Loss of Power

[freakz]

Hey Guys,

I have an 88 bronco II 2.9L auto 4X4 completely stock with 95301 orignal miles. The other day it started acting funny. It starts just fine, but when starting it after it has sat over night or while I'm at work, it idles funny for about 2 or 3 minutes. What it does is idle fine for about 30 sec, then sputters for about 30 sec, then revs to about 1200rpm for about 15 sec, then idles fine again for about 30 sec. This goes on for about 2 or 3 min, sometimes a bit longer, then it idles fine for the rest of the time I'm driving it.

While driving, it seems to be held back by something, like I'm driving with the parking brake on (which I'm not, I checked lol). I realize these things aren't big on power, but the way it runs right now is sad. My 87 with 35's and stock gearing has more get up and go. It doesn't seem to be missing or running rough while driving so I'm at a loss for an answer.

Any ideas on either problem? Maybe they are related?

Thanks
Jason

 

[lost86broncoii]

i had my old 86 bii do some thing similar it was the fuel pressure regulator. pull the vac line too it and see if smells like gas.

 

[IMenriched]

Hey Guys,

I have an 88 bronco II 2.9L auto 4X4 completely stock with 95301 orignal miles. The other day it started acting funny. It starts just fine, but when starting it after it has sat over night or while I'm at work, it idles funny for about 2 or 3 minutes. What it does is idle fine for about 30 sec, then sputters for about 30 sec, then revs to about 1200rpm for about 15 sec, then idles fine again for about 30 sec. This goes on for about 2 or 3 min, sometimes a bit longer, then it idles fine for the rest of the time I'm driving it.

While driving, it seems to be held back by something, like I'm driving with the parking brake on (which I'm not, I checked lol). I realize these things aren't big on power, but the way it runs right now is sad. My 87 with 35's and stock gearing has more get up and go. It doesn't seem to be missing or running rough while driving so I'm at a loss for an answer.

Any ideas on either problem? Maybe they are related?

Thanks
Jason

Agreed...check the FPR.

another thing to check is the AIC, remove and clean thoroughly with carb cleaner, let dry and reinstall. this controls idle.

 

[freakz]

Would either of those cause a drop in mileage? This thing seems to be eating a bunch of gas.

 

[IMenriched]

Would either of those cause a drop in mileage? This thing seems to be eating a bunch of gas.

fpr for sure.

best to see if it tripping codes...could be several things that can cause poor milage

 

[poweranger84]

my 86 ranger is doin the same thing. i have already changed the fpr, no difference. still idle weird after initial startup and doesnt seem to wanna go.

 

[177CIOfPureLove]

Any updates? My 1988 STX is doing the very same. I replaced the FPR as well, whole tune up and new tfi, hall effect sensor, fuel filter, battery cables. One day on the freeway it seemed to buck back and forth going from power to less power, it was kinda scary. then it stopped and left me with a hesitation, it still drives, but nothing like it did....

 

[97fordrunner]

My '89 is acting similar to. When I first start it it idles fin for a few seconds then goes rough and when driving it is good up until giving it more than half throttle then it feels like its being held back to. Smells very rich

 

[IMenriched]

has anyone run a vacuum test yet?

 

[97fordrunner]

I did, it showed up as timing was off, which after checking that was spot on.

 

[IMenriched]

I too had been fight this power loss....intermittent runnablity.
eventually I figured out that the in-tank pump was chief suspect.

today I worked up the nerve to tackle the task...Its my DD...so my hesitation was not get to this repair and end up have to be down for a few days. and its warmer now, in a pinch I could pedal the 4-5 miles to work...if the need arose.

at the risk of sending several wrench warriors to the wrenching....my particular case...was that the rubber hose to the stem pipe form the top of the pump was deteriorated....gone , yep not there...the in-tank pump was shooting a gape of about 1/2 in. Leaving the main pump to do most of the work. Not saying that this id the cure for everybody...just what I found.

What I noticed over course of time, was that it tended not to have "issues" when the tank was full, or nearly so....if the tanks was below 2/3 - 1/2 more "issues' flared up.

I would have to say that the in-tank pump looked to be original.

the top ring did relinquish its hold....but it wasn't in any kind of condition to remain in service....A local service station/ repair garage bailed me out...they had extra new lock rings. PTL!! otherwise I prolly would had to get a new tank to get the lock ring.

I say that so if other who are going to tackle this...make sure you get a new top lock ring too. and fear not just keep tapping on the ring...it'll give up. mine was nearly unnoticeable/recognizable for all the rust....just soak it down juice of choice. and really best to use a brass punch...for no sparks

the inside of the tank looked remarkably good...after a swabbing down the inside to remove the remainder of the rubber hose.