• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' and react to posts.

New engine... Running odd.

KevinSonOfDad

Member
Ford Technician
ASE Certified Tech
Joined
Jul 24, 2022
Messages
44
Reaction score
30
Points
18
Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
I just finished putting in a brand new rebuilt 4.0 in my truck this weekend. It runs and drives but seems underpowered and shakes a lot at idle. I auspect injectors since im using the ones fROM the junkyard motor I rebuilt instead lf my previous ones.

What sympotms have yall had with bad injectors?
 


superj

Well-Known Member
U.S. Military - Veteran
Joined
Oct 1, 2021
Messages
2,147
Reaction score
1,581
Points
113
Location
corpus christi, texas
Vehicle Year
2004
Make / Model
ranger edge
Engine Type
3.0 V6
Engine Size
3 liters of tire smoking power
Transmission
Manual
2WD / 4WD
2WD
Total Lift
none
Total Drop
none
Tire Size
235s
My credo
Grew up in the 70s, 80s, and 90s
pull them and run some cleaner through them. or at least spray them into a jar and make sure they are spraying properly and putting out a similar amount
 

rubydist

Well-Known Member
Joined
Dec 16, 2016
Messages
597
Reaction score
408
Points
63
Location
Denver
Vehicle Year
2009
Make / Model
Ford Ranger FX4
Engine Type
4.0 V6
Transmission
Automatic
2WD / 4WD
4WD
Bad injectors will cause anything from a slight unevenness in how it runs all the way to it won't run at all, depending on how many injectors are sticky and how badly they are clogged. Your symptoms could easily be dirty injectors.
 

dvdswan

Well-Known Member
U.S. Military - Veteran
Joined
Feb 11, 2021
Messages
2,416
Reaction score
2,080
Points
113
Location
Seattle, WA
Vehicle Year
1991
Make / Model
Ranger XLT 2WD
Engine Type
3.0 V6
Transmission
Automatic
2WD / 4WD
2WD
My credo
Keep your mind like an umbrella, it only works if its open... Continually learning.
Why not throw in the previous injectors you have?
 

Shran

Junk Collector
Forum Moderator
Supporting Member
Article Contributor
V8 Engine Swap
Solid Axle Swap
Joined
Mar 4, 2008
Messages
7,763
Reaction score
3,280
Points
113
Location
Rapid City SD
Engine Type
V8
Engine Size
5.0
I sent mine off to be cleaned by Mr. Injector - I did have sort of an uneven idle before, I only really noticed because the transmission shifter would shake. There is a noticeable difference now, idle is much smoother. No difference in power while driving.

The only reason I sent them off was because one got stuck open and it would run horribly rich and smoked a lot. I got a flow chart back with them that indicated a couple of the others were not working quite right either.

In my experience they are probably the last thing I would look at, it's totally possible to have one or more malfunctioning, but far more likely that it's something else.
 

KevinSonOfDad

Member
Ford Technician
ASE Certified Tech
Joined
Jul 24, 2022
Messages
44
Reaction score
30
Points
18
Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
Why not throw in the previous injectors you have?
Thats the plan today. Since so many variables are different from the last engine im trying to narrow down the possibilities
 

KevinSonOfDad

Member
Ford Technician
ASE Certified Tech
Joined
Jul 24, 2022
Messages
44
Reaction score
30
Points
18
Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
Bad injectors will cause anything from a slight unevenness in how it runs all the way to it won't run at all, depending on how many injectors are sticky and how badly they are clogged. Your symptoms could easily be dirty injectors.
Thats my thought. Also because they came from a engine in unknown condition. I plan to swap back to my old ones as a test since my old engine ran good with them and they all test good
 

KevinSonOfDad

Member
Ford Technician
ASE Certified Tech
Joined
Jul 24, 2022
Messages
44
Reaction score
30
Points
18
Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
pull them and run some cleaner through them. or at least spray them into a jar and make sure they are spraying properly and putting out a similar amount
How exactly would i spray them into a jar?
 

