1990 Ford Ranger lacks power and fuel economy
#1
08-17-2018
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1990 Ford Ranger lacks power and fuel economy
I recently purchased a beautiful 1990 Ford Ranger, 2.9 liter, V6 with 76k miles. I am the second owner. The first owner kept very good care of it and provided me with meticulous records. Unfortunately, he got sick in 2012 and the truck pretty much just sat until I bought it in early 2018.
We knew it needed some work but it seemed to run and drive okay. At first, we noticed 2 things: it lacked power and the fuel economy was only about 9.5 in the city. So... we started the process of elimination. Below is a list of all the things we’ve done to it and the results.
1. Full tune up- seemed to run a bit better but still not up to it’s potential
2. New tires- 1 was really bad and I got a deal so we replaced them all
3. New thermostat and radiator- we noticed it was running real good in the morning but then after I shut it off and then turned it back on 30 minutes later, it’d run like a dog. So we paid attention to the gauge and noticed it was running hot. This made a considerable difference. Still only getting 11 mpg/city and 14 mpg/hwy and power is not where I think it should be.
4. New brake pads, calipers and hoses on front- no difference
5. New valve cover gaskets, a/c belt, p/s belt, alt belt- no difference
6. New battery- no difference
7. New fuel pressure regulator- maybe a bit of difference but not enough to note
8. New fuel pump- just did this so not sure on fuel economy yet but power seems to be about the same
Anyways, I’ve got a beautiful, old truck that lacks power and only gets about 11 mpg/city and 14 mpg/ hwy even after we’ve done everything noted above. Anybody got thoughts? Thanks in advance.
We knew it needed some work but it seemed to run and drive okay. At first, we noticed 2 things: it lacked power and the fuel economy was only about 9.5 in the city. So... we started the process of elimination. Below is a list of all the things we’ve done to it and the results.
1. Full tune up- seemed to run a bit better but still not up to it’s potential
2. New tires- 1 was really bad and I got a deal so we replaced them all
3. New thermostat and radiator- we noticed it was running real good in the morning but then after I shut it off and then turned it back on 30 minutes later, it’d run like a dog. So we paid attention to the gauge and noticed it was running hot. This made a considerable difference. Still only getting 11 mpg/city and 14 mpg/hwy and power is not where I think it should be.
4. New brake pads, calipers and hoses on front- no difference
5. New valve cover gaskets, a/c belt, p/s belt, alt belt- no difference
6. New battery- no difference
7. New fuel pressure regulator- maybe a bit of difference but not enough to note
8. New fuel pump- just did this so not sure on fuel economy yet but power seems to be about the same
Anyways, I’ve got a beautiful, old truck that lacks power and only gets about 11 mpg/city and 14 mpg/ hwy even after we’ve done everything noted above. Anybody got thoughts? Thanks in advance.
#3
08-17-2018
2.9l was a good reliable engine.
One simple thing to check is if throttle cable is stretched, Google: Ranger throttle cable mod
Easy fix for no power
2.9l used distributor with TFI spark system, which did need the module on the side of the distributor replace every 10 years or so, sign of that was no start or hard start when engine was warmed up, so not your problem.
But the spark timing DOES NEED to be set manually, you need a timing light to do this and a short 13mm wrench to loosen distributor bolt, back side of distributor at its base.
The computer does the Spark Advance(called vacuum advance on carb'ed engine), and you need to turn that off, same as you did vacuum advance, when you set base spark timing, this is done by disconnecting the SPOUT(SPark OUT) wire.
Ford added a SPOUT disconnect just for this, looks like this: https://broncozone.com/uploads/month...1522400762.jpg
You pull out the plastic insert and SPOUT is disconnected, in the 2.9l Rangers this SPOUT Connector is usually close to the distributor with wiring on lower intake
Once SPOUT is disconnected you can set base spark timing
12deg BTDC is factory, some prefer 10deg BTDC, but if engine starts to Ping/Knock in warmer weather then set it at 12deg BTDC
Check spark timing FIRST you may not need to adjust it
Once you have base spark timing done then you can move one to the other stuff, timing has to be right for everything else to fall into place
2.9l didn't use a MAF(mass air flow) sensor it used a MAP(manifold pressure) sensor, they preformed a similar task, MAP should be located on the firewall and have a Vacuum hose and 3 wire connector, smaller black plastic box
Check vacuum hose for good condition, no leaks
I would change the single O2 sensor just on speculation, they need to be change every 100k or so, but it they sit more than a few years they tend to fail sooner
The O2 sensor sets the MPG after engine warms up, so lower MPG could just be old O2 sensor.
Vacuum Gauge is a VERY GOOD tool to have, can tell you ALOT about any gasoline engine, $20-$25
Good read here: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine
As above poster said check for plugged exhaust, using vacuum gauge
One simple thing to check is if throttle cable is stretched, Google: Ranger throttle cable mod
Easy fix for no power
2.9l used distributor with TFI spark system, which did need the module on the side of the distributor replace every 10 years or so, sign of that was no start or hard start when engine was warmed up, so not your problem.
But the spark timing DOES NEED to be set manually, you need a timing light to do this and a short 13mm wrench to loosen distributor bolt, back side of distributor at its base.
The computer does the Spark Advance(called vacuum advance on carb'ed engine), and you need to turn that off, same as you did vacuum advance, when you set base spark timing, this is done by disconnecting the SPOUT(SPark OUT) wire.
Ford added a SPOUT disconnect just for this, looks like this: https://broncozone.com/uploads/month...1522400762.jpg
You pull out the plastic insert and SPOUT is disconnected, in the 2.9l Rangers this SPOUT Connector is usually close to the distributor with wiring on lower intake
Once SPOUT is disconnected you can set base spark timing
12deg BTDC is factory, some prefer 10deg BTDC, but if engine starts to Ping/Knock in warmer weather then set it at 12deg BTDC
Check spark timing FIRST you may not need to adjust it
Once you have base spark timing done then you can move one to the other stuff, timing has to be right for everything else to fall into place
2.9l didn't use a MAF(mass air flow) sensor it used a MAP(manifold pressure) sensor, they preformed a similar task, MAP should be located on the firewall and have a Vacuum hose and 3 wire connector, smaller black plastic box
Check vacuum hose for good condition, no leaks
I would change the single O2 sensor just on speculation, they need to be change every 100k or so, but it they sit more than a few years they tend to fail sooner
The O2 sensor sets the MPG after engine warms up, so lower MPG could just be old O2 sensor.
Vacuum Gauge is a VERY GOOD tool to have, can tell you ALOT about any gasoline engine, $20-$25
Good read here: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine
As above poster said check for plugged exhaust, using vacuum gauge
#4
08-17-2018
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