Random inability to start truck

ford
ranger

#1

99 Ford Ranger disguised as Mazda B2500. (Same vehicle I think) 5 speed manual, 4 cyl., no a/c. Bought new and maintained according to schedule. Randomly fails to start. Cranks but won’t turn over. I try several hours later and am able to start it. Mechanic has not been able to duplicate the failure to start. Checked thoroughly and finds no problem. I am very hesitant to drive it like this. Suggestions for next step?


#2

@suna

I’m leaning towards a fuel pressure problem . . . possibly the fuel pump

However, here’s what you can do first

Hook up a scanner and check for stored fault codes . . . tell us if there are any

When it won’t start, use a spark tester to check for a strong blue spark

When it won’t start, hook up a fuel pressure gauge the rail. Tell us the reading


#3

Agree with @db4690 but let me add this. I have owned a couple of Ford Rangers and they had the same problem at some time during my ownership. The fuel pump inertia switch caused the same “no start” malfunction as the OP from time to time. I eventually just removed the switch and connected the wires together. The Mazda B2500 has the same switch. It’s located just above the carpet in the passenger compartment just like the Ford Ranger. If they get bumped by the passengers foot…the fuel pump may or may not run.


#4

@missileman

Your inertia switch failed intermittently?

Do you mean it tripped intermittently?


#5

@db4690…No. In both instances the failures were intermittent and no reset of the switch was required. I assume that the switches just go bad with age and any “bump” including one from a passenger’s foot would cause it to malfunction. That’s why I chose to remove the switch and just connect the wires together. I never had the problem again.


#6

@missileman

I’ll go a little off topic here

I actually like the Ford inertia switch, because it’s easily accessible, and I can very quickly backprobe the wires to determine if the fuel pump is getting power, versus crawling under the vehicle. It’s a great time saver


#7

I’ve had this problem on my 2000 Ranger with the 4.0 V6. In my case, the problem turned out to be the crank position sensor. Diagnosis reasoning:

  1. I was able to smell fuel in the exhaust. Fuel pressure was okay.
  2. If the engine computer doesn’t know where the crankshaft is, it doesn’t know when to fire the spark plugs.
  3. When I changed the crank position sensor, it started. Put the old one back in, and it wouldn’t start. Put the new one in and it’s worked ever since. I put the old one back in just to confirm that it was in fact the problem.

On the 4.0, the crank position sensor is mounted to the front of the engine, right next to the fan belt pulley.

I hope this helps!