2006 Ford Ranger 3.0 OHV Cranks, no Start, fuel fouled plugs.

Ok. So I pulled the timing cover today. No revelations there. Although the chain was little stretched, it hadn’t jumped. It wasn’t a total waste of time to pull the cover because I found some pitting on the cover that needed to be addressed (rusty coolant is the devil!).

So now I’ve verified cam timing, spark, fuel pressure, and engine compression. The only flag on the field is that crazy long injector pulse.
I’m thinking I might have to bite the bullet and order a PCM.
This is a last ditch call out for any other ideas.
Thanks guys (and gal) for any helpful last minute advice.

Well I feel pretty stupid right now.

I found the problem and I’m kicking myself. If I had started off old school, I could have diagnosed this thing in a few minutes with a simple vacuum gauge.

I went back to this truck Saturday and decided to check the basics again as if it had just come to me. It hit me when I was trying to run the truck on carb spray to see if it would stay running. I pulled a vacuum line to spray while cranking and noticed it wasn’t pulling much vacuum. So I grabbed a vacuum gauge and installed it, and cranked the engine. It never went below 1.5”hg. It actually went positive for a bit. That’s not good.

Within 20 minutes (pulling 02 sensors) I had the problem found. The rear catalytic converter was clogged.

I had originally checked spark and fuel and timing, found and chased issues in those areas, but I stopped before checking for the other combustion component... air.

Well, it all worked out. If I hadn’t pulled the timing cover we wouldn’t have known it was ready to rot completely through due to corrosion damage. So the extra time spent wasn’t a loss for my buddy.


Next time I’ll check cranking vacuum earlier on. Lesson learned.

I... didn't seen that one coming. :ohmy:

You shouldn't feel stupid about that at all, IMO. I know to a certainty that I wouldn't have had an easier time of figuring it out. I guess when you look back at all your testing, it was one of the only options left. Still not something you see often. :silly:

When do you think would have been the right time to go with the vacuum gauge? After the spark/fuel/compression checks?

I know that this condition could have been spotted with an in cylinder pressure transducer. BUT, I dunno if you have one or not. I do, but I don't know that I'd have thought to use it on this truck if it came to my bay! :lol:

how did it run off of alternative fuel? good job figuring it out though

cheryl hartkorn wrote: how did it run off of alternative fuel? good job figuring it out though

It didn’t run long when I ran it on carb spray . Longer than in clear flood it or after cleaning the spark plugs, and that was enough to make me think I was onto something with the fuel system.

In hindsight I think running it on carb spray just didn’t load the cat as fast.

Tyler wrote: I... didn't seen that one coming. :ohmy:

You shouldn't feel stupid about that at all, IMO. I know to a certainty that I wouldn't have had an easier time of figuring it out. I guess when you look back at all your testing, it was one of the only options left. Still not something you see often. :silly:

When do you think would have been the right time to go with the vacuum gauge? After the spark/fuel/compression checks?

I know that this condition could have been spotted with an in cylinder pressure transducer. BUT, I dunno if you have one or not. I do, but I don't know that I'd have thought to use it on this truck if it came to my bay! :lol:

Definitely not something you see a lot. I’ve seen plenty of restricted cats, but in 25+ years I’ve not seen one this bad. Usually it’ll run long enough to give you a clue.


Yes a transducer would have caught it. I built a homemade one I’ve toyed around with but I wouldn’t have considered it for a no start either.

But, I think I should have tossed a vacuum gauge on the truck after verifying fuel pressure, fuel pulse, and spark. Maybe even before checking cranking compression. We used to use vacuum gauges a lot for engine diagnostics back in the 90’s.

Engine vacuum during cranking should have hit 3-5”hg. When it fired up I should have gotten 18”.
Too little vacuum would show an exhaust restriction. Too high would show an intake restriction.
Fluttering gauge would point me toward internal engine issues.

It’s a quick test I think I will add to my initial checklist, especially on older/high mileage vehicles.