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Unread 09-25-2011, 07:07 PM   #1
Javaboy
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CJ 7 with Howell EFI problems

I just got a CJ-7 that was someones project. Long story short, the project was just about complete when I took over it. I do not have contact with the person doing the work on the jeep.

The jeep has a new Howell TBI system. But I can not get it to run correctly. The jeep has also been to two different mechanics, neither of them have any ideas what is wrong.

The jeep seems to run rich, and floods out. If you pull one of the injectors it runs fine, still maybe a little rich. But with both injectors plugged in it floods out and well not start.

Here is what I have done:
1. I looked at the ignition system. I thought this might be the problem - and still think that it might be. The wire that is suppose to be a good clean 12 v had a terminal that was the wrong size and falling off. It has the GM HEI system.

2. I checked the return fuel line by disconnecting it and running it into a empty fuel can. Same symptoms. The battery was disconnected between starting attempts in hopes to clear the computer of any memory.

3. Plugs and wires are good.

Any thoughts? I just bought a fuel pressure gage and well try to use that tomorrow. Is it possible that I am getting too much fuel pressure, more then 11-12 PSI? But if that is the case shouldn't it just by-pass and hit the return fuel line?

Im going to do some more research tonight, and I emailed Howell for support but haven't heard anything back.

Any help is appreciated!

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Unread 09-26-2011, 06:40 AM   #2
jcal73
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Look at your vacuum line to your MAP sensor. Or it could be your map sensor.


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Unread 09-26-2011, 09:42 AM   #3
dslywalker
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Check your O2 sensor also. Check for a plugged Cat convertor. As mentioned the map sensor. Map sensor should be mounted above the throttle body with as short a hose as possible. Most are mounted on the firewall directly behind the TB. Between your O2 sensor and Map sensor they are the ones that control your fuel.
If you have a check engine light you should be able to pull a code out of the computer. Do you have a Howell manual?
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Unread 09-26-2011, 02:35 PM   #4
Javaboy
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Thanks for the replies.

I'll check the sensors and vacuum system out. I do not have a Howell Manual, but have been on there website and read everything that I could. The check engine light is not on, so in theory the sensors should be functioning right? It has a brand new exhaust system and cat conv.

Bought a new coil today for the GM HEI. Once I played with the timing a little and got it started using both injectors. It ran for about 5 minutes and then stopped. It actually seemed to run a little lean. So I think it might be a ignition problem. I have not been able to get it restarted. I'm going to pull the plugs right now and make sure they are gapped correctly.

Thanks again for your replies, I'll let you know what I find out.

Also, if the check engine light is not on should I assume there are no codes to pull?
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Unread 09-26-2011, 02:41 PM   #5
NJMike
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This probably isn't a big help, but I went through the same thing years ago. I never really figured out what the problem was, after fooling with it on and off for a year, one day it suddenly started working. Never acted up again. Then a friend did a junk yard Howell set up and it did the same thing. He contacted Howell and they told him to get a different computer. It fixed the problem.
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Unread 09-26-2011, 03:57 PM   #6
cj7ole
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Check your fuel pressure with a gauge. I had problems with my Howell conversion years ago because I put the fuel pump up front and it was collapsing the rubber fuel line coming from the tank, especially when it was hot and the line got soft. Eventually fixed it by relocating the pump next to the tank, below the centerline. Also watch out for cheap fuel pumps (like those $50 Mr Gasket AutoZone specials which almost left me stranded). I went with a Carter P5000, about $140 from Rock Auto. Typically a TBI needs 10-15 psi. And, yes, any excess pressure will go back to the tank if the PO plumbed it correctly. My conversion didn't use the Howell TBI, just their harness and pump and computer PROM. It was already a 4.3 TBI.
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Unread 09-26-2011, 04:59 PM   #7
Javaboy
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Okay.... Now for the life of me I can not get it to start... at all. All it does is backfires. I've checked the timing and verified TDC. I'm tempted to spin it 180, but it would run with the other coil and with one of the injectors disconnected, so I don't think it could be timing, could it?

Like I said, this is a recent rebuild and I have never seen this engine run, so anything is possible. Any more ideas?

