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1999 Ford Ranger 3.0L Flex Fuel

13K views 5 replies 2 participants last post by  Bert 
#1 ·
Recently, with 180,000 miles, the truck started to idle rough just a little bit. It would seem to misfire every once in awhile while idling. When I accelerate, I have very little power and it is very sluggish. I have replaced the fuel filter, the spark plugs and PCV valve.

Today, I pulled the spark plugs (have 10k miles) and cleaned them. On the rear left cylinder (sitting in the driver seat) (#5 I think), the spark plug tip was black indicating an excessive fuel mixture. The other spark plugs look fine. The vacuum pressure was fine and the fuel pressure was 60# but quickly dropped to 20# after the engine was stopped. The shop manual indicates the pressure should stay around 60# for quite a few days afterwards. So I am thinking it has something to do with the fuel system but don't know what to do next.

I am thinking of changing out all of the fuel injectors and at the same time the gaskets for the engine. That should solve the idle problem. Please add any suggestions. The sluggish performance I think may have to do with a clogged exhaust system. What are your thoughts? Anything is appreciated.

1999 Ford Ranger XLT
3.0L V6 Flex Fuel
5 speed manual transmission
 
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#2 ·
How about the coil? They can cause that problem too. The fuel pressure is okay as is. If the exhaust is clogged you can check with a vacuum gauge. The reading should be about 20 at idle and when you raise the RPM to about 2500, the reading should drop and raise back a little below what it was at idle. If it stays low, there's a blockage.
 
#4 ·
Yes the ignition coil. The vacuum reading with a plugged exhaust won't go back up close to the idle reading when the RPM is raised. If the exhaust is clear, the reading will drop when the RPM is first raised and will go back up quickly to almost where it was at idle.
 
#5 ·
Thanks for the information. The vacuum reading was holding steady and when the RPM was raised went to zero and never came back up. It is sounding like a clogged exhaust system.

There are two other symptoms, the truck runs better in a lower gear than the higher gears. Once I go from third to fourth gear I can feel the truck change vibrations. It is struggling more in fourth than in the lower gears. Fifth gear is the same as fourth.

How can I test the exhaust system? To test the ignition coil, I can take a multimeter and measure the ohms, correct? What should the reading be.

Thanks for your help.
 
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