Symptoms of a Bad or Failing Accelerator Pump

An accelerator pump is a component on a carburetor. It is commonly found on many older vehicles that are equipped with carburetors. The accelerator pump is responsible for providing the momentary additional fuel needed under heavy acceleration conditions. When the pedal is suddenly pressed, the throttle will suddenly open, immediately adding additional air for additional power. That additional air requires additional fuel, especially in the precise moments after the throttle is opened, this is the fuel the accelerator pump provides. When the throttle is rapidly opened, the accelerator pump will squirt a small amount of fuel into the throat of the carburetor so that the engine can continue running smoothly under increased load. Usually when the accelerator pump is having issues, it will display a few symptoms that can alert the driver that there may be a problem that should be inspected.

Rough acceleration

One of the most common symptoms that the accelerator pump is having a problem is rough or sluggish acceleration. The accelerator pump is supposed to provide additional fuel needed during acceleration. If there is any problem with the pump, then there will be a problem in the fuel mixture during acceleration. Usually, a faulty accelerator pump will result in a momentary lean condition, which can result in rough or sluggish acceleration, and even misfires.

Engine sputtering or stalling

Another symptom of a faulty accelerator pump is engine sputtering or stalling. The sputtering is caused by the lack of fuel that is supposed to be provided by the accelerator pump when throttle is rapidly pressed. In more serious cases of accelerator pump failure, rapidly pressing on the gas may cause the engine to stall, again due to the lean condition that can be created when the accelerator pump is not working.

A faulty accelerator pump will typically produce a noticeable effect on the engine performance when it fails or is having a problem. If you suspect that your accelerator pump may be having an issue, have the vehicle diagnosed by a professional technician, such as one from YourMechanic. If necessary, they will be able to replace your accelerator pump for you and restore proper performance to your vehicle.


Next Step

Schedule Fuel System Inspection

The most popular service booked by readers of this article is Fuel System Inspection. Once the problem has been diagnosed, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Fuel System Inspection reviews

Excellent Rating

(8)

Rating Summary
7
0
0
1
0
7
0
0
1
0

Raymond

38 years of experience
613 reviews
Raymond
38 years of experience
Chevrolet Impala V6-3.4L - Fuel System - Las Vegas, Nevada
Raymond was very knowledgeable mechanic and through in his testing. I trust him for any future from your mechanic.

Geoffrey

21 years of experience
21 reviews
Geoffrey
21 years of experience
Hyundai Sonata L4-2.4L - Fuel System Inspection - Rockville, Maryland
My mechanic Geoffrey showed up ahead of schedule which was fantastic. Very polite and went straight to work and diagnosed my issues.

Johnny

34 years of experience
392 reviews
Johnny
34 years of experience
Toyota Corolla L4-1.6L - Fuel System Inspection - Sacramento, California
Johnny did a great job

Michael

5 years of experience
355 reviews
Michael
5 years of experience
Volkswagen Jetta L5-2.5L - Fuel System Inspection - Indianapolis, Indiana
professional ,informative and knowledgeable

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

P2627 OBD-II Trouble Code: O2 Sensor Pumping Current Trim Circuit Low Bank 1 Sensor 1
P2627 means there is a problem with the oxygen sensor for bank 1 due to malfunctioning sensor, faulty wiring, blown fuse, or leaking exhaust.
How to Replace a Crankshaft Seal
Engine oil leaks are prevented by the crankshaft seal. Replacing one requires several tools, such as a dead blow hammer and a strap wrench.
How Car Acceleration Works
Going from 0 to 60 mainly involves the throttle, engine, differential, and tires of a car. How fast it takes depends on the features of these parts.

Related questions

Ticking sound while accelerating and when the car is in gear
There is technical bulletins for your vehicle using aftermarket (https://www.yourmechanic.com/article/all-about-aftermarket-parts) oil filters. These oil filters (https://www.yourmechanic.com/article/how-do-oil-filters-work) may look like they fit your car model, but do not allow the proper oil flow to the motor and can cause noises and...
When I'm driving the car pauses and when I hit the gas it comes back to life, is it the accelerator sensor?
Hi there. The APP (accelerator pedal position sensor) could cause the vehicle to pause or hesitate (https://www.yourmechanic.com/services/electrical-components-are-not-working-inspection). A faulty TPS (throttle position sensor) (https://www.yourmechanic.com/services/throttle-position-sensor-replacement), a faulty MAF (mass airflow) sensor, incorrectly calculating the incoming air to the engine (https://www.yourmechanic.com/services/mass-airflow-sensor-replacement) are...
2013 GMC Terrain stalls when accelerating from a stop
There are many potential causes for your concern. However, there are a couple common problems with your model vehicle that come to mind. First, this vehicle is known for having problems with the variable valve timing (VVT) system. The VVT...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com