I checked my fuel pressure, and that is good at the Howell.
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Unread 09-26-2011, 07:46 PM   #8
dslywalker
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With the HEI you'll need one of Howells Tach Filters i believe.Get ahold of Troy at Howell and he can answer a lot of questions for you.It might posibily Need a new chip burned. The technology is from a GM 4.3 V6 engine. Watch out for the cheaper distributors.They have hardened gears that can eat a cam in no time or just plain be bad. Howell recommends a DUI distributor.
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Unread 09-26-2011, 08:03 PM   #9
james04si
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No tach filter needed for a hei. I have the Howell and a crt hei and no filter and runs fine.
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Unread 09-26-2011, 08:04 PM   #10
Javaboy
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Ok. Thanks again for your reply.

I'll give them a call tomorrow and see if they have anything good to offer. I'm at a loss, and am afraid this might be out of my skill level. I swapped the coil back to the previous one which would allow me to run it with one injector, but couldn't even get it to start that way. To me it looks like it is spraying less fuel.

To recap on what I've done:

1. Jeep would only start and run with one injector plugged in.
2. Replaced Coil. Jeep started and ran with two injectors for about 5 minutes and died.
3. Unable to restart Jeep. Backfires through intake.
4. I've checked fuel pressure, Vacuum for leaks, sensors.
5. I ca't find where the ALDL connector is but I'll look for it tomorrow.

Not sure what else to do? Bent rod? Could it be the ignition module? What would a common cause of intake backfire be? Lean fuel conditions? Spark plug gap? Not enough sparK?
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Unread 09-26-2011, 10:41 PM   #11
dslywalker
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Your ADL connector should be by the glove box next to the fuse block.Your computer should be on top the glove box.ADL ties into the computer

There's some good reads on Howell if you search the forum.If you open your computer box and see if you have the chip that ends in 7747 i believe.Howells gonna ask you that anyway.
Tell Howell the make of distributor your running in case there's something they need to do
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Unread 09-27-2011, 06:46 AM   #12
CSP
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Quote:
Originally Posted by dslywalker View Post
With the HEI you'll need one of Howells Tach Filters i believe.
Negative. Tach filters are only necessary with multiple spark discharge ignitions.

Quote:
Originally Posted by dslywalker View Post
If you open your computer box and see if you have the chip that ends in 7747 i believe.
Another negative. The 1227747 number will be on a label on the outside of the computer (never seen Howell use anything other than 1227747 computers), and the chip code should also be there, though it may be necessary to pop the cover to verify the chip code. I wouldn't go there just yet anyhow.

A call to Howell will be helpful. The owner's manual, which has troubleshooting procedures, is also downloadable from their website.
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Unread 09-27-2011, 07:25 AM   #13
Javaboy
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Thanks once again for all of your help. I am ready to try to get a carb and scrap this whole thing for now. The jeep is actually my GF's and I need to get it running to drive it from Texas to AK. Not sure if this is going to happen. Frustrating because I don't have very many tools here.

I'm calling Howell today. Also running to the store right now to replace the ignition module. It seems like it might be missing a little. This morning I am getting backfire out of the exhaust.

Any help is still appreciated. All comments and suggestions are going to be read.
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Unread 09-27-2011, 12:16 PM   #14
Javaboy
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This morning I took a very close look at the ignition system. I pulled the ignition module and took it in to have it tested. They tested it three times, it failed each time. So I bought a new one. Installed that and no spark at all. I pulled the capacitor with the ignition module, do you think I screwed that up somehow? I also hear that the new ignition modules have a fairly high failure rate from the factory, so I am thinking about going to a different store and having both of them tested.
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Unread 09-27-2011, 01:23 PM   #15
dslywalker
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Quote:
Originally Posted by CSP View Post
Negative. Tach filters are only necessary with multiple spark discharge ignitions.



Another negative. The 1227747 number will be on a label on the outside of the computer (never seen Howell use anything other than 1227747 computers), and the chip code should also be there, though it may be necessary to pop the cover to verify the chip code. I wouldn't go there just yet anyhow.

A call to Howell will be helpful. The owner's manual, which has troubleshooting procedures, is also downloadable from their website.
Thanx for the corrections CSP i wasn't to sure on that one for the tach filter
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