Misfires and Fuel Pressure
#1
Misfires and Fuel Pressure
Hey all! New the forums but I have been lurking here for years.
I have a situation that I think could be beneficial for others.
I recently bought a house that came with an 04 Ranger on the property that hadnt been driven in a while.
The previous owner passed away, so I couldnt really get an idea of why it hadnt been driven. He was an older guy and the stepdad of a friend, so he opted to just lease a newer car instead of put much work into the truck.
Anyways, after jumping it and getting it going I eventually started getting a flashing CEL, active misfire. This only happens at idle and low RPM's, as soon as I take off it goes solid.
I took it to get the codes read and I had random misfires and misfires on cylinders 1-3 as well as a rich fuel mixture on Bank 1. Autozone said MAF, so I went ahead and slapped a new one in, the truck was a throw in so Ill put some money into it.
I changed plugs, wires, MAF, checked the PCV elbow, checked the PCV, hunted down any vaccum leaks. Everything looked good.
After much thinking, and these incredible forums, I got to fuel pressure and went to harbor freight and got the fuel pressure kit. Pressure at the rail would jump to 65 psi and as soon as the car was off it would start dropping, never holding and eventually getting to zero.
Today I installed a new fuel filter but before I took the old one off I attached my pressure gauge to the outlet of the filter. Same situation, got to 65 psi and immediately started dropping, even with the key on.
Everything is screaming fuel pump assembly check valve.
Heres my theory:
If I remember correctly, I read a post on this forum where someone said that Bank 2 gets fuel before Bank 1. I believe Bank 2 is getting and using the correct amount of fuel and then leaving too much fuel to Bank 1 to handle, this is causing a rich condition and thus a misfire on the entire bank. Its happening at idle, because theres nowhere for that fuel to go, under load it can be passed along through the system without tripping a misfire.
My fuel level seems to fluctuate a bit more than Id expect and the truck gets seemingly bad mpg.
I just wanted to get this thought process out there to you fine folks to see if theres something I may be missing.
Thanks in advance!
I have a situation that I think could be beneficial for others.
I recently bought a house that came with an 04 Ranger on the property that hadnt been driven in a while.
The previous owner passed away, so I couldnt really get an idea of why it hadnt been driven. He was an older guy and the stepdad of a friend, so he opted to just lease a newer car instead of put much work into the truck.
Anyways, after jumping it and getting it going I eventually started getting a flashing CEL, active misfire. This only happens at idle and low RPM's, as soon as I take off it goes solid.
I took it to get the codes read and I had random misfires and misfires on cylinders 1-3 as well as a rich fuel mixture on Bank 1. Autozone said MAF, so I went ahead and slapped a new one in, the truck was a throw in so Ill put some money into it.
I changed plugs, wires, MAF, checked the PCV elbow, checked the PCV, hunted down any vaccum leaks. Everything looked good.
After much thinking, and these incredible forums, I got to fuel pressure and went to harbor freight and got the fuel pressure kit. Pressure at the rail would jump to 65 psi and as soon as the car was off it would start dropping, never holding and eventually getting to zero.
Today I installed a new fuel filter but before I took the old one off I attached my pressure gauge to the outlet of the filter. Same situation, got to 65 psi and immediately started dropping, even with the key on.
Everything is screaming fuel pump assembly check valve.
Heres my theory:
If I remember correctly, I read a post on this forum where someone said that Bank 2 gets fuel before Bank 1. I believe Bank 2 is getting and using the correct amount of fuel and then leaving too much fuel to Bank 1 to handle, this is causing a rich condition and thus a misfire on the entire bank. Its happening at idle, because theres nowhere for that fuel to go, under load it can be passed along through the system without tripping a misfire.
My fuel level seems to fluctuate a bit more than Id expect and the truck gets seemingly bad mpg.
I just wanted to get this thought process out there to you fine folks to see if theres something I may be missing.
Thanks in advance!
The following users liked this post:
DILLARD000 (02-20-2021)
#2
#3
Free Truck = Good Deal!
Per your profile, 2004 Ranger with V6~4.0L~SOHC?
Which TroubleCodes?
You need your own OBD2 scanner that reads both StandardSAE & ProprietaryFord codes; many PartStore scanners will not read both.
They have financial incentive to have you buy extra parts that you may not need.
Anyway, troubeshooting a vehicle in your driveway, depending on a Scanner at the PartsStore, is impractical.
Per your profile, 2004 Ranger with V6~4.0L~SOHC?
Which TroubleCodes?
You need your own OBD2 scanner that reads both StandardSAE & ProprietaryFord codes; many PartStore scanners will not read both.
They have financial incentive to have you buy extra parts that you may not need.
Anyway, troubeshooting a vehicle in your driveway, depending on a Scanner at the PartsStore, is impractical.
Last edited by DILLARD000; 02-20-2021 at 04:14 AM.
The following 2 users liked this post by DILLARD000:
Georgeandkira (02-20-2021),
stumpman (02-20-2021)
#4
Plumbing can't deliver differing pressures in a Y (or other) manifold configuration. The pressure seen at the arms of the Y will match what's applied at its base.
It's why hydraulic brake systems are so nifty.
Deffo on getting your own reader.
You'll quickly recoup the price in drive time, work interruption, fuel and standing around waiting for the counterman to produce the store's toy reader.
BONUS: Your exposure episodes to any circulating viruses will be limited.
Mileage on truck?
Any idea how long it sat idle?
It's why hydraulic brake systems are so nifty.
Deffo on getting your own reader.
You'll quickly recoup the price in drive time, work interruption, fuel and standing around waiting for the counterman to produce the store's toy reader.
BONUS: Your exposure episodes to any circulating viruses will be limited.
Mileage on truck?
Any idea how long it sat idle?
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