1985 240 Stumbling on acceleration

Post by **98T5** » 14 May 2014, 09:20

One of 5 things:

1. bad coil.
2. bad O2 sensor
3. bad cat
4. bad cap/rotor
5. arching/cracked wires

good luck.

Post by **Mr Sabetodo** » 15 May 2014, 01:34

A quick test for bubbles is to slightly loosen the nut above the fuel pressure regulator, listen for air escaping w/ the gas (wear vinyl gloves). A piece of clear vinyl tube spliced in the fuel line just before the fuel rail will show bubbles if they're there. I just did that and the fittings are HARD to find (nobody sells them), so I found a junk engine and cut off the end of the hose connection and 1 inch of the fuel rail, switch them around so they mate up w/ the same fittings in your car, use hose clamps on the vinyl.

jotzgr · Post by **jotzgr** » 09 Jun 2014, 21:20

I think I discovered my problem. The pre-pump (transfer) pump in the tank was completely dead. I would have expected more symptoms than just this occasional hiccup, but I removed it and hooked up direct power and nothing. Most of the time the car was running perfectly, which is pretty amazing. I am also having to replace the sender assembly that holds the pump because the ground connection is so corroded that it is not grounding through the assembly down to the pump. So even if I were to put a new pump in the old assembly, it's still not gonna work. Ordered the parts today, will update on results when I finish.

newmex999 · Post by **newmex999** » 09 Jun 2014, 21:36

Thought about this early on, however when I listened through the fuel filler neck, I heard the in tank pump buzzing. Although this is still one of the things on my list of possibilities. Dealing with other issues now. Both alternator belts shredded the other day. Oh well, one of the joys of owning a 30 year old vehicle!

bloodrootfc · Post by **bloodrootfc** » 10 Jun 2014, 10:24

Nexmex> Smoke test your gas tank. The vent valve hose and filler neck hose has a tendency to crack.

newmex999 · Post by **newmex999** » 10 Jun 2014, 10:35

Can you explain? Thanks

bloodrootfc · Post by **bloodrootfc** » 10 Jun 2014, 10:46

Once you're at speed, the engine is in a sort of steady-state that is mostly governed by the ignition system utilizing the fuel being delivered by the main fuel line. During changes in in engine load such as starting from a stop, the "EVAP" system turns on and delivers fuel vapors to the intake. If there is a leak in that system, it can stumble until the fuel delivery takes over in the "open loop". Not 100% clear about how it all works, but basically your problem sounds like a fuel vapor venting problem, not a liquid fuel delivery problem.

The fuel tank has a couple of thin rubber tubes coming off it that become very brittle as they are exposed to all the crap being kicked up from the road by your tires.

93Regina · Post by **93Regina** » 10 Jun 2014, 21:25

newmex999 wrote:85 240 wagon stumbles bad on acceleration...idol surge when I am stopped

Where did replacement AMM come from? Disconnect AMM, and see what symptoms are. Is tailpipe running rich currently?

93Regina · Post by **93Regina** » 10 Jun 2014, 21:30

jotzgr wrote:all of a sudden nothing

On that Chrysler ignition box, do not pull plug out, but try to wiggle the plug; massage it a pinch

newmex999 · Post by **newmex999** » 15 Jun 2014, 13:35

Resolution to the stumbling/hesitation on acceleration and idle surge-
Had to replace both alternator belts as they broke when alternator came loose.
Replaced alternator bushings and re-tightened everything. Also replaced distributor cap.

Both the hesitation and idle surge are gone!!!!!!!!!!!!!!!

If anyone has insight into this let me know?

1985 240 Stumbling on acceleration

Re: 1985 240 Stumbling on acceleration