I am going back to school (2hours away) tomorrow and need to figure this out.

88 ford ranger 2.9L

So I have been dealing with a problem with my 88 ranger. It misses very badly- but not all the time. I feels like I am running out of gas, misses, and spits. I can be going 65-70 one moment, and 45 the next. Then it will "kick" it back and go right back to doing 65. it is very annoying. No check engine light ever comes on. It is very hit and miss. I can go 20 miles and not have a problem. Go to go somewhere and it happens every mile. On the highway, I didn't make it 9 miles with out it happening again and again.

Things I have done.
-New spark plugs
-Tested Coil
-New ignition module
-Tried a new Throttle positioning sensor- still happened
-New MAP sensor- still did it
-fuel pressure tested- tested fine
-no water in the gas
-cleaned the air intake sensor(?) (next to the intake)
-new fuel filter
-ignition pickup is not too old, same with cap and rotter.
-Battery tested
-Alternator tested
-Computer codes scanned (engine on and off) nothing found
-new air filter

Symptoms- bad missing, usually smoke after problem goes away, intermittent occurrence, i believe poor fuel economy also. If it starts acting up, I have to keep shifting up and down to keep it moving. usually it is down shifting with foot to the floor.

I do not know what else to try. So far I have been suggested take fuel pump and oxygen sensor." The oxygen sensor it my next place.

PLEASE HELP. I have put so much money and time into this and I am running short on both.

 

The next time it does it, check the fuel pressure, It might be an intermittant problem with the fuel pump.

Check compression?
How many miles on the truck?
Do you have to drive 65 to 70? Ever heard of 55? I know it's sooooo Jimmy Carter but you've got an old small truck, it might like coasting the rest of it's life.

 

The truck does have a lot of mileage but when it runs "normal" it has plenty of get up.
"65-70" was just a figure. It acts up at all speeds, all gears. I have taken it to 2 garages and it hasnt acted up when it was there. it is so frustrating. They said it is a good strong motor.

Which fuel pump is the question... I just hate that some times I can go 20 miles with out a problem and next I cant go 2.

the fuel pumps are kind of last on my list bc of the price. I wish I had a pressure gauge that I could carry for when it does act up.
anything to try?

 

You say you tested the coil?..........Sounds exactly like what my old 2.8 V6 Ranger was doing a while back, coil tested as OK, but being that it was 26yrs old, I tried a new one just for kicks.............problem solved.

 

the coil is less than 2 years old, but I can always try a new one...
Keep the ideas coming! I may have to try them all!
Thanks guys!

 

6 hours to go... problem not fixed! HELP!

 

This gets my vote as well, check the fuel press. I love EFI vehicles, a electrical problem can mimic a fuel problem, but on EFI, a electrical problem (failing elect. fuel pump) will cause a fuel problem.............give me a carb. any day.

 

You've been busy on this one!!!!

I like the fuel pressure & spark ideas.

Do you have a CEL lit????? If so pull & post the trouble codes, as they can offer up good trouble shooting clues.
There are instuctions in the Tech Info thread, atop this forum, on how to do this on your OBD-1 system.

If no CEL is lit, when it acts up next, as as been suggested, stop & check the fuel pressure & pull & check the fuel pressure regulators vacuum hose, to see if it's wet with fuel inside, if so, replace it.

If the fuel pressure checks low, thump the fuel pump power relay, as it's a common problem.

Try resetting the fuel pump inertia switch, as some have been bad with high resistance, that drops the fuel pump operating voltage.

Thump the fuel pumps & see if it'll wake em up.

If fuel pressure doesn't seem to be the problem, use an inductive type timing light to see if it's a spark problem when it's acting out.

If so, check the distributor shaft for play. if it has play, it'll mess with the hall effects pickup trigger signal for the ignition module.

Check the ignition module & it's electrical connectors pins & sockets for corrosion, spread sockets, bent pins, or wiring insulation damage.

Have the ignition module bench tested if you come to suspect it, as they're known to cause problems. Maybe even take a hair dryer, or heat gun along,to heat it up during the bench test.

