Q: 20 amp ignition fuse continues to blow

asked by on

I have a 1986 GMC Sierra S15 with a 350 small block Chevy engine. I have an issue where my 20 amp ignition fuse continuously blows. I have an electric fuel pump underneath the driver side of the cab that has power going to it with a inline 20 amp fuse also that is still good, but the fuel pump is not engaging or turning on at all. My starter is engaging when I turn the key over but when I place a new 20 amp fuse Within the fuse panel it immediately blows. I have a Mallory ignition coil underneath the hood that when I place my test light on the positive side of the coil my test light barely turns on at all. Could the ignition coil be the source of my problems?
My car has an automatic transmission.

Hello. All of this depends on what was spliced into that circuit when the engine was swapped out. I usually isolate this problem by disconnecting the circuits in it until it no longer blows. This fuse usually has a problem with the wiring to the fuel injectors at the throttle body. It is common for the wires going to these injectors to wear on the throttle body and short out. It can also be the coil if it is shorted internally. If you need assistance diagnosing this short, consider YourMechanic, as a certified mechanic can come to your home or office to inspect the electrical system and repair this problem.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. 20 amp ignition fuse continues to blow

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Has new alternator, new battery when started , motor dies when battery is disconnected...my mechanics are stumped on this

Hello. If replacing those particular components did not correct the issue then the next thing I would look at is the vehicle's voltage regulator. It appears that this engine's electrical system is equipped with an external voltage regulator that functions,...

Q: Changing gears - 2009 Nissan Altima

Hello. There are a few common causes of this on your vehicle. Most of the time it is caused by an issue with the transmission fluid being old or contaminated or it may be a problem with one of the...

Q: Car starts and runs, battery dies while driving.

Hello there, thank you for asking about your 1998 Dodge Durango. If the battery installed in your car is the correct size, fully charged, and it passes a load test, the only way the battery can lose so much stored...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.