1988 2.9l sputtering

[86ranger4x4owner]

I have a 1988 Ford Ranger 2.9l auto. And after driving it awhile it states to sputter really badly. It idles and sounds like it's misfiring and it takes the gas until about 2k rims then starts to sputter and jerk and you have to put it to the floor to make it smooth out and go but as soon as it get back down between 2-3k rpms it sputters I'm thinking its one of the fuel pumps going out or the ignition module. But afterit sits awhile it runs fine them go drive it again and it starts again. It has all new motorcraft wires plugs cap and rotor button. Any ideas? Thanks.

 

[RonD]

Wouldn't be fuel pumps, if fuel pressure was dropping then it would get worse at higher demand, i.e. if you "put it to the floor" it would really start to stall out, not smooth out, because of the higher fuel demand and dropping fuel pressure.

Your guess about the TFI module would be better direction, they do get heat sensitive
Good worksheet here on testing that system: http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

Also check the TFI wiring closely.

Coils can also get heat sensitive, but hard to test them for that.

Could even be a distributor issue, although rare I have run across distributor "wobble" that only effected certain engine RPMs, worn bushings.
You would pull out distributor and spin it with a drill to watch for that wobble.
This wouldn't be engine temp sensitive however, so long shot

Throttle position sensor(TPS) could also be a suspect but..............this wouldn't be engine temp sensitive either

 

[rhythim]

If it doesn't act up when it's cold, but does after warm up, it could also be related to the O2 sensor ground. Truck runs in open loop until it's warmed up, then closed loop afterwards (where it's taking readings from the O2 sensor). When I reinstalled the trans in my '86 STX last weekend I neglected to bolt that wire back up to the back of the block where the dipstick tube is bolted on. My truck did the exact same thing, and fuel economy took a nose dive. Wires in these trucks are old and have been thru a ton of heat cycles, so maybe it developed a bad connection. I'd check it just to rule it out. Orange wire in the main harness running down the RH side of the intake towards the firewall. Should be bolted to either where the dipstick tube is bolted on, or the RH top bellhousing bolt, I've seen both, but mine is a 65K original mile truck and it was at the dipstick bracket.

 

[Pauls 4x4]

Sounds like the dizzy. The pickup shows its bad when hot. If you are able, hook a timing light up and see if timing is advancing. Once had an explorer that shorted at the spout connector too

 

[86ranger4x4owner]

It happens everytime I drive it 50 miles. It's very weird. I don't think it's heat related. Because it's warmed up before it hits 50 miles. But if you drive it 50 miles straight it starts to sputter when you give it gas and when you floor it smooths out and it runs fine as long as you don't drive it more than 50 miles

 

[RonD]

Long shot, loosen gas cap for next over 50 miles drive

Wondering if EVAP system is building up too much negative pressure in the gas tank.
EVAP uses engine vacuum to suck air from the gas tank.
On a longer drive it could be the fuel being pumped out along with too much vacuum is creating a high negative pressure in the gas tank and the fuel pump can't pump out as much fuel.
When you "floor it" vacuum goes to 0 relieving some of that negative pressure so fuel flow returns.

Loosened gas cap prevents negative pressure build up.
Could be EVAP solenoid is stuck open or gas cap vent(if it has one) isn't working.

 

[Pauls 4x4]

There's an evap valve on the tank not cap

 

[86ranger4x4owner]

It also runs rich when it does this. It blows out black smoke snd smells like rotten eggs and also it idles fine until you Rev it up and it will idle rough. Then you let it idle a while and it smooths out. Any ideas of what it could be? It only happens after driving 50 miles. It's not heat related because it would happen when it warms up. It only happens after you drive it 50 miles or so. And i will give the gas cap a try.

 

[RonD]

On the fuel rail there is a Fuel Pressure Regulator(FPR), it will have the Return Fuel line attached and a Vacuum Hose.
Remove this vacuum hose and check it for gasoline, or gas smell, replace FPR it gas is getting into that vacuum hose.

 

[86ranger4x4owner]

On the fuel rail there is a Fuel Pressure Regulator(FPR), it will have the Return Fuel line attached and a Vacuum Hose.
Remove this vacuum hose and check it for gasoline, or gas smell, replace FPR it gas is getting into that vacuum hose.

The fuel pressure regulator is good.

 

[SNAFUHK]

could be the Manifold Pressure (MAP) Sensor.

 

[88rangr]

Did you check your catalytic converters?

I did a catback on my 88 Ranger 2.9L , rotten egg smell may be that they are bad

https://www.reference.com/vehicles/car-exhaust-smell-like-sulfur-de23b66568600205

I put in a rebuilt distributor and all sensors near the engine, retimed her and she works great, I use Shell or Chevron fuel.

Is yours better yet?

 

[86ranger4x4owner]

could be the Manifold Pressure (MAP) Sensor.

How do you test the map sensor? It doesn't have any codes stored

 

[86ranger4x4owner]

I did a catback on my 88 Ranger 2.9L , rotten egg smell may be that they are bad

https://www.reference.com/vehicles/car-exhaust-smell-like-sulfur-de23b66568600205

I put in a rebuilt distributor and all sensors near the engine, retimed her and she works great, I use Shell or Chevron fuel.

Is yours better yet?

No its not better. I've checked cats by checking engine vacuum amd the cat is working. I've replaced everything in the ignition now and I'm thinking it could possibly be bad injectors

 

[KP650]

Did you solve the issue?