superj

Well-Known Member
U.S. Military - Veteran
Joined
Oct 1, 2021
Messages
2,147
Reaction score
1,581
Points
113
Location
corpus christi, texas
Vehicle Year
2004
Make / Model
ranger edge
Engine Type
3.0 V6
Engine Size
3 liters of tire smoking power
Transmission
Manual
2WD / 4WD
2WD
Total Lift
none
Total Drop
none
Tire Size
235s
My credo
Grew up in the 70s, 80s, and 90s
just pop it out and point the injector into a mason jar. crank the truck over and measure the amount for a certain amount of cranks. you can also power it up with a 9v battery and run some cleaner through it yourself with a spray bottle or a bottle you can add pressure to in order to push the cleaner through when you apply 9v to the power side.

the bmw guys did this alot
 

KevinSonOfDad

Member
Ford Technician
ASE Certified Tech
Joined
Jul 24, 2022
Messages
44
Reaction score
30
Points
18
Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
just pop it out and point the injector into a mason jar. crank the truck over and measure the amount for a certain amount of cranks. you can also power it up with a 9v battery and run some cleaner through it yourself with a spray bottle or a bottle you can add pressure to in order to push the cleaner through when you apply 9v to the power side.

the bmw guys did this alot
Just seems difficult due to the design of the 4.0 fuel rail.
 

KevinSonOfDad

Member
Ford Technician
ASE Certified Tech
Joined
Jul 24, 2022
Messages
44
Reaction score
30
Points
18
Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
UPDATE: after running it for longer I noticed discoloration on all but 2 of the headers. Turns out indeed cylinders 5 and 6 are dead. Got spark and after swapping around injectors to confirm indeed i have 2 bad injectors. Will swap them out today and update with how it went.
 

KevinSonOfDad

Member
Ford Technician
ASE Certified Tech
Joined
Jul 24, 2022
Messages
44
Reaction score
30
Points
18
Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
TLDR: look for bolded underlined questions

Ok so i swapped in my old set. It ran slightly better and 5 and 6 are now firing but now 1 and 2 are dead or partaily dead. Truck is parked till this is fixed as to not damage the brand new engine.

Since swapping to an old set changed the dead cylinders and swapping between cylinders does i know the problem isnt in wiring. But i am curious if my old set had 2 dead injectors just like the new one since the truck ran ok on the old set.

Part of me suspects the fuel pressure regulator now also its cheaper to fix than 400 bucks of injectors.

What are the failure modes of the regulator? I unplugged its vaccum while running and the sound and speed of the engine didnt change(may not be a great test since its already only running on 4 cylinders.

what things should I test before getting new injectors?
 

Shran

Junk Collector
Forum Moderator
Supporting Member
Article Contributor
V8 Engine Swap
Solid Axle Swap
Joined
Mar 4, 2008
Messages
7,763
Reaction score
3,280
Points
113
Location
Rapid City SD
Engine Type
V8
Engine Size
5.0
I would send a set of 6 off to be cleaned and tested... it was only about $150 after shipping when I did it. Totally worth it. And it is not a crap shoot gamble like buying new ones is......... you know they will be tested and working.

I really doubt this is a regulator issue. Usually if that fails it is just the diaphragm inside that ruptures and engine vacuum pulls fuel out of it... bad gas mileage and hard starts when warm are the main symptoms.
 

KevinSonOfDad

Member
Ford Technician
ASE Certified Tech
Joined
Jul 24, 2022
Messages
44
Reaction score
30
Points
18
Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
I would send a set of 6 off to be cleaned and tested... it was only about $150 after shipping when I did it. Totally worth it. And it is not a crap shoot gamble like buying new ones is......... you know they will be tested and working.

I really doubt this is a regulator issue. Usually if that fails it is just the diaphragm inside that ruptures and engine vacuum pulls fuel out of it... bad gas mileage and hard starts when warm are the main symptoms.
Where did you send yours?
 

Shran

Junk Collector
Forum Moderator
Supporting Member
Article Contributor
V8 Engine Swap
Solid Axle Swap
Joined
Mar 4, 2008
Messages
7,763
Reaction score
3,280
Points
113
Location
Rapid City SD
Engine Type
V8
Engine Size
5.0

Sponsored Ad


Sponsored Ad

Top