91 3FE Hesitation & Stumble (1 Viewer)

[STICKP]

Hi,

I'm experiencing hesitation at low speeds, clears up in 2nd & 3rd, then at high speeds it stumbles when dropping into 4th gear.

My idle is a bit high in park, and drops to 650 in gear. At a stoplight, in gear, it stumbles.

Could this be a fuel issue? A buddy of mine swears it's the fuel pump.

The vehicle is a 1991 FJ80, 160K.

Thanks for any feedback.

 

[STICKP]

I should also mention that in the last 6 months, the following has been done:
rotor
d cap
wires
tps - ohms are reading correctly
IAC
AFM- ohms are reading correctly
EGR Deleted
New exhaust w/ 02 sensors
new fuel sock
Belts

I've been chasing a lot of problems. Most have cleared up, but I'm still chasing this last stumbling issue

 

[SUMMIT CRUISERS]

Have you checked (paper clip/ diag box) to see if you have any stored CEL codes?

 

[LS1FJ40]

Unmetered air? Vacuum hose somewhere.

 

[STICKP]

Have you checked (paper clip/ diag box) to see if you have any stored CEL codes?

Got the all clear rapid flash....

 

[STICKP]

All hoses seem good...

 

[SUMMIT CRUISERS]

I would grab a fuel pressure kit at Autozone (free rental). Tap in where the cold start injector line comes out of the fuel rail and check for pressure variations in Drive, AC off and parking brake pulled. If fluctuations consistent with miss, probably the FPR and damper need changing. If fuel pressure constant, then you probably have a vacuum leak as @LS1FJ40 mentioned.

 

[Michael Hanson]

Hi, Spray fuel injection cleaner around valve cover gasket checking for leaks .Check temp sensor on thermostat housing and its wiring. Mike

 

[Marine7]

Easier to take a small BBQ grill gas bottle, crack it open (DONT LIGHT), start the car, and run that gas bottle around all you hoses, manifolds, tb, EVERYWHERE!! Just don't smoke while doing it..... lol

 

[Michael Hanson]

Hi, Check all hoses again, esp. Around air cleaner housing and air flow meter. Mike