2000 mercury mystique fuel pump trouble shooting,replaced fuel pump,engine hesitating

SOURCE: 2004 dodge caravan 2.4 Hesitates during Acceleration and at idele

You should definitely replace the fuel filter though this probably won't fix your hesitation. It wouldn't hurt to replace the spark plugs this is usually the culprit on these engine. I have the same engine in a '99 caravan and found the for some reason the spark plugs on cylinder 3 and 4 loosen up after one year and cause a misfire between 45 and 50 mph under load (when mildly accelerating).

SOURCE: 2000 Ford F450 with V10

have you cleaned the throttle plate? this is done by removing air intake hose and spraying out with cleaner and wiping it down open throttle and wipe off the butterfly and bore. this will usually cure a stumble.

Marvin

• 85242 Answers
• Posted on Nov 02, 2008

SOURCE: Trouble starting 2000 Ford Taurus

Are you useing the recommened grade of fuel, the Taurus will have cold start issues if prem. fuel is used when 89 octane is recommened, saw this many times while working for ford.

SOURCE: I have a 2001 Mercury Sable 24 VOHC. Got P0303

It is likely one of you coils. You can buy one and keep moving across all the cylinders until you find the bad one or wait for it to set a code to tell you which one.

Marvin

• 85242 Answers
• Posted on Mar 24, 2009

SOURCE: Hesitation problem

try cleaning the inside of the MAF sensor and do the following procedure as well.
Here is the most common cause of surges and stalls at stops and low erratic idle speed and rough idle, it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.