Jackson

I've been running my 5.0 F.I. for about 3 years now. It has always seemed underpowered, though got better when I replaced the usual tune-up parts. It has always started right up, hot or cold, and idles perfectly. But it always seemed to struggle getting going. This changed all by itself about 6 months ago, and it had better power on acceleration. Last week it got powerless again, and yesterday I could get only 40 mph on the flat. It started overheating anf boiling up through the coolent tank. I towed it home. It still starts right up and idles perfectly.

It seemed like I was getting no ignition advance and being retarded, was heating up. I don't have experience with the TFI-IV ignition system, but suspect I may have a bad ICM.

Any help is appreciated.

Just call me Sean

iTrader: (1)

I would start by checking for codes, this thread explains how: https://www.f150forum.com/f10/how-retrieve-trouble-codes-obdi-10907/ The ICM most likely won't leave a code so that can be tested at the local parts store. I would check fuel pressure also.

Jackson

Thanks, Sean.

I must have a later diagnostic system. What looks like the self test connector is on the rear left fender apron and is round with two pin connectors, one green and black wire, one red. The other connector I have not located. What now?

Thanks.

Jackson

I finally gave up trying to diagnose the problem myself and getting nowhere, despite throwing some parts in it.

Took it to Dan Clary Auto Service in Santa Rosa, CA. Turned out boths cats had gone bad and were causing an exhaust stoppage.

Just thought this might help someone down the line who has a similar problem.

BTW, He charged me 47.50 for diagnosis and sublet the exhaust system work out which cost me 125.00 labor and 582.00 parts. I would say that was very reasonable, considering, and highly recommend this shop.

Alls well that ends well.