CJ7 w/Howell Running rich and rough - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > General Technical Discussions > Engines & Drivetrain > CJ7 w/Howell Running rich and rough

Introducing MONSTALINER™ UV Permanent DIY Roll On Bed LineSpartan Locker Promo Running now @ ROCKRIDGE 4WD plus FREESpartan Locker Special Forum Prices Dana 30 44 60 Ford 8.8

Reply
Unread 12-01-2012, 02:47 PM   #1
fastener
Registered User
1985 CJ7 
 
Join Date: Jul 2009
Location: Northern California
Posts: 20
CJ7 w/Howell Running rich and rough

I have a 1985 CJ7 258 4.2L that I installed a Howell fuel injection California model on. I also installed a Borla header. When I start the jeep it runs rough and will barely idle. It is running very rich (the plugs are black). Howell is closed on the weekends so I can't call them. Check engine light shows code 33.
Here is what I have checked so far: Fuel pressure is 13 to 13.5 psi. O2 sensor checked with volt meter readings were .9V DC when heat applied and dropped to .1V DC when heat removed. Map sensor checked and reads 4.85 volts and drops 1 volt for every 5 inch Hg added with a vacuum pump. Replaced cap, rotor, plugs, wires and checked timing which was about 5* BTDC. All vacuum lines have been replaced with new lines. Anyway, I don't know what else to check and would appreciate any help or feedback anyone might have.


Last edited by fastener; 12-01-2012 at 08:57 PM..
fastener is offline   Reply With Quote
Unread 12-01-2012, 09:02 PM   #2
fastener
Registered User
1985 CJ7 
 
Join Date: Jul 2009
Location: Northern California
Posts: 20
I did some further checking and I have found the problem. I only have 8 inch Hg of vacuum, (map sensor should have around 20 to operate correctly) but have no idea why my vacuum is so low. Compression on all 6 cylinders are 142, 148, 148, 150, 152, 151. I performed a smoke test on the motor and no leaks anywhere. EGR valve is new. Any ideas???
fastener is offline   Reply With Quote
Unread 12-02-2012, 12:13 PM   #3
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,468
Where is your vacuum hose to the MAP hooked up?
Manifold? Is it clear? No kinks or low spots? It must "cascade" down from the MAP to the intake manifold. No P traps in it.
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 12-02-2012, 05:25 PM   #4
fastener
Registered User
1985 CJ7 
 
Join Date: Jul 2009
Location: Northern California
Posts: 20
The vacuum goes from the MAP to the back of the Howell fuel injection. I think you would call it the throttle body. This is where Howells instructions say to attach it. And it is only about 12" long and has a nice cascade to it.
fastener is offline   Reply With Quote
Unread 12-02-2012, 05:36 PM   #5
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,468
My concern is that if it's above the throttle plate there will be low vacuum. Below the throttle plate is manifold vacuum. Might be worth a look-see.
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 12-02-2012, 05:56 PM   #6
fastener
Registered User
1985 CJ7 
 
Join Date: Jul 2009
Location: Northern California
Posts: 20
In the Howell instructions it states that "the MAP sensor has its own vacuum tap at the right rear of TBI and nothing should be tee'd into this line". I double checked and this is where I have the MAP vacuum connected. FRUSTRATED!!
fastener is offline   Reply With Quote
Unread 12-02-2012, 06:08 PM   #7
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,468
Hook your vacuum gauge to a manifold vacuum source and get a reading.
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 12-03-2012, 07:40 PM   #8
fastener
Registered User
1985 CJ7 
 
Join Date: Jul 2009
Location: Northern California
Posts: 20
Okay, so I read where the timing should be 8* with the Howell install not the factory 5*. I set the timing to 8* BTDC and now the vacuum to the MAP is 10 (increased by 2). I also checked the manifold and it's at 10 at idle as well. If I connect my vacuum gauge to the MAP sensor and pump it up to 15 and keep pumping it a little to keep it there, the engine smooths out some and definitely runs better. My other question is....shouldn't the manifold vacuum be around 20?
fastener is offline   Reply With Quote
Unread 12-03-2012, 07:45 PM   #9
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,468
17 to 21 inches of vacuum at sea level. Does your distributor have a vacuum advance?
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 12-03-2012, 07:56 PM   #10
fastener
Registered User
1985 CJ7 
 
Join Date: Jul 2009
Location: Northern California
Posts: 20
Quote:
Originally Posted by cruiser54 View Post
17 to 21 inches of vacuum at sea level. Does your distributor have a vacuum advance?
yes it does
fastener is offline   Reply With Quote
Unread 12-03-2012, 08:00 PM   #11
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,468
Where is the vacuum advance line hooked up to? Did you set the timing with that line connected or disconnected?
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 12-03-2012, 08:09 PM   #12
fastener
Registered User
1985 CJ7 
 
Join Date: Jul 2009
Location: Northern California
Posts: 20
Quote:
Originally Posted by cruiser54 View Post
Where is the vacuum advance line hooked up to? Did you set the timing with that line connected or disconnected?
It's connected to a splitter coming out of the manifold. I set the timing with the advance line disconnected and plugged. When I checked the manifold pressure earlier, I checked the dedicated line going to the brake booster.
fastener is offline   Reply With Quote
Unread 12-03-2012, 08:11 PM   #13
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,468
Try setting the timing to about 12* with no vacuum connected. And then, find a PORTED vacuum source for your vacuum advance. That's one ABOVE the throttle plate.
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 12-03-2012, 08:46 PM   #14
fastener
Registered User
1985 CJ7 
 
Join Date: Jul 2009
Location: Northern California
Posts: 20
Quote:
Originally Posted by cruiser54 View Post
Try setting the timing to about 12* with no vacuum connected. And then, find a PORTED vacuum source for your vacuum advance. That's one ABOVE the throttle plate.
Did the above and it runs a little better and now I have 13" vacuum. Still really rich and rough though.
fastener is offline   Reply With Quote
Unread 12-03-2012, 08:55 PM   #15
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,468
Vacuum is too low and is indicative of retarded ignition timing. The MAP is probably telling the ECU that the engine is under a load when it's not, so the ECU adds fuel. Are there any adjustments on the Howell?

Any vacuum leaks? Have you tried spraying throttle body cleaner arond the intake manifold to head to see if there's a leak there?
__________________
Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.