258 with Howell EFI Runs Poorly When Cold

258 with Howell EFI Runs Poorly When Cold


Central Point, OR
86 CJ7 with 258ci NP435 Dana 300 Dana 30 Front Dana 44 Rear Howell TBI Sitting on 33s.
I installed the EFI kit on my CJ7 Jeep with a 258 I6. It starts ok in the cold, but then after about 3-5 minutes it acts like it starts to miss and then die. It will continue to do this until it reaches full temp and then it idles a little high. It also seems to be running a bit rich.
The fuel pressure in is 13PSI and 5PSI out. Not sure if that would cause a problem or not.
I have a DUI distributer that says timing can be at 12 initial timing but I'm not sure if that throws off the system in any way or not. I've tried running anywhere from 8 to 12 with no change.

My Webber carb acted similar to the fact that it would miss and made a popping noise in the exhaust system when it was cold. One of the reasons I upgraded in the first place.

Any thoughts as to where to start?
It sounds like you are running rich all the time. Fuel pressure should be checked at the fuel inlet and outlet close to the t.b.i. A rich condition could be due to excessive fuel pressure, but a check engine light should go off in that case, like a code 45. The return line pressure is a bit high, but within Howell spec, maybe a clog in the return line somewhere. Running 12 degrees initial could affect things on the top end where it should be around 28-30 degrees also. Howell is known for an excellent customer service, so you might try giving them a call.
Thanks Torx!

I gave them a shout but they are closed on the weekend. I'll call them again on Monday.

Should I be concerned about the missing and exhaust popping when I drive it? I had the engine rebuilt once already, really don't want to have to do it again.

I'll drop the advance back down to 8 or 10.
You might want to check the condition of the spark plugs to determine the fuel mixture. Maybe try a hotter spark plug with a longer reach, Howell recommends a RFN14LY plug. I run the remanufactured version of the Motorcraft distributor with the large cap and it seems to work best at 6 degrees initial.
I changed them out a few weeks ago, but they were just standard Autolite plugs. All of them were tan on one side and white on the other side except the 6th one had some carbon built up on it. I'll try the plugs you suggested.

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