 Amazon

You really need to: check your fuel pressure
Make sure the lower intake it torqued properly and in proper sequence, you must have clean surfaces for gaskets and use rtv in proper locations and proper amounts

I would suggest you stop buying new parts until you know that the issue is. To do this we have to rule things out
Fuel psi can be tested
Fuel injectors can be bench tested
Spark can be tested

I will have to see what I can do with a tire pressure gauge. I hear they work, but not ideally. If it is too in-accurate I can run and grab a fuel pressure tester. I torqued the lower intake inside-out, in a cross pattern as well. I would let it sit and then gently re-torque. Repeated this about 3 times since they will usually settle/back off over time until it evens out. It does sound like it’s stumbling/misfiring on at least two cylinders. Here is a video I took. Please note this truck has had the muffler removed hence why it is so loud. Planning on adding headers and an aftermarket muffler but might as well have some fun while I’m waiting lol.

 

[wollimann]

I will have to see what I can do with a tire pressure gauge. I hear they work, but not ideally. If it is too in-accurate I can run and grab a fuel pressure tester.

It's always better to have a secured fuel pressure gauge like OTC 5630.
You can hook it up and can see if pressure is fluctuating, more precise and save.

It does sound like it’s stumbling/misfiring on at least two cylinders.

If so the spark plugs will show you which number is bad.
A infrared thermometer will recognize which one isn't firing up
(laser beam on every single header intake, any major differences).
Maybe a spark plug connector plug has bad contact.
Firing order?

Firing order

3 5 2 6 1 4 is this the correct firing order? I replaced my wires not long ago, 4.0 OHV 93 explorer that's the firing order labeled on my wires

www.explorerforum.com

First video sounds good without muffler,
second video is there a constant ticking noise?

I know the injectors are plugged in correctly, and they are all brand new injectors from RockAuto that have been tested thoroughly.

Can't believe that brand new injectors should be bad (if matching part numbers)
They should have optimal spray pattern and should run better than the old ones.

Good luck

 

[410Fortune]

Why would you take the new injectors out and put the old ones back in before you do any diagnostics?
You need to see your fuel pressure

A long crank to start is the first sign of a weak fuel pump

Rent a fuel pressure tester or buy one they are like $35
A tire pressure gauge, the dial type, will work one time to show you pressure.. after that the fuel ruins the insides. These are $2-5 at gas stations