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So you tow your car to the brother’s shop and after he does a diagnostic (he may or not be ASE certified) announces that your electric fuel pump is indeed the cause of your car starting blues and needs to be replaced. Having an auto repair shop replace a fuel pump can run $600 to $1,000 depending on your make and model and where you live.
Now here’s the really interesting part.
If you talk to the warranty people at aftermarket or OEM manufacturers they will tell you that the majority of electric fuel pumps that are returned as flawed are actually just fine and work within their specifications. It’s their contention that car owners (and technicians) are often quick to diagnose a no start/hard start condition as the fuel pump and just swap it out.
How to Avoid a Knee Jerk Diagnoses
If you are going to determine if your fuel pump is the cause of your “no go” condition, follow these steps to ensure the pump is actually malfunctioning because it is flawed and not because some other condition is preventing it from working.
- Make sure you have gas. Yes this seems obvious but someone out there somewhere will pull out the fuel pump, replace it with a new one only to discover they could have put in a whole new engine and the car wouldn’t go because there was no gas in the tank.
- Got juice? It’s called an electric fuel pump because…it runs on electricity. If it isn’t getting sufficient electrical power to spray atomized fuel into the intake path the engine will be either starved or nearly starved. Before you spend time diagnosing anything else check the grounds to the pump and the tank. If they are missing or badly rusted you have probably found your problem.
- Follow the juice. Generally speaking fuel pumps should be capable of generating 35 to 45 psi. Less than that and you will have a hungry engine. Use a DVOM to trace the flow of electricity to ensure the pump is getting the juice it needs. If you discover a voltage drop of greater than .05 amps you have most likely found your problem
- Bad intelligence. If your no start condition occurs immediately after your car stalls out, it’s possible the signal produced by the crankshaft position sensor and monitored by the ECM will kill the pump. If that’s the case your ECM will have to be reset.
- Dirty fuel filter. If the filter is clogged and not allowing a smooth flow of gas the fuel pump will likely create a vacuum as it tries to suck fuel from the tank. When this occurs air bubbles are likely to be formed degrading the “spray” going into the intake path.
- Low oil pressure. If you have a loss of oil pressure or the pressure is sufficiently low that the oil pressure sensor determines the engine is in jeopardy, a signal will be sent from the sensor killing the fuel pump to prevent further damage to the engine.
- Safety sensors. If you are involved in an accident signals from both air bags and impact sensors will kill the fuel pump. The idea is to stop the flow of fuel and kill the engine to prevent a fire. If you are driving a Ford (and some other models) you have something called an inertia switch which will also kill the fuel pump if you get hit in the rear or back into an object.
We hope you’ve found these tips helpful. While we hope you are never in the position where you have gone through all the fuel pump symptoms and discovered that it is in fact the pump that has shot craps, if you do we recommend you check out the Walbro fuel pumps available from our friends at Vivid Racing. They are built to last and are competitively priced.
As always have fun and drive safe.
Photo via: farm4.staticflickr.com