Hi all,

I recently bought a 1999 Ford ranger 3.0 v6 5 speed. It runs pretty good most of the time. But it’s my first manual, and I’ll occasionally kill it, and sometimes when I do it’ll crank but not start. It’s throwing a code for o2 sensors (according to the guy I bought it from, I haven’t ran it myself). the next move seems obvious to do the sensors, but I’ve just never heard of o2 sensors causing an intermittent crank no start. Usually crank sensors or maf sensors come to mind there.

does anyone have any thoughts? I’d appreciate any input, this is my first truck and ford in general, don’t know much about em other than that the 3.0 is allegedly pretty reliable. Thanks much!

edit: its worth noting that the day I bought it it broke down (I’ve got pretty rotten luck with vehicles lol) and wouldn’t crank, no power at all. I ended up shotgunning an alternator and jump starting it since the battery was pretty new and that seemed to fix the issue. Til this morning when I tried to pull out of a steep driveway, killed it, and then it cranked but didn’t start. Funny enough, after turning the radio off and giving it a second it started, which makes me wonder if it’s still voltage related. Could’ve just been coincidence though.

 

You need fuel, spark and compression to start an engine. Which one is missing?


Please provide codes if you want further help.

 

Thanks much for responding. I ran the code, and it’s a p1151. It wouldn’t surprise me if it was causing the crank no start due to a bad fuel air mixture, only happening after killing it because of heat affecting the sensor. I’m planning on looking for vacuum leaks tomorrow, but the guy I bought it from (buddy’s stepdad) gave me the o2 sensors to replace anyway free of charge. I’ll check for leaks but if nothing comes up I think I’ll replace the sensor and go from there.

 

It isn't that will be a separate unrelated issue.

 

Gotcha. Whatever the issue is it’s not throwing any codes then. I’ll go ahead and start troubleshooting the fuel system this week. Hope it’s not any kind of wiring issue, I had an Oldsmobile for a while that intermittently stalled and wouldn’t start at high temps. Ended up getting rid of it since mice got into the wiring harness and it wasn’t worth replacing the whole thing.

 

Bad O2 sensors won't cause a no-start, to get back to your original question. Vacuum leaks won't either, especailly if it was just running. I'd be ready with a spark tester if it was mine. I'd also suggest a fuel pressure tester but using it on a hot engine is dangerous, especially for someone with little expereince.

Also, watch the THEFT light. You might have an intermittent problem there. The starting sequence is - THEFT light flashing slowly, key inserted and turned on THEFT light lights up solidly then goes out, key turned to Start engine cranks, engine starts.

The fact that it starts properly after waiting fits a "key error" PATS shutdown, but you have to watch the THEFT light to be sure. Most of us never notice the THEFT light until there's a problem.

Also, try to notice small details when it won't start. If it pops a few times but doesn't start, or if it almost starts but keeps dying that's different than a completely dead crank with no start.