More thoughts for consideration, let us know how it goes.

 

When it's acting up do the idiot lights on the dash come on?

If not I'd suspect a flaky ignition switch.

The coil and idiot lights are powered from the ignition switch.

 

UPDATE:
I replaced the O2 sensor (it put up a fight). No I just need to drive it around and see it that helps. Gauge said the O2 sensor was the #1 problem listed on their program for "temporary intermittent power loss with no CEL". second was the MAP, already replaced it.

Answers
No Check Engine Light comes on when it acts up. I disconnected the O2 sensor and it took over 3 miles before the check engine light came on.

I had the ignition module already tested and replaced. The pick up inside is less than 2 years old.

I need to pick up a fuel pressure gauge to carry for WHEN it does act up.

Questions
Where are the fuel pump relays?
Where is the fuel pump inertia switch??
Recommend just replacing the relays?

THANKS GUYS, Idk if im out of the water yet.

 

OK, good feedback.
So we know the CEL works, because it lit after you disconnected the O2 sensor & drove it.

Most autoparts stores have fuel pressure gauges & inductive timing lights, multmeter ect, in their Loan-A-Tool program, for a refundable deposit, so no need to buy something rarely used,

Be sure to pull the fuel pressure regulators vacuum line to test for fuel in it.

Also wiggle the distributor shaft to check for play, it shouldn't have any.

The computer & fuel pump power relay is in the under hood power distribution box. If no joy thumping it, try swapping it out for a like relay, not needed to run the engine, like the AC relay & see how it goes, before buying one.

When it acts out, flip the head lights on & see if they are dim, or flicker. If so, check the alternator & battery voltage output under load, voltage drop across the battery post to cable clamp connections & the ground connections. They all need to be clean bright & tight.

The fuel pump inertia cutoff switch is in the cabin, passenger side foot well area. Sometimes on the firewall above the carpet line, sometimes sorta up behind the passenger kick panel. It'll have a red button on top that'll pop up when it's thumped & tripped.

Sometimes the ball & contacts inside corrode & cause voltage drop to the fuel pump.

If you come to suspect it, disconnect & bridge the wiring harness electrical connector contacts with a paper clip or the like & drive it to see if it stopps acting out. If so, replace the inertia switch.

If you come to suspect a fuel pump, try thumping each one when you have the problem & see if it wakes up & runs.
I believe you have a low pressure pump on the tank & a high pressure one on the frame rail, under the drivers side door area, that feeds the fuel rail.

I like the flakey ignition switch idea too, as yours is a vintage one, it's internal contacts are likely worn some. So when it acts out, give it a thump & wiggle & see what happens.
As has been said, if the dash warning lights go out when it cuts out, look to the ignition switch, or a faulty battery, or battery cable connection.

Intemittent problems without a trouble light clue, are the most difficult & time comsuming to work, as we have to wait & be ready to test, when the problem occurs.

So write down your thump, wiggle & test routene & be ready to pounce on the problem when it next acts out.

Lots of simple shadetree mechanic things you can do to help narrow your trouble shoot down some, even without a tool chest full of test tools.

Stay calm & focused & be ready to test when it acts out & you'll likely find the problem.

Let us know how the trouble shoot goes.

 

UPDATE:
After replacing the Oxygen sensor, I drover 115 miles with no problem!!
I had a heck of a time getting the O2 sensor out; basically torched the whole thing out haha.

Put the new one in the autozone parking lot... and the idle never fluctuated and it never "died" on me again.

When I first did my research, the O2 sensor what the first thing that came up on my list. When I called up all my mechanics, all of them said " I would lay money on it that is is NOT your o2 sensor since your CEL never came on. Don't waste your time with that." They just ended up costing my almost $300 of trouble shooting.

I want to thank you guys for the help and insight. If it acts up down the road (hopefully far down the road) I at least know what to check now.

I got to intimately know my ranger this past 5 days.

thanks!

 

Congrats!........Hopefully, thats the last you hear from it.

 

Good find fix, feed back & to hear your on the road again!!!!